Mechanical Properties Of Single Lap-jointed Spr Joints

Due to the urgent demand for energy-efficient vehicles, there is an increasing need to design lightweight structures such as vehicle body shells, and these invariably use lightweight materials which are difficult or impossible to weld. Self-piercing riveting technology is an efficient method of connection for lightweight materials. In this paper, the mechanical properties of single lap-jointed self-piercing riveted (SPR) joints were studied.In this thesis, finite element analysis (FEA) model of a single-lap jointed SPR joint was established, including the static analysis, dynamic analysis and fatigue analysis. In order to get accurate simulation results, a joint simulation of fatigue analysis was done by using ANSYS and FE-SAFE analysis of post-processing modules.The static analysis of riveted connections indicate high tensile stress concentrations in the upper sheet hole, near the faying surface. Static analysis provides the information of stress on the nodes for fatigue analysis. The mechanical behavior of a single lap-jointed SPR and a single lap-jointed clinched joints under the static loads was studied by experiments.The mode shapes show that odd mode shapes of transverse free vibration were found to be symmetrical about the mid-length position and at the peak of the mode shapes; and for even mode shapes of torsional free vibration were found the mode shape at the lap joint was somewhat distorted. Thus, the lap joint is very important and has a very significant effect on the dynamic response of joints. The lap-joint is crucial positions in the fatigue analysis.Through the simulation of fatigue of a single lap-jointed aluminum 5754 SPR joint, fatigue damage was found on the faying surface of upper sheet, adjacent to the hole, and on the contact surface between upper sheet and lower sheet. In order to reveal the influence on the fatigue life and safety roughness caused by surface roughness, different of surface roughness were studied in this thesis, and got the plot of fatigue life versus surface roughness and safety coefficient versus fatigue life. The analysis of a single lap-jointed SPR joint at different constraints reveal that the fatigue strength under shear stress is higher than that under tensile stress. The fatigue performance of different aluminum (AL2024-T351, AL1100-T6, AL2014-T6 and AL5754-O) were also studied. The results indicate that the fatigue characteristic of AL2024-T351 is the best, which is followed by AL2014-T6 and AL5754-O.The fatigue property of AL1100-T6 was the worst. The fatigue properties of AL2014-T6 and AL5754-O are similar.The main goal of this thesis is to establish the FEA models, investigate the mechanical properties of the single lap-jointed SPR joint and to provide a referenced for further research.