Properties Of Glass Fiber Reinforced PA66 Twill Weave Composite

Glass fiber is an inorganic nonmetallic material with excellent properties.It is made by drawing and cooling the molten glass under high temperature melting.Polyamide 66(PA66)has high mechanical properties and good process ability.Compared with traditional materials,(PA)demand for engineering plastics occupies first place in the world,with high strength,light weight,high modulus,anti-fatigue performance and excellent shock absorption and many other advantages.Glass fiber reinforced PA66 twill weave composite material has the coordination of performance and reinforcing each other of structure between the glass fiber and nylon 66,with a single material can't match the superior performance which result in widely using in the automobile domain.The tensile and four-point bending tests were carried out on different samples,and the microscopic damage of the specimens after failure was observed and analyzed.When the composites are stretched in the longitudinal direction,the cracks in the material first appear on the contact surface between the glass fiber and the PA66 matrix.As the stress increases,the crack between the glass fiber and the matrix material will gradually expand,and then the crack extends to the material rich in matrix Area,the phenomenon of delamination between the yarns,PA66 matrix within a large area of yam cracking.Eventually as the stress increases,the glass fibers deform,and the glass fibers produce surface cracks which eventually lead to the breaking of the glass fibers and the failure of the material.When the composite material is subjected to bending,cracks are generated between the yarns and gradually spread,resulting in a large number of layers between the yarns.When the internal cracks accumulate to a certain extent,the load reaches the maximum,and then gradually decreases with the crack propagation.Then,between the glass fiber and the PA66 matrix and the matrix inside the yarn,The micro cracks are rapidly expanding,and the bending failure of the glass fiber is accompanied by tensile fracture and yield fracture of the glass fiber.The results of the influence of relative humidity show that the PA66 matrix will be hydrolyzed with amide bond with the increase of relative humidity which results in the increase of plasticity of PA66.Therefore the break strength and Young's modulus of composite decrease and break strain increase.The effect of[(±45)3]composite is more obvious than that of[(0/90)3]composites.Based on the cyclic loading fatigue test,[(0/90)3]composite can't be break within 100 million cycles under the condition of maximum stress of 80MPa,so no more than 80MPa stress level can meet the needs of the actual use.No more than 40MPa stress level for[(± 45)3]composite materials.The fatigue model(?)predict the fatigue behavior of the composites very accurately.The parameters a = 0.022 and?= 0.465 in the model.