Investigation Of Low-velocity And Residual Bending Strength Characteristics Of Hybrid Sandwich Structures

Corrugated core sandwich structure is a typical 2-D periodic sandwich structure,which has the characteristics of simple manufacturing process and excellent mechanical properties.It is widely used in aerospace,ship structure and so on.Corrugated core sandwich structures is applied to the ship’s side,deck and superstructure,which is often suffered from colliding of dock,falling objects and debris impact,and other forms of impact load.Then damage will be produced in structures,which will cause the mechanical properties reduced.Many foreign scholars have carried out the research on the bahaviour of the low-velocity impact and post-impact residual compressive strength of all composite or metal corrugated core sandwich structures,while the low-velocity impact response and the post-impact flexural behaviour of corrugated core hybridsandwich structuresare less studied.In this paper,the corrugated hybridcore sandwich structures are fabricated with an aluminum corrugated core and two laminated face sheets which will be composed of single or mixed composite materials.The basic mechanical properties,low-velocity impace response and post-impact flexural behaviour are investigated with combination of the experiment,theoretical analysis and numerical simulation method,which can provide the fundmental of theory for safety assessment.It has great engineering significance and theoretical value.The full text mainly includes the following contents:First of all,the low-velocity behaviour of corrugated sandwich structures which is fabricated by an aluminum alloy trapezoidal corrugated core and two CFRP face sheets is studied by experimental and numerical simulattion.The experimental investigations are conducted with different impact energy and impact locations.The law of energy absoption is obtained.Based on ABAQUS software finite element platform,combined with Hashin and Yeh failure criterion,the method of numerical simulation of hybrid composite material impact was established.The simulation of corrugated core hybridsandwich structures under low-velocity impact are carried out.The laws of energy absorption and impact damage are investigated.Second,with combination of experiment and finite element simulation method,the effects of geometrical configuration of core,core thickness,core material and panel material on the impact performance of corrugated core hybridsandwich structures are investigated.By numerical simulation analysis,the effects of five different geometric configurations of the core on theimpact performance of corrugated corehybrid sandwich structures are obtained based on the same weight..Through the numerical analysis and experimenral investigation,the impact characteristics of the hybrid composite material with stainless steel core was analyzed,and the influence of the core material on the impact characteristics was obtained.In order to investigate the effect of material of face sheets on the impact damage characteristics,the corrugated hybridcore sandwich structures with fiber laminated panelsrespectively made of six kinds of low elastic modulus and large fracture strain and corrugated aluminum coreare fabricated and the tests of low-velocity impact are conducted.Then,the post-impact flexural strength of corrugated core hybridsandwich structure is studied with combination of experiment and finite element simulation.The three-point bending tests of corrugated core hybridsandwich structures after impact under different impact energy and impact locations are conducted.In order to investigate the effect of material of face sheets on the post-impact flexural strength characteristics,the corrugated core hybridsandwich structures with fiber laminated panels respectively made of six kinds of low elastic modulus and large fracture strain and corrugated aluminum coreare fabricated and the tests of three-point bending are conducted.Finally,a method for enginerring estimating the impact response of corrugated core hybridsandwich structures is established.Equivalent mechanical properties of corrugated sandwich structure are obtained through simple beam theory analysis.The low-velocity impact problem is simplified to a dynamic problem with two degrees of freedom.The second order nonlinear differential equation is obtained.Based on the quasi-static analysis,the local stiffness and global stiffness of the system are obtained.Combined with the equivalent mechanical properties of corrugated sandwich structure,the numerical solution is obtained with initial boundary conditions.The low-velocity impact force and impact depth estimation results are obtained.The proposed method can be applied to the low-velocity impact dynamic response prediction of corrugated core hybrid sandwich structure.