Development of a Numerical Model of the Hot Air Staking Process Based on Experimental Data

Sebastian Härtel,Michael Gehde,Eric Brueckner,Birgit Awiszus

doi:10.3390/app10207115

Abstract

Intelligent light weight concepts are increasingly designed as multi-material systems in order to achieve optimized properties through a targeted combination of materials. For these applications, the market demands joining technologies that make it possible to join foreign materials reliably (e.g., incompatible thermoplastics, thermoplastic-metal and thermoplastic-thermoset). In view of these industrial challenges, thermoplastic staking is an established forming process. At present, computer-aided development and precise FE-simulation (finite element-simulation) of these processes are not state-of-the-art. Accordingly, the previous design is based on subjective empirical values and empirical tests of the component. Within the framework of the paper, these gaps are to be closed by the development of numerical models for the heating and forming behavior of thermal plastic rivets (hot air staking) and the associated experimental validation. This requires the experimental development of the cause-effect relationships between melt formation and the resulting forming behavior. Finally, the numerical simulation shows a high conformity to the experimental data and allows an evaluation of the minimum heating time as well as initial approaches to evaluating the resulting structures by the simulation.

Highlights

Due to the optimized material adaption by using multi-material-structures, the final part properties can reach maximized performance and efficiency
The melt formation starts at the outside and continues towards the middle of the rivet pin
While at short heating times a non-plasticized area remains in the middle of the rivet pin, an almost complete melting of the protruding rivet pin can be observed from a heating time tE of 8 s

Summary

Introduction

Due to the optimized material adaption by using multi-material-structures, the final part properties can reach maximized performance and efficiency. This fact correlates with the substitution of conventional metal applications by their plastic counterparts and is associated with the increasing demand for joining methods which enable the reliable linking of incompatible materials as well. Based on its cost-efficient processing and typically low cycle time, plastic staking is one of the most commonly used joining processes in this field. It enables the reliable joining of two or more mating parts by having a form-locked and partly force-locked connection. The forming of the rivet pin and the subsequent formation of the rivet head lead to an undetachable undercut [1]

Methods

Results

Conclusion