Finite element modelling of forearm skin wrinkling

Human skin is a complex multilayered material. Although there are many numerical models of skin in existence, which accurately simulate several of its complex mechanical characteristics, there are very few models that simulate wrinkling - a phenomenon common to all human skin. The purpose of this study was to develop a multilayer model of skin, which could simulate wrinkling more realistically than the existing models in the literature.

The skin on the volar forearm was wrinkled by displacing two tabs, which were attached to the skin surface towards each other. Eight volunteers were used in the experiment. The profiles of the wrinkles were measured using a customized laser profilometer system. The maximum range and average roughness of the wrinkle profiles were calculated. The multilayer model of skin consisted of the stratum corneum, dermis and underlying hypodermis. The constitutive equations for each layer were implemented into a finite element model and the wrinkling experiments were simulated. The results of the model were compared with the results of the experiments.

The size of the wrinkles predicted by the model fell within the range of the wrinkle sizes measured in the experiments. The maximum range and average roughness differed by 34% and 43% from the corresponding mean experimental results, respectively. The results show that the proposed three-layer skin model simulates wrinkling more realistically than either a single or a two-layer model.

A three-layer model of skin has been developed and validated under the harsh conditions of wrinkling. It has been shown that a three-layer model better simulates the wrinkling of skin as compared with models of fewer layers. The model has several applications, including simulating skin aging and the design of more realistic artificial skin. The model can also be used to study the interaction of surgical scalpels or razors with human skin with a view to improving their design.