| Book Review: Primer on Composite Materials Analysis | |
Laminated plate theory is the basis of all composite analyses. It is
also the first course taken by most engineers, even before
manufacturing. There should be no surprise, then, at the large number
of books published on this topic.
Primer on Composite Materials Analysis is a classic
reference. It was first published in 1968, in the early days of the
advanced composites industry. It remains a good reference today, with
several features that help it stand out from the rest of the
field. And, although it is concise like a reference book, John Halpin
provides many intuitive descriptions of the math.
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Common throughout the book is the use of rubber/nylon test coupons to demonstrate material behavior. These materials have large deflections under relatively small loads. They provide clear images of shear, twisting and bending behavior.
The strength chapter begins with the usual coverage of first and last ply failure, using both the maximum strain and the Hill critera. It then goes on to cover the strength of nothced laminates (including introductory fracture theory), residual (curing) stresses and strength, and interlaminar stress and delamination. The latter topic shows how differences in stacking sequence alone can have a significant effect on strength.
Analysis of structures includes plates, beams and shells. Anything beyond a brief overview of these topics would be beyond the scope of this book. In plates, for example, Halpin shows how the theory is developed, then presents complete solutions for some special laminates. Of great use are the numerical examples showing the magnitude of the error introduced by simplifying assumptions.
The chapter on structure property relationships covers micromechanics. In contrast to most introductory texts, Halpin provides very thorough coverage of this topic. The chapter begins with a detailed literature view of micromechanics. The theory covered is based on the Halpin-Tsai equations, and includes a survey of constants for various fiber and packing geometries.
Other topics covered under micromechanics include transport and expansion properties. One result I found surprising was that it is possible to have an isotropic coefficient of thermal expansion (CTE) without having a quasi-isotropic laminate.
The book concludes with a chapter on testing. The focus is not so much on the mechanics of testing, but on how test results may not match actual material properties. For example, the sign of shear load does matter when dealing with angle ply laminates. Coupling has a significant effect on test results, and can introduce large errors. Most engineers are probably aware that flexural tests do not provide reliable material data; Halpin shows why this is so. Finally, the shear modulus of a [+/-45]S laminate is not the same as the shear modulus of a [45] laminate.
No matter how many books on laminate theory you may already have, this is one reference you should add to your collection. Even if you don't need it for the math, it provides a lot of practical information you won't find in other, similar references.
Details: Primer on Composite Materials Analysis, by
John C. Halpin, published by
Technomic Publishing Company, 1992, ISBN 0-87762-754-1.
1. Introduction; 2. Properties of an Orthotropic Lamina; 3. Laminated
Composites; 4. Strength of Laminated Composites; 5. Analysis of
Composite Structures; 6. Structure Property Relationships for
Composite Materials; 7. Characterization and Behavior of Structural
Composites; A. Matrices and Tensors; B. Equilibrium Equations for
Plates; C. Trigonometric Functions for Laminated Composites
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