Crashworthiness design of crash box filled with negative Poisson's ratio based on horn structure

In order to improve the crashworthiness of the crash box, the cattle horn is selected as a bionic object. A crash box filled with negative Poisson's ratio honeycomb based on horn structure was designed by extracting its excellent structural characteristics of impact resistance. The axial deformation modes and energy absorption characteristics of bionic crash box are investigated by means of finite element method, and compared with square crash box, diagonal crash box and side-to-side crash box. Under axial impact, the horn-bionic crash box shows significantly better load-carrying and energy-absorbing capacity than the square crash box and the diagonal crash box. On this basis, the thickness parameters, multi-objective optimization design and structure improvement design of horn-bionic crash box are studied successively in this work. The results show that the improved bionic crash box based on horn structure has a typical progressive shrinkage deformation mode. Its SEA reaches 29.9 kJ/kg, which is 2.5 times that of the square crash box, and its PCF is also greatly reduced from 542.4 kN to 391.1 kN. Therefore, the methods of structural improvement such as pre-deformed treatment, constraint beam adjustment and shortening the NPR core can effectively reduce the PCF of the crash box, and improve its energy absorption capacity, so as to obtain better comprehensive crashworthiness. Introducing the key characteristics of the horn structure into the design of the car crash box can effectively improve structural crashworthiness and provide new design guidance for the other energy-absorption components of vehicle.