Homework #08

DUE: Wednesday, November 30, 2016 before noon in Box B in the MAE department.

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Problem 1

A steel tensile link with a circular cross section with no stress concentrations is subjected to a fluctuating load (1000 to 5000 lbs). Use \(S_{ut}=150\mathrm{kpsi}\), \(S_y=120\mathrm{kpsi}\). Assume a highly polished specimen and design factor of 2. Find the diameter for infinite life and for \(10^3\) cycles.

Problem 2

The element shown below is subjected to a fluctuating load that ranges between 4 kip in tension and 14 kip in compression. The dimensions are \(r=0.313 \mathrm{in}\), \(d=0.5\mathrm{in}\), \(h=0.375\mathrm{in}\), \(w=4\mathrm{in}\). Determine the factor of safety if the material is cold drawn AISI 1018 steel.

Problem 3

The AISI hot rolled 1020 steel element shown is welded to the fixed plate with a 0.125" fillet weld. This fillet introduces stress concentration factors of \(K_{t}=1.8\) and \(K_{ts}=1.6\). The dimensions are \(d=0.875\mathrm{in}\), \(l_1=4\mathrm{in}\), \(l_2=3\mathrm{in}\). The load F cycles from 50 lbs to 100 lbs. Using the Goodman criteria for fluctuating stress, find the factor of safety at point A with respect to infinite life or the number of cycles to failure for finite life.