Cover: The Influence of Random Filament Packing on the Elastic Properties of Composite Materials.

The Influence of Random Filament Packing on the Elastic Properties of Composite Materials.

Published 1968

by Donald Frederick Adams, Stephen W. Tsai

Purchase Print Copy

 Format Price
Add to Cart Paperback-245 pages $23.00

A new method of micromechanical analysis of composite materials (such as boron- or glass-fiber-reinforced aluminum or epoxy) that takes account of the randomness of arrangement of the reinforcing filaments. Previous analyses assumed a regular geometric array, in which case a physically unrealistic square array showed surprising agreement with experimental data. Since available computers cannot handle a completely random arrangement, a basic pattern was generated by random-number techniques and was then reflected to obtain symmetry; this unit was assumed to repeat iteself throughout the material. Solutions for the modulus of elasticity were obtained for a 10-by-10 random array, for each of 20 random geometries using constituent stiffness ratios corresponding to boron/aluminum, glass/epoxy, and boron/epoxy composites, for filament volume contents of 39, 55, and 70 percent. The assumed symmetry permitted the use of standard boundary/value solution methods. When the assumed filament packing array is randomized, the more physically realistic "hexagonal random array" is in better agreement with the data than the "square random array." Since the latter results in much higher local stress concentrations, use of the square array model could lead to unduly conservative analyses. 48 pp. Refs. (MW)

This report is part of the RAND research memorandum series. The Research Memorandum was a product of RAND from 1948 to 1973 that represented working papers meant to report current results of RAND research to appropriate audiences.

This document and trademark(s) contained herein are protected by law. This representation of RAND intellectual property is provided for noncommercial use only. Unauthorized posting of this publication online is prohibited; linking directly to this product page is encouraged. Permission is required from RAND to reproduce, or reuse in another form, any of its research documents for commercial purposes. For information on reprint and reuse permissions, please visit

RAND is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.