4. Describe two examples each from mechanical and electronic engineering by which extreme load and

strength values are curtailed, in practical engineering design and manufacture.

7. Electrolytic capacitor leads are designed to withstand a repetitive load applied to a circuit board mounted

on a moving platform. The lead's yield stress is normally distributed with the mean of 100 MPa and the

standard deviation of 20 MPa. The stress generated as a result of the repetitive load during the capacitor's

life time is also normally distributed with the mean of 60 MPa and the standard deviation of 15 MPa:

a Calculate the safety margin, SM.

b Calculate the loading roughness, LR.

c Calculate the expected reliability of the capacitor.

8. A connecting rod must transmit a tension load which trials show to be lognormally distributed, with

the following parameters: = 9.2 and = 1.1. Tests on the material to be used show a lognormal

strength distribution as follows: = 11.8 and = 1.3. A large number of components are to be manufactured,

so it is not feasible to test each one. Calculate the expected reliability of the component using

Monte Carlo simulation.