A. Sammaiah¹, K. V. Padmaja¹, K. I. Suresh^*,2, R. B. N. Prasad¹

Journal of Renewable Materials, Vol.4, No.2, pp. 113-122, 2016, DOI:10.7569/JRM.2015.634118

Abstract This article reports the effect of epoxidized jatropha oil (EJO) on the thermal, cure and viscoelastic properties of epoxy resins. Epoxidized jatropha oil with an oxirane value of 5.0 was prepared and epoxy formulations containing different concentrations of EJO were evaluated for cure, morphology, thermal and viscoelastic properties. The curing temperature of the formulations increased with increasing EJO content. The glass transition temperature of the cured films decreased from 56 °C for unmodified epoxy resin to 23 °C for the sample with 60 wt% EJO reactive diluent, suggesting good plasticizing action. The thermal decomposition was More >

S.D. Akbarov^1,2, T. Kocal³, T. Kepceler¹

CMC-Computers, Materials & Continua, Vol.51, No.2, pp. 105-143, 2016, DOI:10.3970/cmc.2016.051.105

Abstract The paper studies the dispersion of axisymmetric longitudinal waves in the bi-material compound circular cylinder made of linear viscoelastic materials. The investigations are carried out within the scope of the piecewise homogeneous body model by utilizing the exact equations of linear viscoelasto-dynamics. The corresponding dispersion equation is derived for an arbitrary type of hereditary operator and the algorithm is developed for its numerical solution. Concrete numerical results are obtained for the case where the relations of the constituents of the cylinder are described through fractional exponential operators. The influence of the viscosity of the materials… More >

Ali Amiri, Nassibeh Hosseini, Chad A. Ulven^*

Journal of Renewable Materials, Vol.3, No.3, pp. 224-233, 2015, DOI:10.7569/JRM.2015.634111

Abstract Natural fibers have great potential to be used as reinforcement in composite materials. Cellulose, being a critical constituent of natural fibers, provides unquestionable advantages over synthetically produced fibers. Increasing demand for use of bio-based composites in different engineering and structural applications requires proper test methods and models for predicting their long-term behavior. In the present work, the time-temperature superposition principle was successfully applied to characterize creep behavior of flax/vinyl ester composites. The creep compliance vs time curves were determined and shifted along the logarithmic time axis to generate a master compliance curve. The time-temperature superposition More >

Nassibeh Hosseini¹, Samad Javid¹, Ali Amiri¹, Chad Ulven^1,*, Dean C. Webster², Ghodrat Karami¹

Journal of Renewable Materials, Vol.3, No.3, pp. 205-215, 2015, DOI:10.7569/JRM.2015.634112

Abstract In this study, a novel, bio-based polyol was used in the formulation of a polyurethane (PU) matrix for a composite material where fl ax fi ber was used as the reinforcement. The viscoelastic properties of the matrix and fl ax fi ber were determined by a linear viscoelastic model through experimentation and the results were used as input for the material properties in the computational model. A fi nite element micromechanical model of a representative volume element (RVE) in terms of repeating unit cells (RUC) was developed to predict the mechanical properties of composites. Six… 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… 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 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 >

Priyankar Datta¹, Manas C. Ray¹

CMC-Computers, Materials & Continua, Vol.49-50, No.1, pp. 47-80, 2015, DOI:10.3970/cmc.2015.049.047

Abstract This paper deals with the implementation of the one dimensional form of the fractional order derivative constitutive relation for three dimensional analysis of active constrained layer damping (ACLD) of geometrically nonlinear laminated composite plates. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composites (PZCs). The von Kármán type nonlinear strain displacement relations are used to account for the geometric nonlinearity of the plates. A nonlinear smart finite element model (FEM) has been developed. Thin laminated substrate composite plates with various boundary conditions and stacking sequences are analyzed to More >

M. Bendouba¹, A. Djebli¹, A. Aid¹, N. Benseddiq², M. Benguediab³

CMC-Computers, Materials & Continua, Vol.45, No.3, pp. 163-186, 2015, DOI:10.3970/cmc.2015.045.163

Abstract This work focuses on a linear elastic analysis by the finite element method and the development of a shape function, commonly known as geometrical correction factor, for the case of semi-elliptical crack in a cylindrical rod. We used the same shape function to analyze the behavior of the rod in the case of a viscoelastic medium materialized by a polymeric material such as HDPE. A linear viscoelastic model calibrated from a relaxation test was developed and implemented in Abaqus. Results showed a relatively good performance, compared with finite element method. More >

Marion Noël^1,*, Warren Grigsby², Thomas Volkmer¹

Journal of Renewable Materials, Vol.2, No.4, pp. 291-305, 2014, DOI:10.7569/JRM.2014.634118

Abstract Oligomer systems based on poly(lactic acid) (PLA), poly(glycolic acid) (PGA), poly(butylene succinate) (PBS) and poly(butylene adipate) (PBA) were impregnated in wood and polymerized in situ to improve the dimensional stability of the treated wood. Dynamic mechanical thermal analysis (DMTA) was used to characterize the impact on the treated wood properties. Cell wall bulking treatments (PLA and PGA oligomers: OLA and OGA) induced softening and plasticization of wood components. Lumen fi lling treatments (PBS and PBA oligomers: OBS and OBA) led to minor decreases in treated wood stiffness with any softening dependent on the polymer melt More >