Kademeli ve eş merkezli çarpışma kutularının analizi: Tüp sayısının etkisi

In this study, stepped concentric crash tubes with circular AL6063 material are investigated using experimental and numerical methods. Crash tubes are used generally in automotive industry to as a passive safety component. In this study, feasibility of crash tubes in different areas are sought. So, it is designed almost ten times smaller than the conventional car crash 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 peak forces, internal energy and the total deflection are the selected parameters for the comparison of various crash tubes. The stepped concentric tubes have different lengths and different diameters, while the total mass and volume are kept constant. The area of the impacting object is taken as greater than the internal tube's cross sectional area to prevent passing the impacting object through the tube hole. First of all, a comprehensive study about articles on crash tubes presented. Almost 127 scientific articles are reviewed and tabulated information according to solution methods, geometry, material properties, impact velocity and impact mass properties. Table is given in Appendices section. In the next part, one selected model with AL6063 material is fabricated and tested at dynamic and quasi-static velocities. Dynamic tests are done by using INSTRON 8150 Drop Test Machine and quasi-static test is done by using MTS 647 Hydraulic Test Machine. Then, results of experiments compared and validated with results of analysis by using LS-DYNA, an engineering simulation software program In the second part, the effects of the number of the tubes and impact velocity are studied at high dynamic velocities by using LS-DYNA software program. To define optimal mesh quality, results of five different mesh sizes of a sample are investigated and chosen the most proper type of them to use in all analyses. After that, four different models are constituted with 3, 6, 9 and 12 stepped concentric tubes, respectively. All samples are analyzed at three different velocities: 50, 60 and 70 m/s and results are compared with one another. In the third part, stepped concentric crash tubes are modelled with aluminum foam and analyzed at 50 m/s impact velocity. Results of model with foam filled and empty tubes are compared and studied to demonstrate the advantages and disadvantages of foam material. All graphics are established using GRAPHER software program.