Temperature Effects On The Mechanical Properties And Failure Mechanisms Of Composite Sandwich Panels With Y-Shaped Cores

Carbon fiber composite sandwich panels with Y-shaped cores have a wide range of application in marine because of their light weight,high specific stiffness and specific strength and multifunctionality.At present,there is no research focusing on the mechanical properties of composite sandwich panels with Y-shaped cores at different temperatures.The epoxy matrix is sensitive to temperature.In order to understand mechanical properties of the carbon fiber reinforced composite sandwich panels with Y-shaped cores at high and low temperatures and provide data support for its design and application on ships,it is necessary to investigate the effects of temperature on mechanical behaviors of composite sandwich panels with Y-shaped cores.In this dissertation,the mechanical properties and failure mechanisms of carbon fiber composite sandwich panels with Y-shaped cores at high and low temperatures such as out-of-plane compression,three point bending,edge compression and quasi-staic indentation were studied.The out-of-plane compression responses of composite sandwich panels with Y-shaped cores at high and low temperatures were investigated by experimental and theoretical methods.The elastic modulus and strength of composite laminates at high and low temperatures were measured by experiments.The effects of temperature on typical stress-strain curves,compressive stiffness and strength of composite sandwich panels with Y-shaped cores under out-of-plane compression were analyzed.The out-of-plane compression failure mechanisms of composite sandwich panels with Y-shaped cores were revealed.The analytical expressions were presented to predict the compressive stiffness and strength of composite sandwich panels and compared with experimental results at different temperatures.The effects of temperature on the three point bending behaviors of carbon fiber composite sandwich panels with Y-shaped cores were studied.The changes of typical bending load-displacement curves,bending failure load,ultimate peak load and P(T)/(?)(T)were obtained.The three point bending failure mechanisms of composite sandwich panels with Y-shaped cores at different temperatures were revealed.The results showed that the bending failure load and P(T)/(?)(T)of composite sandwich panels decreased with increasing of temperature.The analytical prediction formulas for bending failure load and P(T)/(?)(T)of composite sandwich panels with Y-shaped cores at high and low temperatures were derived.The effects of high and low temperatures on edge compression behaviors of composite sandwich panels with Y-shaped cores were studied,and the causes of changes of edge compression load-displacement curves and failure modes at high and low temperatures were investigated.The theoretical prediction formulas of edge compression failure load at different temperatures were established.The results showed that the load-displacement curves went down and failure load decreased with increasing of temperature.The mechanical responses of quasi-static indentation of composite sandwich panels with Y-shpaed cores at high and low temperatures were explored by experiments.The changes of indentation load-displacement curves and failure load at different temperatures were obtained.The effects of high and low temperatures on failure mechanisms of composite sandwich panels with Y-shpaed cores under quasi-static indentation loading were revealed.The results showed that when the temperature was lower than the glass transition temperature,the failure modes of composite sandwich panels was fiber fracture.However,the fiber microbuckling failure was observed for the composite sandwich panels when the temperature was higher than the glass transition temperature.