Experimental Study of Progressive Crushing Behaviour in Pultruded E-Glass Tubes Using Crown Triggers and A New Perforated Trigger

Abstract

An experimental study is conducted on the progressive crushing behavior and the energy absorption during crushing of pultruded fiberglass tubes, initiated by two types of crush triggers, a previously tested crown trigger, and a new perforated trigger. These crush triggers are introduced at the loading end of a pultruded E-Glass/vinyl-ester, circular tube coupon. Coupons with various trigger diameters and number of holes are crushed under quasi-static compression, to evaluate the trigger effectiveness, crushing response, and energy absorption during sustained crushing. It is observed that all trigger types induced progressive crushing in the splaying mode, characterized by the formation of a debris wedge propagating between the tube wall and a series of fronds or petals on both sides of the tube wall. In terms of trigger response, crown triggers perform better than perforated triggers as the mean crushing load stabilizes and remains relatively uniform across a large displacement, with some periodic oscillations with a small amplitude. Perforated triggers also induced progressive crushing but at significantly lower loads as compared to crown triggers and with crushing load values oscillating with large amplitudes. A combination of a crown and bevel trigger is the most effective in reducing the initial load spike and maintaining a stable load during crushing. Crown triggers with smaller diameters displayed greater energy absorption than those with larger diameters when Specific Sustained Crushing Stress (SSCS) values are compared.