Research On Low-speed Energy Absorption And Low-frequency Vibration Isolation Based On The Negative Stiffness Structure

Improving crash safety and comfort is the core design problem of modern vehicles.Based on the principle of negative stiffness,this dissertation takes the automobile child seat as the research object,and carries out in-depth research on the energy absorption performance of low-speed impact and low-frequency vibration isolation,realizing the design innovation of energy absorption structure and vibration isolation structure.The main research contents are as follows:According to the number of stable states of structural energy and the judgment conditions,the negative stiffness structures are divided into three types: pseudo bistable structures,sub bistable structures and bistable structures.Taking the bistable negative stiffness beam structure as the research object,the quasi-static mechanical characteristics of inclined straight beams,sinusoidal curved beams and prestressed buckling beams without prestress are studied,and the influence rules of different structural parameters on the performance of negative stiffness structures considering different structures or prestress characteristics are revealed,which lays a foundation for the type selection design and parameter selection of energy absorption structures and vibration isolation structures.Aiming at the design problem of the energy absorbing structure of the car child seat,the conventional hexagonal honeycomb structure is improved by using the inclined straight beam bistable structure,and the reusable energy absorbing structure design within the elastic range is realized;the energy absorption characteristics and stability of the inclined straight beam bistable structure under different stacking methods,different constraints and array structures are studied.By adjusting the deformation mechanism of the bistable structure in the negative stiffness stage,an optimized bistable energy absorption structure with smaller size,shorter energy absorption range but stronger energy absorption performance is designed,which realizes the improvement of the low-speed impact energy absorption performance of the car child seat in the horizontal direction.Aiming at the problem of low-frequency vibration isolation of automobile child seats,a quasi zero stiffness vibration isolation structure with adjustable capacity is designed based on the negative stiffness structure of prestressed buckling beam.By studying the performance characteristics of the quasi zero stiffness structure under different loads,the structural parameters are determined,and the quasi zero stiffness vibration isolation structure is trial produced;through simulation and quasi-static loading experiments,the key parameters of the static load-bearing curve of quasi-zero stiffness structure under different loads are determined by fitting;based on the fitting parameters,the dynamic characteristics of the single degree of freedom vibration isolation system based on the prestressed buckling beam quasi zero stiffness structure are studied,and the low frequency(minimum isolation frequency is 1.47 Hz)vibration isolation performance of the quasi-zero stiffness structure under different bearing conditions is realized.