Zhandarov, S. ; Mäder, E.

We have derived the equations which explicitly express the peak force,B>d and

Journal of Adhesion Science and Technology

817-856

http://dx.doi.org/10.1163/1568561054929937

December 2005

**Peak force as function of the embredded length in pull-out and microbond tests: effect of specimen geometry**We have derived the equations which explicitly express the peak force,

*F*_{max}, and the apparent interfacial shear strength,_{app}, measured in the pull-out and microbond tests, as functions of the embedded length. Three types of test geometries were considered: (1) a fiber embedded in a cylindrical block of the matrix material; (2) microbond test with spherical matrix droplets; and (3) pull-out test in which the matrix droplet had the shape of a hemisphere. Our equations include the local interfacial shear strength (IFSS),_{d}, and the frictional interfacial stress,_{f}, as parameters; the effect of specimen geometry appeared in the form of dependency of the effective fiber volume fraction on the embedded length. The values of_{d}and_{f}were determined by fitting our theoretical curves to experimental*F*_{max}(*l*_{e}) plots by using the least squares method. Our analysis showed how the local IFSS and the frictional interfacial stress affected the measured*F*_{max}and_{app}values. In particular, it was revealed that intervals of embedded lengths could exist in which frictional interfacial stress had no effect on*F*_{max}and_{app}, even if the_{f}value was high. We also derived an equation relating the scatter in the interfacial strength parameters (_{d}and_{f}) to the scatter in_{app}, which is experimentally measurable, and proposed a procedure to determine the standard deviations of_{f}from experimental pull-out and/or microbond test data.

**Source**

Journal of Adhesion Science and Technology

**19**

**Pages**

817-856

**DOI**

http://dx.doi.org/10.1163/1568561054929937

**Published**

December 2005