Fatigue life assessment of electromagnetic riveted carbon fiber reinforce plastic/aluminum alloy lap joints using Weibull distribution

Electromagnetic riveting (EMR) has received increasing attention as a new kind of riveting technique in engineering industry. In this paper, EMR process was used to connect carbon fiber reinforced plastics (CFRP) and aluminum alloy (Al) hybrid joints. The mechanical behaviors (including static and fatigue properties) of the electromagnetic riveted lap joints were comprehensively investigated. The microstructure observation and the mechanical property tests were conducted to evaluate the joints performance. The mechanical test results showed that the failure modes of shear specimens were bending of the Al sheet and damage of the CFRP sheet, which was caused by rivet squeezing effect under static loading. However, the failure mode of fatigue specimens under each stress level was all ruptured at the Al sheet and the fracture analysis showed that cracks firstly initiated around the hole of Al sheet. This was caused by the fretting wear between Al sheet and rivet under cyclic loading. Two-parameter Weibull distribution was employed to analyze statistically fatigue cycles results. The S-N curves were drawn for different reliability levels (10%, 36.8%, 50% and 90%) for engineering applications. In addition, Hysteresis loop analysis implied that the specimens had no obvious flaw after EMR.