Problem 8.33 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, asτ (cross) = τ(0) + a(rhod)^1/2where τ0 and a are constants. for some metal, the critical resolved shear stress is 4.9 mpa at a dislocation density of 1.8 x 104 mm-2. if it is known that the value of a for this metal is 2.5 x 10-4 mpa-mm, compute the τcrss (in mpa) at a dislocation density of 2.9 x 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.