“…These assumptions are explained in detail in Gao and Li (2005), Nairn (1997). Since then, the shear lag idea has been widely applied to straight fiber pull-out analysis for different composite systems and has been further developed with various degrees of approximation (Cox 1952(Cox , 1990Gao and Li, 2005;Gao et al, 1988;Hsueh, 1992a;Kerans and Parthasarathy, 1991;Kharrat et al, 2006;Kim et al, 2004;Kim and Mai, 1998;Nairn, 1997;Nairn and Wagner, 1996;Rosen, 1964;Tsai and Kim, 1996;Wu and Davies, 2005;Wu and Yu, 1994). For example, some researchers assumed zero radial displacement and uniform matrix deformation confined in the cylinder geometry (Hsueh, 1988(Hsueh, , 1990Takaku and Arridge 1973).…”