An ‘‘Allen’’ wrench is used to loosen a bolt that has a
hex-head cross section. As shown in Figure P11–18. This wrench is a 5 mm size
and is made of quenched and tempered carbon steel with modulus of elasticity of
200 GPa, Poisson’s ratio of 0.29, and yield strength of 615 MPa. The wrench is
used to loosen a rusty bolt. To simulate the fixity a
surface 2.5 mm in depth from the bottom is held fixed. A
total force of 125 N is applied uniformly over 25 mm at the end of the
horizontal section of the wrench. Determine the maximum von Mises stress in the
wrench. Also determine the maximum displacement. Comment on the safety of the
wrench based on whether it will yield or not. (This problem is compliments of
Justin Hronek.)
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