Search

This paper outlines the design, analysis and physical testing of the material for the front impact attenuator for the Motorsports car. The material selected was a 20 mm thick panel of veiled polypropylene honeycomb. The design programme Solidworks was used to produce three impact attenuator geometries for analysis – a solid block, a three-tier pyramid and a four-tier pyramid. The impact attenuator was simplified to solid blocks specified with the honeycomb material strengths and tested in ANSYS 14.0. The simulations did indicate that the four-tier pyramid had the greatest energy absorption behaviours. Two full size prototypes were manufactured and destructively tested. The force-displacement curve determined that prototype MKII achieved total energy absorption of 7591 J. The average deceleration was 17.66 g and maximum deceleration was 30.58 g. The polypropylene honeycomb energy absorption and deceleration values comply with FSAE requirements. [ABSTRACT FROM AUTHOR]

New products ranging from simple components to complex structures should be designed to be optimal and reliable. In this paper, for the first time, a hybrid uncertain model is applied to system reliability based design optimization (RBDO) of trusses. All uncertain variables are described by random distributions but those lack information are defined by variation intervals. For system RBDO of trusses, the first order reliability method, as well as an equivalent model and the branch and bound method, are utilized to determine the system failure probability; and Improved (µ + λ) constrained differential evolution (ICDE) is employed for the optimization process. Reliability assessment of some engineering examples is proposed to verify our results. Moreover, the effect interval variables on the optimum weight of the truss structures are investigated. The results indicate that the optimal weight depends not only on the uncertainty level but also on the equivalent standard deviation; and a falling-rising behavior is observed. [ABSTRACT FROM AUTHOR]

In this paper dynamic forming limit diagram has been investigated as fracture criteria for St13 steel. In fact, effect of various strain rates has been studied. This fracture criterion is based on the Marciniak-Kuczynski (M-K) theory and solution of equations has been obtained by applying the Newton-Raphson method. After solution, three forming limit diagrams were created: independent strain rate, dependent strain rate and dynamic forming limit diagram. Dynamic damage criteria investigates forming limit diagram in every strain rate. It is observed that the forming limit is increased by increasing the strain rate. Also, for considering the anisotropic and the elastic-plastic behavior of material, the Hill 1948 yield criterion and the Swift hardening rule have been used respectively. This paper is concerned with the uniaxial tensile properties and formability of sheet metal in relation to the strain rate effects. In order to verify the results several experiments were done with a Drop Hammer, which is a high speed impact machine. For comparison between quasi static and dynamic damage criterions, all stages of the experiment were simulated in finite element software Abaqus and results compared. [ABSTRACT FROM AUTHOR]