Question

True of False

1.If a material point has three principal stresses ?1 = ?2 = ?3 = 300????, then the maximum shear stress is ???? = 150????.

2.The endurance limit of a material is independent on the size of a part.

3.The tensile stress in a bolt is usually calculated through tensile force divided by area of unthreaded rod’s cross-section area.

4.Edge shear-out or tear-out is one failure mode in bolted or riveted joints.

5.Pretension of bolts can be controlled by a torque wrench.

6.The material ultimate tensile strength of a spring coil is dependent on its coil diameter.

7.Steels’ surface fatigue strength can be correlated to their Brinell hardnesses.

Answer 1

(1) False Reason Tmax = mar (1521, 1 62-6121.15-21) since 6 = 62.63 Tmax (2) False : Reason: As size increases defects in parts increase reducing limit. endurance (3) False Reason GE= core Aca Area of els at the diameter. Ác (4) Tyye: Reason Edge tear a kind of failure in which the plate tears at the edges, before failure of rivets. out is (s ) True : Reason Pretension can be altered using torque Wrenches. (6) False; Reason Ultimate tensile strength is an material property and don't change with dimensions.

(71 True : Reason surface fatigue strength for steel: (Sew) Sew =(2.76 BHN-70 J MPa