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

by Donald Frederick Adams, Stephen W. Tsai


Purchase Print Copy

 FormatList Price Price
Add to Cart Paperback-245 pages $23.00 $18.40 20% Web Discount

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

Our mission to help improve policy and decisionmaking through research and analysis is enabled through our core values of quality and objectivity and our unwavering commitment to the highest level of integrity and ethical behavior. To help ensure our research and analysis are rigorous, objective, and nonpartisan, we subject our research publications to a robust and exacting quality-assurance process; avoid both the appearance and reality of financial and other conflicts of interest through staff training, project screening, and a policy of mandatory disclosure; and pursue transparency in our research engagements through our commitment to the open publication of our research findings and recommendations, disclosure of the source of funding of published research, and policies to ensure intellectual independence. For more information, visit

The RAND Corporation 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.