Book Review: Dynamic Loading and Characterization of Fiber-Reinforced Composites
If you're interested in the current thinking on the dynamic characterization of composites, this is the book for you. Most of the content is a review of the literature and test methods. Although the title of this book mentions dynamic loading, the focus is really on one type of dynamic loading: impact.
The introductory chapter provides a good background on dynamic loading in general. Dynamic loads are shown to fall into three regimes (for structures) or four regimes (for materials) depending on the duration or natural period of the load. Types of damage caused by each regime are then identified.
The second chapter, Dynamic Properties, is really a review of current impact test methods. The major methods covered include punch, Charpy/Izod, drop-weight, Hopkinson pressure bar, and flyer plate tests. The first three tests are covered only briefly: even though they are the most commonly used (because they are easy to perform), they are not very applicable to composites. The Hopkinson tests give better results for composites, and thus are covered in much more detail.
The third chapter, Wave Motion, briefly describes seven different theories. Only one, effective modulus theory, is covered in detail. This theory is probably chosen because it is the simplest and because many procedures and key results are based upon it. However, the authors also state that it has "serious shortcomings", but these are not pointed out explicitly.
The fourth chapter, Damage Detection and Characterization, reviews the common non-destructive evaluation (NDE) techniques. The techniques are then applied to a study of graphite-, Kevlar-, and fiberglass-epoxy panels. Each panel is subjected to an impact loading, and NDE techniques are used to observe the damage. The damage modes are significantly different for the different types of materials.
The fifth chapter, Damage Tolerance, tries to show how to make composites more resistant to damage. This is probably the most practical chapter in the book. Damage control in metals focuses on cracks. Because there are many more damage modes in composites, however, there is not yet a "unifying idea" for damage resistance in composites. The two most important things to remember from this chapter are:
- Analytical and empirical models of damage tolerance have yet to be translated into proper damage-tolerance design criteria; and
- Most of the existing data has been collected from coupon tests, which do not necessarily scale to full structures.
Finally, the book concludes with a brief chapter on techniques for impact damage modeling. The techniques can be classified in three categories: empirical, semi-empirical, and analytical. Only the latter two are covered in any detail.
Details: Dynamic Loading and Characterization of
Fiber-Reinforced Composites, by Robert L. Sierakowski and Shive
K. Chaturvedi, published by
John Wiley & Sons, 1997, ISBN 0-471-13824-X.
1. Introduction; 2. Dynamic Properties; 3. Wave Motion; 4. Damage
Detection and Characterization; 5. Damage Tolerance; 6. Impact Damage
Modeling