Investigation of clinched AA1100 sheet behaviour under electromagnetic forming: Integrated analytical, experimental, and numerical approach

AA1100 sheets have a wide range of applications in different industries, such as automotive, aerospace, heat exchangers, and nuclear sectors and in its application, joining and forming play an important role. In this process, a simple toolset, which includes a die, a punch, and a punch holder, is used to produce the joint. It is favoured in applications where the sheets interlock without undergoing significant plastic deformation. However, joints created through clinching typically exhibit poor formability. Due to its high strain rate capabilities, impulse electromagnetic (EM) forming plays a critical role in addressing this limitation. This manuscript compares the formability of EM forming in tailored clinched and non-clinched 1 mm sheet thickness AA1100 workpieces at 4.50 kV discharge voltage. An analysis of the magnetic field developed in the rectangular spiral coil and the Lorentz force exerted on the workpiece is conducted, and the dome height is validated through experimental results. A detailed analysis is provided to examine the safe and fracture points at various discharge voltages for the tailored sheets. Additionally, explicit LS-DYNA software was used for the numerical analysis of clinching and EM forming of non-clinched workpieces. The numerical and experimental results are comparable and lie in the acceptance range. The formability of formed clinched is 35% higher than that of non-clinched workpieces at 4.50 kV discharge voltage. The fracture limit of the non-clinched sheet is higher compared to the clinched sheet. The novelty of this research lies in the formability analysis of tailored clinched AA1100 sheets and an in-depth understanding of fracture behaviour under high strain rate conditions, employing analytical, experimental, and numerical approaches.