RECENT ASSIGNMENT

Assignment 1
Stress strain diagram of a material is given in Figure QI after tensile testing was performed. The specimen has an initial diameter of 10 mm and an initial gauge length of 50 mm.

0 0.25 0.5 0.75 I 1.25 1.5 1.75 2 2.25
Strain, %

Fig. QI stress strain diagram of a tensile testing
By using the provided diagram, determine the following
(i) The modulus of elasticity of the material
[20 Marks]
(ii) The Yield Strength
[5 Marks]
(iii) The maximum stress in the elastic region
[5 Marks]
(iv) The allowable stress with a safety factor of 1.1
[5 Marks]
(v) The ultimate strength of the material
[5 Marks]
(vi) The ductility of the materials
[10 Marks]
(vii)The energy generated for the elastic deformation
[10 Marks]
Creep is a continued increase in the strain of material with time under action of constant stress and it can be perfomed under different environmental temperatures. Complete figure Q 2 and explain briefly the effect of the temperature and the stress on the strain behaviour of metal materials.
[20 Marks]
Answer of O I-B

QI-c
You have learnt that the strength of the materials deteriorate under fatigue stress (reversible stress or fluctuated). Complete figure QI-C to show the strength behaviour of mild steel and aluminium metals at different reversible number of cycles.
[20 Marks]
600

Number of cycles to failure
Figure Q I-C Typical strength behaviour of mild steel and aluminium metals under fatigue loading condition