Understanding resilience to contamination in the joint interface for a resistive welded joint in fiber reinforced thermoplastics 2019-01-1273
With a constant push for improving efficiency and lowering emissions of passenger vehicles, the requirement for lightweighting is indisputable. New material systems such as fiber reinforced thermoplastic composites offer very high lightweighting potential.
Most of these parts are currently joined using adhesives and resistive welding provides a promising alternative. Some of the key benefits of resistive welding over adhesive bonding are faster cycle time, recyclability, design flexibility and resilience to contamination. While few of these claims have been scientifically studied, resilience to contamination is widely accepted but hasn’t been validated. To indeed prove the scalability of these joints in automotive applications, they should have tolerance to certain contaminations which are present in the body shop. While it is possible to minimize contaminations in the body shop, it often comes with requiring additional cleaning steps and maintaining large clean rooms which are very expensive.
In this paper, the effect of contaminations, such as particulate contamination, moisture, and presence of residue mold release agents on joint strength are studied for both resistive welded and adhesive bonded joints. Defined quantities of these contaminants are introduced in the joint interface, and the effect on lap shear strength is measured. While adhesives are known to be more sensitive to contamination, the resilience of resistive welded joint needs to be quantified. This information will be critical in the design of the joint geometries and manufacturing lines for fiber-reinforced thermoplastic parts. Less stringent requirements for minimizing contamination will also increase the flexibility and decrease the capital cost of manufacturing plants.