Interlaminar behavior of infrared welded joints of carbon fabric–reinforced polyphenylene sulfide

Abstract

The use of fiber‐reinforced thermoplastics for structural applications is continuously increasing and therefore load‐bearing joints cannot be avoided. Because most well‐established joining techniques for metallic structures are not directly applicable to composites, and because thermoplastics are difficult to bond adhesively because of their chemical inertness, another solution is found, namely fusion bonding. This study assesses the use of infrared welding for a carbon fabric–reinforced polyphenylene sulfide (PPS). After a short description of the welding setup, the welding parameters such as heating time, contact pressure, and consolidation time are optimized using lapshear experiments. Two welding procedures are considered, one with and one without prior consolidation of PPS on the specimens. It can be concluded that the infrared process proves interesting for the material under study and that the process with prior consolidation of PPS yields reproducible results. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Assessment of the interlaminar behaviour of a carbon fabric reinforced thermoplastic lap shear specimen under quasi-static and tension-tension fatigue loading

“…For clarity's sake, the different curves are given an offset along the displacement-axis. In [6,8,7], the benchmark usually yielded higher failure loads than the fusion bonded samples, but for this material, the failure load is around 7 Mpa lower than for the welded joints in the previous study [1]. Thus, the question arises what the origin of this effect may be.…”

“…The idea was to produce a larger plate with the same stacking sequence of the welded overlaps in [1], and then to trim away all unwanted parts to obtain the desired lapshear geometry. By doing so, the overlap of the lapshear specimen is produced using the optimal process parameters for the standard plates.…”

“…Both sets of values are listed in Table 1. The desired geometry of the single lapshear specimen is illustrated in Figure 1 and is is chosen according to the ASTM D5868-01 'Standard Test Method for Lap Shear Adhesion for Fiber Reinforced Plastic Bonding', which was also considered for [1]; the width of the specimen is 25 mm. To obtain such a geometry using the hot pressing process, a very specific and expensive closed mould would be necessary, which would then only be suitable for one specific overlap length.…”

“…The carbon PPS plates were hot pressed at 10 bars and 310 °C; only one stacking sequence was used for this study, namely [(0º,90º) 4s ] s where (0º,90º) represents one layer of fabric. The choice for this stacking sequence was driven by the fact that the experiments in this manuscript will serve as benchmark for the welded specimens, which also have this stacking sequence in their welded overlap [1].…”

“…A first paper was already published on the optimization of the welding parameters of this infrared welding [1], where the results of single lapshear experiments were used for the assessment of quality and reproducibility of the joints. A second study was conducted in order to determine the interlaminar behaviour under pure mode I, using the double cantilever beam test, and pure mode II, using the end notch flexure test, loading conditions [2]; values for G I and G II were also determined, both for initiation and propagation.…”