Study On Energy Absorption Characteristics Of Spruce Wood And Sandwich Structures With Spruce Wood Core Under Static And Dynamic Tests

Spruce wood is a kind of soft wood with flat internal texture.Compared with common metal materials,spruce wood is structurally similar to a loose,porous foam structure,moreover it has lighter specific gravity and is more economical.Therefore,spruce wood was taken as the object of the study in this paper.Static responses were researched and in order to make structures perfect,spruce wood sandwich structures with CFRP(Carbon Fibre Reinforced Plastics)panels were fabricated.Dynamic response characteristics of these sandwich structures were analyzed by the low velocity impact experiments.Spruce wood is a kind of soft wood,due to season/climate and the growth characteristics of the wood itself,mechanical properties of it are different in different locations and directions.In this paper,spruce wood were taken from two locations: south and north,both of these two kind of materials were under quasi-static compression via three directions,i.e.longitudinal,radial and tangential.The influence of location and compression direction on the deformation process of spruce wood under quasi-static compression was assessed according to the analysis of experimental process.The relationship between energy absorption characteristics and the location and compression direction of the samples were obtained through the load-displacement curves.The possible causal relationship between the microscopic failure mechanism and the macroscopic deformation of the spruce wood was studied by microscopic observation.Based upon the experimental results of quasi-static compression,those which have the highest strength and better energy absorption capability were picked for fabricating spruce wood sandwich structures with CFRP panels.In order to simulate actual impact conditions,low velocity impact experiment was carried out to explore effects of impact energy and material thickness on dynamic responses of sandwich structures.The corresponding relationship between material/structure failures and load-time curves during the dynamic test process was analyzed,the energy absorption efficiency was calculated,and the relationship between deformation/energy absorption characteristics of spruce wood and impact energy/ material thickness was given.In this paper,the multi-variable research of the standard specimens of spruce was studied under quasi-static conditions,at the same time the dynamic responses of spruce wood-CFRP sandwich structures under low velocity impact were analyzed.All these works will provide some technical supports for the application of natural green materials in the light weight of automobile,and results of this research have certain guiding significance and reference value for the application of the sandwich structure with natural green materials in the design of anti-impact device.