Week 2

A steel bar of a constant circular cross-section has an initial diameter of 1 cm. When it is subjected to a tensile force of 65 N on both ends, the area is reduced to 65m * m ^ 2 Calculate the true stress and engineering stress at this moment.

• True stress = 1 N/mm², Engineering stress = 82.8N / m * m ^ 2

• True stress 0.828 N/mm², Engineering stress = 1 N/mm²

• True stress 82.8 N/mm², Engineering stress = 1 N/mm²

• True stress = 1 N/mm², Engineering stress = 0.828N / m * m ^ 2

The Figure given below shows the variation of shear stress to shear strain rate for different materials (A, B, C, and D). Consider rheological properties and assign appropriate materials for A, B, C, and D. Choose the best option among the choices given.

• a-iii, b-i, c-ii, d-iv

• a-i, b-iii, c-iv d-ii

• a-i, b-iii, c-ii, d-iv

• a-ii. b - iv ,c-iii,d-i

During the creep deformation of steel, A is constant, whereas during the relaxation of steel, B is constant. What are A and B?

• A is the load acting on steel, and B is the stress acting

• A is the stress acting on steel, and B is the strain

• A is the strain, and B is the stress acting on steel during relaxation

• A is the strain during creep deformation, and B is the Poisson's ratio.

Viscoelastic materials become hardened at lower temperatures and become softer at higher temperatures.

• True

• False

The impact energy absorbed by the sample______as the failure mode of a material changes from brittle to ductile.Increases

• Increases

• Decreases

• Remains same

• Decreases till the brittle to ductile transition temperature and then increases

Which type of the following metals will be best for a different application in the cold region of Alaska (temperature < -30 °C) considering ductile to brittle transition of materials?

• Steel

• Aluminium

• Stainless steel

• Copper

Which of the following load parameters are required to design fatigue-resistant structures?

• Average of stresses

• Amplitude of stress

• Type of stresses

• Range of stress

A building in Dubai is required to be designed for good thermal comfort. Among the options given below, which of the following types of wall material will be suitable?

Note: The thicknesses of all walls are the same.

• Denser concrete block

• Lightweight hollow brick

• High strength steel

• Lightweight concrete block

It is required to construct a Military bridge across the Jhelum River in Jammu and Kashmir. Three materials are considered for building this bridge: materials A, B, and C. The Figure below shows the S-N curve of these materials. Analyze the Figure and choose the appropriate answer(s) from the options.

• Material A should be selected because it could resist a higher number of cycles to failures for a particular fatigue strength as compared to B and C.

• Material C should be selected because it could resist a higher number of cycles to failures for a particular fatigue strength as compared to A and B.

• For 10" number of cycles to failure, Material A will resist higher fatigue strength as compared to B & C

• For fatigue strength of 90 N/mm² and 10' number of cycles to failure, Material C should be selected as compared to A & B.