Question

QUESTION 6 ONLY

QUESTION 5 a) Excluding diamond and graphite, which three ceramic materials in the list of materials for which data has been provided (see spread sheet) have the highest heat/thermal shock resistance. You will need to perform calculations [2] b) Which of these three materials would be best suited for making a boiler window? Indicate why? If none of the three materials are suitable for a boiler window, explain why. [2] QUESTION 6 The modulus of resilience U, is a measure of the energy per unit volume that a material can absorb elastically, i.e. without experiencing significant plastic deformation or fracture. Look up its formula if you have forgotten. It is in the set of slides on Mechanical Behaviour. Use the list of materials for which data has been provided (see spread sheet), to find the material that has the highest modulus of resilience amongst the a) Ferrous alloys b) Non ferrous alloys and metals c) Ceramics d) Polymers When doing the calculation use the strength data for the elastic limit which is in the column marked failure strength (Column J). [4] QUESTION 7 When selecting materials for knife blades, good performance requires good strength, to prevent plastic indentation and/or fracture, and high modulus to prevent elastic flattening which would increase friction. Motion Load P Knife Edge A Block 12

The modulus of resilience Ur is a measure of the energy per unit volume that a material can absorb elastically, i.e. without experiencing significant plastic deformation or fracture. Look up its formula if you have forgotten. Use the list of materials for which data has been provided (see spread sheet), to find the material that has the highest modulus of resilience amongst the

a) Ferrous alloys

b) Non ferrous alloys and metals

c) Ceramics

d) Polymers

When doing the calculation use the strength data for the elastic limit which is in the column marked failure strength. [ Whilst its noted that ' failure strength doesn't indicate elastic limit ', in the case of this question can you please make an assumption as the question was given as it is by my institution?]

Answer 1

Op Assumption - 1 Every given material has definite yield point 27 Yield point is represented as Elastic limit of materials. Modulus of Resilience is the energy absorb by material within Elastic limit. It is Proof Resilience, which gives energy absorb upto Elastic limit. 2 Modulus of Resilience = Jy 2 E Ferrous Alloys :- Considering out of ferrous alley : Highest Yield Strength ith material 44DA Stainless steel, tempered @ 135 315°C Gy= 1650 mpa ; E= 200 G Pa (1650) M.O.R. = = 6.80 m Pq. 2x (200x10) 2

b) Non-ferrous alloys and metals:- Non-ferrous alley / Metal having highest Yield ad strength :- C17200 Beryllium Copper alloy, Solution heat treated, aged @ 330°C :- by = 1125 MPa ; E= 128 G Pa 2 2 бу (1125) 4.94 MPa MOR= - 2E 3 2 x 120 x 10 C) Ceramic: Ceramic having Highest Yield strength. Zirconia , 3 mol % Y₂ 0₃ sintered & Ty= 1265 MPa E = 205 G Pa 2 2 MOR= 2E - (1265) 2x (205) x103 = 3.90mpa. d) - Polymers:- Polymers having Highest Yield Strength ? Poly Ether Ether keton; Ty=95 mpa, E= 1-1 G Pa MOR= 2E oy? (952 2X 1-110 4-10 MPa.

Assangin en Ascending order of MOR.:- [mor} <[MOR}<[ [mor] < [mor Fersous Ceramic Polymer Non- Ferrous Highest Modulus of Resilience is for ferrous-alloys. Considered Highest yield strength for calculating MoR because higher the yield strength, Higher the modulus of Resilience.