Institute of Mechanics,
Chinese Academy of Sciences
2025 Vol.15(6)
column
Display Mode： |
Theoretical and Applied Mechanics Letters 15 (2025) 100608.
doi: 10.1016/j.taml.2025.100608
Abstract:
Submarine pipelines are critical infrastructures for offshore energy transport and communications. Understanding their structural response to near-field explosions is crucial for enhancing their blast resistance and operational safety. This study presents a computational study on the interaction between explosion-induced bubbles and a seabed-mounted pipeline. A recently developed computational framework is employed, which couples a compressible fluid solver with a finite element structural solver via a partitioned procedure. An embedded boundary method and a level-set method are employed to handle the fluid-structure and gas-liquid interfaces. Using this framework, we analyze the flow field evolution, bubble dynamics, and transient pipe deformation. Two distinct response modes are identified: periodic oscillation under low-pressure loading and downward collapse triggered by high-pressure loading and bubble jet impact. Specifically, under high-pressure conditions, the pipe initially deforms inward, generating a localized high-pressure zone within the concave region. During structural rebound, the trapped fluid is expelled upward, giving rise to a bubble jet. Further parametric studies on the pipe’s internal pressure, wall thickness, and support angle reveal several key insights. A higher internal pressure delays structural collapse, and a greater pipe thickness results in more uniform implosion morphologies. The support angle strongly influences the collapse dynamics, with the shortest collapse time occurring at . These findings offer new insights for the protective design of submarine pipelines.
Submarine pipelines are critical infrastructures for offshore energy transport and communications. Understanding their structural response to near-field explosions is crucial for enhancing their blast resistance and operational safety. This study presents a computational study on the interaction between explosion-induced bubbles and a seabed-mounted pipeline. A recently developed computational framework is employed, which couples a compressible fluid solver with a finite element structural solver via a partitioned procedure. An embedded boundary method and a level-set method are employed to handle the fluid-structure and gas-liquid interfaces. Using this framework, we analyze the flow field evolution, bubble dynamics, and transient pipe deformation. Two distinct response modes are identified: periodic oscillation under low-pressure loading and downward collapse triggered by high-pressure loading and bubble jet impact. Specifically, under high-pressure conditions, the pipe initially deforms inward, generating a localized high-pressure zone within the concave region. During structural rebound, the trapped fluid is expelled upward, giving rise to a bubble jet. Further parametric studies on the pipe’s internal pressure, wall thickness, and support angle reveal several key insights. A higher internal pressure delays structural collapse, and a greater pipe thickness results in more uniform implosion morphologies. The support angle strongly influences the collapse dynamics, with the shortest collapse time occurring at . These findings offer new insights for the protective design of submarine pipelines.
Theoretical and Applied Mechanics Letters 15 (2025) 100613.
doi: 10.1016/j.taml.2025.100613
Abstract:
Cell fusion is a basic biological process that plays critical roles in both physiological and pathological processes. However, how mechanical factors influence the fusion process is not fully understood. In this study, we reported filopodia-mediated fusion among MCF-7 cells. We showed that the filopodia protrusion force induced significant bending of the cell membrane, which was essential for membrane fusion between neighboring cells, and then eventually induced the formation of multinucleated syncytia. The inhibition of actin polymerization significantly reduced the fusion ratio, whereas increased actin polymerization promoted fusion. We found that several factors influence the fusion process, e.g., the cell density, substrate pattern, and stiffness. For example, cell density has a significant effect on cell fusion. There was an optimal cell density for cell fusion. The fusion probability increased with increasing cell density within a moderate cell density range but decreased within a high cell density range. Substrate properties also influence the fusion behavior. For example, the fusion ratio was reduced on nanogrooved surfaces and soft substrates because the surface pattern restricted cell alignment and motility, and soft substrates reduced the activity of the actin dynamics of filopodia for cell fusion. This study not only contributes to our understanding of the basic biology of cell fusion but also has important implications for understanding the mechanisms of cancer progression and potential therapeutic intervention methods.
Cell fusion is a basic biological process that plays critical roles in both physiological and pathological processes. However, how mechanical factors influence the fusion process is not fully understood. In this study, we reported filopodia-mediated fusion among MCF-7 cells. We showed that the filopodia protrusion force induced significant bending of the cell membrane, which was essential for membrane fusion between neighboring cells, and then eventually induced the formation of multinucleated syncytia. The inhibition of actin polymerization significantly reduced the fusion ratio, whereas increased actin polymerization promoted fusion. We found that several factors influence the fusion process, e.g., the cell density, substrate pattern, and stiffness. For example, cell density has a significant effect on cell fusion. There was an optimal cell density for cell fusion. The fusion probability increased with increasing cell density within a moderate cell density range but decreased within a high cell density range. Substrate properties also influence the fusion behavior. For example, the fusion ratio was reduced on nanogrooved surfaces and soft substrates because the surface pattern restricted cell alignment and motility, and soft substrates reduced the activity of the actin dynamics of filopodia for cell fusion. This study not only contributes to our understanding of the basic biology of cell fusion but also has important implications for understanding the mechanisms of cancer progression and potential therapeutic intervention methods.
Theoretical and Applied Mechanics Letters 15 (2025) 100614.
doi: 10.1016/j.taml.2025.100614
Abstract:
Open thin-shell structures exhibit advantages such as lightweight properties and high energy absorption efficiency. By randomly stacking these structures as unit cells, adjustable mechanical metamaterials with tunable and stable mechanical properties can be constructed. This study investigates the mechanical performance of randomly stacked open thin-shell mechanical metamaterials using a combined experimental and numerical simulation approach. Results indicate that under compressive loading, shell unit cells primarily dissipate energy through large deformation, snap-fit behavior, friction, and shell relocation. Different combinations of randomly stacked mechanical metamaterials demonstrate nearly identical energy dissipation ratios during the first compression-unloading cycle, indicating that the energy dissipation efficiency exhibits robust stability independent of contact and geometric randomness. However, under limit cycle conditions, increasing the proportion of Type II shells enhances the maximum relative displacement, energy dissipation capacity, and energy dissipation ratio by up to fivefold. Notably, under compressive loading, Type I shells engaged through snap-fit behavior exhibit irreversible deformation after unloading, while Type II shells maintain their configuration without active engagement. The proportion of Type II shells directly determines the mechanical performance of the structure.This research provides new references for the development of lightweight mechanical metamaterials, disordered mechanical metamaterials, and adjustable mechanical metamaterials.
Open thin-shell structures exhibit advantages such as lightweight properties and high energy absorption efficiency. By randomly stacking these structures as unit cells, adjustable mechanical metamaterials with tunable and stable mechanical properties can be constructed. This study investigates the mechanical performance of randomly stacked open thin-shell mechanical metamaterials using a combined experimental and numerical simulation approach. Results indicate that under compressive loading, shell unit cells primarily dissipate energy through large deformation, snap-fit behavior, friction, and shell relocation. Different combinations of randomly stacked mechanical metamaterials demonstrate nearly identical energy dissipation ratios during the first compression-unloading cycle, indicating that the energy dissipation efficiency exhibits robust stability independent of contact and geometric randomness. However, under limit cycle conditions, increasing the proportion of Type II shells enhances the maximum relative displacement, energy dissipation capacity, and energy dissipation ratio by up to fivefold. Notably, under compressive loading, Type I shells engaged through snap-fit behavior exhibit irreversible deformation after unloading, while Type II shells maintain their configuration without active engagement. The proportion of Type II shells directly determines the mechanical performance of the structure.This research provides new references for the development of lightweight mechanical metamaterials, disordered mechanical metamaterials, and adjustable mechanical metamaterials.
Theoretical and Applied Mechanics Letters 15 (2025) 100615.
doi: 10.1016/j.taml.2025.100615
Abstract:
This study evaluates the accuracy of large-eddy simulation (LES) analyses using a commonly used subgrid-scale (SGS) model based on the eddy viscosity hypothesis. The evaluation is performed by examining the Reynolds number dependence of turbulence maintained by anisotropic and isotropic forcing techniques derived from Taylor analytical solutions. The Smagorinsky model, the Vreman model, and the coherent structure model are used as SGS models. LES outcomes were evaluated against those produced by direct numerical simulation (DNS). In contrast to the results with isotropic forcing, the turbulent kinetic energy of anisotropic forcing-induced turbulence, as calculated by DNS, exhibits a minimum in the intermediate Reynolds number range. However, all three LES analyses fail to reproduce this minimum and instead show overestimated values. This discrepancy is attributed to reduced spatial inhomogeneity of the turbulent diffusion, pressure diffusion, and pressure-strain correlation terms in the transport equations of the velocity fluctuation intensities in this Reynolds number range. Visualization results for the LES and DNS analyses further show that within this range, LES analyses reproduce two-dimensional tubular flow structures that are not observed in DNS results.
This study evaluates the accuracy of large-eddy simulation (LES) analyses using a commonly used subgrid-scale (SGS) model based on the eddy viscosity hypothesis. The evaluation is performed by examining the Reynolds number dependence of turbulence maintained by anisotropic and isotropic forcing techniques derived from Taylor analytical solutions. The Smagorinsky model, the Vreman model, and the coherent structure model are used as SGS models. LES outcomes were evaluated against those produced by direct numerical simulation (DNS). In contrast to the results with isotropic forcing, the turbulent kinetic energy of anisotropic forcing-induced turbulence, as calculated by DNS, exhibits a minimum in the intermediate Reynolds number range. However, all three LES analyses fail to reproduce this minimum and instead show overestimated values. This discrepancy is attributed to reduced spatial inhomogeneity of the turbulent diffusion, pressure diffusion, and pressure-strain correlation terms in the transport equations of the velocity fluctuation intensities in this Reynolds number range. Visualization results for the LES and DNS analyses further show that within this range, LES analyses reproduce two-dimensional tubular flow structures that are not observed in DNS results.
Theoretical and Applied Mechanics Letters 15 (2025) 100616.
doi: 10.1016/j.taml.2025.100616
Abstract:
The 13-node quadrilateral and 39-node hexahedral cubic serendipity elements produce nodally integrated positive-definite lumped heat capacity matrices in higher-order finite element analysis. However, these elements display severe convergence deterioration in explicit transient heat conduction analysis with lumped heat capacity matrices. This convergence decay is due to the violation of variational integration consistency by the standard Galerkin formulation with lumped heat capacity matrices. This issue is resolved by introducing the boundary-enhanced Galerkin weak form that incorporates the elemental boundary contribution in the discrete finite element formulation. Subsequently, it is theoretically proven that a direct nodal integration identically fulfills the variational integration consistency in the context of the boundary-enhanced Galerkin weak form. The proposed variationally consistent nodal integration therefore enables optimal convergence for explicit transient heat conduction analysis with lumped heat capacity matrices. The efficacy of the proposed variationally consistent nodal integration formulation for the 13-node quadrilateral and 39-node hexahedral cubic elements is thoroughly demonstrated via numerical examples.
The 13-node quadrilateral and 39-node hexahedral cubic serendipity elements produce nodally integrated positive-definite lumped heat capacity matrices in higher-order finite element analysis. However, these elements display severe convergence deterioration in explicit transient heat conduction analysis with lumped heat capacity matrices. This convergence decay is due to the violation of variational integration consistency by the standard Galerkin formulation with lumped heat capacity matrices. This issue is resolved by introducing the boundary-enhanced Galerkin weak form that incorporates the elemental boundary contribution in the discrete finite element formulation. Subsequently, it is theoretically proven that a direct nodal integration identically fulfills the variational integration consistency in the context of the boundary-enhanced Galerkin weak form. The proposed variationally consistent nodal integration therefore enables optimal convergence for explicit transient heat conduction analysis with lumped heat capacity matrices. The efficacy of the proposed variationally consistent nodal integration formulation for the 13-node quadrilateral and 39-node hexahedral cubic elements is thoroughly demonstrated via numerical examples.
Theoretical and Applied Mechanics Letters 15 (2025) 100617.
doi: 10.1016/j.taml.2025.100617
Abstract:
Hypersonic magnetohydrodynamic (MHD) control effectively enhances the aerothermal environment of aerospace vehicles, demonstrating considerable potential in plasma flow regulation and aerodynamic optimization. As aerospace vehicles progress toward mid-low-altitude hypersonic regimes, their external aerothermal conditions become increasingly severe. This study addresses the challenges of complex aerodynamic force/heat environments and the difficulties in MHD control numerical simulations for hypersonic vehicles at mid-low altitudes. On the basis of the perfect gas model and the low magnetic Reynolds number assumption, we conduct numerical simulations of MHD control under mid-low altitudes, high-Mach-number conditions. The findings reveal the following: (1) the low magnetic Reynolds number assumption is valid and computationally accurate, as corroborated by a comparative analysis with the literature; (2) in the mid-low altitude hypersonic regime, magnetic fields significantly suppress the shock standoff distance and reduce the surface heat flux. Both the magnetically controlled shock wave and the thermal protection exhibit nonlinear variations with the Mach number, increasing and then decreasing as the Mach number increases. The optimal Mach number for shock wave control is 13, whereas optimal thermal protection is achieved at Mach 15. At an altitude of 40 km, the optimal magnetohydrodynamic Mach range spans 13–17, achieving a maximum heat flux attenuation of 28.81%. Additionally, the effects of magnetic shock wave control correlate approximately exponentially with altitude within certain parameters, whereas the efficacy of thermal protection behaves linearly with altitude variations.
Hypersonic magnetohydrodynamic (MHD) control effectively enhances the aerothermal environment of aerospace vehicles, demonstrating considerable potential in plasma flow regulation and aerodynamic optimization. As aerospace vehicles progress toward mid-low-altitude hypersonic regimes, their external aerothermal conditions become increasingly severe. This study addresses the challenges of complex aerodynamic force/heat environments and the difficulties in MHD control numerical simulations for hypersonic vehicles at mid-low altitudes. On the basis of the perfect gas model and the low magnetic Reynolds number assumption, we conduct numerical simulations of MHD control under mid-low altitudes, high-Mach-number conditions. The findings reveal the following: (1) the low magnetic Reynolds number assumption is valid and computationally accurate, as corroborated by a comparative analysis with the literature; (2) in the mid-low altitude hypersonic regime, magnetic fields significantly suppress the shock standoff distance and reduce the surface heat flux. Both the magnetically controlled shock wave and the thermal protection exhibit nonlinear variations with the Mach number, increasing and then decreasing as the Mach number increases. The optimal Mach number for shock wave control is 13, whereas optimal thermal protection is achieved at Mach 15. At an altitude of 40 km, the optimal magnetohydrodynamic Mach range spans 13–17, achieving a maximum heat flux attenuation of 28.81%. Additionally, the effects of magnetic shock wave control correlate approximately exponentially with altitude within certain parameters, whereas the efficacy of thermal protection behaves linearly with altitude variations.
Theoretical and Applied Mechanics Letters 15 (2025) 100623.
doi: 10.1016/j.taml.2025.100623
Abstract:
We evaluated the performance of OpenFOAMGPT (GPT for generative pretrained transformers), which includes rating multiple large-language models. Some of the present models efficiently manage different computational fluid dynamics (CFD) tasks, such as adjusting boundary conditions, turbulence models, and solver configurations, although their token cost and stability vary. Locally deployed smaller models such as the QwQ-32B (Q4 KM quantized model) struggled with generating valid solver files for complex processes. Zero-shot prompts commonly fail in simulations with intricate settings, even for large models. Challenges with boundary conditions and solver keywords stress the need for expert supervision, indicating that further development is needed to fully automate specialized CFD simulations.
We evaluated the performance of OpenFOAMGPT (GPT for generative pretrained transformers), which includes rating multiple large-language models. Some of the present models efficiently manage different computational fluid dynamics (CFD) tasks, such as adjusting boundary conditions, turbulence models, and solver configurations, although their token cost and stability vary. Locally deployed smaller models such as the QwQ-32B (Q4 KM quantized model) struggled with generating valid solver files for complex processes. Zero-shot prompts commonly fail in simulations with intricate settings, even for large models. Challenges with boundary conditions and solver keywords stress the need for expert supervision, indicating that further development is needed to fully automate specialized CFD simulations.
Theoretical and Applied Mechanics Letters 15 (2025) 100618.
doi: 10.1016/j.taml.2025.100618
Abstract:
This study presents a novel methodology to obtain an approximate analytical solution for an isotropic homogeneous elastic medium with displacement and traction boundary conditions. The solution is derived through solving a specific numerical problem under the scope of the linear finite element method (LFEM), so the method is termed computational method for analytical solutions with finite elements (CMAS-FE). The primary objective of the CMAS-FE is to construct analytical expressions for displacements and reaction forces at nodes, as well as for strains and stresses at elemental quadrature points, all of which are formulated as infinite series solutions of various orders of Poisson’s ratios. Like the conventional LFEM, the CMAS-FE forms global sparse linear equations, but the Young’s modulus and Poisson’s ratio remain variables (or symbols). By employing a direct inverse method to solve these symbolic linear systems, an analytical expression of the displacement field can be constructed. The CMAS-FE is validated via patch and bending tests, which demonstrate convergence with mesh and term refinement. Furthermore, the CMAS-FE is applied to obtain the bending stiffness of a beam structure and to estimate an approximate stress intensity factor for a straight crack within a square-shaped plate.
This study presents a novel methodology to obtain an approximate analytical solution for an isotropic homogeneous elastic medium with displacement and traction boundary conditions. The solution is derived through solving a specific numerical problem under the scope of the linear finite element method (LFEM), so the method is termed computational method for analytical solutions with finite elements (CMAS-FE). The primary objective of the CMAS-FE is to construct analytical expressions for displacements and reaction forces at nodes, as well as for strains and stresses at elemental quadrature points, all of which are formulated as infinite series solutions of various orders of Poisson’s ratios. Like the conventional LFEM, the CMAS-FE forms global sparse linear equations, but the Young’s modulus and Poisson’s ratio remain variables (or symbols). By employing a direct inverse method to solve these symbolic linear systems, an analytical expression of the displacement field can be constructed. The CMAS-FE is validated via patch and bending tests, which demonstrate convergence with mesh and term refinement. Furthermore, the CMAS-FE is applied to obtain the bending stiffness of a beam structure and to estimate an approximate stress intensity factor for a straight crack within a square-shaped plate.
Theoretical and Applied Mechanics Letters 15 (2025) 100622.
doi: 10.1016/j.taml.2025.100622
Abstract:
Enhancing gelatin methacryloyl (GelMA) hydrogel mechanics without compromising biocompatibility remains challenging, as conventional chemical crosslinking often disrupts degradation behavior. A cooling-induced entanglement strategy effectively improves mechanical performance while preserving biological properties; however, its underlying mechanisms remain unclear. This study demonstrates that extended cooling durations significantly enhance the mechanical properties of GelMA hydrogels. Microstructural analyses reveal cooling-induced formation of compact polymer networks with reduced mesh sizes. Molecular dynamics (MD) simulations confirm that the cooling process promotes topological entanglements that govern mechanical reinforcement. Guided by these insights, we propose a theoretical model to predict the stress responses of GelMA hydrogels under various cooling durations, establishing quantitative correlations between entanglement mechanisms and mechanical outcomes. This study provides a fundamental understanding of the interplay between cooling conditions, microstructure, and mechanical performance, offering a robust framework for designing GelMA hydrogels with optimized mechanical properties for advanced biomedical applications.
Enhancing gelatin methacryloyl (GelMA) hydrogel mechanics without compromising biocompatibility remains challenging, as conventional chemical crosslinking often disrupts degradation behavior. A cooling-induced entanglement strategy effectively improves mechanical performance while preserving biological properties; however, its underlying mechanisms remain unclear. This study demonstrates that extended cooling durations significantly enhance the mechanical properties of GelMA hydrogels. Microstructural analyses reveal cooling-induced formation of compact polymer networks with reduced mesh sizes. Molecular dynamics (MD) simulations confirm that the cooling process promotes topological entanglements that govern mechanical reinforcement. Guided by these insights, we propose a theoretical model to predict the stress responses of GelMA hydrogels under various cooling durations, establishing quantitative correlations between entanglement mechanisms and mechanical outcomes. This study provides a fundamental understanding of the interplay between cooling conditions, microstructure, and mechanical performance, offering a robust framework for designing GelMA hydrogels with optimized mechanical properties for advanced biomedical applications.
Theoretical and Applied Mechanics Letters 15 (2025) 100626.
doi: 10.1016/j.taml.2025.100626
Abstract:
Submit a Paper
Subscription
News
MORE+
Call for Papers
MORE+
- Crossing-Mechanics Driven by Big Data
- Machine learning in the fluid mechanics research of wind energy
- Mechanics of Origami/Kirigami structures and metamaterials
- New insights and perspectives on impact biomechanics for human tissues: from injury prevention, protection to protective equipment
- Environmental Mechanics for Extreme Natural Events
