COMPOSITE STRUCTURES FOR TENDON AND LIGAMENT PROSTHESES

Composite structures are designed to mimic the mechanical properties o f natural tendons and ligaments. Mechanical and viscoelastic behaviour of a soft composite material based on hydrogel polymer matrix reinfor ced with bundles of PET fibers is analyzed. The typical J-shaped stres s-strain behaviour, displayed by natural tendons and ligaments, is rep roduced. The mechanical characteristics, such as the extent of the ''t oe region'' and the elastic modulus in the linear region, can be contr olled by varying the winding angle of the fibers. The transition from rubbery to glassy behaviour, observed in natural tissues by means of d ynamic-mechanical analysis, can only be reproduced by composite struct ures. The rubbery behaviour observed at low level of strain can be mai nly related to the rubbery behaviour of the matrix while the glassy re sponse, at higher level of strain, is due to the progressive contribut ion of the glassy fibers to the overall viscoelastic response.