DESIGN OF AN EFFECTIVE VEHICLE FRONTAL LONGITUDINAL MEMBER FOR CRASHWORTHINESS APPLICATION

Abstract

It is known that thousands of people throughout the world are killed or seriously injured due to collisions every year. Increasing in population leads to increase in the number of vehicles and hence the probability of accidents. So it's important to find a way to decrease these fatalities caused by accidents. A suitable frontal car energy absorber members design can achieve and reduce the fatalities by increasing the absorbed energy. A direct impact crash, an offset crash with-40 per cent and oblique impact crash with 30-degrees crash angle have been done in this thesis to improve the energy absorption performance. The frontal car design mainly depends on the frontal longitudinal member (tube) which should be improved to enhance the energy absorption. Six different cross-sectional tubes have been implemented as an energy absorber. Each of these tubes has their performance. These performances have wide range of results which makes the selection difficult. Complex Proportional Assessment (COPRAS) method is used to choose which of these tubes is the best which satisfy the designer and customer requirements. The COPRAS shows that the hexagonal tube has been selected as a best choice. Energy absorber member is described as two parts. The inner part represents the tube which is the hexagonal tube, while the outer part represents the support system which consists of three stiff rectangular tubes that fits into each other and slide over each other, like a telescope. The aim of telescope is to prevent or decrease the buckling during collisions especially in offset and oblique crashes. The main aim of this study is to design a frontal vehicle that can dissipate the most energy due to collisions and keep the passengers as safe as possible. Two different materials were used to design the two energy absorber members in this study, steel and magnesium alloy (AZ31). Magnesium alloy was used to investigate its potential as an energy absorber. The three different crashes were applied to the proposed frontal design and were compared with the conventional design for the same conditions. It has been found that the proposed design for both materials shows the ability to absorb energy more than the conventional design in all crash situations.ii The study also showed that the magnesium alloy could be used to improve the crashworthiness since it reveals a high energy absorption and stable folding during crash.