Abstract: An explicit form of the elastic strain-energy function for direction-dependent large elastic strain behaviors of soft fiber-reinforced composites is first presented based upon a decoupled approach for simulating complex nonlinear coupling effects. From this form, the exact closed-form solutions are then obtained for the uniaxial tension responses in the fiber and cross-fiber directions. With such exact solutions, the issue of simultaneously simulating strongly coupling nonlinear responses in the fiber and cross-fiber directions may be reduced to the issue of separately treating each decoupled uniaxial stress-strain response, thus bypassing usual complexities and uncertainties involved in identifying a large number of strongly coupled adjustable parameters. The numerical examples given are in good agreement with the experimental data for large strain responses.

Key words: soft solid, fiber-reinforced composite, large elastic strain, transverse isotropy, strain-energy function, logarithmic strain, decoupling approach