Parametric Study of Hybrid Metal-Composites Clinching Joints

Abstract

In different innovative markets, such as electro mobility and flexible electronics, among others, the mechanical joining processes based on sheet metal forming technologies are gaining a significant relevance due to their low cost and ease of automation as compared to traditional joining techniques of riveting, bolting, fastening, welding, etc. In lightweight hybrid constructions, where a high production rate is required, clinching technology demonstrates a sustainable method to join hybrid metal-composite parts. However, the basic mechanisms of this hybrid joining process are not well studied at present and an accepted design theory in this area has not yet been established. The current contribution presents a parametric study of the hybrid clinching joining process. The Taguchi’s design of experiments method is used to investigate the effects of tools’ geometry on hybrid clinching joints’ quality characteristics, i.e. neck thickness, undercut and final bottom thickness. For this purpose, a 2D axisymmetric modelling approach was adopted for its simplicity. The study results are analyzed using the mean response and signal-to-noise ratio approaches. Accordingly, the relevant geometrical parameters of the tools with the highest influence on the accurate shaping of hybrid clinching joints are determined numerically.

Analysis of the interactions between joint and component properties during clinching

“…To ensure the accuracy of the FE-model, a mesh study, a parametric study of the contact conditions [28], a study of the friction coefficients [29] and a check and adaption of the material modeling for the simulation of a clinching process is necessary [23]. The geometry of the joint can be considered for evaluation and calibration [29] until an acceptable deviation from the real experiment is achieved [28].…”

“…To ensure the accuracy of the FE-model, a mesh study, a parametric study of the contact conditions [28], a study of the friction coefficients [29] and a check and adaption of the material modeling for the simulation of a clinching process is necessary [23]. The geometry of the joint can be considered for evaluation and calibration [29] until an acceptable deviation from the real experiment is achieved [28]. In [30] the influence of strain hardening and the variation of sheet thickness on the joint characteristics t n , f and t b are studied using a metamodel to investigate the robustness of the clinching process.…”

“…For the optimization of the clinching tools, the sensitivities of the most important tool dimensions and a robustness analysis are determined. For exact simulations, it is recommended to consider the damage development [28]. Without the inclusion of damage, the simulation is less accurate and may not be able to determine the correct failure mode and overestimate the loading capacity [6].…”

A FEM‐based virtual test‐rig for hybrid metal‐composites clinching joints

“…For short fiber-reinforced plastics composites sheets, the finite deformation macro-mechanical invariant-based anisotropic elasto-plastic constitutive models are adopted and extended to account for the rate-dependent behavior of composites using a Perzyna type visco-plastic formulation [25][26][27][28][29][30]42]. Herein, the constitutive modeling is briefly described.…”

“…For PA6GF30, the presented constitutive model for SFRP composites in subsection 3.1 is employed. In previous publications [25][26][27][28][29][30]42], these material models are calibrated with experimental data obtained from EN AW 5754 and PA6GF30 for their used in the proposed virtual test-rig. For the sake of completeness, this basic required material parameters are listed.…”