· In the initial loading stage of the short fiber composite, the shear stress "loads" the fiber over the length required to establish an isostrain condition between the fiber and the matrix, both materials remaining in the elastic range.
· The minimum length required to establish this isostrain condition is the "transfer length" L . Load transfer is symmetric at each fiber end over the distance (L /2). 
· For a fiber longer than L , the tensile stress will be constant over the central region of the fiber with a value: σ_f = ε_f E_f , and in this region ε_f = e_m .

· If the applied stress is high enough, the isostress condition in the central region will reach the fiber fracture stress, σ*_f.  The transfer length required to achieve this is the "critical transfer length" L_c.