7078

Formulate the problem of minimum weight design of a power screw subjected to an axial load, F, as shown in Fig. 1.27 using the pitch (P), major diameter (d), nut height (H), and screw length (s) as design variables. Consider the following constraints in the formulation:

1. The screw should be self-locking [1.67].

2. The shear stress in the screw should not exceed the yield strength of the material in shear. Assume the shear strength in shear (according to distortion energy theory), to be 0.577^ where oy is the yield strength of the material.