Feasibility study of using integrated fiber optical sensors to monitor laser-assisted metal\u2013polymer joining

K Schricker,J P Bergmann,M Ganß,C Könke

doi:10.1007/s40194-020-00942-y

K Schricker, J P Bergmann + Show 2 more

Open Access

https://doi.org/10.1007/s40194-020-00942-y

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Abstract

The possibilities and challenges of using fiber optical sensors to monitor the laser-assisted joining of metal–polymer joints have been described in this article. Fundamental investigation proves the basic suitability of the measuring method for this application and studies the effect of essential influencing variables of the joining process—e.g., the clamping force—on the resulting sensor signals. In addition, the strain state (because of the process temperature and shrinkage of the polymer) of the parts to be joined can be traced as a function of the joining partners, the process parameters, and the material thicknesses. It is shown that the fiber optical method is suitable for process monitoring directly in the joining zone of metal–polymer hybrids and providing a tool for detailed strain measurements in the joint zone during subsequent component testing.

Highlights

Introduction and state of the artThe use of the right material at the right place plays a leading role in actual design approaches
The experimental results and discussion from measurements with fiber Bragg grating sensors (FBGs) integrated in the process zone of the metal–polymer hybrid joints are given below
Fiber Bragg grating sensors without a special metal coating have been successfully embedded in the joining zone of metal–polymer hybrids; they were used for process analysis during contour and simultaneous welding

Summary

Introduction

Introduction and state of the artThe use of the right material at the right place plays a leading role in actual design approaches. The realization of multimaterial components depends strongly on the joining technology as a key manufacturing process, especially for materials with dissimilar properties such as metals and polymers. Thermal joining is a potential technology for manufacturing thermoplastic–metal joints without using a filler material (e.g., adhesive) or a joining element (e.g., screw, rivet). In thermal joining, both materials are in contact at the boundary layer (Fig. 1a) and the metal sheet is heated by an energy source like a laser beam. An overarching technology of non-destructive testing, which offers data acquisition during the joining process and the lifecycle, has not been described yet. The application of fiber optical sensors in the joining zone may fulfill these requirements

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