This document discusses material selection and properties in three chapters. Chapter 3 introduces material classes, defining properties important for mechanical design like modulus, strength, damping capacity, and thermal conductivity. The main material classes are metals, polymers, ceramics, glasses, and composites. Metals have high modulus but can fatigue. Ceramics and glasses are also stiff but brittle. Polymers have low modulus but are strong and easy to shape. Composites combine advantages but have limitations. Definitions of properties like density, modulus, strength, and toughness are also provided.
Major classifications of engineering materials include metals, polymers, ceramics and composites. Metals are further divided into ferrous and nonferrous materials. Classification systems identify materials based on chemical composition and mechanical properties. Design considerations for materials depend on factors like strength, stiffness, corrosion resistance, manufacturability and cost. Material selection involves matching properties to product requirements under expected loading and service conditions.
Materials can be grouped into classes based on their chemical composition and properties. The four main classes are metals, ceramics, polymers, and composites. Metals are combinations of metallic elements and alloys, and have properties of strength, ductility, and heat and electrical conductivity. Ceramics are inorganic materials processed at high temperatures and have properties of strength and corrosion resistance but are brittle. Polymers contain chemically bonded units and have properties of low density, strength and different optical properties. Composites contain two or more materials to produce new properties not found in the individual materials.
The document provides an introduction to engineering materials. It begins with an overview of materials classification, including crystalline vs amorphous materials. Key classes of materials are then discussed in more detail, such as metals, ceramics, polymers and composites. Various material properties like mechanical, electrical, magnetic and optical properties are also introduced. The document focuses on providing foundational knowledge on different types of engineering materials and their basic properties.
2. Atomic, molecular, crytalline and amorphous structures for metals.pptxTarek Erin
This document provides an overview of engineering materials, including their basic classification, properties, and selection for engineering purposes. It discusses metals, non-metals, alloys, ceramics, and polymers. For metals specifically, it outlines their general physical and chemical properties. The properties of ceramics include high melting points, hardness, durability, and chemical inertness. Polymers are composed of large molecules called macromolecules and have properties like strength, toughness, and resistance to corrosion. Mathematical problems on stress, strain, and material deformation are also presented.
This document provides an overview of engineering materials, including their basic classification, properties, and selection for engineering purposes. It discusses metals, ceramics, polymers, and their general physical and chemical properties. It also addresses stress-strain diagrams, material behavior, and provides examples of mathematical problems analyzing stresses and forces on cylindrical and plate structures.
Metallurgy P R O P E R T I E S And DefinitionsMoiz Barry
Engineering concepts of metals document discusses various hardness testing methods like Brinell and Rockwell. It explains that hardness is the resistance to deformation and depends on factors like grain size and work hardening. The document also covers tensile stress, shear stress, heat treatment processes to alter material properties like hardening and softening, and concepts like modulus of rigidity and stiffness.
An overview of the major materials used in aeronautical and automotive structures will be given in this section. The mechanical and physical properties of the materials will be highlighted, with an emphasis placed on the stiffness versus density and strength versus density of various materials.
Structural Integrity Analysis: Chapter 3 Mechanical Properties of MaterialsIgor Kokcharov
Structural Integrity Analysis features a collection of selected topics on structural design, safety, reliability, redundancy, strength, material science, mechanical properties of materials, composite materials, welds, finite element analysis, stress concentration, failure mechanisms and criteria. The engineering approaches focus on understanding and concept visualization rather than theoretical reasoning. The structural engineering profession plays a key role in the assurance of safety of technical systems such as metallic structures, buildings, machines, and transport. The third chapter explains the engineering tests and fundamentals of mechanical properties of materials.
Major classifications of engineering materials include metals, polymers, ceramics and composites. Metals are further divided into ferrous and nonferrous materials. Classification systems identify materials based on chemical composition and mechanical properties. Design considerations for materials depend on factors like strength, stiffness, corrosion resistance, manufacturability and cost. Material selection involves matching properties to product requirements under expected loading and service conditions.
Materials can be grouped into classes based on their chemical composition and properties. The four main classes are metals, ceramics, polymers, and composites. Metals are combinations of metallic elements and alloys, and have properties of strength, ductility, and heat and electrical conductivity. Ceramics are inorganic materials processed at high temperatures and have properties of strength and corrosion resistance but are brittle. Polymers contain chemically bonded units and have properties of low density, strength and different optical properties. Composites contain two or more materials to produce new properties not found in the individual materials.
The document provides an introduction to engineering materials. It begins with an overview of materials classification, including crystalline vs amorphous materials. Key classes of materials are then discussed in more detail, such as metals, ceramics, polymers and composites. Various material properties like mechanical, electrical, magnetic and optical properties are also introduced. The document focuses on providing foundational knowledge on different types of engineering materials and their basic properties.
2. Atomic, molecular, crytalline and amorphous structures for metals.pptxTarek Erin
This document provides an overview of engineering materials, including their basic classification, properties, and selection for engineering purposes. It discusses metals, non-metals, alloys, ceramics, and polymers. For metals specifically, it outlines their general physical and chemical properties. The properties of ceramics include high melting points, hardness, durability, and chemical inertness. Polymers are composed of large molecules called macromolecules and have properties like strength, toughness, and resistance to corrosion. Mathematical problems on stress, strain, and material deformation are also presented.
This document provides an overview of engineering materials, including their basic classification, properties, and selection for engineering purposes. It discusses metals, ceramics, polymers, and their general physical and chemical properties. It also addresses stress-strain diagrams, material behavior, and provides examples of mathematical problems analyzing stresses and forces on cylindrical and plate structures.
Metallurgy P R O P E R T I E S And DefinitionsMoiz Barry
Engineering concepts of metals document discusses various hardness testing methods like Brinell and Rockwell. It explains that hardness is the resistance to deformation and depends on factors like grain size and work hardening. The document also covers tensile stress, shear stress, heat treatment processes to alter material properties like hardening and softening, and concepts like modulus of rigidity and stiffness.
An overview of the major materials used in aeronautical and automotive structures will be given in this section. The mechanical and physical properties of the materials will be highlighted, with an emphasis placed on the stiffness versus density and strength versus density of various materials.
Structural Integrity Analysis: Chapter 3 Mechanical Properties of MaterialsIgor Kokcharov
Structural Integrity Analysis features a collection of selected topics on structural design, safety, reliability, redundancy, strength, material science, mechanical properties of materials, composite materials, welds, finite element analysis, stress concentration, failure mechanisms and criteria. The engineering approaches focus on understanding and concept visualization rather than theoretical reasoning. The structural engineering profession plays a key role in the assurance of safety of technical systems such as metallic structures, buildings, machines, and transport. The third chapter explains the engineering tests and fundamentals of mechanical properties of materials.
1) The document is a solved question paper from Gujarat Technological University from November 2013 containing answers to 10 questions on metallurgy and materials science.
2) Key concepts covered in the answers include ionic and covalent bonding properties, secondary bonding characteristics, definitions of space lattice and unit cell, density and melting point, superconductivity, thermal expansion and diffusivity, equilibrium diagrams, solid solutions, alloys, heat treatment objectives, normalizing process steps, microscope principles, and microspecimen preparation steps.
3) Detailed explanations and diagrams are provided for many of the concepts.
This document contains the solved question paper from December 2013 for Parul Institute of Engineering and Technology's Mechanical Engineering program. It includes answers to 7 out of 10 questions on topics like primary and secondary bonds, unit cells, solidification of metals, phase diagrams, heat treatment processes and furnaces. Diagrams are included to illustrate concepts like the BCC and FCC unit cell structures, lever rule on a phase diagram, TTT diagram, iron-carbon phase diagram and the induction hardening process.
This document contains a question and answer bank for a GTU examination on material science and metallurgy. It includes 24 questions on topics like phase diagrams, solid solutions, cooling curves, heat treatment processes, and properties of steel alloys. For each question there is a detailed multi-sentence answer explaining key concepts and providing examples to illustrate the responses. Diagrams are included with some of the answers to further enhance understanding of the material.
Torsional evaluation of Tapered Composite Cone using Finite Element AnalysisIOSR Journals
Composite material is one of the most important and economical material for the various application
due to its favorable properties .Recently many researches are going on the various properties of the these
materials .In this paper an anisotropic behavior of the composite tube is to be modeled and analysis is to be
performed under torsional loading conditions. Torsion is a tricky phenomenon in composite cylinders as the
twist effects and their interactions with composite shells induce complex stress patterns. The objective behind
the study is to understand interaction of conical angle, length of tube and torsional moment .it also includes
comparative analysis of deformation and stresses developed in tapered composite cone due to use of various
materials like steel, orthotropic composite and laminated composite etc. The effect of taper angle, thickness of
the tube and fiber orientations in case of laminated composite is studied by using finite element analysis (ANSYS
software). The finite element analysis is especially versatile and efficient for the analysis of complex structural
behavior of the composite laminated structures. It is found that deformation in case of laminated composite and
deformation in between steel and laminated composite cone. At membrane stresses are observed at the middle of
cone in length direction for three materials.
Structural Integrity Analysis features a collection of selected topics on structural design, safety, reliability, redundancy, strength, material science, mechanical properties of materials, composite materials, welds, finite element analysis, stress concentration, failure mechanisms and criteria. The engineering approaches focus on understanding and concept visualization rather than theoretical reasoning. The structural engineering profession plays a key role in the assurance of safety of technical systems such as metallic structures, buildings, machines, and transport. The chapter 9 explains the engineering fundamentals of composite materials and structures. Copyright 2013 Igor Kokcharov, Andrey Burov
This document discusses the physical, mechanical, and chemical properties of materials. It describes key physical properties like density, specific heat, thermal conductivity, and electrical conductivity. It also outlines important mechanical properties such as tensile strength, ductility, malleability, brittleness, elasticity, plasticity, toughness, and hardness. Finally, it briefly touches on relevant chemical properties including corrosion resistance and erosion resistance.
This document discusses various mechanical properties of engineering materials including hardness, creep, elasticity, hardening, and plasticity. It defines each property and describes methods for measuring hardness, factors that influence creep, the hardening process, and how plastic deformation occurs at the atomic level resulting in a permanent change in shape even after removal of stress. Measurement techniques for hardness include Rockwell, Brinell, Vickers, Knoop, and shore hardness tests. Creep is influenced by load, temperature, composition, grain size, and heat treatment. Hardening increases hardness through metallurgical processes.
This document discusses various material properties including mechanical properties. It lists 11 categories of material properties and provides definitions and explanations for several important mechanical properties. These include fatigue strength, endurance limit, tensile strength, compressive strength, elasticity, plasticity, ductility, brittleness, malleability, toughness, stiffness, resilience, hardness, and creep. The document serves to define and explain key terms related to the mechanical properties of materials.
This document provides an overview of steel material properties and characteristics. It begins with a brief history of steel use in construction from the late 18th century. It then defines steel as an alloy of iron and carbon, and classifies steel types as carbon steel, low alloy steel, and light steel based on their chemical compositions. Key mechanical properties of steel discussed include modulus of elasticity, shear modulus, and Poisson's ratio. The behaviors of steel under tension loading and at high temperatures are also summarized.
1. The document discusses the hardenability of steels, which is defined as a steel's ability to transform to martensite during quenching and is measured by the maximum diameter of a cylinder that achieves 50% martensite at the center.
2. There are two main methods to determine hardenability - Grossman's method which measures the critical diameter, and the Jominy end quench method which involves quenching one end of a bar and measuring hardness variations.
3. Factors that influence hardenability include austenite grain size, carbon content, alloying elements, and quenching media. Alloying elements have multiplying factors that increase the ideal
The document discusses various physical properties of materials including volumetric and melting properties, thermal properties, mass diffusion, electrical properties, and electrochemical processes. It provides details on density, thermal expansion, specific heat, thermal conductivity, resistivity, conductivity, and how these properties are important in manufacturing processes such as machining, microelectronics fabrication, casting, and heat treating. Materials are selected based on their physical properties to achieve desired performance in applications.
This document provides an overview of material science and engineering, including:
1) It discusses the historic development of materials from the Stone Age to modern times and defines materials science as relating the structure and properties of materials.
2) Materials are classified into metals, ceramics, polymers, composites, semiconductors, and biomaterials based on their atomic structure and properties.
3) Advanced materials either have enhanced traditional materials properties or are newly developed with high performance capabilities for applications like integrated circuits.
2850 20 unit 202 physical and mechanical properties of materialsmattweetman
This document discusses the physical and mechanical properties of materials. It defines key properties like hardness, ductility, malleability, conductivity, and explains the ordering of common materials according to each property. Methods for modifying material properties through heat treating techniques like annealing, case hardening, precipitation strengthening, tempering and quenching are also covered. The document also addresses degradation of materials through corrosion, environmental factors, and means of protecting materials.
The Effects of Welding Processes and Microstructure on 3 Body Abrasive Wear R...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Theoretical work submitted to the Journal should be original in its motivation or modeling structure. Empirical analysis should be based on a theoretical framework and should be capable of replication. It is expected that all materials required for replication (including computer programs and data sets) should be available upon request to the authors.
The International Journal of Engineering & Science would take much care in making your article published without much delay with your kind cooperation
The document provides an overview of material properties and atomic structure. It discusses various physical, mechanical, and chemical properties of common materials like metals, ceramics, polymers and lists them in order of properties such as density, tensile strength, conductivity, and hardness. It also summarizes different atomic models including Thomson's plum pudding model, Rutherford's nuclear model, and Bohr's early quantum model which explained the stability of an atom.
The Effects of Copper Addition on the compression behavior of Al-Ca AlloyIOSR Journals
The Al-Ca-Cu alloys containing varying amount of Cu are used to study the effect of Cu addition on
their deformation behavior at varying strain rate (0.001/s, 0.01/s, 0.1/s, 1/s).The material is prepared using stir
casting technique The yield stress, flow stress and elastic limit are measured from the true stress-strain graph
.The Strain Rate sensitivity and strain hardening exponent are also determined for each material at different
strain rate. The Strain Rate Sensitivity of this alloy is very low. These values strongly demonstrate that
compressive deformation of Al-Ca-Cu alloys almost independent to the strain rate at room temperature
deformation.
Introduction to Mechanical Metallurgy (Our course project)Rishabh Gupta
The document summarizes key concepts in materials science and engineering. It discusses:
1. The importance of selecting high quality materials for better product design and performance.
2. The four main components in materials science - processing, structure, properties, and performance - and how they interrelate.
3. The main classes of materials - metals, ceramics, polymers, composites, semiconductors, and elastomers - and some of their key characteristics.
4. Crystal structures of metals and how they are classified based on atomic packing efficiency. Factors that determine a material's density are also covered.
Stress-Strain Curves for Metals, Ceramics and PolymersLuís Rita
Homework II - Biomaterials Science
We are interested about studying and comparing stress-strain curves of metals, ceramics and polymers. Primarily, differences are due to their different chemical bonding properties.
IST - 4th Year - 2nd Semester - Biomedical Engineering.
1) The document is a solved question paper from Gujarat Technological University from November 2013 containing answers to 10 questions on metallurgy and materials science.
2) Key concepts covered in the answers include ionic and covalent bonding properties, secondary bonding characteristics, definitions of space lattice and unit cell, density and melting point, superconductivity, thermal expansion and diffusivity, equilibrium diagrams, solid solutions, alloys, heat treatment objectives, normalizing process steps, microscope principles, and microspecimen preparation steps.
3) Detailed explanations and diagrams are provided for many of the concepts.
This document contains the solved question paper from December 2013 for Parul Institute of Engineering and Technology's Mechanical Engineering program. It includes answers to 7 out of 10 questions on topics like primary and secondary bonds, unit cells, solidification of metals, phase diagrams, heat treatment processes and furnaces. Diagrams are included to illustrate concepts like the BCC and FCC unit cell structures, lever rule on a phase diagram, TTT diagram, iron-carbon phase diagram and the induction hardening process.
This document contains a question and answer bank for a GTU examination on material science and metallurgy. It includes 24 questions on topics like phase diagrams, solid solutions, cooling curves, heat treatment processes, and properties of steel alloys. For each question there is a detailed multi-sentence answer explaining key concepts and providing examples to illustrate the responses. Diagrams are included with some of the answers to further enhance understanding of the material.
Torsional evaluation of Tapered Composite Cone using Finite Element AnalysisIOSR Journals
Composite material is one of the most important and economical material for the various application
due to its favorable properties .Recently many researches are going on the various properties of the these
materials .In this paper an anisotropic behavior of the composite tube is to be modeled and analysis is to be
performed under torsional loading conditions. Torsion is a tricky phenomenon in composite cylinders as the
twist effects and their interactions with composite shells induce complex stress patterns. The objective behind
the study is to understand interaction of conical angle, length of tube and torsional moment .it also includes
comparative analysis of deformation and stresses developed in tapered composite cone due to use of various
materials like steel, orthotropic composite and laminated composite etc. The effect of taper angle, thickness of
the tube and fiber orientations in case of laminated composite is studied by using finite element analysis (ANSYS
software). The finite element analysis is especially versatile and efficient for the analysis of complex structural
behavior of the composite laminated structures. It is found that deformation in case of laminated composite and
deformation in between steel and laminated composite cone. At membrane stresses are observed at the middle of
cone in length direction for three materials.
Structural Integrity Analysis features a collection of selected topics on structural design, safety, reliability, redundancy, strength, material science, mechanical properties of materials, composite materials, welds, finite element analysis, stress concentration, failure mechanisms and criteria. The engineering approaches focus on understanding and concept visualization rather than theoretical reasoning. The structural engineering profession plays a key role in the assurance of safety of technical systems such as metallic structures, buildings, machines, and transport. The chapter 9 explains the engineering fundamentals of composite materials and structures. Copyright 2013 Igor Kokcharov, Andrey Burov
This document discusses the physical, mechanical, and chemical properties of materials. It describes key physical properties like density, specific heat, thermal conductivity, and electrical conductivity. It also outlines important mechanical properties such as tensile strength, ductility, malleability, brittleness, elasticity, plasticity, toughness, and hardness. Finally, it briefly touches on relevant chemical properties including corrosion resistance and erosion resistance.
This document discusses various mechanical properties of engineering materials including hardness, creep, elasticity, hardening, and plasticity. It defines each property and describes methods for measuring hardness, factors that influence creep, the hardening process, and how plastic deformation occurs at the atomic level resulting in a permanent change in shape even after removal of stress. Measurement techniques for hardness include Rockwell, Brinell, Vickers, Knoop, and shore hardness tests. Creep is influenced by load, temperature, composition, grain size, and heat treatment. Hardening increases hardness through metallurgical processes.
This document discusses various material properties including mechanical properties. It lists 11 categories of material properties and provides definitions and explanations for several important mechanical properties. These include fatigue strength, endurance limit, tensile strength, compressive strength, elasticity, plasticity, ductility, brittleness, malleability, toughness, stiffness, resilience, hardness, and creep. The document serves to define and explain key terms related to the mechanical properties of materials.
This document provides an overview of steel material properties and characteristics. It begins with a brief history of steel use in construction from the late 18th century. It then defines steel as an alloy of iron and carbon, and classifies steel types as carbon steel, low alloy steel, and light steel based on their chemical compositions. Key mechanical properties of steel discussed include modulus of elasticity, shear modulus, and Poisson's ratio. The behaviors of steel under tension loading and at high temperatures are also summarized.
1. The document discusses the hardenability of steels, which is defined as a steel's ability to transform to martensite during quenching and is measured by the maximum diameter of a cylinder that achieves 50% martensite at the center.
2. There are two main methods to determine hardenability - Grossman's method which measures the critical diameter, and the Jominy end quench method which involves quenching one end of a bar and measuring hardness variations.
3. Factors that influence hardenability include austenite grain size, carbon content, alloying elements, and quenching media. Alloying elements have multiplying factors that increase the ideal
The document discusses various physical properties of materials including volumetric and melting properties, thermal properties, mass diffusion, electrical properties, and electrochemical processes. It provides details on density, thermal expansion, specific heat, thermal conductivity, resistivity, conductivity, and how these properties are important in manufacturing processes such as machining, microelectronics fabrication, casting, and heat treating. Materials are selected based on their physical properties to achieve desired performance in applications.
This document provides an overview of material science and engineering, including:
1) It discusses the historic development of materials from the Stone Age to modern times and defines materials science as relating the structure and properties of materials.
2) Materials are classified into metals, ceramics, polymers, composites, semiconductors, and biomaterials based on their atomic structure and properties.
3) Advanced materials either have enhanced traditional materials properties or are newly developed with high performance capabilities for applications like integrated circuits.
2850 20 unit 202 physical and mechanical properties of materialsmattweetman
This document discusses the physical and mechanical properties of materials. It defines key properties like hardness, ductility, malleability, conductivity, and explains the ordering of common materials according to each property. Methods for modifying material properties through heat treating techniques like annealing, case hardening, precipitation strengthening, tempering and quenching are also covered. The document also addresses degradation of materials through corrosion, environmental factors, and means of protecting materials.
The Effects of Welding Processes and Microstructure on 3 Body Abrasive Wear R...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
Theoretical work submitted to the Journal should be original in its motivation or modeling structure. Empirical analysis should be based on a theoretical framework and should be capable of replication. It is expected that all materials required for replication (including computer programs and data sets) should be available upon request to the authors.
The International Journal of Engineering & Science would take much care in making your article published without much delay with your kind cooperation
The document provides an overview of material properties and atomic structure. It discusses various physical, mechanical, and chemical properties of common materials like metals, ceramics, polymers and lists them in order of properties such as density, tensile strength, conductivity, and hardness. It also summarizes different atomic models including Thomson's plum pudding model, Rutherford's nuclear model, and Bohr's early quantum model which explained the stability of an atom.
The Effects of Copper Addition on the compression behavior of Al-Ca AlloyIOSR Journals
The Al-Ca-Cu alloys containing varying amount of Cu are used to study the effect of Cu addition on
their deformation behavior at varying strain rate (0.001/s, 0.01/s, 0.1/s, 1/s).The material is prepared using stir
casting technique The yield stress, flow stress and elastic limit are measured from the true stress-strain graph
.The Strain Rate sensitivity and strain hardening exponent are also determined for each material at different
strain rate. The Strain Rate Sensitivity of this alloy is very low. These values strongly demonstrate that
compressive deformation of Al-Ca-Cu alloys almost independent to the strain rate at room temperature
deformation.
Introduction to Mechanical Metallurgy (Our course project)Rishabh Gupta
The document summarizes key concepts in materials science and engineering. It discusses:
1. The importance of selecting high quality materials for better product design and performance.
2. The four main components in materials science - processing, structure, properties, and performance - and how they interrelate.
3. The main classes of materials - metals, ceramics, polymers, composites, semiconductors, and elastomers - and some of their key characteristics.
4. Crystal structures of metals and how they are classified based on atomic packing efficiency. Factors that determine a material's density are also covered.
Stress-Strain Curves for Metals, Ceramics and PolymersLuís Rita
Homework II - Biomaterials Science
We are interested about studying and comparing stress-strain curves of metals, ceramics and polymers. Primarily, differences are due to their different chemical bonding properties.
IST - 4th Year - 2nd Semester - Biomedical Engineering.
This document discusses strategies for maximizing fracture toughness through microstructure design. It explains that toughness can be increased by minimizing defects like cracks, and by designing microstructures that require additional energy to propagate cracks. Specific strategies discussed include laminating materials to deflect cracks, adding stiff fibers for crack bridging, including particles that transform under stress or microcrack to absorb energy, and minimizing grain size to reduce maximum crack size. The document also notes that optimization of toughness often requires balancing strength, and discusses approaches for characterizing crack size distributions.
This document provides a historical overview and introduction to composite materials. It discusses the early uses of composites in ancient times and the modern revival starting in the mid-20th century. Composites are now widely used in applications like aerospace and transportation due to properties like strength and lightweight. The document classifies composites based on matrix material (polymer, metal, ceramic) and reinforcement form (fiber, laminate, particulate). It describes different types of polymer matrices like thermosets and thermoplastics and gives examples of fiber reinforcements.
This document provides a historical overview and introduction to composite materials. It discusses:
1) The early uses of natural fiber composites throughout history for applications like bows and buildings.
2) The modern revival and increasing use of composites in aircraft and spacecraft in the late 20th century to improve structural performance.
3) Future trends toward more integrated design processes, cost reduction, and use of natural fibers to make composites more environmentally friendly.
Composites are materials made from two or more constituent materials with different physical or chemical properties. The materials remain separate within the finished structure to produce properties that are superior to those of the individual components. Composites consist of a reinforcement material, such as fibers, sheets or particles, embedded within a matrix material that maintains the relative positions of the reinforcements and allows for load transfer from the matrix to the reinforcement. Common reinforcement materials include glass, carbon and organic fibers while matrix materials include polymers, metals and ceramics. Composites offer advantages over traditional materials like high strength, light weight, design flexibility and resistance to corrosion.
Experimental evaluations and performance of the aluminum silicon carbide par...IAEME Publication
This document summarizes an experimental study on aluminum-silicon carbide particle metal matrix composites. Ring-shaped composites were fabricated using solid-state processing with varying sintering temperatures and times. The composites were subjected to thermal shock at +800C and -800C, and their radial crushing strength was tested. Micrographs of the fractured surfaces were analyzed. Thermal shock from sub-ambient temperatures was found to be more damaging than from elevated temperatures. Failure from elevated temperatures was dominated by cavity formation at interfaces, while sub-ambient temperatures caused more interfacial and matrix damage. The study evaluated the effect of reinforcement particles on the mechanical properties of the composites.
Experimental evaluations and performance of the aluminum silicon carbide par...IAEME Publication
Stresses induced due to thermal mismatch between the metal matrix and the ceramic reinforcement in metal matrix composite may impart plastic deformation to the matrix there by
resulting in a reduction of the residual stresses. Thermal mismatch strains also may quite often crack
the matrix resulting in a relaxation of the residual stresses. The interface in MMCs is a porous, noncrystalline portion in comparison with the matrix or the reinforcement (metal matrix and ceramic reinforcement in this case).
Experimental Test of Stainless Steel Wire Mesh and Aluminium Alloy With Glass...IJERA Editor
At present, composite materials are mostly used in aircraft structural components, because of their excellent properties like lightweight, high strength to weight ratio, high stiffness, and corrosion resistance and less expensive. In this experimental work, the mechanical properties of laminate, this is reinforced with stainless steel wire mesh, aluminum sheet metal, perforated aluminum sheet metal and glass fibers to be laminate and investigated. The stainless steel wire mesh and perforated aluminum metal were sequentially stacked to fabricate, hybrid composites. The aluminum metal sheet is also employed with that sequence to get maximum strength and less weight. The tensile, compressive and flexure tests carried out on the hybrid composite. To investigate the mechanical properties and elastic properties of the metal matrix composite laminate of a material we are using experimental test and theoretical calculation. The experimental work consists of Tensile, compressive and flexural test. The expectation of this project results in the tensile and compressive properties of this hybrid composite it is slightly lesser than carbon fibers but it could facilitate a weight reduction compared with CFRP panels. So this hybrid laminates composite material offering significant weight savings and maximum strength over some other GFRP conventional panels.
Experimental Test of Stainless Steel Wire Mesh and Aluminium Alloy With Glass...IJERA Editor
This document summarizes an experimental study that tested the mechanical properties of a hybrid composite material made of stainless steel wire mesh, aluminum alloy sheets, glass fibers, and an epoxy matrix. Nine-ply composite laminates were fabricated using compression molding. Tensile, compressive, and flexural tests were conducted on the laminates according to standards. The results found the tensile and compressive properties to be slightly lower than carbon fibers but offered weight savings compared to conventional glass fiber reinforced panels. This hybrid composite material provides significant weight reduction and maximum strength.
Analysis of Stress Concentration of Laminated Composite Plate With Circular Holeijiert bestjournal
Composite materials are finding a wide range of applications in structural design,especially for lightweight structure that have stringent stiffness and strength requirements. They are attractive replacement for metallic materials for many structural applications. By finding efficient composite str ucture design that meets all requirements of specific application. This is achieved by tailoring of material properties through selective choice of orientation,no. of stacking sequence of layers that make up composite material. Composites are used more and more often for load carrying and safety structures in all kind of applications foe aviation and space technology,for vehicles etc. Composite materials have been introduced progressively in automobiles,followingpolymer materials,a few of which have be en used as matrices. It is interestingto examine the relative masses of different materials which are used in theconstruction of automobiles. Even thoughthe relative mass of polymer - based materials appears low,one needs to take intoaccount that the specif ic mass of steel is about 4 times greater than that of polymers.This explains the higher percentage in terms of volume for the polymers.
Composite materials are made from two or more constituent materials that form a single component. The matrix material holds the reinforcement materials together and allows load transfer between them. Common composite materials include fiber-reinforced plastics with polymer matrices and fibers such as carbon, glass or Kevlar. Composites provide advantages like high strength and stiffness to weight ratios, as well as design flexibility. They also have drawbacks like higher costs and difficulty in recycling. Composites are widely used in applications that require lightweight and high strength, such as aircrafts, ships, sports equipment and buildings.
Composite materials are made by combining two or more materials with different properties to create a new material with unique characteristics. The document discusses the history, types, manufacturing, and applications of composite materials. It notes that composite materials are increasingly being used in industries like automotive and aerospace due to advantages like higher strength and stiffness compared to traditional materials, while remaining lightweight. New techniques like textile composites aim to lower costs and improve performance of composites.
IRJET- Study Analysis of Metal Bending in a Sheet Metal using Finite Elem...IRJET Journal
This document summarizes a study that analyzed the bending of aluminum sheet metal and aluminum sandwich panels with different core materials using finite element analysis software. Sandwich panels with cores of polypropylene, polystyrene, carbon fiber, and glass fiber were modeled and their deformation and stress distributions under bending forces were compared to a monolithic aluminum sheet. The sandwich panels exhibited better bending resistance and damage resistance than the aluminum sheet. Overall, sandwich panels with the same thickness are recommended over aluminum sheets due to their better resistance to external forces. The study aims to find alternative materials to aluminum for use in aircraft to improve resistance to impacts from bird strikes.
The document discusses an experimental and analytical study on the bending capacity of 42 cold-formed channel steel sections according to European design standards. Tensile coupon tests found the steel's average yield strength was 541 MPa, with an average ultimate-to-yield strength ratio of 1.06. Pure bending tests were conducted on the sections, which ranged from simple to complex stiffened designs. The test results were compared to bending capacity calculations in Eurocode 3. While Eurocode 3 allows for inelastic capacity, specifications like AS/NZS 4600 do not. The test data showed some non-slender sections had significant inelastic behavior and capacity beyond yield. Therefore, modifications to Eurocode 3 may be needed for accurate design of
This document provides an overview of metal forming processes. It discusses how plastic deformation occurs in crystal structures through slip and twinning. It introduces common yield criteria like von Mises and Tresca criteria that define the onset of plastic deformation. The document contrasts hot and cold working processes. Hot working is done above the recrystallization temperature to allow recovery and recrystallization during deformation, while cold working is below this temperature and results in work hardening without recovery. The advantages and disadvantages of each process are outlined. Higher strain rates lower the recrystallization temperature.
The matrix in a composite is the continuous phase that transfers stress to the dispersed phase. Common matrix materials include metals, ceramics, and polymers. There are two possible strengthening mechanisms for particle reinforced composites: load transfer from the matrix to the particles and restriction of dislocation movement. The Young's modulus of a large particle composite can be calculated using upper and lower bounds. The critical length (Lc) of a fiber depends on factors like fiber diameter and matrix-fiber bond strength. Fibers of different lengths experience different stress distributions relative to the critical fiber length.
Strengthening mechanisms in metals include work hardening, solid solution strengthening, and precipitation hardening. Work hardening increases yield strength by introducing dislocations through plastic deformation, which impede further dislocation movement. Solid solution strengthening adds solute atoms that distort the crystal lattice and interfere with dislocations. Precipitation hardening involves heat treating alloys to form precipitates that impede dislocations. These mechanisms strengthen metals by making dislocation motion and propagation more difficult.
This document discusses deformation and stress in metals. It begins by introducing different types of material variations engineers must consider, including shape, strength, elasticity and resistance. It then defines elastic and plastic deformation, explaining that elastic deformation is reversible while plastic deformation causes permanent changes. Different material types - rigid, elastic and plastic - are described based on their deformation behavior. The document continues exploring elasticity, plasticity, stress-strain curves, work hardening, deformation mechanisms, and fracture analysis in metals. Key concepts like yield strength, tensile strength and ductile versus brittle fracture are covered.
This document provides an overview of general properties of materials relevant to manufacturing processes. It discusses various material types and their mechanical, physical and chemical properties. Key mechanical properties discussed include strength, toughness, hardness, ductility, elasticity, fatigue, creep, failure under tension, compression, torsion, impact and bending. Testing methods for properties like tensile strength, hardness and impact strength are also covered. The document aims to help understand how material selection and properties influence manufacturing process selection and design.
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
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Answers about how you can do more with Walmart!"
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
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Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
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A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
বিসিএস ও ব্যাংক এর লিখিত পরীক্ষা ...+এছাড়া মাধ্যমিক ও উচ্চমাধ্যমিকের স্টুডেন্টদের জন্য অনেক কাজে আসবে ...
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024
2. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
BAB 3
Rekayasa Material & Propertinya
3.1 Intro & Sinopsis
3.2 Kelas Rancang bangun Material
3.3 Definisi Properti Material
3.4 Rangkuman & Kesimpulan
3.5 Bacaan lanjut
3.6 Evaluasi
3.1 Intro & Sinopsis
Material, bisa dikatakan, adalah makanan utk disain. Sebuah produk yg sukses -
adalah yg performanya bagus, yaitu bernilai baik utk uang & memberi kepuasan
utk pemakai — memerlukan material terbaik utk tugasnya, & memaksimalkan
semua potensi & karakteristiknya: boleh dikatakan, menerbitkan bumbu mereka.
Bab ini menyajikan menu: daftar belanja material yg lengkap. Kelas-kelas material;
logam, polimer, keramik, dsb., dikenalkan di sesi 3.2. Tetapi ini bukanlah akhir dari
suatu material yg kita cari; itu adalah merupakan profil tertentu ttg properti.
Properti (sifat-sifat) yg penting utk disain thermomekanik didefinisikan di sesi 3.3.
Pembaca yg sdh tahu definisi moduli, kekuatan, kapasitas redaman, konduktivitas
thermal dsb, bisa melompati sesi ini, & menggunakannya sbg referensi, bila perlu,
utk arti persisnya & satuan data pd diagram seleksi yg akan dibahas kemudian.
Bab ini diakhiri dg, spt biasa, sebuah rangkuman & evaluasi.
3.2 Kelas-kelas Material rekayasa
Cara konvensional untuk menggolongkan bahan-bahan rekayasa ke dalam enam
kelas yg ditunjukkan di gb. 3.1: logam, polimer, elastomer, keramik, kaca dan
komposit. Anggota suatu kelas mempunyai fitur utama: properti yg serupa, rute
pengolahan yg serupa, dan, seringkali, aplikasi yg serupa.
Logam memiliki moduli relatif tinggi. Mereka dapat dibuat kuat dg paduan atau
campuran logam dan oleh perlakuan panas dan mekanik, tetapi mereka tetap ulet
shg dapat dibentuk, memungkinkan mereka utk dibentuk dg proses deformasi.
3. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
Paduan logam kekuatan tinggi tertentu (baja pegas, sebagai contoh) memiliki
keuletan serendah 2%, tetapi meskipun ini cukup utk memastikan bahwa yield
material sebelum patah dan retak itu, manakala itu terjadi pd suatu material jenis
tangguh. Sebagian oleh karena keuletan mereka, logam adalah mangsa utk
kelelahan; dan dari semua kelas material, mereka adalah paling sedikit bersifat
tahan karatan/korosi.
Keramik & kaca, juga, mempunyai moduli tinggi, tetapi, tidak sama dg logam,
mereka rapuh. “Kekuatan” mereka dalam tegangan tarik artinya kekuatan retak yg
rapuh; dalam tegangan tekan, kekuatan hancur yg rapuh, yg mana adalah sekitar
limabelas kali lebih besar. Dan sebab keramik tidak punya keuletan/duktilitas,
mereka mempunyai suatu toleransi rendah utk konsentrasi tegangan (seperti
lubang atau retakan) atau utk tegangan kontak yg tinggi (pd titik-titik pengekleman,
sebagai contoh). Material ulet mengakomodasi konsentrasi tegangan dg deformasi
(perubahan bentuk) dg cara yg mana membagi-bagi lagi beban lebih merata; dan
oleh karena ini, mereka dapat digunakan di bawah beban statis dg suatu
batas/margin yg kecil thd kekuatan luluh mereka. Keramik & kaca tidak bisa.
4. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
Brittle materials always have a wide scatter in strength and the strength itself
depends on the volume of material under load and the time for which it is applied. So
ceramics are not as easy to design with as metals. Despite this, they have attractive
features. They are stiff, hard and abrasion-resistant (hence their use for bearings and
cutting tools); they retain their strength to high temperature; and they are corrosion-
resistant. They must be considered as an important class of engineering material.
Polymers and elastomers are at the other end of the spectrum. They have moduli
which are low, roughly fifty times less than those of metals, but they are strong —
nearly as strong as metals. A consequence of this is that elastic deflections can be
large. They creep, even at room temperature, meaning that a polymer component
under load may, with time, acquire a permanent set. And their properties depend on
temperature so that a polymer which is tough and flexible at 20°C may be brittle at
the 4°C of a household refrigerator, yet creep rapidly at the 100°C of boiling water.
None have useful strength above 200°C. If these aspects are allowed for in the
design, the advantages of polymers can be exploited. And there are many. When
combinations of properties, such as strength per unit weight, matter, polymers are as
good as metals. They are easy to shape: complicated parts performing several
functions can be moulded from a polymer in a single operation. The large elastic
deflections allow the design of polymer components which snap together, making
assembly fast and cheap. And by accurately sizing the mould and precolouring the
polymer, no finishing operations are needed. Polymers are corrosion resistant, and
they have low coefficients of friction. Good design exploits these properties.
Composites combine the attractive properties of the other classes of materials while
avoiding some of their drawbacks. They are light, stiff and strong, and they can be
tough. Most of the composites at present available to the engineer have a polymer
matrix — epoxy or polyester, usually — reinforced by fibres of glass, carbon or
Kevlar; we restrict ourselves to these. They cannot be used above 250°C because
the polymer matrix softens, but at room temperature, their performance can be
outstanding. Composite components are expensive and they are relatively difficult to
form and join. So despite their attractive properties the designer will use them only
when the added performance justifies the added cost.
5. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
The classification of Fig. 3.1 has the merit of grouping together materials which have
some commonality in properties, processing and use. But it has its dangers, notably
those of specialization (the metallurgist who knows nothing of polymers) and of
conservative thinking (“we shall use steel because we have always used steel”). In
the following sections we examine the engineering properties of materials from a
different perspective, comparing properties across all classes of material. It is the first
step in developing the freedom of thinking that the designer needs.
3.3 Definisi Properti Material
Setiap material dpt dipikirkan seperti mempunyai satu set atribut: yaitu propertinya.
Bukanlah material, yg di dalam dirinya, bahwa perancang mencari; ini merupakan
suatu kombinasi spesifik dari atribut ini: suatu profil properti. Nama material adalah
identifier untuk properti profil tertentu.
Properti itu sendiri adalah standar: density, modulus, strength, toughness, thermal
conductivity dll. (Table 3.1). Utk kelengkapan dan presisi, mereka didefinisikan, dg
batasannya, di bab ini. Ini membuat pembacaan yang membosankan. Jika kamu
berpikir kamu mengetahui bagaimana properti digambarkan, kamu boleh melompat
ke sesi 3.4, kembali ke bagian ini hanya jika kebutuhan muncul.
The density (usual units: Mg/m3
) is the weight per unit volume. We measure it today
as Archimedes did: by weighing in air and in a fluid of known density.
The elastic modulus (usual units: GPa or GN/m2
) is defined as “the slope of the
linear elastic part of the stress — strain curve” (Fig. 3.2). Young’s modulus, E,
describes tension or compression; the shear modulus, 0, describes shear loading;
and the bulk modulus, K, describes theeffect of hydrostatic pressure, Poisson’s
ratio, v, is dimensionless: it is the negative of the ratio of the lateral strain to the
axial strain ~ in axial loading. In reality, moduli measured as slopes of stress —
strain curves are inaccurate (often low by a factor of 2 or more), because of the
contribution of inelasticity and other factors. Accurate moduli are measured
dynamically: by exciting the natural vibrations of a beam or wire, or by measuring
6. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
the velocity of waves in the material. In an isotropic material, the moduli are related
in the following ways:
E=
٣G
١G/٣K ;
G=
E
٢١v ;
K=
E
٣١−٢v (3.1)
7. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
Biasanya v l 1/3
menghasilkan G l 3/8E (3.2)
dan K l E
Data books and databases like those described in Chapter 11 list values for all four
moduli. In this book we examine data for E; approximate values for the others can be
derived from equations (3.2) when needed.
The strength, sf, of a solid (usual units: MPa or MN/m2
) requires careful definition.
For metals, we identify sf with the 0.20% offset yield strength sy (gb. 3.2); that is, the
stress at which the stress — strain curve for axial loading deviates by a strain of
0.20% from the linear elastic line. It is the stress at which dislocations move large
distance through the crystals of the metal, and is the same in tension and
compression. For polymers, sf is identified as the stress a, at which the stress —
strain curve becomes markedly non-linear: typically, a strain of 1% (gb. 3.3).
This may be caused by “shear-yielding”: the irreversible slipping of molecular chains;
or it may be caused by “crazing”: the formation of low density, crack-like volumes
which scatter light, making the polymer look white. Polymers are a little stronger (~
20%) in compression than in tension. Strength, for ceramics and glasses, depends
strongly on the mode of loading (gb. 3.4). In tension, “strength” means the fracture
8. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
strength, of. In compression it means the crushing strength of which is much larger;
typically
sf
c
l 15 sf
t
(3.3)
We identify a,,- for a ceramic with the larger compressive strength sf
c
. The strength
of a composite is best defined by a set deviation from linear elastic behaviour: 0.5%
is sometimes taken. Composites which contain fibres (and this includes natural
composites like wood) are a little weaker (up to 30%) in compression than tension
because the fibres buckle. In subsequent chapters, sf for composites means the
tensile strength.
Strength, then, depends on material class and on mode of loading. Other modes of
loading are possible: shear, for instance. Yield under multiaxial loads are related to
that in simple tension by a yield function. For metals, the Von Mises yield function
works well:
(s1 - s2 )2
+ ( s2 - s3) 2
+ ( s3 – s1) 2
= 2sf
2
(3.4)
For polymers the yield function is modified to include the effect of pressure, p
9. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
(s1 - s2 )2
+ ( s2 - s3) 2
+ ( s3 – s1) 2
= 2sf
2
( 1−
b
s
)(
p
f
)) (3.5)
where b is a numerical coefficient which characterises the pressure dependence of
the flow strength and
p = - 4( s1 +s2+s3)
where s1 , s2 and s3 are the principal stresses, positive when tensile. For ceramics,
a Coulomb flow law is used:
s1 - Bs3 = C (3.6)
dg B dan C adalah konstanta.
When the material is difficult to grip (as is a ceramic), its strength can be measured
in bending. The modulus of rupture or MOR (usual units MPa or MN/m2) is the
maximum surface stress in a bent beam at the instant of failure (gb. 3.5). One might
expect this to be exactly the same as the strength measured in tension, but for
ceramics it is larger (by a factor of about 1.3) because the volume subjected to this
maximum stress is small and the probability of a large flaw lying in it is small also; in
simple tension all flaws see the maximum stress.
10. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
The ultimate (tensile) strength su (usual units MPa) is the nominal stress at which a
round bar of the material, loaded in tension, separates (Fig. 3.2). For brittle solids —
ceramics, glasses and brittle polymers — it is the same as the failure strength in
tension. For metals, ductile polymers and most composites, it is larger than the
strength sf, by a factor of between 1,1 dan 3 because of
work hardening or (in the case of composites) load transfer to the reinforcement.
The hardness, H, of a material (usual units: MPa) is a crude measure of its strength.
It is measured by pressing a pointed diamond or hardened steel ball into the surface
of the material. The hardness is defined as the indenter force divided by the
projected area of the indent. It is related to the quantity we have defined as sf by
H j 3 sf (3.7)
The toughness, GC (usual units: kJ/m2), and the fracture toughness, KC (satuan
biasa: MPa mb1/2
atau MN/m3/2), measure the resistance of the material to the
propagation of a crack. The fracture toughness is measured by loading a sample
containing a deliberately introduced crack of length 2c (gb. 3.6), recording the tensile
stress o~ at which the crack propagates. The quantity K~ is then calculated fromK~
= Yo~/iê (3.8)
and the toughness from
K~ -
— E(1 + v) (3.9)
where Y is a geometric factor, near unity, which depends on details of the sample
geometry, and E is Young’s modulus and v is Poisson’s ratio. Measured in this way K~
and G~ have well-defined values for brittle materials (ceramic, glasses, and many
polymers). In ductile materials a plastic zone develops at the crack tip, introducing new
features into the way in which cracks propagate which necessitate more involved
characterisation. Values for K~ and G~ are, nonetheless, cited, and are useful as a way
of ranking materials.
The loss-coefficient, i~ (a dimensionless number), measures the degree to which a
material dissipates vibrational energy (Fig. 3.7). If a material is loaded elastically to a
11. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
stress a, it stores an elastic energy
r°max 1 ~2
U=j
per unit volume. If it is loaded and then unloaded, it dissipates an energy AU = ~a dr
The loss coefficient is
AU
— 2nU (3.1O~
The cycle can be applied in many different ways — some fast, some slow. The
value of ~ usually depends on the timescale or frequency of cycling. Other measures of
damping include
AU
the specific damping capacity, D = the log decrement, A (the log of the ratio of
successive amplitudes of natural vibrations), the phase lag, 6, between stress and
strain, and the “Q” factor or resonance factor, Q. When damping is small (~<0.01) these
measures are related by
D A 1
(3.11)
but when damping is large, they are no longer equivalent.
Cyclic loading not only dissipates energy; it can also cause a crack to nucleate and grow,
culminating in fatigue failure. For many materials there exists a fatigue limit: a stress
amplitude below which fracture does not occur, or occurs only after a very large
number (>108) cycles. This information is captured by the fatigue ratio,f (a
dimensionless quantity). It is the ratio of the fatigue limit to the yield strength, O~.
The rate at which heat is conducted through a solid at steady state (meaning that the
temperature profile does not change with time) is measured by the thermal
conductivity, A (usual units: W/m K). Figure 3.8 shows how it is measured: by
recording the heat flux q (W/m2
) flowing from a surface at temperature T1
to one at
1’2 in the material, separated by a distance X. The conductivity is calculated from
Fpurier’s law:
12. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
— A~T_A(TIT2)
q— dX X (3.12)
The measurement is not, in practice, easy (particularly for materials with low
conductivities), but reliable data are now generally available.
When heat flow is transient, the flux depends instead on the thermal diffusivity, a (usual
units: m2
/s), defined by
A
a — (3.13)
where p is the density and Cp is the specific heat at constant pressure (usual units:
kJ/kg K). The thermal diffusivity can be measured directly by measuring the decay of a
temperature
use when a heat source, applied to the material, is switched off; or it can be calculated
from via the last equation. This requires values for C,, (virtually identical, for solids, with
C~, the
c heat at constant volume). They are measured by the technique of calorimetry, which
the standard way of measuring the melting temperature, Tm, and the glass temperature,
~ual units for both: K). This second temperature is a property of non-crystalline solids,
do not have a sharp melting point; itcharacterises the transition from true solid to very
liquid. It is helpful, in engineering design, to define two further temperatures: the
imE~m service temperature T,,,~ and the softening temperature, T~ (both: K). The
first tells
us the l4ghest temperature at which the material can reasonably be used without
oxidation, chemicaichan~e or excessive creep becoming a problem; and the second
gives the temperature needed t~ make the material flow easily for forming and shaping.
Most thaterials expand when they are heated (Fig. 3.9). The thermal strain per degree is
measured by the linear thermal-expansion coefficient, a (units: K ‘). If the material is
thermally isotropic, the volume expansion, per degree, is 3a. If it is anisotropic, two or
more coefficieflts are required, and the volume expansion becomes the sum of the
principal thermal strains.
13. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
The thermal shock resistance (units K) is the maximum temperature difference through
which a material can be quenched suddenly, without damage. It, and the creep
resistance, are important in high-temperature design. Creep is the slow, time-dependent
deformation which occurs when materials are loaded above about +Tm or +T~ (Fig.
3.10). It is characterised by a set of creep constants: a creep exponent n
(dimensionless), an activation energy Q (usual units: kJ/mole), a kinetic factor A (units:
s~ I), and a reference stress o~ (units: MPa or MN! m2). The creep strain-rate rat a
temperature Tcaused by a stress a is described by the equation
= A [~~] CX~ [~] (3.14)
Wear, oxidation and corrosion are harder to quantify, partly because they are surface, not
bulk, phenomena, and partly because they involve interactions between two
materials, not just the properties of one. When solids slide (Fig. 3.11) the volume of
material lost from one surface, per unit distance slid, is called the wear rate, W. The
wear resistance of the surface is characterised by the Archard wear constant, KA
(units: m2/MN or MPa’) defined by the equation
w
~KAP (3.15)
where A is the area of the surface and P the normal pressure pressing them together. Data
for KA are available, but must be interpreted as the property of the sliding couple, not
of just one member of it.
Dry corrosion is the chemical reaction of a solid surface with dry gases (Fig. 3.12).
Typically, a metal, M, reacts with oxygen, 02, to give a surface layer of the oxide MO2:
M+O2-~MO2
If the oxide is protective, forming a continuous, uncracked film (thickness, X) over the
surface, the reaction slows down with time, t:
14. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
dX
dT X (3.16)
Here R is the gas constant, T the absolute temperature, and the oxidation behaviour is
characterised by the parabolic rate constant for oxidation Ic,, (units: m2/s). Wet corrosion
— corrosion in water, brine, acids or alkalis, is much more complicated and cannot be
captured by rate equations with simple constants. It is more usual to catalogue corrosion
resistance by a simple scale such as A (very good) to E (very bad).
3.4 Summary and Conclusions
There are six important classes of materials for mechanical design: metals, polymers,
elastomers, ceramics, glasses and — finally — composites, which combine the
properties of two or more of the others. Within a class there is certain common ground:
ceramics are hard and brittle; metals are ductile and conduct heat well; polymers are
light and have large expansion coefficients, and so on — that is what makes the
classification useful. But, in design, we wish to escape from the constraints of class, and
think, instead, of the material name as an identifier for a certain property profile — one
which will, in later chapters, be compared with an “ideal” profile suggested by the
design, guiding our choice. To that end, the properties important in thermomechamcal
design were defined in this chapter. In the next we develop a way of displaying
properties so as to maximise the freedom of choice.
3.5 Further Reading
Definisi properti material dapat ditemukan di sejumlah buku teks ttg rekayasa material,
ini 5 judul di antaranya.
Ashby, M. F. and Jones, D. R. H. (1980, 1986) Engineering Materials, Parts 1 and 2.
Pergamon Press, Oxford, UK.
Dieter, G. E. (1988) Mechanical Metallurgy. McGraw Hill, Singapore.
Fontana, M. G. and Greene, N. D. (1967) Corrosion Engineering. McGraw Hill, New
York, USA.
15. Ariosuko, Pemilihan Bahan & Proses, terjemahan versi 1.0. 04/13/06
Van Vlack, L. H. (1982) Materials for Engineering. Addison-Wesley, Reading, Mass.,
USA.