Studies On Property And Design Of 3-d Braided Kevlar Fiber Reinforced Resin Composites

In this paper, K3D/PMMA and K3D/EP composites were prepared by using impregnated technology and RTM technology. The fiber treatment, preparation technology, mechanical properties, moisture absorption behavior, friction and wear characteristics of composites were researched; And 3-d braided composites were simulated by cross model and FEA model. By using FEA software ANSYS, the stress of artificial hip joint was analyzed.The regularities of mechanical properties of composites affected by fiber volume(Vf) and fiber braiding angle(θ) are as the follows. Vf andθare dramatic factor which have an effect on mechanical properties of braided composites. With the increase of Vf or the decrease ofθ, flexural properties, shear properties and impact properties are rising. According to the analysis of the stress, which be used to analyze the rule and mechanics of 3-d braided composites affected by Vf andθ, how to select the braid parameters of 3-D braided composites has a correlation with the form and value of the load which composites bear.The laws of mechanical properties of composites affected by Vf, moisture absorption temperature and moisture absorption medium are as the follows. With the increase of Vf, hygroscopic degree of composites declined; With the temperature rising, hygroscopic degree of composites conspicuous increased; hygroscopic degree of composites in PBS is more than in distilled water's; Moisture absorption of composites results in the drop of flexural properties and shear properties, however, makes impact properties increased.Vf , fiber orientation, fiber surface treatment, load and velocity have an great effect on friction and wear properties of K3D/EP composites. With the increase of Vf or load, friction factor and wear rate also decreased; When sliding surface is parallel to fiber braided axis, the friction factor is less than vertical direction's, but wear rate is more than its. Under dry friction condition, SEM results showed that the wear mechanisms of K3D/EP composites are abrasive wear and slightly adhesive wear at a lower velocity and lower load, and adhesive wear and abrasive wear at a higher velocity or load. Under PBS lubrication condition, the wear mechanisms of K3D/EP composites are abrasive wear.The results of 3-d braided composites simulating are as the follows. The cross model is twice modified which can simulate 3-d braided composites better. The results indicate that longitudinal modulus, transversal modulus and shear modulus increased with the increase of Vf . With the decline ofθ, longitudinal modulus increased, however, transversal modulus and shear modulus decreased. The displacement fields and stress fields of 3-d braided composites are gained at tensile load by using ANSYS which their reinforced mechanics are proved; it exist stress bonded area on interface of fiber and matrix of 3-d braided composites. Fiber absorbs more stress.The stress analysis results of artificial hip joint are: the largest synthesized displacement is DMX=1.598 × 10-3m. The largest stress is 18652Pa at the position of the joint counterforce on caput auriculars. As SMX=41946Pa＜ σ, 3-d braided composites met the needs of fixation devices of fracture which don't exist stress barrier.