Interface shearing

Critical interface shear stress t, (Pa). This is a shear stress that causes a relative slide on the phase interface of the two components,... 

The interface shear stress can be derived from the observed fragment length if one assumes that its absolute value is constant over the whole fragment length. Based on simple equilibrium of length, one can derive that in each point along the fiber... 

Cross-flow filtration systems utilize high liquid axial velocities to generate shear at the liquid-membrane interface. Shear is necessary to maintain acceptable permeate fluxes, especially with concentrated catalyst slurries. The degree of catalyst deposition on the filter membrane or membrane fouling is a function of the shear stress at the surface and particle convection with the permeate flow.16 Membrane surface fouling also depends on many application-specific variables, such as particle size in the retentate, viscosity of the permeate, axial velocity, and the transmembrane pressure. All of these variables can influence the degree of deposition of particles within the filter membrane, and thus decrease the effective pore size of the membrane. 

The average shear strength at the interface, t., whether bonded, debonded or if the surrounding matrix material is yielded, whichever occurs first, can be approximately estimated from a simple force balance equation for a constant interface shear stress (Kelly and Tyson, 1965) ... 

Fig 3.8 shows the interface shear bond strength, tb, determined from Eq. (3.7), which is not a material constant but varies substantially with embedded fiber length, L. However, to evaluate all the relevant interface properties properly, which include the interface fracture toughness, Gic, the coefficient of friction, p, and the residual clamping stress, qo, it is necessary to obtain experimental results for a full range of L and plot these characteristic fiber stresses as a function of L. More details of the... 

In the second approach shown in Fig 3.12(b), a force is applied continuously using a Vickers microhardness indenter to compress the fiber into the specimen surface (Marshall, 1984). For ceramic matrix composites where the bonding at the interface is typically mechanical in nature, the interface shear stress, Tf, against the constant frictional sliding is calculated based on simple force balance (Marshall, 1984) ... 

Fig. 3.15. Interface shear strength. Xb, of (a) untreated and (b) treated LXA500 carbon fiber-epoxy matrix system measured at 10 different laboratories and using different testing methods. (O) fiber pull-out test ( ) microdebond lest ( ) fiber push-out lest (A) fiber fragmentation test. After Pitkelhly el al. (1993).

Fig. 3.27. Effect of the interface shear strength on mechanical properties of carbon fiber-epoxy matrix composites ( ) tran.sverse tensile strength (A) maximum transverse tensile strain (O) transverse tensile modiilns. After Madhukar and Drzal (1991),...

Fig. 4.2. Variations of fiber axial stress, of, and interface shear stress, Tj, according to Eqs. (4.1) and (4.2),...

Fig. 4.7. Distributions of (a) fiber axial stress, a, (b) matrix axial stress, Om., and (c) interface shear stress. T along half the embedded fiber length, L, in the fiber fragmentation test.

Fig. 4.10. Distribution of (a) normalized fiber axial stress, a)/a, and (b) normalized interface shear stress, along the fiber axis, r/a, for elastic moduli E = 1,5. 3.0 and 6.0 GPa with a constant f = 230 GPa.

Fig. 4.11. Plot of interface shear bond strength, ib, as a function of fiber length, 2L. showing the interface debond criteria, according to Eq. (4.71). After Kim et al. (1993b).

Fig. 4.15. Plots of interface shear bond strength, tb, as a function of normalized debond length, H/a, illustrating the areas corresponding to debonding only (region A), fiber fragmentation without further...

Fig. 4.31. Distributions of (a) fiber axial stress and (b) interface shear stress along the axial direction obtained from micromechanics analysis for different fiber volume fractions, Vf = 0.03, 0.3 and 0.6 (—) single fiber composite (--------) three cylinder composite model. After Kim et al. (1994b).

Fig. 4.34. Maximum interface shear stresses obtained at loaded and embedded fiber ends from FEM...

Fig. 4,40. Distributions of interface shear stress, r, along the fiber length at a constant applied stress o = 4.0GPa for carbon fiber-epoxy matrix composites in fiber pull-out and fiber push-out. After...

Schrader (1974) reported that the interface shear strength in a hygrothermal environment is at its maximum when the multi-layer silanes on the glass fibers remain after being washed in boiling water. On the other hand, the pull-out strength... 

Interface shear bond strength of epoxy droplets on a UHMWPE fiber"... 

Fig. 5.24. Effect of ammonia plasma treatment lime on interface shear strength. After Li et al. (1992).

Fig. 536. Interface shear strength as a function of coating thickness for Nicalon SiC fiber-SiC matrix...

Fig. 7.11. Normalized interface shear stress distributions along the fiber length for composites with and without PVAL coating coating thickness t = 5 pm and Young s modulus ratio of coating to matrix...

Fig. 7.12. Maximum interface shear stresses plotted (a) as a function of Young s modulus ratio of coating to matrix, Ej/Em for coating thickness t = 50 /tm, and (b) as a function of coating thickness t for Young s modulus ratio of coating to matrix, Ei/Em = 0.5. After Kim et al. (1994c)...

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