Co-authors​ :

 Serdar DEMIR (CHINA), Nuri ERSOY (TURKEY) 

Crashworthy structures are included in the most crucial components in transporting vehicles. They are mounted in vehicles to absorb the energy transmitted during collision. Thus, preventing the harmful effects of the impact on passengers. Improving the crashworthiness is also important for the safety and repairability of the critical parts, such as engine, in vehicles. Carbon fiber-reinforced plastic (CFRP) composites are becoming widespread to be used in crashworthy structures due to their advantageous features such as lightweight, high strength, better durability and high energy absorption rates over traditional metallic materials. However, predicting the energy absorption rate of a CFRP composite crashworthy structure is challenging due to their complexity of the damage mechanisms which involves intralaminar and interlaminar damage modes. Over the years, an extensive amount of work is conducted about predicting the energy absorption characteristics of composites and the parameters that effect these characteristics. These parameters includes the geometry of the composite crashworthy component and material structure of the composites. Along the studies that is focused on the parameters of the crashworthy structure itself, there are also studies exists in the literature that is based on the effect of plug initiators on crushing characteristics. Crush plugs can significantly change the damage characteristics of crashworthy structures improve their energy absorption capacities. Yet, a general unsureness exists on how the applied plug initiator geometry influence the crushing behavior of the composite structure and the energy absorption values.

In this study, the influence of the different crush plug geometries on the crushing characteristics of CFRP composite tubes manufactured from plain-weave carbon/epoxy prepregs are investigated. Crush plug geometries investigated in the study includes basic inwards and outwards crusher plugs and more complex plugs with different crushing area geometries that steer the tube wall during crushing. Finite element method (FEM) is used to simulate the crushing behavior of the specimens crushed with different crush plug designs after validating the model with the experimental results of basic crush plug tests. FE models are generated in ABAQUS/Explicit software using the built-in VUMAT subroutine for fabric reinforced composites to model the intralaminar behavior. The interlaminar behavior is modeled using cohesive surface method. CFRP tube in the simulations is modelled using stacked-shell approach where each ply is constructed and modelled separately with continuum shell elements. The comparison of the influence of different crushing plugs are carried out by investigating the results in terms of crushing morphology, energy absorption values and load-displacement curves.