quiz answer

MCQ

1) C

2) A

3) D

True/false

1) True

2) False

3) True

Answer the following

1)

The temperature of the body will reach maximum at the necking region. Necking, is a mode of tensile deformation where relatively large amounts of strain localize disproportionately in a small region of the material leading to a considerably large amount of inter-molecular disturbance which may lead to higher temperatures.

2)

The compressive testing machine requires higher capacity as the compressive loads are generally much larger compared to tension loading. Generally bodies under compressive loading show a much greater resistance to deformation under tensile loading. Hence very high magnitude force is required to reach the point of failure.

3) a>c>b

Smooth and geometrically continuous transition edges help in reducing stress concentration. The fillets distribute the stress over a broader area and effectively make the parts more durable and capable of bearing larger loads. The object a has a very sharp corner so has maximum stress concentration. The object c has two sharp corners but one broad edged corner which helps to reduce stress concentration to some extent. Object b has a rounded edge which can help in uniform distribution of stress around the corner leading to least stress concentration.

Stress concentration is the accumulation and localization of mechanical stress at certain specific regions in a given body owing to geometrical or shape related discontinuities or discontinuities in loading conditions. Stress concentration usually happen at sharp edges or corners or cracks wherein there is a sudden change in shape size. The more uniform a design is the lesser is the stress concentration. Other modes of avoiding stress concentration are to make holes at corners.

4)

A r/d=0.1 D/d=2 K=1.82

B d/w=0.25 d/h=1 K=1.8

5

a)

Rubber has the least resistance to deformation.

It has the least young’s modulus and therefore force required to deform it is the least as compared to the other materials.

b)

Concrete has the least contraction strain amongst the given materials.

Poisson\'s ratio is the ratio of transverse contraction strain to longitudinal extension strain in the direction of stretching force.

6)

please refer to the link for solution photo

https://drive.google.com/open?id=1CVAcyB_a716FGvgJE44_Dy1slhcbSOZp

a)

K= 20 -20 0 0

-20 50 -30 0

0 -30 70 -40

0 0 -40 40

b)

D2= 0.0724m

D3=0.054m