Study On Delamination Damage Of Composite Materials Based On Digital Image Correlation And Acoustic Emission

The preparation and application of composite materials in the process of the external impact of composite laminates will frequent delamination,fiber breakage,matrix cracking and other forms of damage,and these defects easily lead to an overall structure of the composite damage accumulation and final failure,thus the composite lifetime seriously shortens.Therefore,it is very important to study the delamination damage evolution of composite materials.In this paper,the size of prefab delamination depth,the number of variables as a reference,design a variety of prefabricated layered laminates with different,thus to study the effect of different pre stratification on bearing capacity and fatigue life of composite laminates.In this paper,the uniaxial compression test of laminated composite structures with different size,location and depth is presented.Based on digital image correlation method(DIC)and acoustic emission(AE)technology on monitoring the evolution process of the delamination damage,analysis of the change of size,location and buried depth on the damage effect and damage of composite acoustic emission signal spectrum and the probability space.Combined with the theory of composite mechanics,relativity,phase and damage state probability entropy evolution of the physical mechanism of multi scale evolution of delamination damage evolution,correlation between real-time deformation and acoustic emission characteristics of composite materials of layered and mechanical damage and composite delamination damage failure mechanism.(1)The failure load of the prefabricated laminated composite specimen is smaller than that of the prefabricated laminated composite specimen,which indicates that the stratified damage affects the bearing capacity of the composite material;(2)When the prefabricated stratification size is the same,the greater the distance between the prefabricated layer and the center layer of the laminated plate,that is,the smaller the prefabricated stratum buried depth,the smaller the carrying capacity of the laminated plate;(3)When the prefabricated stratified depth is the same,the larger the prefabricated stratification size,the weaker the carrying capacity of the laminate;(4)For the coupled prefabricated stratified specimen,the more prefabricated stratum near the surface layer,the smaller the carrying capacity;(5)Preloading on the same side of the carrying capacity is more weak than the different side of the carrying capacity;(6)The acoustic emission signals such as amplitude,impact cumulative number,duration and relative energy can be used to analyze and evaluate the layered damage development behavior of glass fiber composites.Composites layered damage phase corresponds to high amplitude,high duration,high energy acoustic emission signal;(7)The displacement and strain field information obtained by the two-dimensional digital image correlation method,which reflects the deformation and damage characteristics of glass fiber composites in the process of delamination damage.The complementary technology of acoustic emission technology and two-dimensional digital image correlation method provides a reference for damage assessment,damage prediction and health monitoring.