title: Analysis of effects of friction on the deformation behavior of soft tissues in unconfined compression tests.
abstract: Frictionless specimen/platen contact in unconfined compression tests has traditionally been assumed in determining material properties of soft tissues via an analytical solution. In the present study, the suitability of this assumption was examined using a finite element method. The effect of the specimen/platen friction on the mechanical characteristics of soft tissues in unconfined compression was analyzed based on the published experimental data of three different materials (pigskin, pig brain, and human calcaneal fat). The soft tissues were considered to be nonlinear and viscoelastic; the friction coefficient at the contact interface between the specimens and platens was assumed to vary from 0.0 to 0.5. Our numerical simulations show that the tissue specimens are, due to the specimen/platen friction, not compressed in a uniform stress/strain state, as has been traditionally assumed in analytical analysis. The stress of the specimens obtained with the specimen/platen friction can be greater than those with the frictionless specimen/platen contact by more than 50%, even in well-controlled test conditions.
authors.affiliation: National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA. jwu@cdc.gov
authors.forename: John Z
authors.initials: JZ
authors.lastname: Wu
authors.forename: Ren G
authors.initials: RG
authors.lastname: Dong
authors.forename: Aaron W
authors.initials: AW
authors.lastname: Schopper
mesh_terms: D000273:Adipose Tissue / Q000502:physiology; D000818:Animals; D001921:Brain / Q000502:physiology; D019245:Compressive Strength / Q000502:physiology*; D003238:Connective Tissue / Q000502:physiology*; D004548:Elasticity; D017276:Friction; D006801:Humans; D008954:Models, Biological; D017711:Nonlinear Dynamics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012879:Skin Physiological Phenomena; D013314:Stress, Mechanical; D013552:Swine; D014783:Viscosity; D016474:Weight-Bearing / Q000502:physiology*