If for some viscoelastic polymer, the stress decays over time and follows the equation σ(t)=σ(0)exp(-t/τ), (equation 15.10). determine the relaxation modulus at 15s if the initial stress was 3mpa, the intial strain was 0.5 and the relaxation time is 20s.

Abrake has a normal braking torque of 2.8 kip in and heat-dissipating cast-iron surfaces whose mass is 40 lbm. suppose a load is brought to rest in 8.0 s from an initial angular speed of 1600 rev/min using the normal braking torque; estimate the temperature rise of the heat dissipating surfaces.

Afull journal bearing has a journal diameter of 27 mm, with a unilateral tolerance of -0.028 mm. the bushing bore has a diameter of 27.028 mm and a unilateral tolerance of 0.04 mm. the l/d ratio is 0.5. the load is 1.3 kn and the journal runs at 1200 rev/min. if the average viscosity is 50 mpa-s, find the minimum film thickness, the power loss, and the side flow for the minimum clearance assembly.

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