Question

Problems 9.10. 11. & 12 The stress-strain diagrams for two materials are provided oksi 60 Material A 40 - Material B 0.015 &, in in 0.001 0.006 0.009 Problem 9 Determine modulus of elasticity for material A. a) 0,0001 ksi b) 10,000 ksi c) 29,000 ksi d) 40,000 ksi e) 60,000 ksi Problem 10 What is the modulus of resilience for material B? a) 0.58 kip-in/in b) 0.36 kip-in/in c) 0.18 kip-in/in d) 0.02 kip-in/in e) None of the above Problem 11 Which material is tougher as determined by the modulus of toughness? a) A is tougher b) B is tougher c) None of the above d) Not enough information Problem 12 What axial load will cause a bar with a 2" by 2" cross section made from material Bto yield? a) 240 kips b) 15 kips c) 160 kips d) 10 kips e) None of the above

Answer 1

Problem 9. We know that Modulus of elasticity for Material Ao → TXE 5 = EE From stress-strain diagram: Ty= = 60ksi E = 0.006 } upto elastic linat 10,000ksi. Ty So E= 0.006 E Hence, B is correct. Problem 100 Modulus of resilience for Material B; Modulus of resilience = Area of curre under the elastic limit, 2 x 40 x 0.001 0.02 kip-in /ins Hence, D is correct. So, Toughness = Total area For A ; Problem 11 = Total area under stress-strain curie upto fracture (5 x 60X 0.006 ) + ( 60 X 0.003 0.184 0.18 0.36 kip- ensin For B; Toughness: → (2 x 40 x 0.001) +(40X0.014) - 0.02 +0.56 0.58 kip-infin Hence Material B is tougher option B.

Prob. 12 Areaz 2"x2" e 4 in 2 For Material B, yelld stress = 40 1. Ksi stress a → So, Load Area. P oya Area 40= P 4 P= 160 kips.