P.C. Chen^∗,†, C.W. Colwell^†, D.D. D’Lima^†,‡

Molecular & Cellular Biomechanics, Vol.8, No.2, pp. 135-148, 2011, DOI:10.3970/mcb.2011.008.135

Abstract A nonlinear viscoelastic finite element model of ultra-high molecular weight polyethylene (UHMWPE) was developed in this study. Eight cylindrical specimens were machined from ram extruded UHMWPE bar stock (GUR 1020) and tested under constant compression at 7% strain for 100 sec. The stress strain data during the initial ramp up to 7% strain was utilized to model the "instantaneous" stress-strain response using a Mooney-Rivlin material model. The viscoelastic behavior was modeled using the time-dependent relaxation in stress seen after the initial maximum stress was achieved using a stored energy formulation. A cylindrical model of similar dimensions was created using a… More >

Nikolai Steklov^*, Ajay Srivastava^*, K.L.P. Sung^†, Peter C. Chen^†, Martin K. Lotz^*, Darryl D. D’Lima^‡

Molecular & Cellular Biomechanics, Vol.6, No.2, pp. 113-119, 2009, DOI:10.3970/mcb.2009.006.113

Abstract The biomechanical properties of articular cartilage change profoundly with aging. These changes have been linked with increased potential for cartilage degeneration and osteoarthritis. However, less is known about the change in biomechanical properties of chondrocytes with increasing age. Cell stiffness can affect mechanotransduction pathways and may alter cell function. We measured aging-related changes in the biomechanical properties of chondrocytes. Human chondrocytes were isolated from knee articular cartilage within 48 hours after death or from osteochondral specimens obtained from knee arthroplasty. Cells were divided into two age groups: between 18 and 35 years (18 -- 35); and greater than 55 years… More >

Hong Qian^*

Molecular & Cellular Biomechanics, Vol.5, No.2, pp. 107-118, 2008, DOI:10.3970/mcb.2008.005.107

Abstract At the molecular and cellular level, mechanics and chemistry are two aspects of the same macromolecular system. We present a bottom-up approach to such systems based on Kramers' diffusion theory of chemical reactions, the theory of polymer dynamics, and the recently developed models for molecular motors. Using muscle as an example, we develop a viscoelastic theory of muscle in terms of an simple equation for single motor protein movement. Both A.V. Hill's contractile component and A.F. Huxley's equation of sliding-filament motion are shown to be special cases of the general viscoelastic theory of the active material. Some disparity between the… More >

Yunfa Zhang¹, Zihui Xia^1,2

CMC-Computers, Materials & Continua, Vol.2, No.3, pp. 213-226, 2005, DOI:10.3970/cmc.2005.002.213

Abstract In the present study, the initiation and evolution of the interphase damage and their influences on the global stress-strain relation of composite laminates are predicted by finite element analysis on a micromechanical unit cell model. A thin layer of interphase elements is introduced and its stress-strain relation is derived based on a cohesive law which describes both normal and tangential separations at the interface between the fiber and matrix. In addition, a viscous term is added to the cohesive law to overcome the convergence difficulty induced by the so-called snap-back instability in the numerical analysis. The matrix behavior is described… More >

S. D. Akbarov¹, N. Yahnioglu², E. E. Karatas²

CMC-Computers, Materials & Continua, Vol.30, No.1, pp. 1-18, 2012, DOI:10.3970/cmc.2012.030.001

Abstract In Akbarov, Yahnioglu and Karatas (2010) a buckling delamination problem for a rectangular viscoelastic composite plate with a band and edge cracks was investigated under uniaxial compression of the plate. In the present study this investigation is developed for the case where the mentioned rectangular plate contains an embedded rectangular crack and in addition it is assumed that the plate is subjected to two-axial compression.
It is supposed that all end surfaces of the considered plate are simply supported and that these ends are subjected to uniformly distributed normal compressive forces with intensity p₁ and p₃ which act along… More >

S.D. Akbarov^1,2, N. Yahnioglu¹, A. Tekin¹

CMC-Computers, Materials & Continua, Vol.29, No.1, pp. 41-74, 2012, DOI:10.3970/cmc.2012.029.041

Abstract A three-dimensional buckling delamination problem for a rectangular sandwich plate made from elastic and viscoelastic materials is studied. It is supposed that the plate contains interface embedded rectangular cracks and that the edge-surfaces of these cracks have initial infinitesimal imperfections. The evolution of these initial imperfections with an external bi-axial compressed force (for the case where the materials of the layers of the plate are elastic) or with duration of time (for the case where the materials of the layers of the plate are viscoelastic) is investigated. The corresponding boundary value problem is formulated within the framework of the piecewise… More >

H.Q. Nguyen¹, C.-D. Tran¹, T. Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.109-110, No.4, pp. 361-403, 2015, DOI:10.3970/cmes.2015.109.361

Abstract In this paper, an Integrated Radial Basis Function (IRBF)-based multiscale method is used to simulate the rheological properties of dilute fibre suspensions. For the approach, a fusion of the IRBF computation scheme, the Discrete Adaptive Viscoelastic Stress Splitting (DAVSS) technique and the Fibre Configuration Field has been developed to investigate the evolution of the flow and the fibre configurations through two separate computational processes. Indeed, the flow conservation equations, which are expressed in vorticity-stream function formulation, are solved using IRBF-based numerical schemes while the evolution of fibre configuration fields governed by the Jeffery’s equation is captured using the principle of… More >

Ala Tabiei¹, Suraush Khambati²

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.1, pp. 25-45, 2015, DOI:10.3970/cmes.2015.105.025

Abstract A constitutive model to describe the behavior of rubber from low to high strain rates is presented. For loading, the primary hyperelastic behavior is characterized by the six parameter Ogden’s strain-energy potential of the third order. The rate-dependence is captured by the nonlinear second order BKZ model using another five parameters, having two relaxation times. For unloading, a single parameter model has been presented to define Hysteresis or continuous damage, while Ogden’s two term model has been used to capture Mullin’s effect or discontinuous damage. Lastly, the Feng-Hallquist failure surface dictates the ultimate failure for element deletion. The proposed model… More >

Diptiranjan Behera¹, S. Chakraverty²

CMES-Computer Modeling in Engineering & Sciences, Vol.104, No.3, pp. 211-225, 2015, DOI:10.3970/cmes.2015.104.211

Abstract This paper presents the numerical solution of a viscoelastic continuous beam whose damping behaviours are defined in term of fractional derivatives of arbitrary order. Homotopy Perturbation Method (HPM) is used to obtain the dynamic response with respect to unit impulse load. Obtained results are depicted in term of plots. Comparisons are made with the analytic solutions obtained by Zu-feng and Xiao-yan (2007) to show the effectiveness and validation of the present method. More >

M. Toujani¹, R. Djebali², L. Hassini¹, S. Azzouz¹, A. Belghith¹

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.5, pp. 469-485, 2014, DOI:10.3970/cmes.2014.098.469

Abstract In the present work we aim to simulate unsteady two-dimensional evolution of the moisture content, temperature and mechanical stress in a parallelepiped apple sample during convective drying. The model is based on the heat and mass transfer equations and the mechanical equilibrium equation under the assumptions of plane deformation, viscoelasticity and isotropic hydric shrinkage. The Finite Elements COMSOL Multiphysics solver is used to solve the developed model. The hydro-thermal model was validated on experimental data drawn in our laboratory for moisture and temperature internal profiles of the product. Excellent agreement has been obtained between numerical and measured data for different… More >