A new representation for viscoelastic behavior of materials in two- and three-dimensional problems

2021 ◽  
Author(s):  
Kaveh Rajabi ◽  
Hesam Khajehsaeid ◽  
Li Li ◽  
Sina Ghahnavieh
Keyword(s):  
Three Dimensional ◽  
Viscoelastic Behavior

Microstructural characterization and effective viscoelastic behavior of magnetorheological elastomers with varying acetone contents

2016 ◽  
Vol 26 (1) ◽  
pp. 104-118 ◽  
Author(s):  
Robbie Damiani ◽  
LZ Sun
Keyword(s):  
Mechanical Properties ◽  
Smart Materials ◽  
Three Dimensional ◽  
Viscoelastic Behavior ◽  
Microstructural Characterization ◽  
Iron Particle ◽  
Magnetorheological Elastomers ◽  
Micro Particles ◽  
Particle Alignment ◽  
Magnetorheological Effect

Magnetorheological elastomers (MREs), a class of polymer-based composites with dispersed ferromagnetic micro-particles, fall in the class of smart materials, because their macroscopic or effective rheological properties can be continuously, rapidly, and reversibly changed with the application of a magnetic field. Conventional magnetorheological elastomers exhibit poor mechanical properties and magnetorheological effect as a result of their matrix materials and the particle-matrix interfaces. Here, we investigate the effect of acetone contents on the magnetorheological elastomer microstructure at the interfacial regions using the scanning electron microscope and the three-dimensional nano-CT imaging, as well as determining the overall or effective mechanical properties of magnetorheological elastomers. It is shown that acetone increases both the overall storage modulus and loss factor along with the magnetorheological effect due to acetone’s reaction on the interface as well as its effect on iron particle alignment.

A viscoelastic Timoshenko shaft finite element for dynamic analysis of rotors

2016 ◽  
Vol 24 (11) ◽  
pp. 2180-2200 ◽  
Author(s):  
Smitadhi Ganguly ◽  
A Nandi ◽  
S Neogy
Keyword(s):  
Finite Element ◽  
Elastic Strain ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Viscoelastic Behavior ◽  
Beam Shape ◽  
Unit Step ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
The Time Domain

A new shaft element is proposed for viscoelastic rotors in a spinning frame considering the shear deformation in addition to bending deformation. The Maxwell–Wiechert model is considered here to replicate linear viscoelastic behavior. This model considers additional internal damping displacement variables between elastic and viscous elements and the stress depends not only on the elastic strain and elastic strain rate, but also on additional strains and their rates corresponding to the damping variables. The present work assumes that these additional strains can be derived from continuous fictitious displacement variables, which in turn are interpolated from their nodal values using the Timoshenko beam shape functions. Therefore, in addition to the standard degrees of freedom for a three-dimensional shaft, extra degrees of freedom are defined at the nodes. The finite element matrices are assembled in state space. The time domain equations are then used for stability analysis and computation of response to a unit step load and an unbalance.

Three-Dimensional Viscoelastic Interactions of a Center of Dilatation with a Penny-Shaped Interfacial Crack

2011 ◽  
Vol 117-119 ◽  
pp. 471-475 ◽  
Author(s):  
Yu Zhou Sun ◽  
Ya Dong Bian ◽  
Zhong Guo Zhang
Keyword(s):  
Rock Fracture ◽  
Auxiliary Problem ◽  
Viscoelastic Model ◽  
Three Dimensional ◽  
Interfacial Crack ◽  
Viscoelastic Behavior ◽  
Inverse Laplace Transform ◽  
Bimaterial Interface ◽  
Thermal Dilatation ◽  
The Time Domain

This paper presents a three-dimensional viscoelastic model to study the interactions of a penny-shaped interfacial crack and a center of dilatation in the infinite viscoelastic bimaterial, which can model the rock fracture subjected to stress and thermal dilatation during some engineering process. A distinct issue associated with the present work is the incorporation of viscoelastic behavior of bimaterial. The proposed problem is first transformed into the Laplace space, and the solution in the transform space is obtained by decomposing the original problem into two auxiliary problems: (I) a center of dilatation near a bimaterial interface (no crack); and (II) a penny-shaped interfacial crack subject to internal tractions that cancel out those induced in auxiliary problem (I). The mode I, II and III stress intensity factors (SIFs) in the time domain are obtained with the inverse Laplace transform.

A study on warpage behavior of EMC in post-mold cure stage using Moldex3D

2016 ◽  
Vol 2016 (DPC) ◽  
pp. 000826-000850 ◽  
Author(s):  
Hsu Chih-Chung ◽  
Srikar Vallury ◽  
Srikar Vallury ◽  
Kai Lin ◽  
Anthony Yang
Keyword(s):  
Three Dimensional ◽  
Viscoelastic Behavior ◽  
Product Yield ◽  
Maxwell Model ◽  
Factors Affecting ◽  
Numerical Predictions ◽  
Linear Viscoelastic Material ◽  
Cure Time ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Warpage and residual stress are the two most important factors affecting product yield rate and reliability in IC encapsulation process. This study presents the prediction of warpage in post-mold cure stage using a three-dimensional finite element approach coupled with linear viscoelastic material property. Furthermore, cure-induced volumetric shrinkage and thermal expansion mismatch are considered. The shrinkage of the EMC is described by Pressure-Volume-Temperature-Cure (PVTC) model, and Generalized Maxwell model; WLF relation is adopted to describe the viscoelastic behavior of EMC. In order to obtain accurate numerical results, Cure-Time-Temperature superposition is considered. For verifying the numerical predictions of three dimensional simulations, the calculated results are compared with the available experimental data from literature.

Influence of Mechanical Behavior of Adhesives on Shear Stress Distributions in the Single-Lap Adhesive Joints

2011 ◽  
Vol 306-307 ◽  
pp. 1126-1129
Author(s):  
Xiao Cong He
Keyword(s):  
Shear Stress ◽  
Mechanical Behavior ◽  
Three Dimensional ◽  
Viscoelastic Behavior ◽  
Adhesive Layer ◽  
Adhesive Joints ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Element Analysis ◽  
Three Dimensional Finite Element

This paper deals with the effects of mechanical behavior of adhesives on the shear stress distributions of single-lap adhesive joints under tension using the three-dimensional finite element analysis (FEA) technique. Numerical examples are provided to show the influence on the shear stresses of the joints using adhesives of different characteristics which encompass the entire spectrum of viscoelastic behavior. FEA solutions of the shear stress distributions in the adhesive layer have been obtained for four typical characteristics of adhesives. The results indicate that Young’s modulus and Poisson’s ratios of adhesives strongly affect the shear stress distributions of the joints.

A New Approach for Simulation of Hot Mix Asphalt; Numerical and Experimental

2015 ◽  
Vol 31 (6) ◽  
pp. 701-711
Author(s):  
M. Vadood ◽  
M.S. Johari ◽  
A.R. Rahai
Keyword(s):  
3D Model ◽  
Hot Mix Asphalt ◽  
Asphalt Binder ◽  
Three Dimensional ◽  
Viscoelastic Behavior ◽  
Cylindrical Sample ◽  
Two Phase ◽  
Novel Approach ◽  
Compressive Loads ◽  
Volumetric Objects

ABSTRACTIn this study a novel approach for 3D modeling of cylindrical sample of hot mix asphalt (HMA) is presented. To this end, the cylindrical sample was divided into several slices and using a developed algorithm the processed images were extended to 3D volumetric objects to reconstruct the 3D microstructure of HMA. To evaluate the efficiency of the presented 3D model for prediction of mechanical behavior, HMA was regarded as a two-phase mixture; mastic phase and aggregate phase. The asphalt binder, filler, air voids and fine aggregates were considered as mastic with viscoelastic behavior and the aggregate was considered as an elastic material. Two models (Burger and generalized Kelvin) were studied for determining viscoelastic behavior of mastic. Finally, to verify the model using Finite Element Method (FEM) the behavior of the 3D model was simulated under different uniaxial compressive loads. A good agreement was observed between the simulated results and corresponding experimental data which indicates the efficiency of the proposed model to simulate three-dimensional asphalt.

A Single Integral Finite Strain Viscoelastic Model of Ligaments and Tendons

1996 ◽  
Vol 118 (2) ◽  
pp. 221-226 ◽  
Author(s):  
G. A. Johnson ◽  
G. A. Livesay ◽  
S. L-Y. Woo ◽  
K. R. Rajagopal
Keyword(s):  
Finite Strain ◽  
Viscoelastic Model ◽  
Three Dimensional ◽  
Uniaxial Extension ◽  
Viscoelastic Behavior ◽  
Nonlinear Behavior ◽  
Biological Tissues ◽  
Model Parameters ◽  
Three Dimensional Model ◽  
Single Integral

A general continuum model for the nonlinear viscoelastic behavior of soft biological tissues was formulated. This single integral finite strain (SIFS) model describes finite deformation of a nonlinearly viscoelastic material within the context of a three-dimensional model. The specific form describing uniaxial extension was obtained, and the idea of conversion from one material to another (at a microscopic level) was then introduced to model the nonlinear behavior of ligaments and tendons. Conversion allowed different constitutive equations to be used for describing a single ligament or tendon at different strain levels. The model was applied to data from uniaxial extension of younger and older human patellar tendons and canine medial collateral ligaments. Model parameters were determined from curve-fitting stress-strain and stress-relaxation data and used to predict the time-dependent stress generated by cyclic extensions.

Sign in / Sign up

Export Citation Format

Share Document