Possible questions for the Mid-term exam 1. Why do we study Engineering Material
ID: 1766835 • Letter: P
Question
Possible questions for the Mid-term exam 1. Why do we study Engineering Materialst? 2. What is a material property? Please indicate how material properties are divided? Give two examples of each property. Give real life applications for each example of property Briefly explain the followings with their characteristics: metals, ceramics, polymers, composites. 3. 4. List five of the physical properties. 5. What are the steps of materials selection process? 6. What is the MSE triangle? 7. What is the tensile testing? Please draw a proper stress-strain curve to explain the following: yield point, Tensile strength, ductility, modulus of elasticity, percent elongation at fracture, toughness, resilience What is the purpose of a notched Izod test? Picase define the property evaluated during an impact (Izod) test? What is the theoretical principle underlying the test? Please explain in Idetail? Name a couple of real life examples in which lzod test should be pertformed 8. 9. Label the following diagrams: Hild SteelExplanation / Answer
1) the value of any material is because of its properties. while making any product, a suitable material is chosen and it may be because of its elastisity, strength, heat resistance, ductility or for any other reason; but they all relate to properties. and all these properties are because of their microscopic structure. the way the atoms are joined, the way their groups are formed, etc. all these things influence the properties. in engineering materials, one learns how to control the structure so that properties which are desired are expressed in the final product whilst remaining economical.
2) it is an intensive attribute or characteristic of the material that distinguishes one material from another. the properties are categorised as :
a) chemical property :- i) corrosion resistance- eg. chosing of material for turbine blades
ii) reactivity- eg. in refrigeration, copper pipes are not chosen when ammonia is used as refrigerant because of their reactivity
b) electrical property: i) resistivity- eg. in designing the resistances for electrical circuit
ii) peizoelectricity- eg. the crystals are used in watches for this property
c) magnetic property : i) permeability- eg. property used for selectng suitable materials for electromagnets
ii) hysterisis - eg. signal filters in thermostats
d) manufacturing properties-: i) machinability- eg. sulfur is added to steel so that it can be machined
e) mechanical properties: i) ductility- copper is chosen for making electrical wires
ii) specific weight- aluminium for making aeroplane fuselage
f) optical property: i) refractive index- eg. choosing of material for optical fibres
ii) photosensitivity- eg. solar panels
g) thermal property: i) coefficient of thermal expansion: eg. use of shrink fits
ii) thermal conductivity : eg choosing materials for fins
3) metals- they have metallic bonds, that is, they have electrons that are shared by each and every atom. chracteristic- lustre, good electrical conductivity, high melting temperatures
ceramics- crystalline compounds between metals and non metals. char: britlle, high hardness, insulators.
polymers- large molecular chains of carbon and hydrogen derivatives. char: low density, flexible, insulators
composites- compostion of two or three materials. char: the characterisitcs of composites depend upon the constituents.
4) physical properties: ductility, malleability, strength, toughness, hardness