Some phenomena in structural impact and structural crashworthiness
Professor Norman Jones
Impact Research Centre, Department of Engineering, The University of Liverpool,
Liverpool L69 3GH, U.K. Norman.Jones@liv.ac.uk
The response of ductile structures subjected to various dynamic loads, which produce large
inelastic strains of interest for structural crashworthiness applications and the design of
energy absorbing systems, are discussed in this seminar. Some comments are offered on the
theoretical procedures which are being developed for predicting the threshold of ineslatic
failure under sufficiently severe dynamic loadings. Also mentioned are recent studies on the
influence of dynamic material properties and on the laws for scaling up the results on
small-scale models to predict the dynamic response of full-scale prototypes.
Recent developments are reported on the dynamic plastic instability of various basic structural
members, subjected to large axial impact loads. The analyses, for the dynamic axial loading of
rods, shells and tubes, retain the simultaneous influence of elastic and plastic stress waves
(axial inertia) and the structural response (lateral inertia). The predictions reveal the
profound influence of stress wave propagation phenomena which explain the characteristics of
many of the experimental results obtained in laboratories over the years. These more complete
analyses are vital for the higher velocity impact scenarios encountered increasingly in designs
and for comparing properly the relative merits of different ductile materials in potential
energy absorbing systems.
