Research On Prediction Methods Of Residual Strength And Fatigue Life Of Laminated Composites Containing Delamination

Composite laminated structures cannot avoid initial damage to a certain extent,such as delamination and voids.Delamination is an important failure form of composite materials.The initial delamination damage will reduce the interlaminar mechanical properties of composite laminated structures,and result in the failure of the whole structures when they are subjected to loads lower than the designed value.Therefore,in order to improve the safety and reliability of laminated structures,it is necessary to study the residual strength and fatigue performance of composite structures containing initial delamination damage.In this paper,T300/BMP316 composite laminates are used as research objects to study the static strength and fatigue life prediction methods of composite laminates with initial delamination damage.For laminates with initial delamination,there are many existing interlamination models and delamination failure criteria,but there are few comparative analyses on different interlamination models and their applicable delamination failure criteria.Therefore,this paper focuses on three interlamination models and the corresponding delamination failure criteria.Based on this,the analytical models and prediction methods for the static strength and fatigue life of laminates are established,so as to comprehensively compare and evaluate the applicability and correctness of the three interlamination models and their delamination failure criteria.Research works in this paper can be summarized as follows:1.For the composite laminates with initial delamination damage,the interlamination models are established by three methods: node merging,node coupling and three-dimensional solid element.The delamination failure criteria are selected for different models.The node merging model uses the threedimensional Hashin delamination failure criterion,the power index criterion is selected for the node coupling model,and the delamination damage is determined for the three-dimensional solid model by the criterion based on the crack zone model and related to the energy release rate.2.Based on the progressive damage analysis method,three interlamination models and corresponding delamination failure criteria are introduced.Combined with the Hashin failure criteria and the material performance degradation method,the analytical models and prediction methods for residual strength of composite laminates containing initial delamination damage are established.3.Based on the static strength analysis,three interlamination models and corresponding delamination failure criteria are introduced into the progressive damage analysis method.The Hashin fatigue failure criteria,material performance degradation method,residual stiffness model and residual strength model are adopted to establish the analytical models and prediction methods for fatigue life of composite laminates containing initial delamination damage.4.Aiming at the T300/BMP316 carbon fiber resin matrix composites,the interlaminar fracture toughness tests of composites are carried out to obtain the interlaminar fracture toughness of ?-type and ?-type,and the relevant parameters are provided for the power index criterion based on energy release rate.5.Combined with the test results of composite laminates with initial delamination damage,the comprehensive comparative analyses of the predicted damage development rules,residual strength and fatigue life are carried out to verify the applicability and correctness of the three interlamination models and delamination failure criteria used in this paper.