Fracture of composite materials

Petmas D, Cantwell WJ, Compston P. The influence of strain-rate on the mode 111 interlaminar fracture of composite materials. J Compos Mater 2007 41 2595-614. http //dx.doi.Org/10.1177/0021998307078690. 

Our book Macromolecular Chemistry presents from the theoretical and experimental point of view the main problems of this field, including the results obtained in more than a century of research. It is organised in two volumes Polymer Mechanochemistry and Polymers with Chemomechanical Functions, respectively. The present volume (which is in two parts) deals with Chained Multistage Character of Mechanochemical Process (1), Mechanochemistry of Polymers Deformation (2) Mechanochemistry of Polymer Fracture (including also the Fracture of Composite Materials) (3), and Mechanochemical processes for Energy Conversion (4). In this framework, the theoretic and experimental material is organised in correlation to the reaction mechanism, the type of mechanical solicitation, and the nature of environmental medium. 

The tensile fracture of composite materials is usually observed using SEM. NDZ-101 and NDZ-102 are the coupling agents to modify calcium carbonate whiskers, with 20% filling. The SEM photographs of tensile fractures are shown in Figure 5.16. 

Fatigue Crack Propagation of Sheet Molding Compounds in various Environments, Fracture of Composite Materials, Polymer Composites, 4 (2004) 2, p. 162 - 166... 

Kopyov, I.M., Ovchinsky, A.S. and Bilsagayev, N.K., Computer simulation of various fracture mechanisms in fibrous composite materials- In Fracture of Composite Materials, eds. G.C. Sih and V.P. Tamuzh, Martinus Nijhoff Publishers, The Hague/Boston/London, 1982, pp.45-52. 

Cherepanov G.P. (1983) Fracture mechanics of composite materials. Nauka, Moscow (in Russian). 

Two approaches have been taken to produce metal-matrix composites (qv) incorporation of fibers into a matrix by mechanical means and in situ preparation of a two-phase fibrous or lamellar material by controlled solidification or heat treatment. The principles of strengthening for alloys prepared by the former technique are well estabUshed (24), primarily because yielding and even fracture of these materials occurs while the reinforcing phase is elastically deformed. Under these conditions both strength and modulus increase linearly with volume fraction of reinforcement. However, the deformation of in situ, ie, eutectic, eutectoid, peritectic, or peritectoid, composites usually involves some plastic deformation of the reinforcing phase, and this presents many complexities in analysis and prediction of properties. 

Composite materials have many distinctive characteristics reiative to isotropic materials that render application of linear elastic fracture mechanics difficult. The anisotropy and heterogeneity, both from the standpoint of the fibers versus the matrix, and from the standpoint of multiple laminae of different orientations, are the principal problems. The extension to homogeneous anisotropic materials should be straightfor-wrard because none of the basic principles used in fracture mechanics is then changed. Thus, the approximation of composite materials by homogeneous anisotropic materials is often made. Then, stress-intensity factors for anisotropic materials are calculated by use of complex variable mapping techniques. 

G. C. Sih and E. P. Chen, Fracture Analysis of Unidirectional Composites, Journal of Composite Materials, April 1973, pp. 230-244. 

M. E. VVaddoups, J. R. Eisenmann, and B. E. Kaminski, Macroscopic Fracture Mechanics of Advanced Composite Materials, Journal of Composite Materials, October... 

H. J. Konish, Jr., J. L. Swedlow, and T. A. Cruse, Experimental Investigation of Fracture in an Advanced Fiber Composite, Journal of Composite Materials, January... 

Tsai, H.C., Arocho, A.M. and Cause, L.W. (1990). Prediction of fiber-matrix interphase properties and their influence on interface stress, displacement and fracture toughness of composite materials. Mater. Sci. Eng. A126, 295-304. 

Davies, P. and Roulin. A. (1989). A standard for interlaminar fracture testing of composites. In Proc. ECCM 3, Developments in the Science and Technology of Composite Materials. (A.R. Bunsell, P. Lamicq and A. Massiah eds.), Elsevier Appl. Sci., London, pp. 419-424. 

O Brien, T.K. and Martin, R.H. (1992). Results of ASTM round robin testing for mode I interlaminar fracture toughness of composite materials, NASA TM 104222. 

Russell, A.J. and Street, K.N. (1984). Factors affecting the interlaminar fracture energy of graphite/epoxy laminates. In Proc. 4th Intern. Conf. on Composite Materials. (T. Hayashi, K. Kawata and S. Umekawa eds.), Japan Society of Composites Materials, Tokyo, p. 129. 

Wang, Y. and Williams, J.G, (1992). Corrections for mode II fracture toughness specimens of composite materials. Composites Sci. Techno . 43, 251-256. 

Whitney, J.M. (1989). Experimental Characterization of delamination fracture, in Interlaminar Response of Composite Materials (N.J. Pagano ed.), Elsevier Science Publishers, Amsterdam, pp. 161-250. 

The first generation of resins developed for use in high performance carbon fiber composites emphasized high modulus and high glass transition temperature, Tg. Due to the low interlaminar fracture resistance of these resins, in particular under hot and wet conditions, a second generation of matrix materials has been developed with special focus on the resistance to interlaminar fracture of composites. 

Structural applications of composite materials require not only acceptable static mechanical properites but the ability to withstand the generation and propagation of cracks without premature failre. For example, impact resistance, fracture toughness and fatigue resistance are desireable composite properties. Fiber-matrix structure at the interphase can affect the values attainable for these properties. 

Several studies of polymer/silane coupling agent interphases have involved the use of scanning electron microscopy (SEM) [5-7]. For example, Vaughan and Peek [6] have used SEM to examine fracture surfaces to determine the mode of failure of composite materials and to draw conclusions about interfacial interactions of various coupling agents and epoxide and polymer resin systems. 

The addition of SiC whiskers to silicon nitride matrices resulted in only moderate increases in the fracture toughness a compared to monolithic materials. Fracture strengths of composite materials showed increases in some cases and slight decreases in others. Summaries of the variations in toughness and strength are given in Tables 2.3 and 2.4. The moderate increases in... 

A. G. Evans and B. J. Dalgleish, Some Aspects of the High Temperature Performance of Ceramics and Ceramic Composites, in Creep and Fracture of Engineering Materials and Structures, eds. B. Wilshire and R. W. Evans, The Institute of Metals, London, U.K., 1987, pp. 929-955. 

Williams, J.G. (1985) Fracture mechanics of polymers. Ellis Horwood, Chichester. Unpublished values determined at Imperial College (GF-PMMA) and EMPA (CF-Epoxy). Daniel, I.M. and Ishai, O. (1994) Engineering mechanics of composite materials. Oxford University Press. 

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