REVIEWED BY M. H. RICHMAN 1 THIS WORK by John Wulff and his associates consists of four individual volumes each devoted to a different aspect of materials science. The subjects of the various volumes are as follows: (1) Structure, (2) Thermodynamics of Structures, (3) Mechanical Behavior, and (4) Electronic Properties. The series is designed to offer a comprehensive introduction to the structure, properties and behavior of solid materials-metals, polymers, and ceramics. The authors have tried to balance the physics and chemistry of solids and have placed emphasis on the principles relating properties and behavior to structure and environment. At present, only volumes 1 and 2 are available for review.

BOOK REVIEWS a fluid-filled tube in which the tube can be elastic or viscoelastic but the fluid is assumed to be incompressible and inviscid. All articles are very mathematically and analytically oriented. Nevertheless, the articles cover a fairly wide range of wave propagation phenomena in viscoelastic media. In view of the fact that there are not many books available on viscoelasticity and even fewer on wave propagation in viscoelastic media, the appearance of this volume is welcome. It would serve as a useful reference for those who want to venture into this field.

This paper treats the development of pertinent theories that establish the properties of the fiber-matrix interface needed to achieve efficient composites and the development of a test technique to measure these properties. An equation is derived that relates the externally applied load to the failure mode, fiber tensile strength, and interface shear strength. This equation makes it possible to establish the interface strength that is required to obtain overall composite failure instead of interface failure. The effect of interface on the bending stiffness and Young's modulus of filamentary composites is investigated. A technique, based on shear-lag theory, that will measure the properties of the interface is presented. This technique involves pullout tests on fibers that are imbedded in a matrix. An approximate solution also is presented for the shear-stress distribution around a discontinuous fiber that is surrounded by six continuous fibers. The seven fibers are a part of a composite of infinite extent that is subjected to a remotely applied tensile stress. It is shown that there is a significant variation in the shear-stress distribution along the fiber length as well as around its circumference.

Theoretical solutions and results are given for stress concentrations and failure stresses in orthotropic and anisotropic composite plates. Solutions for the stresses around the opening are given for plates subjected to uniaxial, biaxial, and shear loading. The types of composites for which equations are given for stress concentration factors include unidirectional laminates, unidirectional laminates with oriented fibers, bidirectional balanced laminates, and multilayered laminates. A failure criterion based on modified Hencky-Von Mises distortion energy theory is also presented for predicting (1) the externally applied load which will initiate failure at the opening and (2) the location of the failure. The strength of composite plates with cutouts is less sensitive to stress concentrations than the strength of plates made of isotropic materials. Typical numerical results are presented for stress concentrations and strength of fiberglass/epoxy, boron/epoxy, and graphite/epoxy plates with cutouts. A test-theory comparison is also shown for stress concentrations in fiberglass plate containing circular opening and subjected to uniaxial tensile loading.

A new test technique for measuring the shear moduli of isotropic and composite materials is described. The test technique employs circular rings subjected to out-of-plane four-point loading: four forces of equal magnitude, two upward at 0 and 180 deg and two downward at 90 and 270 deg. The pertinent equation relating ring deformation to applied loading, ring-section properties, and elastic properties is given. It is shown that by selecting appropriate specimen geometry, the deflection of the ring subjected to four-point loading is governed primarily by shear deformations. The reliability and accuracy of the test method are demonstrated by conducting tests on metallic rings as well as on rings made of various composite materials. Room as well as elevated-temperature shear-moduli data are measured using the ring tests. The results from the four-point ring-twist tests are compared with data presented in the literature. The test is simple and fast, with no requirement for elaborate instrumentation or setup. Moreover, the test is applicable for measuring the shear moduli at room temperature, cryogenic temperatures, and elevated temperatures.