| As a means of transportation,automobiles inevitably experience various impact loads.In order to reduce the damage caused by crushing loading on passengers and cargo,improving the crashworthiness has become a hot research topic in the field of passive vehicle safety.The honeycomb structure with auxetic properties has broad application prospects in the field of passive vehicle safety due to its special mechanical properties and excellent energy absorption characteristics.In order to improve the passive safety of vehicle and reduce the damage to passengers and cargo in collision accidents,this article takes the star-shaped auxetic honeycomb filled with vehicles as the research object,and carries out the mechanical and energy absorption characteristics of the star-shaped auxetic honeycomb under compressiveshear combined loading conditions.Furthermore,the crashworthiness application of the crash box filled with star-shaped expanding honeycomb is investigated in combination.The main research work of this article is as follows:(1)The star-shaped auxetic honeycomb specimens were prepared using additive manufacturing technology,and the experimental investigation of the combined loading condition of star-shaped auxetic honeycomb compression was carried out by combining a self-designed variable angle loading fixture with a universal testing machine to form a composite loading system.The loading-displacement curve of the star-shaped auxetic honeycomb under quasi-static conditions was obtained through a three-axis force sensor,and the deformation behavior of the specimen was analyzed and discussed in combination with the deformation process.(2)Based on finite element technology,the combined compression-shear quasi-static and dynamic loading simulations of the star-shaped honeycomb were conducted.Combined with the experimental results,the reliability of the numerical simulation model was verified,and then the mechanical properties of the star-shaped honeycomb were investigated.The deformation mechanism of the star-shaped honeycomb was analyzed based on the stressstrain curve,and the yield criteria and yield surfaces of the star-shaped honeycomb were given for different loading conditions.This can be used to guide the subsequent research on the star-shaped honeycomb under combined compression-shear loading conditions.(3)Combining the key energy absorption indicator parameters,an investigation was conducted on the energy absorption characteristics of star-shaped auxetic honeycomb under combined loading.In response to the plastic shock wave effect generated by the star-shaped auxetic honeycomb under dynamic loading conditions,the formation mechanism of local deformation and stress enhancement phenomena was explained through stress-strain analysis at the loading and fixed ends.The kinetic energy and internal energy of the star-shaped auxetic honeycomb under dynamic loading were analyzed and discussed,and a theoretical model for energy absorption of the star-shaped auxetic honeycomb under dynamic loading was derived through theoretical deduction.The theoretical model was compared and verified with a simulation model,and the numerical simulation results were in great agreement with the theoretical results,effectively verifying the reliability of the proposed theoretical model,which can provide guidance for research on energy absorption of star-shaped auxetic honeycomb.(4)Based on a certain model of vehicle crushing box,a numerical simulation model of the vehicle crash box was established.Using the star-shaped auxetic honeycomb as the filling core and combining with the actual collision conditions of the vehicle,the crashworthiness of traditional vehicle crash boxes and filled vehicle crash boxes was investigated under quasistatic and dynamic loading.Combining the deformation mechanism of the star-shaped auxetic honeycomb and the thin-walled structure of the vehicle crash box,an analysis and discussion of four key energy absorption index parameters including the Mean Crushing Force(MCF),Peak Crushing Force(PCF),Crusing Loading Efficiency(CLE),and Energy Absorption(EA)of the vehicle crash box were conducted.It was determined that the crashworthiness of the vehicle crash box filled with the star-shaped auxetic honeycomb was significantly improved compared to traditional vehicle crash boxes under all conditions.The research results of this paper can provide a certain theoretical basis and technical support for the investigation of the mechanical behavior and energy absorption characteristics of honeycomb filled for vehicles,as well as the development of filled vehicle crushing boxes. |
PDF Full Text Request