Enhancing Load Capacity of Plastic Gears Via the Application of Woven Composite Blankets

Abstract

In this work, the application of a woven composite fabric covering the surface of the fillets of the teeth of plastic gears is proposed to increase their loading capacity. Tip-relief is also applied to avoid severe edge contacts and peaks of high contact stresses as well as to achieve a smooth load transfer between consecutive pairs of contacting teeth. The investigation is carried out using the finite element method (IGD/ANSYS). A five-tooth model is applied for the gears, and nylon and carbon/nylon are adopted as materials. The evolution of the maximum contact stresses as well as maximum bending stresses is evaluated over two cycles of meshing for both the pure plastic (nylon) gears and the gears with the composite blanket (carbon/nylon). The results indicate that, for the case considered, covering the fillets of the gears with composite blankets reduces the bending stresses in the plastic material at the fillet region but does not consistently alleviate the contact stresses, and subjects the composite blankets to high level of stresses. However, in general, for the specific case studied, the set of gears safely tolerated double the torque recommended by VDI 2545 standard and consequently may be a viable method for increasing the load capacity of plastic gears.