Optimised design of nested oblong tube energy absorbers under lateral impact loading

Dynamic lateral crushing of mild steel (DIN 2393) nested tube systems was conducted using a ZWICK ROELL impact tester. The tests were performed with impact velocities ranging between 3 and 5 m/s, achieved using a fixed mass impinging onto the specimens under the influence of gravity. The various nested tube systems consisted of one standard and one optimised design. Their crushing behaviour and energy absorption capabilities were obtained and analysed. In addition to the experimental work, numerical simulations using the explicit code LS-DYNA were conducted; boundary conditions matching those observed in experiments were applied to the models. Results from the numerical method were compared against those obtained from experiments. An over-prediction in force-deflection responses was obtained from the numerical code. An attempt was made to explain this inconsistency on the basis of the formation of plastic hinges and the validity of strain rate parameters used in the Cowper Symonds relation. It was found that the optimised energy absorbers exhibited a more desirable force-deflection response than their standard counterparts due to a simple design modification which was incorporated in the optimised design

Analysis of nested tube type energy absorbers with different indenters and exterior constraints

The present work presents both numerically and experimentally the quasi-static lateral compression of nested systems with vertical and inclined side constraints. The force-deflection response of mild steel short tubes compressed using two types of indenter’s is examined. The variation in response due to these indenters and external constraints are illustrated and how these can contribute to an increase the energy absorbing capacity of such systems. The implicit version of the Finite Element code via ANSYS is used to simulate these nested systems and comparison of results is made with those obtained in experiments and were found to be in good agreement

Metallic tube type energy absorbers: a synopsis

This paper presents an overview of energy absorbers in the form of tubes in which the material used is predominantly mild steel and/or aluminium. A brief summary is also made of frusta type energy absorbers. The common modes of deformation such as lateral and axial compression, indentation and inversion are reviewed. Theoretical, numerical and experimental methods which help to understand the behaviour of such devices under various loading conditions are outlined. Although other forms of energy absorbing materials and structures exist such as composites and honeycombs, this is deemed outside the scope of this review. However, a brief description will be given on these materials. It is hoped that this work will provide a useful platform for researchers and design engineers to gain a useful insight into the progress made over the last few decades in the field of tube type energy absorbers

Quasi-static response and multi-objective crashworthiness optimization of oblong tube under lateral loading

University of Alepp