Research On Mechanical Properties Of Sierpinski Triangular Structure With Thickness Gradient And Fractal Design

The development of the automobile industry has made people’s living space wider,communication more convenient and work efficiency increased.As an indispensable means of transportation for people’s daily travel,the safety of automobiles is a subject of increasing concern for consumers and designers,and thin-walled structures with excellent mechanical properties are the key to the safety of vehicle protection.Therefore,this paper proposes a thin-walled structure design method that combines material grad ient and geometric fractal,in order to improve the impact stability and energy absorption characteristics of thin-walled protective structures.The main research contents are as follows:(1)Study of the axial mechanical properties of the Sierpinski triangle thinwalled structures with fractal gradients.A thin-walled structure design method that combining gradient design and the geometric fractal principle of the Sierpinski triangle is proposed to design a novel fractal gradient thin-walled protective structure.The impact stability and energy absorption capacity of the Sierpinski triangle thin-walled structure with the fractal gradient are investigated through experimental and numerical simulation methods under axial impact.The results show that the thickness gradient design can effectively improve the stability of the thin-walled structure under axial impact,and the fractal design can significantly improve the energy absorption characteristics of the thin-walled structure compare to the single walled structure to form a more efficient energy-absorbing protective structure.In addition,a theoretical model of the average crash force and energy absorption of the fractal gradient thin-walled structure is further developed using the Super Folding Element(SFE)theory,which reveals the energy absorption mechanism of the metal thin-walled structure and makes accurate predictions.(2)Study of the tilting impact resistance of the Sierpinski triangle thinwalled structures with fractal gradients.The tilting impact resistance of the fractal gradients thin-walled structures with different fractal orders was further investigated by numerical simulation to fully explore the mechanical properties of the Sierpinski triangular fractal gradient thin-walled structures.The study shows that the thin-walled structure combining the thickness gradient and fractal design can improve its tilt impact resistance,significantly improve the energy absorption and reduce the initial peak force compared with the traditional single-walled structure.Finally,Response Surface Methodology(RSM)model and Non-dominated Sorting Genetic Algorithms(NSGA)are used to carry out multi-objective optimization of the Sierpinski triangular fractal gradient thin-walled structure to design a thin-wall protective structure with higher energy absorption or lower impact forces.(3)The application of the fractal gradient design method to other polygons and its crashworthiness study.The paper further develops its design extension research in polygonal thin-walled structures,proposes and investigates the impact resistance of fractal gradient structures with quadrilateral,pentagonal and hexagonal cross-section.The results further show that the fractal gradient design not only improves the energy absorption capacity of thin-walled structures in the impact process,but also promotes the deformation stability of the structure and reduces its initial impact force,providing theoretical support and data accumulation for the design of thin-walled protective structures with efficient energy absorption capacity.