Is there any contradiction between the stress and energy failure criteria in micromechanical tests? Part II. Crack propagation: Effect of friction on force-displacement curves

Adhesional pressure as a criterion for interfacial failure in fibrous microcomposites and its determination using a microbond test

“…Many papers have been published in support of each, referring both to different theoretical models of interfacial failure and experimental results obtained in micromechanical tests. In our papers [18,26,32,[57][58][59], we consistently support the conclusion that these two parameters can equally well describe the behavior of real interfaces in micromechanical tests, but neither of them can be regarded as a ''universal'' or ''true'' interfacial parameter which is constant under any conditions.…”

“…Some of them are based on different versions of the shearlag approach [4,9,14,32,54], others on variational mechanics [55] or finite element analysis [56,61,62]. The use of the local interfacial shear strength, s d , as a failure criterion, implies that interfacial debonding at a given point of the interface occurs when the local interfacial shear stress at this point reaches its critical value (local IFSS, s d ).…”

“…However, numerous experiments have shown that the apparent IFSS depends on the embedded length [4][5][6]14,18,20,[23][24][25][26][27]. Moreover, the s app values have been found to be highly affected by interfacial friction between the fiber and the matrix which develops during the debonding process [9,[28][29][30][31][32][33][34]; thus, s app appeared to represent a complex combined effect of interfacial bonding and friction rather than pure bond strength. Therefore, it is obvious that the apparent IFSS cannot be regarded as a true interfacial parameter or a criterion of interfacial failure.…”

Effect of humidity during manufacturing on the interfacial strength of non-pre-dried flax fibre/unsaturated polyester composites

“…The estimation of and was performed following the model developed by Zhandarov et al [16,17], which is based on the shear lag model of stress transfer to the matrix, and assumes that for any current crack length, a, the shear stress at the crack tip, ( ) , is constant ( ( ) = = ).…”

Nanocomposite coatings for healing surface defects of glass fibers and improving interfacial adhesion

“…The pull-out test was carried out on a self-made pull-out apparatus with force accuracy of 1 mN and displacement accuracy of 0.07 µm with identical pull-out velocities (0.01 µm s -1 ) at ambient temperature. The local interfacial adhesion strength, d , and the critical interphase energy release rate, G ic , can be determined by using the algorithm described previously [11]. 5 We first examined the morphology of nanoreinforcements in coatings.…”