2-DIMENSIONAL ELASTIC PROPERTIES OF HUMAN SKIN IN TERMS OF AN INCREMENTAL MODEL AT THE IN-VIVO CONFIGURATION

The two-dimensional biomechanical behaviour and the collagen content o f human skin samples from different anatomical sites was examined. The axes of minimum and maximum shrinkage after excision were determined and correlated with the 'Langer' cleavage lines. Test equipment was de veloped to restore the original geometry and to measure the loads acti ng perpendicular to the circumference of the skin specimens. These loa ds were normalized with respect to the thickness and collagen content and considered as the in vivo tension generated by the surrounding ski n area. Using the in vivo geometry of the specimen as reference a set of incremental strains was applied. After stress relaxation was comple ted the final values of stresses were recorded and related to the incr emental strains. The two-dimensional stress-strain relationship was th e basis for the evaluation of the incremental elastic moduli. Orthotro pic mechanical behaviour was found mainly in regions of reduced in viv o tension. The relationship between the degree of anisotropy at the in vivo configuration and the morphological structure is discussed.