Analysis Of In-Plane Mechanical Behaviors Of I-Beam Honeycomb

With excellent performance in structure and energy absorption,I-beam honeycomb provides a wide range of applications such as aerospace industry,heat transfer system,noise suppression and radio frequency shielding.In view of the fact that more and more engineering designs have required the in-plane mechanical behaviors to strengthen functionality in recent years,this thesis researches the in-plane dynamic behavior of double-walled I-beam metal honeycomb cores in the x₁ direction with the aid of the finite element analysis.Firstly,the deformation mechanism is an important part of the in-plane mechanical behavior of honeycomb materials.So the in-plane deformation modes at different impact velocities are studied.Local inverted"V"shaped deformations appear at the top and bottom of the honeycomb cores at low impact velocities;At moderate impact velocities,"W"shaped deformations appear at the top of the honeycomb cores firstly,and the front of the deformations zone moves down by the"V"shape as time goes on;At high impact velocities,deformations become transverse"I"shaped.During the deformation process,the von mises stress distribution contours show that the stress of I-beam honeycomb cores vary with the degree of their deformation and exist a phenomenon of stress oscillation.Secondly,the energy absorption is another important part of the in-plane mechanical behavior of honeycomb materials,and the dynamic peak stress which related to the impact velocity and the structure parameters can characterize it well.So attention focus on the influences of ratio between cell wall thickness and edge length,edge length ratio,expanding angles and impact velocities on in-plane dynamic compressive properties of double-walled I-beam metal honeycomb cores.In x₁ directions,when all configuration parameters are kept constant,the peak stresses are proportional to the square of impact velocities;For the given impact velocities,the peak stresses are related to the ratio between cell wall thickness and edge length or edge length ratio by approximative power laws,while conic relation with the expanding angles.And the formula of the in-plane peak stresses of double-walled I-beam metal honeycomb cores are derived.The influences of structure parameters on in-plane densification energy absorption per unit mass are similar to the influence law of dynamic peak stress,they fit the same formula,just have the difference in value.By comparing with the in-plane densification energy absorption per unit volume of double-walled hexagonal metal honeycomb cores,the superiority of I-beam honeycomb cores mechanical properties is proved.Finally,cushioning performance is the important aspect in the application of honeycomb materials while the energy absorption diagram can characterize it effectively.According to the forming theory,the energy absorption diagram of the double-walled I-beam metal honeycomb cores under different ratio between cell wall thickness and edge length,edge length ratio,expanding angles and impact velocities are obtained.The evaluation indexes such as"the best energy absorption point","the best energy absorption efficiency"and"minimum dynamic cushioning coefficient"are applied to evaluate the in-plane cushioning performance of I-beam honeycomb cores.It is proved that I-beam honeycomb cores have good in-plane cushioning properties and this evaluation method is feasible.The analysis of the mechanical behavior of I-beam honeycomb is the basis of transportation and cushioning packaging design,beneficial to alleviate the problems of poor selection of honeycomb materials,excessive packaging and the waste of resources,and can also extend to other areas such as heat transfer,sound and electricity,the value of scientific research is self-evident.