Xu, Hongli
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Publication Access status: Metadata only , A new resistance insert spot welding method for injection-molded FRP–steel component(2024); For weight reduction, multi-material designs comprising metal and fiber-reinforced plastic (FRP) components in vehicle body structures have been increasingly used. However, the commonly used resistance spot welding (RSW) technology for car body assembly cannot be employed to join sheet metal and FRPs, limiting the use of FRPs. To solve this problem, a novel resistance insert spot welding (RISW) technique was developed in this work for RSW of steel parts and FRP structure parts made by injection molding. Small inserts were developed by using finite element method and experiments that may be welded to different micro-alloyed and dual-phase sheet steels using the projection welding method. The usual flange width of original equipment manufacturers could be kept unchanged. Using the developed insert and welding parameters, the maximum temperature in the FRPs surrounding the inserts was limited to 255 °C, minimizing the damage to polyamide 6 (PA6) material (with 40 wt% glass fiber). A weldability range between 2.5 and 7 kA could be achieved. The joining strength of RISW between a micro-alloyed HC340 steel in 0.75 mm and 1.5 mm thickness and a 2.5 mm/3.0 mm PA6-GF40 material is 20 to 80% higher than self-piercing riveting (SPR). For high-speed loading, RISW strength increases by 39 to 56% further. Finally, RISW was successfully applied to an FRP–steel roof-frame sub-assembly that consists of 19 simultaneously integrated inserts, achieving 10% weight reduction.Source Type:Article2 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Resistance insert spot welding: a new joining method for thermoplastic FRP–steel component(2023); Recently, multi-material designs consisting of metal and FRP components are being increasingly used in vehicle body structures to reduce weight and thus energy consumption and emission. Because the most commonly used resistance spot welding (RSW) technology for body assembly cannot be applied to join sheet metals and FRPs, the usage of FRPs is strongly limited. Therefore, a new resistance insert spot welding (RISW) method was developed. During the manufacturing process of FRPs, here compression molding of PA6 GF40 materials, specially designed steel inserts are directly integrated into the FRP part. Later, via the steel inserts, the FRP part can be spot welded to other steel parts in the structure. In this work, the design and development process of RISW is presented. Starting with the design concept of inserts, welding tests were conducted, and the parameters for the welding simulation were calibrated. After that, the detailed insert design was performed using welding simulation and tests with several restrictions, such as insert dimensions, the temperature in FRPs, the weldability range, and joining strength. In the end, an appropriate insert geometry was found, which met all requirements. The mechanical properties of RISW joining are better than or equal to those of SPRs. The new RISW technology was also demonstrated on a real vehicle component. A seat cross member was designed using FRP with 42% weight reduction and produced by compression molding with 30 simultaneously integrated inserts. The cross member was finally successfully welded to a steel closing plate using RISW.Source Type:Article1
