Two-way debonding

Hsueh C.H. and Becher, P.F. (1993). Some consideration of two-way debonding during fiber pull-out. J. Mater. Sci. Lett. 12, 1933-1936. 

Measurements of the sliding stress, t, and the debond energy, T, have been obtained by a variety of approaches (Table 1.1). The most direct involve displacement measurements. These are conducted in two ways (1) fiber push-through7push-in, by using a small-diameter indentor 33 38,39 and (2) tensile loading in the presence of matrix cracks,5,44,45 Indirect methods for obtaining r... 

The process of buckle driven delamination can be described in either of two ways. One point of view is that the mismatch stress in the film is the independent variable. As the stress is increased, it induces budding from debonded zones, followed by delamination. The goal then is to determine the size of the delamination as a function of the film stress according to some delamination criterion. An alternate point of view is that the size of the zone of delamination is the independent variable. For a fixed level of film stress, the goal is to determine the size of buckles which form and the final size which can be achieved by buckle-driven delamination. The latter point of view is pursued next. 

There are many features in the analysis of the fiber push-out test which are similar to fiber pull-out. Typically, the conditions for interfacial debonding are formulated based on the two distinct approaches, i.e., the shear strength criterion and the fracture mechanics approach. The fiber push-out test can be analyzed in exactly the same way as the fiber pull-out test using the shear lag model with some modifications. These include the change in the sign of the IFSS and the increase in the interfacial radial stress, (o,z), which is positive in fiber push-out due to expansion of the fiber. These modifications are required as a result of the change in the direction of the external stress from tension in fiber pull-out to compression in fiber push-out. 

The creep resistance of discontinuous magnesium composites can be significantly improved by comparison with the unreinforced matrix alloys in two separate ways. Direct strengthening of the composites arises mainly from effective load transfer provided that no debonding of the... 

The results of the previous sections can be used to design check valves that control fluid motion in powerful ways. Consider the geometry shown in Figure 39.12 [40] a wall of thickness w separates two fluidic channels within a single layer. At low pressure, the check valve closes the channel by seating on this wall. When a critical pressure is reached, the valve film debonds from its seat and allows fluid to pass from one channel to the other. Assuming displacements are much smaller than the film thickness (such that plate behavior applies) the critical pressure required to release the check... 

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