Biomechanical studies of rabbit abdominal wall. Part II.--The mechanical properties of specimens in relation to length, width, and fibre orientation.

In a biomechanical investigation of tractus iliotibialis and abdominal wall tissue from rabbits, an analysis was made of the influence that the fibre orientation in specimens as well as the length and width of specimens has on the measured parameters. The mechanical testing was performed with a materials testing machine (Alvetron). The investigation showed that the mechanical characteristics of specimens, when the width was kept constant, depended upon the fibre orientation in the specimens and the length of the specimens. The investigation further demonstrated that in intact abdominal wall no proportionality exists between, on the one side, the width of specimens (2, 4, 6 and 8 mm) and, on the other, the breaking strength, the energy absorption, and the elastic stiffness, respectively. For the 6 day old abdominal wall wounds a proportionality, however, could be demonstrated between the 4 and 8 mm broad specimens on the one side and the breaking strength, the energy absorption, and the elastic stiffness on the other. A possible explanation of the difference between the mechanical characteristics of short and long specimens can be given by the theoretical possibility that the short specimens contain relatively more fibres running all the way through the specimen from clamp to clamp than do the long specimens. The consequences on biomechanical investigations rendered by the result of the analyses are discussed.