应用数学和力学

2026 Vol. 47, No. 6

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Chief Editor’s Note
Special Topic of Southwest Symposium on Applied Mathematics and Mechanics
Solid Mechanics
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Chief Editor’s Note

Special Topic of Southwest Symposium on Applied Mathematics and Mechanics

Rayleigh-Taylor Instability of Viscoelastic Soft Solids in Hypergravity

XIONG Honglei, YE Han, LI Kecheng, LÜ Chaofeng

2026, 47(6): 699-711. doi: 10.21656/1000-0887.460243

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Abstract:
Under hypergravity conditions, the free surface of confined viscoelastic soft solids can become unstable due to Rayleigh-Taylor instability, with the evolution behavior governed by both material rheology and geometric confinement. The confined cylindrical viscoelastic soft solids were studied, and a linear stability analysis for free-surface perturbations was developed based on linear viscoelastic constitutive relations. The governing equations were formulated and solved in the frequency domain, to deduce the dispersion relation between the perturbation growth rate and the wavenumber. Then, the roles of hypergravity, surface tension, material compressibility and viscous dissipation were systematically investigated in the instability process. Finite geometric effects were incorporated through introduction of circumferential boundary conditions in a cylindrical coordinate system, to discretize the admissible wavenumbers and reveal the effects of finite confinement on the instability critical values and mode selections. Furthermore, the finite element method was used to verify the theoretical predictions and to investigate the relationship between instability modes and the subsequent evolutions of surface patterns. This study provides a coherent theoretical and numerical approach for analyzing interfacial stability in confined viscoelastic soft solids under hypergravity, and offers a guidance for experiment design and pattern control of soft materials.

Investigation of a Voronoi-Based Hybrid Seepage Flux Finite Element Method

LUO Chao, ZHANG Rui, GUO Ran, GAI Wenhai

2026, 47(6): 712-722. doi: 10.21656/1000-0887.460148

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Abstract:
The soil-rock mixtures and naturally anisotropic dam foundations were treated as composite porous media, and the seepage flow was assumed to follow 2D Darcy's law with continuous hydraulic head distributions within the soil-rock mixture. A hybrid seepage flux finite element method (HS-FEM) model was developed for analyzing seepage fields in soil-rock mixtures with interfaces and anisotropic homogeneous dam foundations. For this model, independently assumed higher-order seepage flux variables was adopted within element domains with hydraulic head values prescribed on element boundaries. Only a limited number of elements were required to effectively simulate confined seepage conditions involving soil-rock interfaces, thereby to overcome the drawback of traditional FEMs necessitating dense mesh refinement at material interfaces. Additionally, the method is capable of solving 2D orthotropic steady-state linear seepage problems. Numerical examples demonstrate that the proposed HS-FEM achieves comparable accuracy to traditional dense-mesh FEMs while maintaining computational efficiency through sparse discretization.

A Simplified Load Analysis Method and Load Characteristics of Coated Turbine Blades

LIU Linchuan, HOU Cheng, FAN Xueling, ZHOU Ziyang

2026, 47(6): 723-735. doi: 10.21656/1000-0887.460201

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Abstract:
To address the challenges of complex modeling and low efficiency in load analysis of coated turbine blades with cross-scale multilayer coating-substrate systems, an efficient load analysis method based on a shell conduction model and a simplified mechanical model was proposed. The equivalent thermal resistance was introduced into the temperature analysis, and the consistency relation of the interfacial total strain tensors was established in the mechanical modeling, to effectively avoid mesh proliferation, distortion, and computational divergence induced by cross-scale interfaces. The results indicate that, compared with the conventional explicit modeling method, the proposed approach improves the minimum Jacobian ratio by approximately 51.9%, reduces the number of elements by about 80.8%, and enhances computational efficiency by more than an order of magnitude, while keeping temperature and mechanical load prediction errors below 5%. Furthermore, the analysis of coated turbine blades shows that, temperature hotspots are concentrated at the blade tip, while mechanical load hotspots are mainly distributed at the leading edge of the blade root. The load distribution in the coating exhibits a trend highly consistent with that of the substrate, reflecting a strongly coupled response behavior.

Effects of Fracture Characteristics of Cross-Linking Proteins on the Mechanical Responses of Actin-Microtubule Composite Networks

GONG Bo, LIU Yuanjia, YUAN Liren, XU Wei

2026, 47(6): 736-749. doi: 10.21656/1000-0887.470001

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Abstract:
The mechanical properties of the cytoskeleton are crucial for maintaining cell morphology and enabling life processes such as cell movement and division. Actin filaments and microtubules, as core components of the cytoskeleton, are interconnected by cross-linking proteins to form a complex polymer network structure, of which the macroscopic mechanical behavior is closely related to the physical properties of cross-linking proteins. Based on a coarse-grained actin-microtubule composite network model, the effects of 2 key parameters of cross-linking proteins: the fracture distance threshold and the formation distance threshold, on the network's mechanical properties were systematically investigated. The simulation results show that, the fracture distance threshold of microtubule cross-linking proteins plays a dominant role in the network's mechanical responses: reducing this threshold leads to an overall downward shift of the stress-strain curve and a decrease in structural loading-bearing capacity. In contrast, changes in the fracture distance threshold of actin filament cross-linking proteins have a weak impact on the macroscopic mechanical behavior, and the formation distance threshold of cross-linking proteins has no significant effect on the network's mechanical properties. This study reveals that the macroscopic mechanical properties of the actin-microtubule composite network are mainly dependent on the fracture distance threshold of cross-linking proteins while being insensitive to the formation distance threshold, providing a new sight for understanding the role of dynamic cross-linking in the mechanical stability of the cytoskeleton.

Coupling Effects of Initial Stresses and Nonlinear Elasticity on the Propagation Characteristics of Elastic Waves

MI Hongrui, LI Wenqiang, HU Hengshan

2026, 47(6): 750-772. doi: 10.21656/1000-0887.470002

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Abstract:
The propagation of elastic waves in solids is influenced by initial stresses and material nonlinearity. Accurately characterizing the propagation of elastic waves in initially stressed media is crucial for stress nondestructive testing, structural health monitoring, and geophysical exploration. However, the distinct roles of stress-related geometric nonlinearity and material nonlinearity remain unclear. A theoretical framework based on acoustoelasticity and coupling finite initial deformation with material nonlinearity was developed. Approximate analytical solutions for the phase velocities of body waves were derived with the perturbation theory, to give an efficient approach for the rapid calculation of elastic wave propagation in initial stress media. Furthermore, the characteristic equation was solved for plane waves, the coupled effects of initial stress and nonlinear elasticity were systematically analyzed. The results show that, the effects of initial stresses stem from the competition between geometric and physical nonlinearity. Under tensile initial stresses, geometric nonlinearity will increase wave speeds, while physical nonlinearity will decrease them. Physical nonlinearity induces more pronounced changes in phase velocity and velocity anisotropy of shear waves. For the 7075-T651 aluminum alloy, the shear wave anisotropy reaches 2%~3%.

Study on the Choking Model for Elimination of Severe Slugging in Offshore Oil and Gas Fields

XU Luhan, YAN Yiwei, WU Quanhong, DU Yaohua, WANG Hanxuan, ZOU Suifeng

2026, 47(6): 773-786. doi: 10.21656/1000-0887.460140

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Abstract:
Laboratory experiments were performed to establish a model for predicting the valve opening of the topside choking method for elimination of severe slugging in offshore oil and gas pipeline-riser systems. Based on the outflow characteristics of liquid slug at the riser top at the flow regime transition, which can be regarded as those of transient single-phase liquid flow, the condition for gas-liquid blowout mitigation was determined, i.e. the peak value of pressure drop across the valve shall be twice its time-average value just at the elimination moment of severe slugging, corresponding to the transient single-phase liquid flow. Then, the target resistant factor and the flow coefficient were derived successively according to the defined equations. Finally, the valve opening was worked out according to either the specification document of the valve or the calibration of the flow characteristics of the valve. The prediction model innovatively correlates the peak pressure drop across the choke valve with the physical process of instantaneous single-phase flow, resolving the inconsistency of mapping averaged 2-phase parameters to single-phase valve characteristics in conventional models. The average deviation of prediction for 2 experimental loops (150-m/DN 50 and 380-m/DN 80) is +0.55% and +1.8%, respectively, for experimental data from 2 experimental pipelines; while the deviation from automatic control result is smaller than ±2% in a field case. The established model can guide manual operations and serve as a setpoint for automatic control systems in offshore fields.

Experimental Study on the Association Mechanism Between Liver Disease and Cardiac Function Based on Hemodynamics

BAI Taoping, XUE Jiezhong, ZHANG Jiyang, JIANG Wentao, LI Zhongyou, LI Yalan, WEI Han

2026, 47(6): 787-798. doi: 10.21656/1000-0887.460191

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Abstract:
The non-alcoholic fatty liver disease is increasingly becoming a prevalent chronic liver condition worldwide. Although previous studies have focused on the relationship between liver injury and cardiac dysfunction, the specific underlying mechanisms remain inadequately elucidated. Hemodynamic changes, which are closely linked to cardiac dysfunction, may be a key influencing factor. Based on the structure and physiological functions of the cardiovascular system, an in vitro simulated circulatory system was constructed to replicate various hemodynamic parameters. Grouped experiments were conducted, to simulating 3 states: healthy, moderate and severe liver injuries, with real-time pressure and flow data collected for each group. The results show that, as the liver injury degree increases, the pressure in the ascending aorta and hepatic artery will rise. In the case of severe liver injury, the peak pressures in the ascending aorta and hepatic artery will increase by 25.7% and 19.3%, respectively, while the trough pressures will increase by 49.7% and 26.7%, respectively. Additionally, the average portal vein pressure significantly increases. Under liver injury conditions, the blood flow will be redistributed to other branches of the arterial system, with larger-diameter vessels experiencing greater flow increases. The blood flow in the brachiocephalic artery, the right common iliac artery, and the right renal artery will increase by approximately 15%, 12%, and 28%, respectively. Meanwhile, the flow in the hepatic artery and portal vein will decrease simultaneously, with the proportion of the hepatic artery flow to the total liver inflow remaining essentially at 20%. The discussion indicates that, the hemodynamic environmental changes induced by liver injury provide a basis for the development of cardiac dysfunction, such as cirrhotic cardiomyopathy, and complement the traditional theory of metabolic abnormalities to some extent. The findings offer hemodynamic evidences for understanding how liver injury leads to changes in cardiac function and hold certain clinical significance.

Solid Mechanics

Research on the Integration Methods for Fiber Optic Sensors in Deep Sea Mining Flexible Pipes

CUI Xinyu, XU Wanhai, WANG Yingying, SHEN Fei, KE Liaoliang

2026, 47(6): 799-813. doi: 10.21656/1000-0887.460110

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Abstract:
Based on the health monitoring requirements for unbonded flexible pipes in deep-sea mining operations, the integration process schemes for optical fiber sensors with flexible pipes were investigated. Three integration processes (the aramid fiber rope and sensor winding, the pre-impregnated tape with embedded sensors, and the lining grooving for sensor placement) were designed, and the effects of different process parameters on mechanical performances of sensors and flexible pipe structures werw analyzed through finite element simulations. Simulation results indicate that, in the aramid fiber rope winding process, variations of the tension force and the winding angle minimally affect sensor elongation rates and inner liner layer stresses, both below material limits. For the pre-impregnated tape embedding scheme, changes of the tension force and the winding angle do not significantly compromise the sensor performances. For the lining grooving solution, under an internal burst pressure load of 60 MPa, the sensor elongation rate exceeds its limit, posing a risk of failure. A comprehensive evaluation demonstrates that, the aramid fiber rope winding process offers low stress, high reliability, and process simplicity, making it the optimal choice. This research provides a theoretical foundation and a process optimization strategy for sensor integration of deep-sea flexible pipes.

Impact Resistance of Repaired Composite Honeycomb Sandwich Panels With Internal Patch Reinforcement

PANG Jiankang, WU Zhibo, WANG Zhe, WANG Zengxian, ZHAO Jiatao, QIAN Yuan, DENG Jian

2026, 47(6): 814-824. doi: 10.21656/1000-0887.460080

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Abstract:
Current repair methods for composite honeycomb sandwich panels primarily employ scarf repair techniques, but they are limited by complex procedures and high equipment requirements. Given equipment shortages and time constraints in emergency situations, there is an urgent need to develop rapid temporary repair techniques for sandwich panels. An internal patch reinforcement repair scheme combining operational simplicity with design flexibility was proposed. By drop-weight impact tests and the establishment of a finite element model for low-velocity impact analysis on repaired composite honeycomb sandwich structures, the effects of different reinforcement schemes on impact responses and damage mechanisms were comparatively analyzed through combination of mechanical response curves with failure morphology characteristics. The results indicate that, interfacial voids in conventional patch repairs reduce the impact load-bearing capacity. Due to the increase of contact area during impact, the proposed internal patch reinforcement enhances the impact resistance with a delay of the adhesive failure a constraint on structural deformation. The research provides a theoretical base for rapid repair technologies in composite structures.

Cover And Contents

2026, 47(6)

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Chief Editor's Note

After Tools, Problems Remain: From the Impact of Finite Element Software to Human Growth in the Age of Artificial Intelligence

LU Tianjian

2026, 47(6): 687-698. doi: 10.21656/1000-0887.472033

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Abstract:
Previous editorials of this journal have discussed academic lineage, intelligent tools, research criteria, and disciplinary direction. After these discussions, a more fundamental question remains: when tools become increasingly powerful, can human researchers still preserve their ability to ask questions, make judgments, and grow? From the perspective of mechanics, artificial intelligence is not the first powerful tool revolution. The finite element method, computers, and engineering software once liberated mechanicians from tedious mathematical calculations and enabled complex structures, boundaries, and loading conditions to become computationally tractable. Yet they also reshaped the identity, confidence, and institutional space of mechanics. In many universities and engineering schools, independent mechanics, applied mechanics, or engineering mechanics programs were compressed, merged, or marginalized during broader disciplinary reorganizations. The unease and sense of displacement brought by AI today are therefore not entirely new; they echo, and in some ways deepen, the impact once brought by computational tools and finite element software. AI goes beyond numerical solution. It enters literature retrieval, writing, coding, diagram generation, scheme construction, and even the appearance of problem formulation.In the age of powerful tools, what is truly scarce is not the ability to call tools more skillfully, but the ability to see the object, explain the mechanism, formulate the question, and take responsibility. Being able to build a model, generate a mesh, and obtain a contour plot does not mean that one has understood the object, the boundary conditions, the underlying mechanisms, or the responsibility of engineering judgment. Generating answers, texts, or schemes is not the same as posing questions, forming judgment, or creating knowledge. Generating a new appearance is not the same as opening a zero-to-one original entry point; such an entry point can only be recognized, undertaken, and advanced by human researchers through real objects, real contradictions, real boundaries, and real responsibility. In a recent MechanoEngineering Editorial, Gao Huajian emphasized that mechanism must precede performance and that AI may accelerate search, but mechanics must judge what is real. This statement captures a central issue in the age of powerful tools: tools may generate candidate outcomes faster, but they cannot automatically provide physical admissibility; algorithms may expand the search space, but they cannot replace conservation laws, constitutive structures, boundary conditions, stability criteria, failure envelopes, or experimental validation. Speed without mechanism is not progress; it is only faster motion.AI is not a matter of whether it should be used, but of how it is used, by whom, to what extent, and with what responsibility. True education is to help students pass through the fear and illusion created by powerful tools and bring them above tools. After tools, problems remain; after problems, human growth begins.