Design And Impact Resistance Of Sandwich Structures With Negative Poisson’s Ratio

Ship protection structure,as an important structure to ensure the navigation of ships in the complex marine environment,has now become the focus of research in the field of marine engineering.Protection structure should not only consider strength,stiffness,etc.,but also have excellent crashworthiness and energy absorption ability.The design method of improving performance by thickening contradicts the requirement of light weight of modern ships,therefore,there is an urgent need to achieve the balance of structural light weight and excellent performance through new material and structural design.The negative Poisson’s ratio material has excellent impact resistance and energy absorption ability due to its special auxetic characteristics,and has important application value in the field of ship protection.In this thesis,a sandwich structure with a core layer of negative Poisson’s ratio re-entrant honeycomb is designed to replace the traditional marine stiffened plates,and the crashworthiness and influence of the negative Poisson’s ratio sandwich structure are studied.For the problem of complex structural parameters of negative Poisson’s ratio,the multiobjective optimization design is realized by intelligent optimization algorithm.The details of the study are as follows:(1)Design a sandwich structure with a core layer of negative Poisson’s ratio material.Based on the principle of equal mass,a re-entrant honeycomb sandwich material with simple structure,good impact resistance and negative Poisson’s ratio effect is designed based on the replacement target of traditional marine stiffened plates to form a design scheme of negative Poisson’s ratio sandwich protection structure.Based on this analysis,the mechanism of impact resistance of the negative Poisson’s ratio sandwich structure is characterized by the analysis of the tensile and expansion deformation process of negative Poisson’s ratio,and it is found that its internal concave deformation is the key to its high energy absorption.(2)The crashworthiness simulation technology of sandwich structure with negative Poisson’s ratio is established and compared with the experimental results.The finite element model of sandwich structure with negative Poisson’s ratio was established based on ANSYS/LS-DYNA software,and the crash-resistance performance of sandwich structure with negative Poisson’s ratio was analyzed.The accuracy of the simulation technology was verified by comparing with the experimental results.The crashworthiness of the sandwich structure with negative Poisson’s ratio is compared with that of the replaced stiffened plate,and the feasibility of the sandwich structure with negative Poisson’s ratio in improving the crashworthiness and energy absorption capacity of the ship protective structure is demonstrated.(3)The crashworthiness analysis of negative Poisson’s ratio sandwich under different impact conditions and structural parameters is carried out.Focusing on the influence of geometric parameters of negative Poisson’s ratio on the crash-performance of the structure,a parametric analysis is carried out to obtain the influence law of design parameters on the crash-performance of the sandwich structure,determine the main influence parameters,and establish the sample data of the optimization design,which lays the foundation for the subsequent optimization design.(4)A multi-objective optimization design method for crashworthiness of sandwich structures with negative Poisson’s ratio is established.Based on the optimal Latin hypercube test design,collision sample data of sandwich structure with negative Poisson’s ratio were selected to build a radial basis surrogate model,and multi-objective optimization of sandwich structure with negative Poisson’s ratio was realized by using multi-objective particle swarm optimization algorithm.The optimized sandwich structure with negative Poisson’s ratio realized the improvement of crash-resistance under the premise of total weight control.The feasibility of the optimal design method and the effect of improving the crashworthiness of the sandwich structure with negative Poisson’s ratio are demonstrated.