Effect of Inclusion Morphology on the Coefficient of Thermal Expansion in Filled Epoxy Matrix (Preprint)
COMPOSITE TECHNOLOGY DEVELOPMENT INC LAFAYETTE CO
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The paper presents material development research performed at Composite Technology Development, Inc. towards optimization of the design for linerless composite cryogenic tanks. In a cryogenic composite tank, large thermal strains develop through the thickness of the tank laminate due to the mismatch in the coefficient of thermal expansion of adjacent plies with different fiber orientations. These thermal strains are primarily caused by the thermal contraction of the matrix material. Excessive thermal strains can cause microcracks in the matrix and inter-ply delamination, leading to leakage of the fluid contained by the tank. Reduction of the thermal expansion of the matrix is viewed as an essential design tool for optimizing these tanks. Addition of inclusions that are much stiffer than the matrix is an effective means to reduce thermal expansion of the matrix for the composite, as long as it doesnt compromise the toughness. The paper presents an analytical scheme to predict the effective thermal expansion properties of the filled matrix with embedded inclusions and investigates the effect of inclusion morphology, shape and aspect ratio on the same. The analytical predictions are compared with actual test results of thermal expansion measured for the matrix. The inductions and trends are being used to select the best material and to improve their processing to achieve the most optimized cryogenic tank design.
- Laminates and Composite Materials