Research On Low-Velocity Impact And Residual Strength Of Composite Laminates

With the widespread use of composite materials in aircraft structures,it is increasingly important to evaluate the damage to composite structures during aircraft operations and maintenance.Due to the sensitivity of composite materials to impact,it is necessary to evaluate the damage of composite structures under low-velocity impact to determine whether the composite structures with low-velocity impact damage still meet the safety requirements.At present,residual strength after imapct is the main appointment for evaluating the low-velocity impact damage of composite materials.Therefore,low-velocity impact and residual strength after impact of composite laminates were studied in this paper.The main contents are as follow:(1)Through the sorting and the analysis of the airworthiness requirements related to the damage tolerance of composite materials,residual strength after impact was determined as the evaluation appointment for the low-velocity impact damage of composite laminates.Aiming at the limitation of common damage tolerance analysis methods of composite materials,a simulation analysis method for the whole process of low-velocity impact damage of composite laminates was proposed.The main modules and contents of the verification test were also designed.(2)Taking P2352W-19 composite laminates as the analysis object,the tests of low-velocity impact under different impact energies and of residual strength evaluation after impact were conducted.The test results provided a reference for the determination of the model damage mode and the optimization of constitutive model in the whole process simulation analysis method and provided the basis for the verification of the effectiveness of the simulation analysis method.(3)P2352W-19 composite laminates were taken as the analysis object to simulate the whole process from the beginning of low-velocity impact to the evaluation of impact damage.The simulation results and the experimental results were compared from three aspects of impact response,damage status and residual strength.The validity and accuracy of the simulation analysis model were verified.Based on the established model,the process of the low-velocity impact and the process of destruction under compressive load after impact were further analyzed.