Identification of invisible fatigue damage of thermosetting epoxy resin by non-destructive thermal measurement using entropy generation

Kudo, Norihiro; Fujita, Ryohei; Oya, Yutaka; Sakai, Takenobu; Nagano, Hosei; Koyanagi, Jun

doi:10.1080/09243046.2023.2230687

Cited by 5 publications

(4 citation statements)

References 51 publications

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“…Here, we introduce a previous experimental study on cyclic loading for the same thermosetting polymer as that used in this study. Kudo et al reported that the density decreases after 100 cyclic loadings [61], which is qualitatively consistent with our results (Figure 7). This decrease in density cannot be reproduced with standard MD simulations without considering bond dissociation [48,49].…”

Section: Resultssupporting

confidence: 93%

Molecular Dynamics Simulation of Cumulative Microscopic Damage in a Thermosetting Polymer under Cyclic Loading

Yamada,

Morita,

Takamura

et al. 2024

Polymers

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To develop durable composite materials, it is crucial to elucidate the correlation between nanoscale damage in thermosetting resins and the degradation of their mechanical properties. This study aims to investigate this correlation by performing cyclic loading tests on the cross-linked structure of diglycidyl ether bisphenol A (DGEBA) and 4,4′-diaminodiphenyl sulfone (44-DDS) using all-atom molecular dynamics (MD) simulations. To accurately represent the nanoscale damage in MD simulations, a bond dissociation algorithm based on interatomic distance criteria is applied, and three characteristics are used to quantify the microscopic damage: stress–strain curves, entropy generation, and the formation of voids. As a result, the number of covalent bond dissociations increases with both the cyclic loading and its amplitude, resulting in higher entropy generation and void formation, causing the material to exhibit inelastic behavior. Furthermore, our findings indicate the occurrence of a microscopic degradation process in the cross-linked polymer: Initially, covalent bonds align with the direction of the applied load. Subsequently, tensioned covalent bonds sequentially break, resulting in significant void formation. Consequently, the stress–strain curves exhibit nonlinear and inelastic behavior. Although our MD simulations employ straightforward criteria for covalent bond dissociation, they unveil a distinct correlation between the number of bond dissociations and microscale damage. Enhancing the algorithm holds promise for yielding more precise predictions of material degradation processes.

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Section: Resultssupporting

confidence: 93%

Molecular Dynamics Simulation of Cumulative Microscopic Damage in a Thermosetting Polymer under Cyclic Loading

Yamada,

Morita,

Takamura

et al. 2024

Polymers

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“…Therefore, the measurement of C p values was suggested to be effective in quantifying the initial fatigue state. However, the increase in C p observed in the epoxy resin during fatigue testing was 4.9% [4], indicating that the CFRP results exceeded that value. For future works, we will conduct experiments in a vacuum environment, where thermal losses can be neglected, and verify reproducibility.…”

Section: Resultsmentioning

confidence: 87%

“…Proc. 2023, 51, 34 2 of 5 changing rate of 𝐷 and 𝐶 [3,4]. This paper reports the results of the changing rate of 𝐷 and 𝜌𝐶 with fatigue load cycles on a single CFRP fatigue specimen.…”

Section: Methodsmentioning

confidence: 99%

“…Our research group has developed a method to measure D and ρC p without contact by using a lock-in thermography (LIT)-based laser periodic heating method [2]. Using this technique, we have proposed a new approach to evaluate fatigue damage based on the measurement of the changing rate of D and C p [3,4]. This paper reports the results of the changing rate of D and ρC p with fatigue load cycles on a single CFRP fatigue specimen.…”

Section: Introductionmentioning

confidence: 99%

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Non-Destructive Fatigue Evaluation through Thermophysical Properties Using Lock-In Thermography

Fujita,

Kudo,

Abe

et al. 2023

The 17th International Workshop on Advanced Infrared Technology and Applications

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Evaluation of Volumetric Strain on Polyamide 6 by Thermodynamic Entropy Generation

Sakai,

Oya,

Koyanagi

2023

Exp Mech

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Identification of invisible fatigue damage of thermosetting epoxy resin by non-destructive thermal measurement using entropy generation

Cited by 5 publications

References 51 publications

Molecular Dynamics Simulation of Cumulative Microscopic Damage in a Thermosetting Polymer under Cyclic Loading

Molecular Dynamics Simulation of Cumulative Microscopic Damage in a Thermosetting Polymer under Cyclic Loading

Non-Destructive Fatigue Evaluation through Thermophysical Properties Using Lock-In Thermography

Evaluation of Volumetric Strain on Polyamide 6 by Thermodynamic Entropy Generation

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