{'fraction_non_alphanumeric': 0.016864459712679577, 'fraction_numerical': 0.0, 'mean_word_length': 5.209302325581396, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Experimental investigation of strain rate effects on the crushing characteristics of composite sandwich panels

In the present work, the influence of strain rate on the collapse modes, the crushing mechanisms and the energy absorption characteristics of four types of composite sandwich panels was investigated in a series of impact and static in-plane tests. The tested sandwich specimens were formed combining two types of glass fibre reinforced plastic (FRP) faceplate laminates with three types of polymer foam core (poly-methacryl-imide (PMI) foam and two grades of cross-linked poly-vinyl chloride (PVC) foam) in four different material combinations. Three modes of collapse were observed in the series of impact and static compression tests, but only one of them – which was observed only at higher strain rates – was a stable mode featuring progressive end-crushing of the sandwich panel and significant crash energy absorption. The analysis of the test results showed that the increase of the strain rate influenced significantly the mode of collapse of the tested sandwich panels and some of their energy absorption characteristics such as the critical load for failure initiation and the peak collapse load. Apart from the strain rate effects, the analysis of the test works focused on the mechanics of progressive deformation and crushing related to each mode of collapse and the influence of significant parameters of the sandwich panel construction – such as the properties of the foam core and the faceplates – on the overall crushing response and the energy absorption characteristics.