Singular Integral Equations. By N.I. Muskhelishvili. Translated fromthe 2nd Russian edition by J.R.M. Radok. Pp. 447. F1. 28.50. 1953. (Noordhoff, Groningen)

Mathematica--A System for Doing Mathematics by Computer.

Nonlinear transient thermoelastic analysis of functionally graded ceramic-metal plates

Composites science and technology

THE appearance of a treatise in English upon the mathematical theory of elasticity is an event the potential importance of which may be judged by the that the author, in his frequent suggestions for collateral reading, refers to only three such, those of Southwell, Timoshenko, and Love. In spirit and content Sokolnikoff}s book differs greatly from each and all of these. It may be described by a possible sub-title: “A pure mathematician surveys topics related to certain problems in the mathematical theory of elasticity”. It is symptomatic of the change in outlook of American mathematics over the past few decades. Mathematical Theory Of Elasticity Prof. I. S. Sokolnikoff with the collaboration of Asst. Prof. R. D. Speche. Pp. xi + 373. (New York and London: McGraw-Hill Book Co., Inc., 1946.) 22s. 6d.

Mathematical Theory Of Elasticity

Predicting failure load of a non-crimp fabric composite by means of a 3D finite element model including progressive damage

The objective of this chapter is the study of the interfiber–matrix failure under tension. The initial micromechanical stages of this damage mechanism are identified and studied. The boundary elements method is employed and interfacial fracture mechanics concepts are used for the analysis of the results. Two complementary studies are also presented: The first analyzes the influence of the presence of a secondary transverse load (perpendicular to the transverse tension nominally responsible for the failure) on the micromechanical stages previously identified, and the second focuses on the effect of thermal residual stresses (originated in the cooling-down step associated with the curing process).

Fiber–matrix debonding in composite materials: Transverse loading

In this paper, the Symmetric Galerkin Boundary Element Method for Linear Elastic Fracture Mechanics is extended to non-linear cohesive cracks propagating through homogeneous linear elastic isotropic media. The cohesive model adopted is based on the concept of free energy density per unit undeformed area. The corresponding constitutive cohesive equations present a softening branch which induces a potential instability. Thus, a suitable solution algorithm capable of following the growth of the cohesive zone is needed, and in the present work the numerical simulation is controlled by an arc-length method combined with a Newton-Raphson algorithm for the iterative solution of nonlinear equations. The Boundary ElementMethod is very attractive for modeling cohesive crack problems as all nonlinearities are located on the boundaries of linear elastic domains. Moreover a Galerkin approximation scheme, applied to a suitable symmetric boundary integral equation formulation, ensures an easy and efficient treatment of cracks in homogeneous media and an excellent convergence behavior of the numerical solution. The cohesive zone model is applied to simulate a pure mode I crack propagation in concrete. Numerical results for three-point bending test are used to check the numerical results for mode I and are compared with some numerical results obtained by FEM analysis found in the literature.

SGBEM for Cohesive Cracks in Homogeneous Media

The heterogeneous character of fibrous composite materials implies mechanisms of damage that are frequently associated, at least at the micromechanical level, with the generation of interface cracks and, thus, with interfacial fracture mechanics. The particular case of matrix/interfibre failure, typically appearing in impact problems and in cross-ply laminates, and caused by a dominant traction acting transversely to the fibres, is directly associated to the appearance and growth of cracks at the fibre/matrix interfaces that eventually lead to macrofailure. The present work studies the evolution of this mechanism of damage under compression and compares the results obtained for two different bimaterial systems: glass fibre–epoxy matrix and carbon fibre–epoxy matrix. To this end, a boundary element model of a single fibre cell is performed, and its results are analysed using the concepts derived from interfacial fracture mechanics. The conclusions obtained establish the morphological differences existing i...

BEM analysis of inter-fibre failure under compression in composites: comparison between carbon and glass fibre systems

Composites have been widely used in applications where there is a risk of impact, due to the excellent properties these materials display for absorbing impact energy. However, composites during impact situations typically generate an enormous number of small pieces, due to the energy absorption mechanism of these materials, a mechanism which does not include plastic deformation. This can prove dangerous in sports competitions, where the small fragments of the original structure may harm competitors. This study was designed to explore the possibility of incorporating a material which, whilst maintaining a high level of energy absorption without any plastic deformation mechanism, was able to maintain its original form, or at least significantly reduce the number of pieces generated after impact. The addition of a polyamide layer, NOMEX ® , to a monolithic fabric laminate was investigated in this paper. The process of fabrication is described and the different properties of the material under consideration: interlaminar fracture toughness energy ( G IC ), indentation ( id ) and delamination after impact ( A i ) and compression after impact ( σ CAI ), were measured and compared with those of the original monolithic fabric.

Federico París

Papers

Predicting failure load of a non-crimp fabric composite by means of a 3D finite element model including progressive damage

Fiber–matrix debonding in composite materials: Transverse loading

SGBEM for Cohesive Cracks in Homogeneous Media

BEM analysis of inter-fibre failure under compression in composites: comparison between carbon and glass fibre systems

Design of composite materials with improved impact properties