Very fast full vehicle simulations through the use of effective, but drastically simplified digital models is a topic of great interest to automotive manufacturers and research communities. A nonconventional modelling and simulation approach using the macro-element methodology, embedded in Visual Crash Studio (VCS), is assessed. Modelling practices for converting finite element models to macro-element models are developed and presented. A large number of automotive systems, ranging from components and sub-systems to full vehicle models, is investigated. Numerical results obtained from VCS and the finite element code LS-DYNA compared moderately in the majority of the cases. The accuracy and efficiency of the macro-element methodology for vehicle crashworthiness analysis as well as the necessity for model corrections are discussed. Through improved functionality and accuracy, the macro-element methodology could potentially enable engineers to evaluate multiple conceptual designs in shorter times and revolutionise the vehicle development phase. KEYWORDSSimplified crashworthiness modelling and simulation; macro-element methodology; roof strength test; full width frontal impact

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High Pressure Die Casting is an economical means of manufacturing complex thin walled parts in high volumes. However, the process is prone to high levels of surface turbulence and fluid break-up, which results in the entrainment of bifilm defects. A study was carried out on a commercial casting to identify how changes in melt velocity and mould geometry affected the distribution of damaging bifilm defects, and the distribution of fracture stress. The statistical analysis of tensile test data indicated that two distinct defect populations existed; one of which caused relatively few failures, but often accounted for a large reduction in fracture stress when present. Where this defect population was not significant, Weibull moduli of 20 to 30 were achieved, comparable to sand castings with well-designed running systems. SEM fractography was also performed on a selection of samples to determine the probable cause of failure. A comparison of the SEM analysis to the statistical results indicated that bi-film defects initiated the fracture of those samples that failed at significantly lower stresses. Additionally, it was demonstrated that the geometric distribution of these cases was strongly correlated to changes in fluid flow conditions, suggesting that targeted modifications to mould geometry could increase the in-service reliability of High Pressure Die Castings.

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