دانلود رایگان مقاله تحقیقات برشی در صفحه از کامپوزیت بافته سطح هسته ای سه بعدی

Abstract

In-plane shear properties of three-dimensional (3D) surface-core braided composite are investigated by numerical simulation and experimental tests. Based on RVE models, the mechanical responses under in-plane shear load and the basic shear properties related to braiding parameters are predicted by using finite element method. Numerical results indicate that two groups of surface-cores possess distinct sensitivities to shear loads and identify the main load bearing components. In-plane shear tests are conducted to compare the effects of surface cuttings on the mechanical properties of present material and 3D 4-directional braided composite. The experimental data reveal that the cuttings degrade the shear moduli and strengths of the two materials to varying degrees. 3D surface-core braided composite can effectively restrain the decline of shear properties caused by cuttings. Scanning electron microscopy (SEM) is used to identify the distinct damage mechanisms of tested materials.

5. Conclusion

RVE models are established to study the in-plane shear properties of 3D surface-core braided composite by using finite element method. The numerical results indicate that the surface-cores parallel to material surface bear primary shear load by producing tensile or compressive axial stress in the fibers while the surfacecores perpendicular to material surface are insensitive to the load. Then the basic shear properties affected by braiding angle and fiber volume fraction are obtained by adopting homogenization approach and volume averaging method. In-plane shear properties of undamaged and pre-damaged 3D surface-core and 3D 4- directional braided composites are respectively measured by Arcan method. The experimental data show that 3D surface-core braided composites possess better performance to restrain the degradation of shear properties caused by surface cuttings. For both the materials, only the uncut specimens fail with fractures while the cut ones fail leaving larger shear deformations. The fracture surfaces are observed by scanning electron microscopy (SEM), and the corresponding failure mechanisms of the two materials are identified.