Zana Eren

Numerical investigation of stepped concentric crash tubes subjected to axial impact: The effects of number of tubes

The purpose of this study is to examine the energy absorption characteristics of stepped concentric crash tubes subjected to an axial impact load. The stepped concentric tubes with circular cross section are analyzed numerically by using LS-DYNA. The total mass and volume are kept constant when the number of tubes is increased. As the number of concentric tubes is increased, it is observed a smooth transition of the peak forces during the impact. Also increasing the number of tubes reduces the maximum peak force and leads to a reduction of the initial peak force due to lower wall thickness of the tubes.

Crashworthiness Optimization of Nested And Concentric Circular Tubes Using Response Surface Methodology And Genetic Algorithm

In this study crashworthiness optimization of nested and concentric circular tubes under impact loading is performed by coupling Finite Element model, Response Surface Models and Genetic Algorithm. Specific Energy Absorption SEA and Crash Force Efficiency CFE are used in crashworthiness optimization since these criteria are important indicators for evaluating crashworthiness performance. Length and thickness of three concentric tubes as well as radius of one tube are adopted as design variables which are effective parameters on SEA and CFE. To reduce the computational cost of the optimization procedure, simple and computationally cheap Response Surface Models are created to replace finite element analyses in further calculations. The Non‐dominated Sorting Genetic Algorithm –II NSGAII is applied to obtain the Pareto optimal solutions. Optimization results are presented for different selected designs that indicate relative importance of multi‐objective functions. Results show that the total weight of the vehicles can be reduced by using nested tubes comparing to single tubes with identical masses. These designs can be adopted for use in practice.

Experimental investigation of auxetic structures subjected to quasi static axial load

The purpose of this study is to examine the energy absorption characteristics of two different auxetic honeycombs that have negative Poissons ratio (NPR) subjected to an axial quasi-static load. The total mass and volume are kept nearly equal. As the load-extension graphs are examined, it is observed a smooth transition of the peak forces during the crush for the second one which has more strut. On the other hand, first one has better energy absorption capability.