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Nonlinear Viscoelastic Analysis

In order to validate the nonlinear viscoelastic model, three uniaxial test cases are analyzed. The results are compared with the laboratory tests conducted on similar specimens by Peretz and Weitsman.(27) The material properties used in the verification analysis are those reported by Becker et The creep data, together with other relevant material properties, are given in Table 3. [Pg.381]

A constant value for the Poisson ratio is assumed for the adhesive. The results from a linear viscoelastic analysis are also presented for comparison. [Pg.381]

The third test involves creep under a constant stress of 10 MPa with a linearly varying [Pg.381]

FIGURE 8. Creep under step load and constant temperature of a viscoelastic coupon. [Pg.381]

FIGURE 9. Creep under linearly varying stress and temperature for a viscoelastic coupon. [Pg.382]


In the solid state deformation, the nonlinear viscoelastic effect is most clearly shown in the yield behavior. The type of stresses applied to a system has little effect on the linear viscoelastic relaxation, but becomes very important as the stress level increases. At high stress levels, the contribution from the external work done on a lattice cell has to be included in the nonlinear viscoelastic analysis. By taking into account the long range cooperative interaction, the external work can,... [Pg.174]

Schaffer and Adams< 2) carried out a nonlinear viscoelastic analysis of a unidirectional composite laminate using the finite-element method. The nonlinear viscoelastic constitutive law proposed by Schapery<26) was used in conjunction with elastoplastic constitutive relations to model the composite response beyond the elastic limit. [Pg.364]

In this section results of a number of linear elastic, linear viscoelastic, and nonlinear viscoelastic analyses are discussed in light of available experimental or analytical results. All results are obtained using NOVA on an IBM 3090 computer in double precision arithmetic. First, the results of geometric nonlinear analysis are presented and compared with those obtained by other finite-element programs. Then linear and nonlinear viscoelastic analysis... [Pg.376]

S. Roy and J. N. Reddy, Nonlinear Viscoelastic Analysis of Adhesively Bonded Joints, Report No. VPI-E-86.28, ONR, Department of Engineering Science and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA (November 1986). [Pg.392]

Variation of maximum adhesive shear stress in double lap joints based on nonlinear viscoelastic analysis, using O Eq. 23.78 with a stress-dependent shift factor, and linear viscoelastic analysis, using the Maxwell model with variable relaxation time,... [Pg.570]

Eracture mechanics concepts can also be appHed to fatigue crack growth under a constant static load, but in this case the material behavior is nonlinear and time-dependent (29,30). Slow, stable crack growth data can be presented in terms of the crack growth rate per unit of time against the appHed R or J, if the nonlinearity is not too great. Eor extensive nonlinearity a viscoelastic analysis can become very complex (11) and a number of schemes based on the time rate of change of/have been proposed (31,32). [Pg.547]

In a previous article (2) we described a new approach to the analysis of nonlinear viscoelasticity as encountered in such large-strain cyclic deformation of polymers. In this chapter, we describe the apparatus used and the method of treating the data obtained. [Pg.36]

The Method of Analysis and Temperature Dependence of Nonlinear Viscoelastic Functions, Trans. Soc. Rheol. (1973) 17(1), 47. [Pg.52]

This equation represents nonlinear viscoelastic behavior. For simplicity of analysis it is often reduced to the form... [Pg.283]

Fourier transform rheology (FTR) [Wapner and Forsman, 1971] was used for the analysis of CPNCs. The experiments were performed in the ARES using the software developed by Wilhelm [2002]. It was expected that the method may be suitable for characterization of the nonlinear viscoelastic response of CPNC. The FTR analysis is based on the expression... [Pg.672]

Pego, R. Phase transitions in one dimensional nonlinear viscoelasticity admissibility and stability. Archive for Rational Mechanics and Analysis 97 (1987) 353-394. [Pg.336]

The stresses in an adhesive joint depend, once a constitutive model is chosen, on the geometry, boundary conditions, the assumed mechanical properties of the regions involved, and the type and distribution of loads acting on the joint. In practice, most adhesives exhibit, depending on the stress levels, nonlinear-viscoelastic behavior, and the adhetends exhibit elastoplastic behavior. Most theoretical studies conducted to date on the stress analysis of adhesively bonded joints have made simplifying assumptions of linear and elastic and/or viscoelastic behavior in the interest of tracking solutions. [Pg.360]

The present discussion has a twofold objective First, to review the literature in the stress analysis of adhesive joints using the finite-element method. Second, to present a finite-element computational procedure for adhesive joints experiencing two-dimensional deformation and stress fields. The adherends are linear elastic and can undergo large deformations, and the adhesive experiences linear strains but nonlinear viscoelastic behavior. Following these general comments, a review of the literature is presented. The technical discussion given in the subsequent sections comes essentially from the authors research(i 2> conducted for the Oifice of Naval Research. [Pg.360]

Botha, Jones, and Brinson,Henriksen,(22) Becker et a/.,(23) and Yadagiri and Papi Reddy(24,25) reported results of viscoelastic finite-element analysis of adhesive joints. Henriksen used Schapery s(26) nonlinear viscoelastic model to verify the experimental results of Peretz and Weitsman(27) for an adhesive layer. The work of Becker et is largely... [Pg.363]

Analysis of crack growth in viscoelastic media is mainly limited to linear isotropic, homogeneous materials. Schapery(34) proposed the use of parameters similar to the J integral for quasi-static crack growth in a class of nonlinear viscoelastic materials subject to finite strains. [Pg.364]

The present section deals with the review and extension of Schapery s single integral constitutive law to two dimensions. First, a stress operator that defines uniaxial strain as a function of current and past stress is developed. Extension to multiaxial stress state is accomplished by incorporating Poisson s effects, resulting in a constitutive matrix that consists of instantaneous compliance, Poisson s ratio, and a vector of hereditary strains. The constitutive equations thus obtained are suitable for nonlinear viscoelastic finite-element analysis. [Pg.370]

M. Henriksen, Nonlinear viscoelastic stress analysis—A finite element approach, Comput. Struct. 18,133-139 (1984). [Pg.392]

E. The Method of Analysis for Nonlinear Viscoelastic Properties of Polymer Liquids... [Pg.143]

The interrelationships for linear viscoelasticity in Sections B to F are accepted with almost the confidence given deductions from the laws of thermodynamics. Relations from nonlinear viscoelasticity theory are less well established. Many nonlinear constitutive equations have been proposed. Some predict certain relations which are in close accord with experiment and can be accepted with confidence but fail in other respects. A very thorough analysis with emphasis on viscoelastic liquids is provided by the treatise of Bird, Armstrong, and Hassager." °... [Pg.76]

Nanoparticles, compared with traditional fillers, provide more reinforcement due to the higher interfacial area. Introduction of these particles into the mbber matrix improves many of its properties, in particular tensile strength, thermal stability, elasticity, processability or barrier improvement. The final properties of nanocomposites are determined by the filler-filler and polymer-filler interactions. Therefore, it is very important to have knowledge of the characteristics of nonlinear viscoelastic behavior for mbber reinforced systems, especially an analysis of the low strain dynamic mechanical properties (Payne effect). [Pg.68]


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