7.32 experimentally, it has been observed for single crystals of a number of metals that the critical resolved shear stress τcrss is a function of the dislocation density rhod aswhere τ0 and a are constants. for copper, the critical resolved shear stress is 2.10 mpa (305 psi) at a dislocation density of 105 mm-2. if it is known that the value of a for copper is 6.35  10-3 mpa-mm (0.92 psi-mm), compute the crss at a dislocation density of 107 mm-2.

Ajournal bearing has a journal diameter of 3.250 in with a unilateral tolerance of 20.003 in. the bushing bore has a diameter of 3.256 in and a unilateral tolerance of 0.004 in. the bushing is 2.8 in long and supports a 700-lbf load. the journal speed is 900 rev/min. find the minimum oil film thickness and the maximum film pressure for both sae 20 and sae 20w-30 lubricants, for the tightest assembly if the operating film temperature is 160°f. a computer code is appropriate for solving this problem.

Draw the engineering stress-strain curve for (a) bcc; (b) fcc metals and mark important points.

Which from the following instrument is commonly used to detect the high pitch butzing sound in bearings? [clo4] a)-digital ultrasonic meter b)-infrared camera c)-spectroscopic d)-vibrometer