Numerical analysis of failure modeling in clinching process chain simulation

Abstract

Abstract. The application of the mechanical joining process clinching allows the assembly of different sheet metal materials with a wide range of material thickness configurations, which is of interest for lightweight multi-material structures. In order to be able to predict the clinched joint properties as a function of the individual manufacturing steps, current studies focus on numerical modeling of the entire clinching process chain. It is essential to be able to take into account the influence of the joining process-induced damage on the load-bearing capacity of the joint during the loading phase. This study presents a numerical damage accumulation in the clinching process based on an implemented Hosford-Coulomb failure model using a 3D clinching process model applied on the aluminum alloy EN AW-6014 in temper T4. A correspondence of the experimentally determined failure location with the element of the highest numerically determined damage accumulation is shown. Moreover, the experimentally determined failure behavior is predicted to be in agreement in the numerical loading simulation with transferred pre-damage from the process simulation.

A calibration method for failure modeling in clinching process simulations

“…Furthermore, data from tensile tests were used for the calibration, since these represent the stressing of the material under uniaxial tension with η = 1/3 and ξ = 1 at the beginning and move over to biaxial stress states with η = 2/3 for increasing plastic deformation. These non-proportional load paths are also present in clinching processes [21]. Experimentally determined failure strains of tensile tests for the material were taken from [22].…”

“…For the calibration of the models, at first the most failure-critical element from each of the numerical models was evaluated in terms of plastic strain, stress triaxiality, and Lode angle according to the crack initiation determined from the experiments. To take the non-proportional loading paths of the experiments into accountalso in view of the later application to clinching [21] a non-linear damage accumulation law is applied, Eq. 8 with the damage exponent 𝑛 𝑑 > 0, herein chosen a priori as 2.…”