A model for the compressible, viscoelastic behavior of human amnion addressing tissue variability through a single parameter.
A viscoelastic, compressible model is proposed to rationalize the recently reported response of human amnion in multiaxial relaxation and creep experiments. The theory includes two viscoelastic contributions responsible for the short- and long-term time-dependent response of the material. These two contributions can be related to physical processes: water flow through the tissue and dissipative characteristics of the collagen fibers, respectively. An accurate agreement of the model with the mean tension and kinematic response of amnion in uniaxial relaxation tests was achieved. By variation of a single linear factor that accounts for the variability among tissue samples, the model provides very sound predictions not only of the uniaxial relaxation but also of the uniaxial creep and strip-biaxial relaxation behavior of individual samples. This suggests that a wide range of viscoelastic behaviors due to patient-specific variations in tissue composition can be represented by the model without the need of recalibration and parameter identification.
Department of Mechanical and Process Engineering, Institute of Mechanical Systems, ETH Zurich, Zurich, 8092, Switzerland. mauri@imes.mavt.ethz.ch.
Arabella
A
Mauri
Department of Mechanical and Process Engineering, Institute of Mechanical Systems, ETH Zurich, Zurich, 8092, Switzerland.|Empa. Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, 8600, Switzerland.
Alexander E
AE
Ehret
Division of Materials, Mechanics and Structures, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, UK.
Davide S A
DS
De Focatiis
Department of Mechanical and Process Engineering, Institute of Mechanical Systems, ETH Zurich, Zurich, 8092, Switzerland.|Empa. Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, 8600, Switzerland.
Edoardo
E
Mazza
D000650:Amnion / Q000502:physiology*; D004548:Elasticity; D006801:Humans; D008954:Models, Biological; D013314:Stress, Mechanical; D014783:Viscosity
Biological membrane; Compressible viscoelastic model; Creep; Human amnion; Specimen variability; Stress relaxation