On the experimental investigation of silicone-based soft composites under mode I loading using Digital Image Correlation

There is a growing interest in understanding the mechanical behavior of fibrous soft biological materials under several loading conditions. Due to difficulties in manipulating and testing these materials, synthetic composites have already been employed in literature. In this work, a fiber-reinforced soft composite was manufactured and tested to extract its mechanical behavior at two different fiber orientations under mode I loading. The domain J-integral was evaluated by means of DIC using a pure shear (planar) configuration. The coefficients of the fourth-order strain energy function proposed by Luo and Chou were adjusted to describe the mechanical behavior of the considered soft composite and its isolated components (i.e., pure silicone rubber and extensible cotton knit fabric) under tensile loading. The values of the J-integral were validated using a classical formulation for homogeneous rubber-like materials. For the soft composite with fibers oriented at theta(0) = 90 degrees, in which the fiber contribution was not considerable, a satisfactory matching was found between J-integral and classical results in the absence of fiber reinforcement (homogeneous materials), resulting in approximately 13.67% of mean relative error. In fact, the J-integral obtained by DIC and the fourth-order hyperelastic strain energy function can be employed to estimate the energy release rate of fiber-reinforced soft composites.