
216 Computational Modelling of Biomechanics and Biotribology
where E
and E
are direction-dependent constants, and x aligns in the
direction of bres or primary bres if there are secondary bres such as in the
meniscus. Replacing x with y and z , respectively, will derive the correspond-
ing equations for the transverse directions. Obviously, this formula will not
be valid when the tensile strain is large. Fortunately, when cartilage is com-
pressed from the articular surface, the lateral tensile strain is only a fraction
of the compressive strain. Therefore, this simple formula can approximate
moderate compressions. In the case of ...