Papers by Author: António Pinho

Abstract: This study presents results of denting resistance of 6111-T4 aluminium alloy. Experimental results of dynamic denting were compared with numerical simulations performed using LS-DYNA software. The experimental tests were performed on 1mm thick plates clamped in a circular area with a diameter of 80mm. Dynamic denting was accomplished by dropping different indenters from heights ranging from 0.36 to 1.7 m. The obtained results indicate a high suitability of the aluminium alloy for use in automotive panels. The results of the numerical simulations display a good correlation with experiments if dynamic effects are introduced in the constitutive equation of the material through the Cowper-Symonds coefficients.

Abstract: This work presents results of tensile testing of advanced high strength steels of interest for crashworthy structures: Dual-Phase and TRIP (Transformation Induced Plasticity) steels. The improvements in vehicle crashworthiness observed in recent years have been closely linked to advanced high-strength steels that are currently being produced or in process of development. Amongst these, Dual-Phase and TRIP steels have presented excellent properties for use in crashworthy structures. For these steel grades an understanding of material behaviour at relevant strain rates is needed as well as constitutive equations suitable for use in analytic and numerical calculations. For that purpose an experimental program of tensile testing was performed in a range of strain rates of interest for crashworthiness problems: 0.0001 /s to 1000 /s. The test results were used to compare material properties and to evaluate the Cowper-Symonds constitutive equation and a modified version. Crush tests were performed at different speeds for top-hat and hexagonal tubes manufactured using laser welding and the results discussed in view of energy absorption.

Abstract: The improvements in vehicle crashworthiness observed in recent years have been closely linked to advanced high-strength steels that are currently being produced or in process of development. Amongst these, Dual-Phase and TRIP (Transformation Induced Plasticity) steels have presented excellent properties for use in crashworthy structures. For these steel grades an understanding of material behaviour at relevant strain rates is needed as well as constitutiv eequations suitable for use in analytic and numerical calculations. In this study the crashworthiness of thin-walled sections made of Dual-Phase and TRIP steels was investigated. Tensile tests were performed at different strain rates in a range of interest for crashworthiness problems. The results allowed the determination of parameters of Cowper-Symonds equation. Crush tests were performed at different speeds for top-hat and hexagonal tubes manufactured using laser welding. The experimental results were compared with numerical simulations obtained with LS-DYNA software. The influence of different material parameters on the accuracy of the simulations was examined.