An analysis of riveting process by theoretical, nonlinear finite element and experimental methods.

摘要

In this dissertation, the riveting technique and the research on this area are concluded and classified based on the extensive literature review. Multiple parameters that affect riveting process and the quality of riveted joint are investigated using theoretical, nonlinear finite element simulation and experimental methods.; Riveting using a slug rivet is simpler than using other rivets, comparatively. Using thick wall theory, a formula, considering the effect of friction between the dies and rivet ends, is developed to calculate upset force during the compression of single rivet or initial stage of the riveting process. Formulas used for the calculation of material growth and stress are conducted. A governing equation that involves the effects of radial pressure, clamp pressure, critical upset force, current upset force and other material and geometric parameters, is also derived.; Due to the high non-linearity of the riveting process, research using only theoretical methods is limited. HI-DYNA2D, an explicit, nonlinear finite element code, is used to simulate axisymmetric riveting problem of two circular sheets riveted by a slug or a countersunk rivet. Material type 3 with bilinear strain and stress relationship and strain hardening is used to model both rivet and sheet material. Automatic contact function in the code is used to generate the contact interface condition. The friction existing between each two contacting parts is considered in the model. The effects of friction coefficient to the formation of rivet driven head and the whole riveting process are investigated.; Currently, in the riveting process the clamp is used only to hold parts and avoid the effect of hole drilling to the riveting. In this dissertation, clamping method is investigated for its effect on material and residual stress. Riveting using the countersunk rivet is modeled and analyzed with DYNA2D.; To support the FEA model, simple compression tests of single rivet are performed. Furthermore, the upset force variation with die displacement in low speed riveting is studied with the riveting machine modified from MTS instrument, and the spring back of the rivet after riveting is observed and measured. The non-homogenous hole expansion is observed after being cut through the center plane of riveted joint, and the value of material growth at hole edge is measured with Optical Comparator instrument. (Abstract shortened by UMI.)