Investigation Of Self-Piercing Riveting With Half-Hollow Rivets

Technology of self-piercing riveting (SPR) with half-hollow rivets has been successfully applied to joining difficult-to-weld as well as dissimilar materials for lightweight automobile body construction. However, systematic theoretical and experimental investigations of SPR have been lacking. In this thesis, the technology of SPR with half-hollow rivets is investigated thoroughly using experiments and numerical simulations with 6063 aluminum alloy sheet. The mechanical properties of riveted joints of are studied. The main contributions of this dissertation are as follow:1. A set of design principles for SPR with half-hollow rivets are proposed based upon thorough investigation of the SPR process. Methods for rivet size selection and die geometry parameters calculation are given. Relationships between rivet size, die cavity, pip height and sheet thickness are also established.2. The mechanics of SPR process is investigated using the SPR system designed by the candidate and her faculty team. Experiments and numerical simulation are used to obtain a punch load vs. punch displacement curve, which relates to the four phases of rivet piercing, insertion and deformation process.3. A set of criteria for visual inspection of SPR joint quality are proposed. Experimental method is used to study the effect of die geometric variables, rivet geometric variables, rivet hardness and sheet thickness on the riveting load and riveted joint apparent quality in the riveting process. Using finite element method, the effect of the geometric parameters of die, rivet and sheet on riveting process is analyzed comprehensively.4. Computation and experiments are carried out to study the static load performance characteristics of SPR lap joints and T-joints. The effect of die geometry, rivet hardness and material thickness on tensile strength is analyzed. It was discovered that the die pip height and sheet thickness have a strong influence on the tensile behavior.5. The concept of"Equivalent Width"and its calculation method are proposed by comparing the strength of a sheet sample with the strength of a SPR joint."Equivalent Width"provides guidance in designing the pitch in multi-riveted structures.6. The performance of SPR joints is compared with the resistance spot welded (RSW) joints of the same sheet material. It is shown that SPR joints have superior static and fatigue performance. The displacement to failure in SPR joints is also higher than RSW joints. Therefore, SPR joints can absorb more energy than RSW joints.