Glass matrix composites fracture toughness

Chlup, Z., Dlouhy, I., Boccaccini, A.R. (2001), Fracture toughness of thermally shocked SiC-fibre reinforced glass matrix composite , in Krenkel, W., Naslain, R., Schneider, H. (editors), High Temperature Ceramic Matrix Composites, Wiley, 463-468. 

The following factors have been identified as important in determining the fracture strength and fracture toughness values of dispersion-reinforced glass matrix composites ... 

FIGURE 6. The dependence of the mechanical properties of alumina platelet reinforced borosilicate glass matrix composites on the platelet volume fraction (a) Young s modulus, (b) fracture strength and (c) fracture toughness... 

The variation of the elastic modulus, fracture strength and fracture toughness of a model alumina platelet-reinforced borosilicate glass matrix composite with the volume fraction of platelets is shown in Figure 6 [17,128]. The material exhibited a pore-free matrix, uniform distribution of the platelets and strong matrix/platelet interfacial bonding. In Figure 6 both... 

As it is well-known, the ultimate objective in the development of ceramic and glass matrix composites is to increase the fracture toughness of the brittle matrix. In order to analyse the toughening achieved, most researchers have used conventional measurement of fracture toughness by indentation. The fracture toughness (Kic) from the micro-hardness indentation method can be calculated by means of the following equation [73] ... 

A.R. Boccaccini, V. Winkler, Fracture Surface Roughness and Toughness of AI2O3 Platelet Reinforced Glass Matrix Composites. Composites A, 33, 125 13 (12002). 

A composite material for a car-repair kit consists of a random mixture of short glass fibres in a polyester matrix. Estimate the maximum toughness of the composite. You may assume that the volume fraction of glass is 30% the fibre diameter is 15 pm the fracture strength of the fibres is 1400 MPa and the shear strength of the matrix is 30 MPa. 

The mechanical properties of the blend of silane/size and bulk epoxy matrix (at concentrations representing likely compositions found at the fiber-matrix interface region) also suggest that the interaction of size with epoxy produces an interphase which is completely different to the bulk matrix material (Al-Moussawi et al., 1993). The interphase material tends to have a lower glass transition temperature, Tg, higher modulus and tensile strength and lower fracture toughness than the bulk matrix. Fig. 5.4 (Drown et al., 1991) presents a plot of Tg versus the amount of... 

Ac can be approximated to Cf if Cm is neglected in brittle matrix composites (Harris, 1980). It is shown that Rd( contributes substantially to the total fracture toughness of glass fiber-polymer matrix composites (Harris et al, 1975 Kirk et al., 1978 Beaumont and Anstice, 1980 Munro and Lai, 1988). 

Fig. 6.8. Fracture toughness, K, of short glass fiber-thermoplastics injection molded composites as a function of weight fraction of fiber, fVr. (O) and (A) polyethylene terephthalate (PET) matrix ( ) and (A) polycarbonate (PC) matrix. Notches made transverse (O, ) and parallel (A, A) to the mold fill direction,...

Fig. 6.9. Normalized fracture toughness, (Kc - AKQ)/K. of short glass fiber-thermoplastics injection molded composites as a function of reinforcing effectiveness parameter, ft (O) polyetheretherketone (PEEK) matrix (K = 6.5 MPa m) (A) polytetrafluoroethylene (PTFE) matrix (K = 1.9 MPaym).

Fig. 7.24. Predicted fracture toughness of carbon and glass fiber-polymer matrix composites (CFRP and GFRP) with varying matrix shrinkage stress, n. After Piggott (1981).

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