Delamination occurs due to the separation of adjacent layers in a composite material. It can be caused by manufacturing defects, stresses that act transverse to the layers, or laminate geometry issues like free edges, notches, cut-outs, poor bonding, or ply drops. Delamination reduces strength and stiffness, causes stress concentrations, and can lead to further growth and compressive failure of the laminate.
Autoclave is a closed vessel (Round or Cylindrical) in which processes occur under simultaneous application of high temperature and pressure. Autoclave molding technique is similar to vacuum bag and pressure bag molding method with some modifications. This method employs an autoclave to provide heat and pressure to the composite product during curing.
Autoclave is a closed vessel (Round or Cylindrical) in which processes occur under simultaneous application of high temperature and pressure. Autoclave molding technique is similar to vacuum bag and pressure bag molding method with some modifications. This method employs an autoclave to provide heat and pressure to the composite product during curing.
An insight to modern material used in aircraft and automobile known for its low weight and high strength. This gives an understanding of carbon fiber reinforced plastics(CFRP), its properties, applications, processing technologies.
Wear is a process of removal of material from one or both of two solid surfaces in solid state contact, occurring when these two solid surfaces are in sliding or rolling motivation
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.
Presentation on Composite Materials
Rana zia ur rehman
Graduate Researcher at KAIST (Korea Advanced of Science & Technology)
My Email ID: ranazia517@gmail.com
Composites are made by combination of two or more natural or artificial materials to maximize their useful properties and minimize their weaknesses.
Example: The oldest and best-known composites,
Natural: Wood combination of cellulose fibre provides strength and lignin is the "glue" that bonds and stabilizes. Bamboo is a very efficient wood composite structure.
o is a very efficient wood composite structure
Artificial: The glass-fibre reinforced plastic (GRP), combines glass fiber (which are strong but brittle) with plastic (which is flexible) to make a composite material that is tough but not brittle.
70 to 90% of load carried by fibers
Provide structural properties to the composite
Stiffness
Strength
Thermal stability
Provide electrical conductivity or insulation
Example: Glass, Carbon, Organic Boron, Ceramic, Metallic
Function of Fiber/Dispersion phase
An insight to modern material used in aircraft and automobile known for its low weight and high strength. This gives an understanding of carbon fiber reinforced plastics(CFRP), its properties, applications, processing technologies.
Wear is a process of removal of material from one or both of two solid surfaces in solid state contact, occurring when these two solid surfaces are in sliding or rolling motivation
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.
Presentation on Composite Materials
Rana zia ur rehman
Graduate Researcher at KAIST (Korea Advanced of Science & Technology)
My Email ID: ranazia517@gmail.com
Composites are made by combination of two or more natural or artificial materials to maximize their useful properties and minimize their weaknesses.
Example: The oldest and best-known composites,
Natural: Wood combination of cellulose fibre provides strength and lignin is the "glue" that bonds and stabilizes. Bamboo is a very efficient wood composite structure.
o is a very efficient wood composite structure
Artificial: The glass-fibre reinforced plastic (GRP), combines glass fiber (which are strong but brittle) with plastic (which is flexible) to make a composite material that is tough but not brittle.
70 to 90% of load carried by fibers
Provide structural properties to the composite
Stiffness
Strength
Thermal stability
Provide electrical conductivity or insulation
Example: Glass, Carbon, Organic Boron, Ceramic, Metallic
Function of Fiber/Dispersion phase
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
Ceramics have historically been limited in structural applications due to poor tensile strength and brittle fracture behaviour, leading to structural unreliability.SO To optimize the Zirconiato obtain high hardness and toughness.
Inadequate Stability or Strength
Loss of binding action
Loss of base course materials
Inadequate wearing course
Use of inferior materials and crushing of base course materials
Lack of lateral confinement for the granular base course.
Engineering Fracture Mechanics. Engineers try to have high-strength, high ductility, high crack resistance, and faultless structures. The most reliable approach is "No cracks - no problems,"
When all is not possible, there are different methods of prevention of catastrophic failure: increase crack resistance by ductile material, by local heating; decrease SIF by placing holes on the crack path, by patching, by stiffing elements or by using composite materials. "Leak-before-break" is an effective strategy to prevent catastrophic failure of pressure vessels. It is better to allow a semi-elliptical crack to grow through the wall and to detect it by leaking than to have the dynamic start and failure of the whole vessel. There are two characteristics of the material: crack resistance for semi-elliptical crack and crack resistance for through crack.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
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2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
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Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
2. Causes of delamination
a) Manufacturing Defects
1 .Improper laying of laminae
2 .insufficient curing temperature; pressure and duration of curing
3 . Air pockets and inclusions
3. b) Loading Generating Transverse Stresses
The interface is weaker in transverse strength as compared to the layers.
Hence, its failure is dominated by the transverse stresses.
4. c) Laminate Geometry
1.Free edges
The free edges of the laminate have very high transverse normal and
shear stresses.
It is shown that significant interlaminar stresses are induced in regions
near the laminate free edges.
5. 2 .NOTCH
Notch in the laminates acts like an
external crack giving rise to high three
dimensional stress state in the vicinity of
the notch
3. CUT- OUT
The cutout boundaries act like free
edges leading to significant transverse
stresses.
6. 4. BOUNDED JOINT
Improper bonding leads to weaker joints.
When such weak joints are subjected to
serve loading conditions delamination
can occur.
5. PLY DROP
The region of ply termination acts like a
region of high stresses for neighboring
laminae which can be a reason for
delamination of the plies adjacent to the
ply drop region.
7. EFFECTS OF DELAMINATION
1 .Reduces the strength and stiffness
2. It causes stress concentration in load bearing plies and a local
instability leading to a further growth of delamination which results
in a compressive failure of the laminate.
9. Two types of matrix cracks
The cracks are either perpendicular or parallel to the fibre direction.
> In the first type, the cracks are developed when axial stress in
the lamina is tensile in nature.
>In the second type, the cracks are developed when the inplane
transverse stress in the lamina is tensile in nature.
Causes of matrix cracking
10. Coupled Micro-Macro level Failure Mechanisms
There can be another scenario that this crack terminates at the neighboring
interface. This crack front act as a stress concentration site for interface
between the adjacent layer causing it to weaken, thus initiating delamination
crack in the interface.
11. Suppression of Delamination
The primary cause of delamination is the low inter laminar fracture
toughness.
This is due to brittle nature of most resins (epoxy) used as matrix
material, which have low mode I fracture toughness.
The suggested models for improving this property are:
>.Adding second phase materials to matrix like rubber;
chopped fibre, fibrils, etc