Date of Award

Summer 1994

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Engineering Mechanics

Committee Director

Yozo Mikata

Committee Member

Gene Hou

Committee Member

Chuh Mei

Call Number for Print

Special Collections; LD4331.E57C4466

Abstract

An interphase in a composite material has a important role for the composite performance. It influences directly or indirectly the strength, fatigue performance and effective properties of the composite. Recently, interphase has drawn increasing attention in composite mechanics. To the best of our knowledge, however, no one seems to have considered the effect of the variable material prope1ty in the interphase on the stress field in the composite material. In this research, the stress fields are determined in the continuous fiber composite and the particulate composite by using the four concentric circular cylinders model and the four phase spheres model, respectively. Particular attention is paid to the discussion of the stress field in the interphase, which has linearly changing material properties in the radial direction. In the present problem, axisymmetric as well as spherical symmetric thermo-mechanical loadings are considered for continuous fiber composites and particulate composites, respectively. It is assumed in our model that each region is at most transversely isotropic for the cylinder system and isotropic for the sphere system. Base upon the above considerations, the equilibrium equation in each region becomes quite simple except in the interphase. The equation in the interphase is of course still linear but has variable coefficients. An exact closed form solution is constructed for this equation in a series form. Exact closed form solutions for the other regions can be easily obtained. Combining all these solutions, the displacement field in the entire composite is expressed with certain unknown coefficients, By imposing the boundary conditions as well as interphase conditions these unknown coefficients are obtained. Several typical composites are considered for numerical results and some assumptions of interphase properties are made for carrying out the applications of the model.

Rights

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DOI

10.25777/1q4f-4681

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