This paper presents an experimental investigation of the ModeⅡdelamination resistance of curved CFRP laminates reinforced with Z-pins.A Pre-Hole Z-pinning(PHZ)process is developed to reduce the in-plane damage of the...This paper presents an experimental investigation of the ModeⅡdelamination resistance of curved CFRP laminates reinforced with Z-pins.A Pre-Hole Z-pinning(PHZ)process is developed to reduce the in-plane damage of the Z-pinned laminates.The microstructural observation of the Z-pinned laminate specimens indicates that the PHZ process can effectively decrease the defects including the Z-pin offset angle and the area of eyelet zone.The influences of the volume fraction and diameter of Z-pin on the fracture toughness and the delamination crack growth rate of the specimens under End Notch Flexure(ENF)loading are then determined experimentally.The test results show that Z-pin increases the interlayer stiffness of the laminate.The delamination crack growth rate is reduced with the increase of Z-pin diameter and volume fraction,and a reduction up to 40%is achieved compared with the specimens without pins.Furthermore,the ModeⅡfracture toughness is significantly improved with the increase of Z-pin volume fraction.When Z-pin volume fraction increases by 1%,the achieved fracture toughness is about 200%higher compared to the unpinned laminates.展开更多
In this study,the micro curing residual stresses of carbon fiber-reinforced thermoset polymer(CFRP)composites are evaluated using a multiscale modeling method.A thermochemical coupling model is developed at the macros...In this study,the micro curing residual stresses of carbon fiber-reinforced thermoset polymer(CFRP)composites are evaluated using a multiscale modeling method.A thermochemical coupling model is developed at the macroscale level to obtain the distributions of temperature and degree of cure.Meanwhile,a representative volume element model of the composites is established at the microscale level.By introducing the information from the macroscale perspective,the curing residual stresses are calculated using the microscale model.The evolution of curing residual stresses reveals the interaction mechanism of fiber,matrix,and interphase period during the curing process.Results show that the curing residual stresses mostly present a tensile state in the matrix and a compressive state in the fiber.Furthermore,the curing residual stresses at different locations in the composites are calculated and discussed.Simulation results provide an important guideline for the analysis and design of CFRP composite structures.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFF0500100)the National Natural Science Foundation of China(No.11872310)。
文摘This paper presents an experimental investigation of the ModeⅡdelamination resistance of curved CFRP laminates reinforced with Z-pins.A Pre-Hole Z-pinning(PHZ)process is developed to reduce the in-plane damage of the Z-pinned laminates.The microstructural observation of the Z-pinned laminate specimens indicates that the PHZ process can effectively decrease the defects including the Z-pin offset angle and the area of eyelet zone.The influences of the volume fraction and diameter of Z-pin on the fracture toughness and the delamination crack growth rate of the specimens under End Notch Flexure(ENF)loading are then determined experimentally.The test results show that Z-pin increases the interlayer stiffness of the laminate.The delamination crack growth rate is reduced with the increase of Z-pin diameter and volume fraction,and a reduction up to 40%is achieved compared with the specimens without pins.Furthermore,the ModeⅡfracture toughness is significantly improved with the increase of Z-pin volume fraction.When Z-pin volume fraction increases by 1%,the achieved fracture toughness is about 200%higher compared to the unpinned laminates.
基金Supported by the National Key Research and Development Program of China(Grant No.2017YFB1102800)the National Natural Science Foundation of China(Grant Nos.11872310 and 51761145111).
文摘In this study,the micro curing residual stresses of carbon fiber-reinforced thermoset polymer(CFRP)composites are evaluated using a multiscale modeling method.A thermochemical coupling model is developed at the macroscale level to obtain the distributions of temperature and degree of cure.Meanwhile,a representative volume element model of the composites is established at the microscale level.By introducing the information from the macroscale perspective,the curing residual stresses are calculated using the microscale model.The evolution of curing residual stresses reveals the interaction mechanism of fiber,matrix,and interphase period during the curing process.Results show that the curing residual stresses mostly present a tensile state in the matrix and a compressive state in the fiber.Furthermore,the curing residual stresses at different locations in the composites are calculated and discussed.Simulation results provide an important guideline for the analysis and design of CFRP composite structures.
