In designing lead screws, not intended to carry large loads, is often choice to use a material combination of steel screw and polymer nut. Due to significant strength differences, the nut is considered as a critical component. The thesis presents a comparison between analytical and numerical methods for stress determination in critical points of a thread. Comparison has shown accuracy limitations of analytical methods, which are based on threaded fasteners theory. With the use of finite element method, we have analyzed the influence of thread geometric parameters on stress concentration in two critical points. Different boundary conditions on the nut of lead screw, were evaluated from the stress concentration point of view. It was concluded that the most effective way for reducing contact stress is aligning screw thread tip with the nut thread root.
|
