Modified creep constitutive equation for an epoxy-based adhesive with nonlinear viscoelastic behavior

Abstract

This article presents the procedure to obtain constitutive equations to express the creep behavior of Araldite 2015 epoxy adhesive using the results of the uniaxial creep tests. The experimental data show that the examined adhesive has a nonlinear viscoelastic behavior. Three types of constitutive equations have been used: (a) Bailey-Norton equation, (b) generalized time-hardening model and (c) rheological model which is a series combination of springs and dampers known as Maxwell and Zener combination. The first two models have vast application in commercial finite elementbased software. It is shown that the generalized time-hardening model can simulate the creep behavior of the adhesive better than the Bailey-Norton model. However, this model is less accurate at the elevated temperatures. Therefore, an empirical equation based on Maxwell and Zener's was proposed which demonstrates a very good consistency with the results of the experimental data over the assumed range of stress and temperatures.

Time-Dependent Mechanical Properties in Polyetherimide 3D-Printed Parts Are Dictated by Isotropic Performance Being Accurately Predicted by the Generalized Time Hardening Model

“…The better predictive performance of the GTH model compared with other well-known phenomenological viscoelastic models included in FEM packages, such as time hardening or strain hardening, could be predicted because of the creep compliance which is dependent on applied stress [31,32]. The GTH model has the ability to effectively adapt to the increase in compliance modulus (r in Equation (1), Figure 4), whereas the models mentioned above are unable to exhibit different values for creep compliance in a given material for different stress levels.…”

“…Because nonlinear viscoelastic/plastic behavior in plastics are expected to be exhibited in prior studies, as in work by Salazar-Martín et al [27], and because finding a practical approach for predicting creep and stress relaxation behavior in Finite Element Method (FEM) simulations is the aim of this study, the Generalized Time Hardening (GTH) model was chosen [31,32]. This model is capable of explaining the creep behavior of different materials in contrast to time hardening and strain hardening equations more accurately, since GTH is able to model materials' behavior in which creep compliance is not a constant value in the studied domain, extending its capability from viscoelastic to viscoplastic characterization [31,32]. For instance, in the GTH model, the coefficients are polynomial functions of stress, whereas, in the time hardening equation, these coefficients are constants.…”

Effect of Reduced Graphene Oxide Reinforcement on Creep Behavior of Adhesively Bonded Joints

“…Then the mixture was stored in a vacuum machine to remove the entrapped air during the mixing process. Bulk specimens were produced according to ASTM D638 recommendation and the method which has been described by Zehsaz et al [33]. In this method, the prepared adhesive and adhesive-RGO are casted in the molds of silicone sheet.…”

Experimental Characterization and Modified Constitutive Modeling of the Strain Rate Dependent Compressive Behavior of Adhesives

“…The various constitutive material models have been proposed to represent the stress–strain response of adhesives . An elastoplastic constitutive formula has been developed to simulate both the reversible elastic and irreversible inelastic deformation of a ductile polymeric adhesive in adhesively bonded aluminum components .…”

“…An elastoplastic constitutive formula has been developed to simulate both the reversible elastic and irreversible inelastic deformation of a ductile polymeric adhesive in adhesively bonded aluminum components . The rheological or time‐hardening models were applied to quantify the nonlinear viscoelastic behavior of epoxy‐based adhesives in sandwich structures. A chemomechanical model was established to incorporate the influence of curing on viscoelastic properties of epoxy .…”