Stress concentrations Develop on polished smooth surfaces in

Stress concentrations Develop on polished smooth surfaces increase rapidly under static loading Amplify crack inducing bending stresses All of the above None of the above steel(1100 MPa ultimate strength) coupon specimen falls after 150,000 cycles. What stress was applied? 724 MPa 624 MPa 650 MPa None of the above Yielding implies: plastic deformation below the elastic limit Elastic stress proportional to curvature Loading beyond the elastic limit Linear spring defining elasticity None of the above A machine part must break to fail True False A new connecting rod design proposes to use a new chromium steel alloy which is capable of 260 ksi ultimate strength. Give Marin factors of 0.158 and 0.907, what is its endurance limit? 14.3 ksi 18.6 ksi 10.0 ksi None of the above Misalignment in machines can produce wear between gear Align bearings and wheels Reduce vibration and noise All of the above None of the above A load line defines the neutral axis of bending True False Name: In considering material treatment and fabrications methods decisions, Factor of safety is automatic compare strength with damaging stress principal stresses must be tensile All of the above None of the above Iron alloys differ from aluminum in that iron alloys are always more ductile are much less susceptible to fatigue can be sized for infinite life have coupon tests All of the above None of the above endurance strength of a coupon specimen machined from AISI 1035 cold drawn steel is: 40.0 ksi 33.5 ksi 39.5 ksi 59.0 ksi None of the above One advantage of maximum shear stress over distortion energy failure analysis is accuracy improved shear stress failure prediction better correlation with normal stress theory more conservative none of the above steel machine part differs from its coupon specimen because Marin factors increase endurance strength Different materials are generally used for steel S - N curves Different surface treatment is used All of the above None of the above

Solution

1 C. The stress concentration takes place at the cracks and notches.

3 C. The yielding signify the load beyond elastic limit and start of plastic deformation.

4 False machine parts are taken as failed as they are plastically deformed.

6 E. Misalignment results in vibration and noise.