Simulation and experimental modeling
Research materials: Copper, Shape memory alloys (SMAs), AM Inconel 718, etc.
Predicting the mechanical behavior of a structure through simulation has the cost advantage over experiment trials and is able to measure a variation of properties that is challenging to be identified through experimental works (stress concentration and distribution, dislocation density, etc.). An ideal simulation tool would be able to allow engineers to oversee a structural design for early inspections of limitations and drawbacks of the work, which in turn be able to make corrections and improvements before the occurence of any catastropic events.
Up till date, the classical continuum theory is widely used as a basic theory for predicting, designing, and analyzing the behavior of macrostructures such as automobiles and ships. However, the classical continuum theory does not correctly predict the behavior of small structures. The behavior of structures predicted by the classical continuum theory is often much more flexible than the behavior of actual structures obtained from experiments, which might lead to a decrease in accuracy of the behaviors predicted in small-scales. Moreover, as the characteristic dimension of components decreases, the material behavior in small-scales greatly differs from its bulk counterparts, leading to a need of a different simulation model to predict the mechanical responses in micro/ nano-scales.
Spearheaded by Prof. Jae-Hoon Choi with an emphasis on the couple stress theory, we aim to understand the size effects on the mechanical behaviors of different materials. In particular, there are limited reports on the existence of size effects in the elastic region of materials, but our recent works have shown to differ as the effective elastic modulus and bending rigidity varied across a change in the thickness. We work on understanding these effects and to propose different mechanisms behind our experimental findings. The experimental results obtained from our micro/ nano-scale tests were also effectively utilized hand-in-hand to cross-validate the reliability of the simulation models developed. Future expansion on the study of size effects could be broadened into evaluation of different materials, refining the fracture models for structural analysis, and improving the electro- and thermo-mechanical coupling evaluations in small-scale systems.
Predicting the mechanical behavior of a structure through simulation has the cost advantage over experiment trials and is able to measure a variation of properties that is challenging to be identified through experimental works (stress concentration and distribution, dislocation density, etc.). An ideal simulation tool would be able to allow engineers to oversee a structural design for early inspections of limitations and drawbacks of the work, which in turn be able to make corrections and improvements before the occurence of any catastropic events.
Up till date, the classical continuum theory is widely used as a basic theory for predicting, designing, and analyzing the behavior of macrostructures such as automobiles and ships. However, the classical continuum theory does not correctly predict the behavior of small structures. The behavior of structures predicted by the classical continuum theory is often much more flexible than the behavior of actual structures obtained from experiments, which might lead to a decrease in accuracy of the behaviors predicted in small-scales. Moreover, as the characteristic dimension of components decreases, the material behavior in small-scales greatly differs from its bulk counterparts, leading to a need of a different simulation model to predict the mechanical responses in micro/ nano-scales.
Spearheaded by Prof. Jae-Hoon Choi with an emphasis on the couple stress theory, we aim to understand the size effects on the mechanical behaviors of different materials. In particular, there are limited reports on the existence of size effects in the elastic region of materials, but our recent works have shown to differ as the effective elastic modulus and bending rigidity varied across a change in the thickness. We work on understanding these effects and to propose different mechanisms behind our experimental findings. The experimental results obtained from our micro/ nano-scale tests were also effectively utilized hand-in-hand to cross-validate the reliability of the simulation models developed. Future expansion on the study of size effects could be broadened into evaluation of different materials, refining the fracture models for structural analysis, and improving the electro- and thermo-mechanical coupling evaluations in small-scale systems.
Read more in our publications:
[1] Choi, J. H., Ryu, H., Sim, G. D. (2024). Elastic Size Effect of Single Crystal Copper Beams under Combined Loading of Torsion and Bending, Thin-Walled Structures, 197, 111602.
[2] Choi, J. H., Ryu, H., Lim, K. H., Kim, J. Y., Kim, H., Sim, G. D. (2023). Effect of Strain Gradient on Elastic and Plastic Size Dependency in Polycrystalline Copper, International Journal of Plasticity, 171, 103824.
[3] Choi, J. H., Lee, B. C., & Sim, G. D. (2023). Mixed finite elements based on superconvergent patch recovery for strain gradient theory. Computer Methods in Applied Mechanics and Engineering, 411, 116053.
[4] Choi, J. H., Zaki, W., & Sim, G. D. (2023). Size-dependent constitutive model for shape memory alloys based on couple stress elastoplasticity. Applied Mathematical Modelling, 118, 641-664.
[5] Kim, H., Choi, J. H., Park, Y., Choi, S., & Sim, G. D. (2023). Mechanical characterization of thin films via constant strain rate membrane deflection experiments. Journal of the Mechanics and Physics of Solids, 173, 105209.
[1] Choi, J. H., Ryu, H., Sim, G. D. (2024). Elastic Size Effect of Single Crystal Copper Beams under Combined Loading of Torsion and Bending, Thin-Walled Structures, 197, 111602.
[2] Choi, J. H., Ryu, H., Lim, K. H., Kim, J. Y., Kim, H., Sim, G. D. (2023). Effect of Strain Gradient on Elastic and Plastic Size Dependency in Polycrystalline Copper, International Journal of Plasticity, 171, 103824.
[3] Choi, J. H., Lee, B. C., & Sim, G. D. (2023). Mixed finite elements based on superconvergent patch recovery for strain gradient theory. Computer Methods in Applied Mechanics and Engineering, 411, 116053.
[4] Choi, J. H., Zaki, W., & Sim, G. D. (2023). Size-dependent constitutive model for shape memory alloys based on couple stress elastoplasticity. Applied Mathematical Modelling, 118, 641-664.
[5] Kim, H., Choi, J. H., Park, Y., Choi, S., & Sim, G. D. (2023). Mechanical characterization of thin films via constant strain rate membrane deflection experiments. Journal of the Mechanics and Physics of Solids, 173, 105209.
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Updated on 2025.04.05
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