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![Material Selection Criteria
Criteria
Availability The material should be already available in the market in the abundant
quantity.
Cost The cost of the material selected for a particular job from several
alternatives should be minimum.
Material
Properties
The properties of the materials selected should meet the functional
requirements and the service conditions.
Manufacturing
Considerations
It has been the most important factor while selecting the material for a
particular job. The materials should be selected for particular part
based on the process by which it is going to be manufactured.
Environmental
Considerations
The effect of environmental conditions [Like temperature, humidity,
etc.] should be given more attention during selection of material.
Machinability
Machinability is the case with which a given metal can be machined.
Machinability of the material depends upon hardness, strength and
chemical Composition of materials.
Formability
It is an indication of suitability of the metal for a machine part that
requires forming. Forming depends upon ductility and tensile Strength.
N
itin
Shekapure](https://image.slidesharecdn.com/bmeunitiibynitinshekapure-191002024546/85/Design-Fundamentals-84-320.jpg)
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Design Fundamentals
- 1. Basic Mechanical Engineering By NitinG Shekapure Unit II Design Fundamentals (L10) N itin Shekapure
- 2. By: Nitin Shekapure UnitII Design Fundamentals Design: Steps in design process, Mechanical Properties (Strength, Toughness, Hardness, Ductility, Malleability, Brittleness, Elasticity, Plasticity, Resilience, Creep), and selection of Engineering materials, Applications of following materials in Engineering – Aluminum, Plastic, Steel, Brass, Cast Iron, Copper, Rubber. Mechanism (Descriptive Treatment Only): Definition and comparison of Mechanism and Machine, Four Bar Mechanism, Slider Crank Mechanism. N itin Shekapure
- 3. What is design? Designis about progress. It is the conceptualization and creation of new things: ideas, interactions, information, objects, typefaces, books, posters, products, places, signs, systems, services, furniture, websites, and more. “Any man made thing is a design” N itin Shekapure
- 4. Living and Non-LivingThings There are living and non-living things all around us. Go outside and explore. You can find both living and non-living things. Look inside your house and other buildings such as a grocery store. Can you name five things that you think are living? How do you know they are living? Can you name five things that you think are non-living? How do you know they are not living? N itin Shekapure
- 5. Both lists showmany different things. Some of these things can move while others cannot. Some of these things need food while others do not. Some can grow, others do not grow. Some breathe, others do not breathe. A table, chair, pencil, and clothes cannot grow. These things cannot talk or walk. Things, which do not grow, move, or respond are called non-living things. A baby plant grows into a big plant or into a tree. A puppy grows into a dog. A baby grows into a person. Things that grow, breathe, and respond are called living things. All man-made things are non-living things, but not all natural things are living things. While people, animals, and plants are living natural things, stars, mountains, clouds, air, and water are non-living natural things. N itin Shekapure
- 6. Man made things Clothes Furniture Pencil, Pen, Books Car,Bicycle Paper Natural things Rocks Butterflies Trees Sun, Moon, Stars People N itin Shekapure
- 7. Design: Formulation of aplan for satisfaction of human needs. Machine Design: Machine design is the process of selection of the materials, shapes, sizes, and arrangement of mechanical elements so that the resultant machine will perform the prescribed task. Engineering Design: “ The process of applying various techniques and scientific principles for the purpose of defining a device, a process, or a system in sufficient detail, to permit it’s realization” N itin Shekapure
- 8. Purpose of Designand design improvements. • To create new products and gadgets for use. • To improve existing commodities to make them more user friendly and comfortable. • To satisfy changes of human needs of enjoyment and beauty. • To introduce automation • To improve efficiency • To face competition in market N itin Shekapure
- 9. • To solveexisting problem • To improve the performance • To increase safety • To improve economy • To reduce cost • To increase human comfort • To develop new products Design is needed: N itin Shekapure
- 10. Why Product Needsto be Designed? Why Product Needs to be Designed? For Compactness For Functional Requirements For Cost ReductionFor Appearance For Optimization For Safety For Innovation For User Comfort N itin Shekapure
- 11.
- 12. Steps in designDefinition of Problem Synthesis Analysis of forces Selection of Materials Determination of Mode of failure Selection of factor of safety Determination of Dimensions Modification of Dimensions Preparation of Drawing Preparation of Design Report N itin Shekapure
- 13. Design considerations Design considerationsare the characteristics which influence the design of the component or the system. Some of the important design considerations are as follows Strength Rigidity Reliability Safety Cost Weight Size Ergonomics Aesthetics Manufacturing method Shape Effective life Vibrations Thermal constrains Lubrication Maintenance Flexibility Compatibility Noise Standards Assembly Wear and tear N itin Shekapure
- 14. Ergonomics “The scientific disciplineconcerned with understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, methods and data to design in order to optimize human well-being and overall system performance”. Ergonomics means “fitting the job to the worker” From the Greek Ergo = Work Nomos = Laws “The Goal of ergonomics is to ‘fit the job to the person,’ rather than making the person fit the job. N itin Shekapure
- 15. • Physical Size •Endurance • Strength • Manipulative • Environmental • Cognitive Types of Problems or Mismatches N itin Shekapure
- 16. • Clearance • Reach •Equipment Size • Personal Protective Equipment (PPE) Physical Size N itin Shekapure
- 17. Endurance (Capacity forWork) N itin Shekapure
- 18. Environmental • Noise • Lighting •Thermal • Chemical N itin Shekapure
- 19. Cognitive • Machine Pacing •Shift Work • Morale • Psychosocial N itin Shekapure
- 20. Strength • Force Requirements •Male/Female • Manual Materials Handling N itin Shekapure
- 21. • Decreased injuryrisk • Increased productivity • Decreased mistakes/rework • Increased efficiency • Decreased lost work days • Decreased turnover • Improved morale Benefits of Ergonomics N itin Shekapure
- 22. Man – machineSystem N itin Shekapure
- 23. Man – machineSystem N itin Shekapure
- 24. What Do They(Customers) Want? • End Users – Performance & Functionality – Affordability – Ease of use including ergonomics – Reliability and Long life – Usefulness – Safety – Low maintenance and easy assembly – Esthetics N itin Shekapure
- 25. External Customers • Retailers –Small and attractive packaging – Long shelf life – Low cost/performance and Exciting features • Maintenance – Ease of maintenance N itin Shekapure
- 26. • Government /Standards / Society – Conformance to laws and regulations – Promotion of public health and safety – Protection of environment – Solution to chronic problems in society • Traffic • Energy • Noise • Drugs, abuse and other crimes • Diversity / Social tolerance / Security External Customers N itin Shekapure
- 27. • Management – Makea big profit – On time delivery – Low failure risk – Documentation – Process: Conformance to company product development process Internal Customers N itin Shekapure
- 28. • Marketing – Attractivefeatures to target buyers – Low production cost – Esthetics – Attractive packaging – On time delivery – Long Warrantees Internal Customers N itin Shekapure
- 29. Internal Customers • Manufacturing –Manufacturability using standard methods and schedules. – Conformance to company documentation formats. – Use of products from preferred vendors. N itin Shekapure
- 30. • Legal – Nopatent infringements – Safety • All required safety warnings and labels • Designed protection against reasonable abuse – Codes and regulations Internal Customers N itin Shekapure
- 31. MCQ: 1. The processof selection of materials, shapes, sizes and arrangements of mechanical elements is known as, a) Product development b) Machine design c) Material selection. d) None of the above N itin Shekapure
- 32. MCQ: 2. Machine designdoes not include a) Selection of materials. b) Selection of arrangements of mechanical elements. c) Selection of shapes and sizes. d) Selection of machine N itin Shekapure
- 33. MCQ: 3. Machine designincludes a) Selection of materials. b) Manufacturing of components c) Testing of components d) All of the above N itin Shekapure
- 34. MCQ: 4. The machinedesign includes a) Selection of materials. b) Selection of sizes and shapes c) Selection of arrangements d) All of the above N itin Shekapure
- 35. MCQ: 5. Product needsto be designed for a) Functional requirements b) Appearance c) User comfort d) All of the above N itin Shekapure
- 36. MCQ: 6. The designof a computer chair is a best example of a) Computer aided design b) System design c) Machine design d) Ergonomic design N itin Shekapure
- 37. MCQ: 7. The productor system is required to be designed so as to ensure that it performs the prescribed task satisfactorily. It is known as a) Design for comfort b) Design for Functional requirements c) Design for comfort d) All of the above N itin Shekapure
- 38. MCQ: 8. ________is notthe step in design process. a) Synthesis b) Interference checking c) Analysis of forces d) Selection of material N itin Shekapure
- 39. MCQ: 9. The firststep in any design process is a a) Selection of material b) Preparation of drawings c) Determination of dimensions d) Definition of problem N itin Shekapure
- 40. MCQ: 10. Drawing freebody diagram and determination of forces acting on the machine element is part of the step :________, in design process a) Determination of Dimensions b) Preparation of drawings c) Analysis of Forces d) Synthesis N itin Shekapure
- 41. MCQ: 11. In designprocedure, the last step is a) Selection of material b) Preparation of drawings c) Determination of dimensions d) Preparation of design report N itin Shekapure
- 42. MCQ: 12. Ability ofthe machine element to avoid the failure due to yielding or fracture under load is known as a) Rigidity b) Strength c) Safety d) Toughness N itin Shekapure
- 43. MCQ: 13. Ability ofthe machine element to keep the deflections within the permissible limit under the load is known as a) Rigidity b) Strength c) Safety d) Toughness N itin Shekapure
- 44. MCQ: 14. The objectiveof ergonomics is a) To make user adopt himself to the machine b) To make machine fit for user c) To make the product economical d) To make the product stronger N itin Shekapure
- 45. MCQ: 15. Stiffness isan important consideration in design of a) Springs b) electric switches c) TV d) Music system N itin Shekapure
- 46. MCQ: 16. Ergonomics dealswith the a) Economy of the product. b) Appearance of the product. c) Man-machine-working environment relationship. d) Safety of the product N itin Shekapure
- 47. MCQ: 17. Ergonomics dealswith the a) User comfort b) Safety of the product c) Cost of the product d) Optimization of product N itin Shekapure
- 48. MCQ: 18. The designof dash board of a car is an example of a) Optimum design b) Ergonomic design c) Cost effective design d) Element design N itin Shekapure
- 49. MCQ: 19. The designof a computer chair is a best example of a) Optimum design b) Ergonomic design c) Cost effective design d) Element design N itin Shekapure
- 50. MCQ: 20. The importantarea covered under ergonomics is a) Energy expenditure in hand and foot-operations b) Cost of the material c) Cost of manufacturing process d) Both (a) and (b) N itin Shekapure
- 51. MCQ: 21. The importantarea covered under ergonomics is a) Communication between user and machine. b) Human anatomy and posture while using the machine. c) Working environment. d) All of the above N itin Shekapure
- 52. MCQ: 22. Every closedloop type man-machine system essentially has a) Display unit b) Control unit c) Electric supply d) Both (a) and (b) N itin Shekapure
- 53. MCQ: 23. In aman-machine system, the display unit is used for a) Information reception b) Machine control c) Corrective action d) All of the above N itin Shekapure
- 54. MCQ: 24. In aman-machine system, the control unit is used for a) Corrective action b) Display of information c) Controlling the operator d) Both (a) and (b). N itin Shekapure
- 55. MCQ: 25. The workingenvironment factor in ergonomic considerations can be a) Worker salary b) Other perks c) Lighting d) Promotions of worker N itin Shekapure
- 56. MCQ: 26. The followingis an important guideline in aesthetic design a) The appearance should contribute to the performance of the product. b) The appearance should reflect the cost of the product. c) The product should be comfortable to the user. d) All of the above N itin Shekapure
- 57. MCQ: 26. The followingis an important guideline in aesthetic design a) The appearance should contribute to the performance of the product. b) The appearance should reflect the cost of the product. c) The product should be comfortable to the user. d) All of the above N itin Shekapure
- 58. Basic Mechanical Engineering By NitinG Shekapure Unit II Design Fundamentals (L13, L14 & L15) N itin Shekapure
- 59. Engineering Materials Over 70,000different kinds and grades of engineering materials This number grows daily N itin Shekapure
- 60. What are thekind of questions that a student of materials science would like answers for? • Why is glass brittle, while copper is ductile? What is meant by a ductile material? • If we take two rods, one of Al and one of steel, why is it easier to bend the Al rod as compared to the steel rod? • How can I change properties like hardness, without changing the composition. • Why is wire of copper conducting, while piece of brick or wood non-conducting? • Why is glass transparent, while any typical metal is opaque? • Why does the electrical conductivity of Cu decrease on heating, while that of Si increases? • Why does Iron corrode easily, while Aluminium does not (or does not seem to?!)? • Usually, good thermal conductors are also good electrical conductors. Why is this so? Why is diamond a good thermal conductor, but not a good electrical conductor? • If I pull a spring and then release the load, it ‘comes back’ to its original shape. However, a if I bend an aluminium rod, does not come back to its original shape. How can one understand these observations? N itin Shekapure
- 61. Materials Class Definition Examples PropertiesApplications Metals Metals are combinations of one or more "metallic elements," such as iron, gold, or lead. Alloys are metals like steel or bronze that combine more than one element, and may include non-metallic elements e.g. carbon. Steel, aluminium, titanium iron, gold, lead, copper, platinum, brass, bronze, pewter, solder Strong, dense, ductile, electrical and heat conductors Electrical wiring, structures (buildings, bridges), automobiles (body, springs), airplanes, trains (rails, engine components, body, wheels), shape memory materials, magnets Ceramics Ceramic materials are inorganic materials with non- metallic properties usually processed at high temperature at some time during their manufacture Structural ceramics, refractories, porcelain, glass Lower density than metals, strong, low ductility (brittle), low thermal conductivity, corrosion resistant Dinnerware, figurines, vases, art, bathtubs, sinks, electrical and thermal insulation, sewage pipes, floor and wall tile, dental fillings, abrasives, glass windows Polymers A polymer contains many chemically bonded parts or units that are bonded together to form a solid. Plastics (synthetic, nylon, liquid crystals, adhesives, elastomers (rubber) Low density, poor conductors of electricity and heat, different optical properties Fabrics, car parts, packaging materials, bags, packing materials (Styrofoam*), fasteners (Velcro*), glue, containers, telephone headsets, rubber bands Composites Composites are two or more distinct substances that are combined to produce a new material with properties not present in either individual material. Fibreglass (glass and a polymer), plywood (layers of wood and glue), concrete (cement and pebbles) Properties depend on amount and distribution of each type of material. Collective set of properties are more desirable and possible than with any individual material. Golf clubs, tennis rackets, bicycle frames, tires, cars, aerospace materials, paint N itin Shekapure
- 62. Mechanical Properties ofMaterial N itin Shekapure
- 63. Mechanical Properties ofMaterial • It is defined as the ability of material to resist load without failure. • If a material withstand a grater load, then material has a more strength. Strength In materials science, the strength of a material is its ability to withstand an applied load without failure or plastic deformation. The field of strength of materials deals with forces and deformations that result from their acting on a material. By: Nitin Shekapure N itin Shekapure
- 64. Mechanical Properties ofMaterial Toughness It is the ability of material to absorb energy just before fracture takes place Toughness = the ability to absorb energy up to fracture = the total area under the strain-stress curve up to fracture N itin Shekapure
- 65. Mechanical Properties ofMaterial Hardness • Resistance to penetration or plastic deformation. It is related to wear resistance • Hardness and Strength correlate well because both properties are related to in-molecular bonding. By: Nitin Shekapure N itin Shekapure
- 66. Ductility • Ability todeform when subjected to tensile load. • Copper, aluminum, and steel are examples of ductile metals. The opposite of ductility is brittleness, where a material breaks when tensile stress is applied to lengthen it. Examples of brittle materials include cast iron, concrete, and some glass products. Mechanical Properties of Material N itin Shekapure
- 67. Brittleness Ability to rupturewith negligible deformation. Mechanical Properties of Material N itin Shekapure
- 68. Malleability Mechanical Properties ofMaterial Malleability is the quality of something that can be shaped into something else without breaking, like the malleability of clay. Ability to deform under compressive load. By: Nitin Shekapure N itin Shekapure
- 69. Elasticity Mechanical Properties ofMaterial It is the ability of material to regain original shape on the removal of deforming load.N itin Shekapure
- 70. Plasticity Mechanical Properties ofMaterial It is the ability of material to retain the deformation produced by deforming loadN itin Shekapure
- 71. Creep Mechanical Properties ofMaterial Creep (sometimes called cold flow) is the tendency of a solid material to move slowly or deform permanently under the influence of mechanical stresses. It can occur as a result of long-term exposure to high levels of stress that are still below the yield strength of the material. It is the time dependent plastic deformation of material under constant load and high temperature. N itin Shekapure
- 72. Fatigue Mechanical Properties ofMaterial When a material is subjected under repeated load then it fails below yield point stress, it is called a fatigue. Academic Fatigue In materials science, fatigue is the weakening of a material caused by repeatedly applied loads. It is the progressive and localised structural damage that occurs when a material is subjected to cyclic loading. N itin Shekapure
- 73. Resilience Mechanical Properties ofMaterial It is the ability of material to absorb and store energy when loaded within elastic limit. Desirable in materials for springs. In material science, resilience is the ability of a material to absorb energy when it is deformed elastically, and release that energy upon unloading. ... The modulus of resilience is defined as the maximum energy that can be absorbed per unit volume without creating a permanent distortion. N itin Shekapure
- 74. Formability Mechanical Properties ofMaterial Formability is the ability of a given metal workpiece to undergo plastic deformation without being damaged. The plastic deformation capacity of metallic materials, however, is limited to a certain extent, at which point, the material could experience tearing or fracture (breakage). Formability may be defined as the ease with which material may be forced into a permanent change of shape. By: Nitin Shekapure N itin Shekapure
- 75. Castability Mechanical Properties ofMaterial Castability is the ease of forming a quality casting. Castability is the ease of forming a quality casting. A very castable part design is easily developed, incurs minimal tooling costs, requires minimal energy, and has few rejections. By: Nitin Shekapure N itin Shekapure
- 76. Weldability Mechanical Properties ofMaterial The weldability, also known as joinability, of a material refers to its ability to be welded.N itin Shekapure
- 77. Stiffness Mechanical Properties ofMaterial Stiffness is the rigidity of an object — the extent to which it resists deformation in response to an applied force. Stiffness resistance to deformation. By: Nitin Shekapure N itin Shekapure
- 78. Types of Stresses TensionCompression TorsionShear N itin Shekapure
- 79. Torsion is reallya combination of tension, compression, and shear N itin Shekapure
- 80. How to normalizedeformation Rest Tension Compression l l + Dl l - Dl F F l l Strain N itin Shekapure
- 81. By: Nitin Shekapure Stress-Straindiagram N itin Shekapure
- 82.
- 83. Material Selection Basics Why -To make full use of the engineering materials - To avoid unnecessarily expensive structures - To avoid failures When - A new product is developed - A product is modified and redesigned - Failures have occurred Who - Design engineers in collaboration with materials engineers How - Specify the requirements for the component - Transfer the requirements to materials properties - Find the material groups that satisfy the specification - Find the individual materials that satisfy the specification - identify the "best" materials that satisfy the specification N itin Shekapure
- 84. Material Selection Criteria Criteria AvailabilityThe material should be already available in the market in the abundant quantity. Cost The cost of the material selected for a particular job from several alternatives should be minimum. Material Properties The properties of the materials selected should meet the functional requirements and the service conditions. Manufacturing Considerations It has been the most important factor while selecting the material for a particular job. The materials should be selected for particular part based on the process by which it is going to be manufactured. Environmental Considerations The effect of environmental conditions [Like temperature, humidity, etc.] should be given more attention during selection of material. Machinability Machinability is the case with which a given metal can be machined. Machinability of the material depends upon hardness, strength and chemical Composition of materials. Formability It is an indication of suitability of the metal for a machine part that requires forming. Forming depends upon ductility and tensile Strength. N itin Shekapure
- 85. Cast Iron • Itis hard, brittle, nonmalleable (i.e. it cannot be bent, stretched or hammered into shape) and more fusible (capable of being melted) than steel. Its structure is crystalline and it fractures under excessive tensile loading with little prior distortion. • Most cast irons have a chemical composition of 2.5–4.0% carbon, 1–3% silicon, and the remainder iron. What is the use of cast iron? It is used to make pots and pans and all sort of instruments that are used for heating purposes. This is because the cast iron surface distributes the heat from the stone evenly all over its surface. It can also be used for baking purposes. It is even used to make stoves from a single piece of mould. Why cast iron is very brittle? The reason why is there is no carbon in it. N itin Shekapure
- 86. By: Nitin Shekapure Propertiesof Cast Irons • It has a crystalline structure, and it is weak in tension • It has excellent machinability • It has excellent wear resistance, and • It has ability to damp vibrations N itin Shekapure
- 87. By: Nitin Shekapure Advantagesof Cast Irons • It can be casting properties • It as very high compressive strength • It has a good wear resistance. • It has excellent machinability. • It has good vibration damping • It is low cost material • It can withstand greater load and has a good degree of resistance against corrosion N itin Shekapure
- 88. Applications of CastIrons • Machine tool beds, columns • Guide-ways bearing housings • Plummer blocks • I.C. engine cylinder blocks • Cylinder heads • Hydraulic cylinders gears • Gears • Pulleys • Flywheels • Couplings • Brake drums • Clutch plates Cast iron is used as a material for the following machine element N itin Shekapure
- 89. Types of CastIrons • Grey cast iron –most widely usedmaterial • White cast iron • Malleable cast iron • Ductile or nodular cast iron • Wrought iron Alloy Cast Irons Cast iron is alloyed with the alloying elements like : nickel, chromium, molybdenum, vanadium and silicon to form the alloy cost iron. The alloy cast irons are commonly usedin automobile partslike cylinders,pistons,piston rings,brakedrums,etc N itin Shekapure
- 90. Plain carbon steels •Carbon steel, or plain-carbon steel, is a metal alloy. • It is a combination of two elements, iron and carbon. • Other elements are present in quantities too small to affect its properties. • The only other elements allowed in plain-carbon steel are: manganese (1.65% max), silicon (0.60% max), and copper (0.60% max). N itin Shekapure
- 91. Types of Plaincarbon steels Low carbon steels or mild steels: The plain carbon steels with less than 0.3 % carbon are called low carbon steel or mild steel Medium carbon steels: The plain carbon steels with carbon content between 0.3 % to 0.6 % are called medium carbon steels. High carbon steels The plain carbon steels with carbon content above 0.6 % are called high carbon steels N itin Shekapure
- 92. Properties of PlainCarbon Steels • They are ductile and exhibit yielding before failure. • They have high fatigue strength, • They have high resilience and toughness. Advantages of Plain Carbon Steels • They have high tensile strength. • They are ductile, and hence exhibit yielding before failure. • They are stronger against fatigue and impact loading. • They have high resilience and toughness N itin Shekapure
- 93. Limitations of PlainCarbon Steels • They have poor wear resistance. • They cannot be cast into complex shapes. • They are poor in vibration damping. Applications of Plain Carbon Steels • Low carbon steels are used as materials for automobile body, spindles, levers, rocker arms, light duty gears, etc. • Medium carbon steels are used as materials for nuts and bolts, axles, transmission shafts crankshafts, spindles, gears, cylinders, connecting rods, etc. • High carbon steels are used as materials for coil springs, leaf springs washers, etc N itin Shekapure
- 94. Alloy Steels • Alloysteel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. • Alloy steels are broken down into two groups: low-alloy steels and high- alloy steels. • Alloy steel is a steel that has had small amounts of one or more alloying elements (other than carbon) such as such as • Manganese (Improves the strength of the steel) • Silicon (Improves elastic limit and resilience of steel) • Nickel (improves toughness, ductility, and strength) • Titanium (Improves hardness and toughness) • copper, chromium and aluminum (Improve, hardness, wear resistance, and corrosion resistance) added. N itin Shekapure
- 95. Advantages of AlloySteels Properties of Alloy Steels • Alloy steels are ductile. • They have high static strength and fatigue strength. • They are stronger than plain carbon steels. • They have high resilience and toughness • Very high tensile strength. • Very high fatigue strength. • Good wear resistance and corrosion resistance. • High resilience and toughness. • Good creep resistance N itin Shekapure
- 96. Limitations of AlloySteels Applications of Alloy Steels • Alloy steel are costlier than the cast irons and plain carbon steels • Complicated casting is not possible • They are poor in vibration dumping Alloy steels are used as materials for : • High tensile bolts • Levers • welded structures • Transmission shafts • crank shafts • Spindles • Axles • Turbine blades • Heavy forgings • High strength gears • Coil springs • Leaf springs N itin Shekapure
- 97. High Alloy Steels(Stainless Steels) • Iron based alloys i.e. steel containing at least 12 percent chromium are called stainless steels. As the content of alloying elements in these steels is more, they are also known as high alloy steels. • The most important property of stainless steels is their high corrosion resistance and have excellent heat resisting properties • They are used for high temperature chemical handling equipment, food processing equipment, spring, etc. N itin Shekapure
- 98. Non-ferrous Metals andAlloys • Non-ferrous alloys are those, which have a metal other than iron as their main constituent • The non-ferrous alloys are preferred in certain applications because of the following properties: Corrosion resistance Special electrical and magnetic properties Castability Softness and facility of cold working • The commonly used non-ferrous alloys are: Copper Alloys – Brass, Bronze Aluminium Babbits N itin Shekapure
- 99. Aluminium Alloys A largenumber of aluminium alloys are used in mechanical engineering applications. The most useful alloying elements for aluminium are : copper, silicon, manganese, magnesium, and iron. Properties of Aluminium Alloy • Low specific weight • Good corrosion resistance • High thermal conductivity • High electrical conductivity • Good castability • Low cost material • Low strength • Expensive than steel • Soft in nature N itin Shekapure
- 100. Applications of AluminiumAlloys • I.C. engine cylinder blocks • Cylinder hade • Piston • Gear box casing • Crank case • Chain covers • Pulleys • Fan blades • Aircraft parts • Ship building • Windows and door frames • Rivets N itin Shekapure
- 101. Non Metals (Nonmetallic materials) • Rubber • Plastics • Ceramics • Carbon • Glass • Leather • Asbestos • Wood N itin Shekapure
- 102. Rubber • Rubber isan elastomer (elastic material), capable of: Extension of minimum 200%, when subjected to tensile load; and Returning rapidly to original dimensions when load is removed. • Rubber behaves like a spring. Advantages of Rubber • High elasticity • Excellent resilience • Good electric insulation • Good tear resistance • Low cost N itin Shekapure
- 103. Plastics • The plasticsare synthetic materials which are moulded into shape under pressure and with the application of heat. • The plastics can be cast, rolled, extruded, laminated or machined. • The name plastic has been derived form the state of plasticity existing at a certain stage in their manufacturing. • This makes it possible to give plastic products any desired shape. N itin Shekapure
- 104. Advantages of Plastics •Low density, resulting in light weight construction • Better resistance to shock and vibrations • Better resistance to corrosion • Higher abrasion and wear resistance • Low coefficient of friction and self lubricating property • Ability to mould into complex shapes • Better surface finish and pleasing appearance • Low thermal conductivity Low cost • Easy for recycling. N itin Shekapure
- 105. Limitations of Plastics •Low strength and rigidity • Poor heat resistance • Poor dimensional stability • High coefficient of thermal expansion (five to ten times that of metal) • High creep • High deformation under continuous loading • Embrittlement (make brittle) with age and hence short life. N itin Shekapure
- 106. Type of Plastics 1.Thermoplastics or Thermoplasts 2. Thermosetting Plastics or Thermosets Thermoplastics The thermoplastics do not under go chemical change or do not become hard with the application of heat and pressure. They remain soft at elevated temperatures until they are hardened by cooling. They can be repeatedly remoulded with the application of heat and pressure. Commonly used thermoplastics : Celluloid, polyamide, polyethylene, teflon poly-vinyl-chloride (P.V.C) etc. N itin Shekapure
- 107. MCQ: 27. Mechanical propertiesof material are those properties which describe a) Mechanical strength of the material. b) Behavior of the material under use. c) Fatigue strength of the material. d) None of the above. N itin Shekapure
- 108. MCQ: 28. ________ ofmaterials are those properties which describe the behavior of the material under use a) Physical properties b) Mechanical properties c) Strength properties d) Chemical properties N itin Shekapure
- 109. MCQ: 29. The abilityof material to resist stress without failure, when subjected to a load is known as a) stiffness b) load carrying capacity c) Strength d) Toughness N itin Shekapure
- 110. MCQ: 30. The staticstrength of a material is measured by a) Yield strength b) Ultimate strength c) Fatigue strength d) both (a) and (b) N itin Shekapure
- 111. MCQ: 31. The fluctuatingload varies in a) Magnitude only b) Direction only c) Magnitude and direction both d) Magnitude and/or direction N itin Shekapure
- 112. MCQ: 32. The graphof load versus time is a straight line parallel to time axis. Then it must be a case of a) Impact load b) Static load c) Fatigue load d) Time depend load N itin Shekapure
- 113. MCQ: 33. The abilityof a material to resist stress without failure, when subjected to fluctuating load is known as a) Ultimate strength b) Static strength c) Fatigue strength d) Yield strength N itin Shekapure
- 114. MCQ: 34. The propertyof a material which enables it to regain its original shape after the external load is removed is called as a) Ductility b) Elasticity c) Malleability d) Resilience N itin Shekapure
- 115. MCQ: 35. The propertyof a material which enables it to regain the permanent deformation after external load is removed is called as a) Deformity b) Elasticity c) Malleability d) Plasticity N itin Shekapure
- 116. MCQ: 36. The propertywhich is important in forging and press work is a) Stiffness b) Elasticity c) Brittleness d) Plasticity N itin Shekapure
- 117. MCQ: 37. The propertyof elasticity is required in a) Forging and stamping b) Press work c) Ornamental work d) None of the above N itin Shekapure
- 118. MCQ: 37. The abilityof material to resist the deformation under the load is called as a) Strength b) Toughness c) Stiffness d) Ductility N itin Shekapure
- 119. MCQ: 38. The materialthat shows lack of deformation before rupture is called as a) brittle material b) ductile material c) weak material d) rigid material N itin Shekapure
- 120. MCQ: 39. If thepercentage elongation is more than 5%, it is rated a) Brittle material b) Ductile material c) Weak material d) Rigid material N itin Shekapure
- 121. MCQ: 40. If thepercentage elongation is less than 5%, it is rated a) Brittle material b) Ductile material c) Weak material d) Rigid material N itin Shekapure
- 122. MCQ: 41. _______ isan example of ductile material a) Mild steel b) Aluminum c) Copper d) All of the above N itin Shekapure
- 123. MCQ: 42. _______ isan example of brittle material a) Mild steel b) Aluminum c) Cast iron d) All of the above N itin Shekapure
- 124. MCQ: 43. In ductilematerial, the failure take place due to a) Fracture b) Fatigue c) Yielding d) Wear N itin Shekapure
- 125. MCQ: 44. In brittlematerial, the failure take place due to a) Fracture b) Fatigue c) Yielding d) Wear N itin Shekapure
- 126. MCQ: 45. Which ofthe following statements is correct ? a) Ductile as well as brittle materials show greater plastic deformation prior to fracture. b) Ductile materials show negligible plastic deformation while brittle material show greater plastic deformation before fracture. c) Ductile materials show greater plastic deformation while brittle material show negligible plastic deformation before fracture. d) Ductile as well as brittle materials show negligible plastic deformation before fracture. N itin Shekapure
- 127. MCQ: 46. The propertyof material which enables it to undergo change in shape; and size without rupture, under external load is called a) Ductility b) Malleability c) Plasticity d) Toughness N itin Shekapure
- 128. MCQ: 47. The propertywhich is important in wire drawing is a) Ductility b) Malleability c) Plasticity d) Resilience N itin Shekapure
- 129. Basic Mechanical Engineering By NitinG Shekapure Unit II Design Fundamentals (L16 & L17) N itin Shekapure
- 130. Mechanism and Machine By:Nitin Shekapure Machine is a device which receives energy and transforms it into some useful work. A machine consists of a number of parts or bodies. Mechanism is a system of parts working together in a machine; a piece of machinery A mechanism is something that changes an input motion and force into an output motion and force. N itin Shekapure
- 131. Mechanisms require sometype of Motion There are four types of motion: N itin Shekapure
- 132. Structure It is anassemblage of a number of resistant bodies (known as members) having no relative motion between them and meant for carrying loads having straining action. A railway bridge, a roof truss, machine frames etc., are the examples of a structure. By: Nitin Shekapure N itin Shekapure
- 133. Different types ofmechanisms • Levers • Linkages • Gears • Wheels • Cranks and ratchets • Cams • Chain & Sprocket By: Nitin Shekapure N itin Shekapure
- 134. Levers A lever isa rigid beam that can rotate about a fixed point called the fulcrum (support). An effort applied to one end of the beam will cause a load to be moved at the other. By: Nitin Shekapure N itin Shekapure
- 135. Linkage A linkage isa mechanism made by connecting together levers. The linkage can be made to change the direction of a force or make two or more things move at the same time. Push/pull linkageReverse motion linkage N itin Shekapure
- 136. Gears Gears are toothedor pegged wheels meshed together to transmit motion and force. In any pair of gears the larger one will rotate more slowly than the smaller one, but will rotate with greater force. By: Nitin Shekapure N itin Shekapure
- 137. A Cam changesrotary motion to linear motion. They are found in many machines and toys. Cam By: Nitin Shekapure N itin Shekapure
- 138. Crank and SliderMechanism This mechanism is composed of three important parts: The crank which is the rotating disc, the slider which slides inside the tube and the connecting rod which joins the parts together. N itin Shekapure
- 139. Ratchet Mechanisms A ratchetmechanism is based on a wheel that has teeth cut out of it and a pawl that follows as the wheel turns. By: Nitin Shekapure N itin Shekapure
- 140. Mechanisms • Mechanisms areused to convert between one type of motion and another. • Mechanisms are used to make machines. • Machines are made to do repetitive tasks with consistently uniform output. • Machine is a device consisting of mechanisms to perform intended tasks. N itin Shekapure
- 141. Kinematic Link orElement Each part of a machine, which moves relative to some other part, is known as a kinematic link (or simply link) or element. Types of Link In order to transmit motion, the driver and the follower may be connected by the following three types of links : • Rigid link • Flexible link • Fluid link By: Nitin Shekapure N itin Shekapure
- 142. Rigid link: A rigidlink is one which does not undergo any deformation while transmitting motion. Strictly speaking, rigid links do not exist. However, as the deformation of a connecting rod, crank etc. of a reciprocating steam engine is not appreciable, they can be considered as rigid links. N itin Shekapure
- 143. Flexible link: A flexiblelink is one which is partly deformed in a manner not to affect the transmission of motion. For example, belts, ropes, chains and wires are flexible links and transmit tensile forces only. N itin Shekapure
- 144. Fluid link: A fluidlink is one which is formed by having a fluid in a receptacle and the motion is transmitted through the fluid by pressure or compression only, as in the case of hydraulic presses, jacks and brakes. N itin Shekapure
- 145. Mechanisms are madeof links/elements Link: It is a resistant body, which does not deform while transmitting motion, force or power. Kinematic pair: Two elements or links joined together such that the relative motion between them is predefined. Link - It must be a resistant body. It must be connected to the other parts of the machine. It must have motion relative to other connected parts of the machine. By: Nitin Shekapure N itin Shekapure
- 146. Kinematic Pair Two linksconnected together to produce a definite constrained motion is called kinematic pair. Examples • A rounder in a compass box • Scissors • A folding knife By: Nitin Shekapure N itin Shekapure
- 147. Kinematic Chain A kinematicchain is formed by arranging number of links which move relative to each other following a definite constrained motion. Types of Kinematic Chain 1. Four Bar Chain 2. Slider crank chain 3. Double slider crank chain N itin Shekapure
- 148. Four Bar Chain(Quadric Cycle Chain) • Four bar chain is the simplest and the basic kinematic chain. • It consists of four links, each of them forms a turning pair at A, B, C and D. • The four links may be of different lengths. • According to Grashof ’s law for a four bar mechanism, the sum of the shortest and longest link lengths should not be greater than the sum of the remaining two link lengths if there is to be continuous relative motion between the two links. • A very important consideration in designing a mechanism is to ensure that the input crank makes a complete revolution relative to the other links, Such a link is known as crank or driver . N itin Shekapure
- 149. • In afour bar chain, one of the links, in particular the shortest link, will make a complete revolution relative to the other three links, if it satisfies the Grashof’s law. Such a link is known as crank or driver. • AD (link 4 ) is a crank. • The link BC (link 2) which makes a partial rotation or oscillates is known as lever or rocker or follower • and the link CD (link 3) which connects the crank and lever is called • connecting rod or coupler. • The fixed link AB (link 1) is known as frame of the mechanism. Four Bar Chain (Quadric Cycle Chain) N itin Shekapure
- 150. Single Slider CrankChain • single slider crank chain is a modification of the basic four bar chain. • It consist of one sliding pair and three turning pairs. • It is, usually, found in reciprocating steam engine mechanism. • This type of mechanism converts rotary motion into reciprocating motion and vice versa. The links 1 and 2, links 2 and 3, and links 3 and 4 form three turning pairs while the links 4 and 1 form a sliding pair. N itin Shekapure
- 151. Single Slider CrankChain • The link 1 corresponds to the frame of the engine, which is fixed. • The link 2 corresponds to the crank. • The link 3 corresponds to the connecting rod. • The link 4 corresponds to cross-head. • As the crank rotates, the cross-head reciprocates in the guides and thus the piston reciprocates in the cylinder. By: Nitin Shekapure N itin Shekapure
- 152. Double slider crankchain • A kinematic chain which consists of two turning pairs and two sliding pairs is known as double slider crank chain, • We see that the link 2 and link 1 form one turning • pair and link 2 and link 3 form the second turning pair. The link 3 and link 4 form one sliding pair and • link 1 and link 4 form the second sliding pair. By: Nitin Shekapure N itin Shekapure