Composites fracture energy

Figure 12.15. Effect of filler content on composite fracture energy at 20 C (Trachte and Di-Benedetto, 1971). (O) Glass fiber/PPO ( ) glass bead/PPO (O) A-1100 glass bead/PPO (the term A-1100 refers to the silane used as a coupling agent).

Table 3. Effect of Fiber Braiding on Fracture Energy of Alumina Fiber/Al—Li Composite ...

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. 

Outwater, J.D. and Murphy, M.C. (1969). On the fracture energy of unidirectional laminates. In 24th Annual Tech. Conf. Reinforced Plast. Composites Inst. SPI, New York, Paper IIC. 

Fitz-Randolph J., Phillips D.C., Beaumont P.W.R. and Tetelman A.S. (1972). The fracture energy and acoustic emission of a boron-epoxy composite. J. Mater. Sci. 7, 289-294. 

Munro M. and Lai C.P.Z. (1988). The elevated-temperature dependence of fracture energy mechanisms by hybrid carbon-glass fiber reinforced composites. J. Mater. Sci. 23, 3129-3136. 

In general, an increase in conversion increases Tg and series prepared with non-stoichiometric compositions, the minimum value of fracture energy is obtained when the stoichiometric ratio of both functionalities is used (Morgan et al., 1984 Won et al., 1990), as expected (maximum values of both Tg and [Pg.385]

For the in-situ phase-separation process, an increase in the TP molar mass modifies the phase diagram (it lowers cnl), increases the viscosity - which is a drawback for processing and impregnation of composites - but increases the fracture energy associated with the crack-bridging mechanism. 

The reduced hardness and improved machinability are attributed primarily to the crack deflection process. It can be seen in Fig. 13.8 that the composite showed obvious particle pullout and significant crack deflection along interphase boundaries due to the weak interface bonding. The crack deflection mechanism (absorbing fracture energy and blunting crack tip) could lead to an increase in machinability. As described above, the thermal expansion... 

In (15.36) rm is the matrix fracture energy, t is the interfacial shear strength, and Ex is the axial modulus of the composite. In (15.37) e refers to the effective properties of the composite, which, for unidirectional fiber reinforcement, can be calculated with good approximation by the rule of mixtures. 

In both derivations of toughening behavior, increases in toughness for whisker-reinforced composites are dependent on the following parameters (1) whisker strength, (2) volume fraction of whiskers, (3) elastic modulus of the composite and whisker, (4) whisker diameter, and (5) interfacial fracture energies. 

For bulk specimens, Kic and Gic convey the same information. However, for adhesively bonded structures, such as the specimens described in this report, Kic and Gic differ. E in Equation 3 is the modulus of the adherend (the PMMA) rather than the adhesive, and so Kic is not characteristic solely of the PS layer but of the composite as a whole. The other expression for fracture behavior is the effective fracture surface energy, y. It is related to the fracture energy by... 

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