B Pre Lab Quiz Answers

MAE244

Tensile Test and Impact Test

Pre-Lab Quiz - 1

Pre-Lab Quiz for Tensile and Impact Tests Section ### : Name (Print): Student ID : 1.

In determining the load-deformation behavior of materials, why is the data presented in the form of P/A vs. ∆L/L instead of P vs. ∆L? The stress-strain plot is independent of the dimensions of the specimen.

2. What is Young's modulus and what are the units? Elastic constant relating strain to stress, i.e. stiffness constant (amount of stress per unit strain), measured in units of pressure, as the slope of the stress-strain diagram. The ratio of lateral to longitudinal strain in uniaxial stress is referred to as _ Poisson's ratio .

4.

For a given alloy, the stress-strain curve is obtained as shown in the figure, estimate the yield Stress. 66 ksi

5. What is Young's Modulus for the alloy shown in the figure? 66 ksi / 0.003 = 22 msi Or 66 ksi / 0.003 = 22 x 106 psi 6.

Stress (ksi)

3.

80 70 60 50 40 30 20 10 0 0

0.002

0.004

0.006

0.008

Strain (in/in)

Impact test is used to evaluate material’s resistance to __Fracture___.

7. In an impact test, the hammer with the mass of 10 kg, is released from the height 1.3m and strikes and breaks the specimen and rises to 0.7m. What is the impact energy of the specimen? Cv = mg(h-h’) = 10kg x 9.8m/s2 x (1.3-0.7)m = 58.8 J 8. Fracture surface can provide the information of material toughness. Ductile materials show a _

_fibrous__

materials show _ _cleavage_ __ failure.

_ failure on the fracture surface, while brittle