Frictional stress transfer

Based on the Coulomb friction law, which governs the frictional stress transfer in the debonded interface, and combining Eqs. (4.12) and (4.18) yield the MAS at the interface (r = a)... 

The fibers treated with Z-6040 showed some interesting results. When viewing under the microscope, two modes of failure were observed at different areas across the fiber (14) these are frictional stress transfer (interface unbonding) depicted below. 

Pinchin, D. J., Taboi D. J. (1978) Interfacial contact pressure and frictional stress transfer in steel fibre cement , in Proc. RILEM Symp. Testing and Test Methods of Fibre Cement Composites, R. N. Swamy ed., Sheffield, Lancaster The Construction Press, pp. 337—44. 

In a more recent paper. Ho and Drzal [94] used a three-phase nonlinear finite-element analysis to investigate the stress transfer phenomenon in the singlefiber fragmentation test. The effect of fiber properties, interphase properties and thickness on the stress distribution in the vicinity of the fiber break was evaluated. Also, the stress fields for various fiber-matrix interface debonding conditions and the effect of frictional stress transfer were investigated. In this model, the fiber was assumed to be a linear elastic transversely isotropic material, the interphase as an elastic material and the matrix as a nonlinear material. It was found that... 

This relationship is derived from Eqs3.1-3.3. For frictional stress transfer, with a constant interfacial shear stress, xfu, the average stress in the fibre is ... 

The length efficiency factor in the pre-cracking zone for the frictional stress transfer mechanism can be calculated from Eq. 4.6, and its value is a function of the strain in the composite ... 

Figure 4.29 Calculated minimum crack spacing as a function of Vm/Vf for glass fibre reinforced cement composite (after Laws [62]) Frictional stress transfer only, curve C elastic stress transfer only, curve B combined elastic and frictional stress transfer, curve A.

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