DYNAMIC CRUSHING TESTS OF THIN-WALLED MEMBERS UNDER COMPRESSION

The paper deals with the experimental investigation into crushing collapse behaviour of two types of thinwalled structural members: tubular multi-member element subject to lateral crushing load and top hat-section column under axial compression. Especially designed experimental stand, in which a dynamical crushing load is realized by means of hydraulic system, is presented. Experimental, dynamical load-deformation curves are compared with those obtained from FE simulations and obtained from quasi-static tests. Conclusions concerning an agreement between results of numerical simulations and results of static and dynamic tests are derived. Increasing number of impacting events of many types like traffic accidents, collisions of ships or collisions of a ship either with an iceberg or ship grounding on a narrow rock, etc. induced the rapid development of the impact crashworthiness dealing with research into impact engineering problems, particularly in the field of dynamic response of structures in the plastic range and the design of energy absorbers. Since demands of general public of the safe design of components of vehicles, ships, etc. have increased substantially in the last few decades, a new challenge appeared to design special structural members which would dissipate the impact energy in order to limit the deceleration and finally to stop a moveable mass (e.g. vehicle) in a controlled manner. Such a structural member termed energy absorber converts totally or partially the kinetic energy into another form of energy. One of the possible design solutions is the conversion of the kinetic energy of impact into the energy of plastic deformation of a thinwalled metallic structural member. There are numerous types of energy absorbers of that kind that are cited in the literature [1]. Namely, there are steel drums, thin tubes or multi-corner columns subject to compression, compressed frusta (truncated circular cones), simple struts under compression, sandwich plates or beams (particularly honeycomb cells) and many others. Among the mentioned types the multi-corner columns , namely hat-sections subject to bending and compression are widely used in car doors for side impact protection. A separate type of the collapsible energy absorber is a system of moderately thin-walled tubes subject to lateral crushing. Such laterally loaded cylindrical clusters have been used in impact attenuation devices of vehicles. They are also employed as crush cushions in roadside safety applications.