An Improved Model based on a Shear Strength Criterion

An improved model based on a shear strength criterion 

For the cylindrical coordinates of the shear-lag model shown in Fig. 4.6, the governing conditions adopted in this analysis are essentially the same as those described in Section 4.2.3, There is one exception in that the mechanical equilibrium condition between the external stress, r, and the internal stress components given by Eq. (4.11) is replaced by 

It is assumed here that the axial displacements are independent of the radial position, and the stress components in the radial and circumferential directions are neglected for Eqs. (4.8) and (4.9). Also, the radial displacement gradient with respect to the axial direction is neglected compared to the axial displacement gradient with respect to the radial direction in Eq. (4.10). Combination of Eqs. (4.10) and (4.16) for the boundary condition of the axial displacement continuity at the bonded interface (i.e. i/ (a,z) = u z)) and integration gives  

The solution of Eq. (4.56) and the corresponding solutions for the IFSS arc obtained for the boundary conditions 

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) 

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