Creep deformation simulation of adhesively bonded joints at different temperature levels using a modified power-law model

Sadigh, Mohammad Ali Saeimi; Paygozar, Bahman; Silva, Lucas F. M. da; Tahami, Farid Vakili

doi:10.1016/j.polymertesting.2019.106087

Cited by 23 publications

(12 citation statements)

References 17 publications

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“…This regime is stress-controlled and is clearly seen in all samples, regardless of the catalyst concentration and temperature for T > T g ; however, primary creep is seen to last longer and is more readily discernible for samples at T ≪ T v . Similar power law dependencies between creep strain and time have been previously reported for the creep response of epoxy adhesives and other polymers. ,,,,,,,, …”

Section: Resultssupporting

confidence: 79%

“…Similar power law dependencies between creep strain and time have been previously reported for the creep response of epoxy adhesives and other polymers. 2,4,22,32,37,39,40,44,45 Primary creep depends on the slack of the polymer chains when all samples are tested at T > T g . We postulate that the primary creep regime corresponds to the conformational freedom of the polymer chains relative to each other before a percolated path of loaded crosslinks emerges.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Creep Mechanics of Epoxy Vitrimer Materials

Hubbard

Ren

Picu

et al. 2022

ACS Appl. Polym. Mater.

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Epoxy materials are an indispensable class of polymers due to their excellent mechanical properties and high thermal resistance. However, traditional epoxy materials are typically non-recyclable and face issues with fatigue and creep. To combat the issue of recyclability, research interest is increasingly centered on epoxy vitrimer materials, which exhibit a dynamic covalent bond exchange reaction at high temperatures allowing for self-healing, recycling, and shape reprogramming. Herein, we discuss the creep mechanics of epoxy vitrimers; we postulate that gaining a fundamental understanding of what causes creep in vitrimers will garner advances in vitrimer creep resistance for future applications. Isothermal creep results demonstrate the presence of three distinct creep regimes: primary creep associated with polymer chain mobility, secondary creep associated with network rearrangement due to the dynamic covalent bond exchange reaction, and tertiary creep associated with errors in this reaction. We note at low temperatures (T ≪ T v ) and catalyst concentrations, vitrimers simply behave as a traditional epoxy material. In contrast, at high temperatures and catalyst concentrations, vitrimers exhibit significantly more creep with strong correlations to catalyst concentration, heating rate, and temperature, which are quantified in this work.

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Section: Resultssupporting

confidence: 79%

Section: ■ Results and Discussionmentioning

confidence: 99%

Creep Mechanics of Epoxy Vitrimer Materials

Hubbard

Ren

Picu

et al. 2022

ACS Appl. Polym. Mater.

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“…In fitting M(x,t), a function of an independent variable t and a vector of n parameters x, to a set of m data points (t i ,  i ), the summation of the weighted squares of the differences between the experimental data (ti) and the value of the preassumed function M(x,t i ) should be minimized [21], (Eqn. 9).…”

Section: Optimization Methodsmentioning

confidence: 99%

“…An approach that help to overcome this problem consists to use an improved solving method, which is enhanced with additional convergence criterion, can fulfill a good convergence with merely random initial conditions. In order to simulate the creep deformations behavior of the adhesive joints through finite element-based numerical analyses, Sadigh et al [21] have used the called Levenberg-Marquardt algorithm to fit a power-law model at a variety of stress and temperature levels. The goodness of the fitting procedure was checked using the Standard Error of their estimations.…”

Section: Introductionmentioning

confidence: 99%

On the use of the stepped isostress method in the prediction of creep behavior of polyamide 6

Sedira

Tedjini

Guerira

et al. 2022

Frattura Ed Integrità Strutturale

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The stepped isostress method (SSM) is an advanced technique which allows the prediction of the long-term behavior and enables the construction of creep master curves of materials with short-term experimental tests. However, the performance of this method is highly dependent on the numerical model and the time spent in data processing. In this paper, the effect of the extrapolation techniques on the creep curves trend is investigated using the SSM data of Polyamide test. Three extrapolation functions are used to offset the delay of the stress history: polynomial, power and exponential functions. Furthermore, a numerical routine is developed during the last step of the SSM, where the shift factors are computed taking into account the rescaling and the dwell times of each level of stresses. The processing of the SSM raw data has revealed that the rescaling parameters are the most determining factors to reach an accurate long-term creep curves. The rescaling process has shown an appropriate time, whether achieved by the exponential or power functions. Larger shift factors for exponential functions are assessed and therefore a long period of creep master curve was obtained.

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“…The empirical modeling is to establish the correlations between the creep rate and other independent variables such as temperature and stress using testing data. Examples of this type of model include, but are not limited to, the stress-dependent phenomenological viscoelastic–plastic model [ 46 ], the modified power law model with temperature- and stress-dependent correction factors [ 47 ], and the improved Findley–Khosla model with the Schapery’s integral [ 48 ]. For empirical modeling, the detailed mechanisms of the creep behavior are not fully explained.…”

Section: Introductionmentioning

confidence: 99%

A Phenomenological Primary–Secondary–Tertiary Creep Model for Polymer-Bonded Composite Materials

et al. 2021

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This study develops a unified phenomenological creep model for polymer-bonded composite materials, allowing for predicting the creep behavior in the three creep stages, namely the primary, the secondary, and the tertiary stages under sustained compressive stresses. Creep testing is performed using material specimens under several conditions with a temperature range of 20 °C–50 °C and a compressive stress range of 15 MPa–25 MPa. The testing data reveal that the strain rate–time response exhibits the transient, steady, and unstable stages under each of the testing conditions. A rational function-based creep rate equation is proposed to describe the full creep behavior under each of the testing conditions. By further correlating the resulting model parameters with temperature and stress and developing a Larson–Miller parameter-based rupture time prediction model, a unified phenomenological model is established. An independent validation dataset and third-party testing data are used to verify the effectiveness and accuracy of the proposed model. The performance of the proposed model is compared with that of an existing reference model. The verification and comparison results show that the model can describe all the three stages of the creep process, and the proposed model outperforms the reference model by yielding 28.5% smaller root mean squared errors on average.

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Creep deformation simulation of adhesively bonded joints at different temperature levels using a modified power-law model

Cited by 23 publications

References 17 publications

Creep Mechanics of Epoxy Vitrimer Materials

Creep Mechanics of Epoxy Vitrimer Materials

On the use of the stepped isostress method in the prediction of creep behavior of polyamide 6

A Phenomenological Primary–Secondary–Tertiary Creep Model for Polymer-Bonded Composite Materials

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