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The cytoskeleton, a dynamic network of structural proteins within cells, is essential for cellular deformation and responds to external mechanical cues. Here, based on the structure of the cytoskeleton, combined with the biochemical reactions of the activator RhoA and the inhibitor F-actin, we develop a novel mechanochemical cytoskeleton model to investigate the mechanical behavior of cells. Interestingly, we find that active stress fibers exhibit diverse dynamical modes at specific inhibitor concentration thresholds. The existence of concentration differences and sustained mechanochemical feedback in activators and inhibitors trigger a global oscillation of isolated cells. In addition, under uniaxial and biaxial stretches, activators and inhibitors preferentially diffuse toward the more significantly deformed cytoskeletal elements, and their dynamic interactions regulate the cell to align with the main stretching direction. Our findings, consistent with many experimental results, provide fundamental insights into cytoskeletal remodeling and cellular mechanosensing mechanisms. [ABSTRACT FROM AUTHOR]

We present experimental demonstration and modeling of mechanical wave propagation in a quasi-one-dimensional (quasi-1D) phononic crystal (PnC) waveguide (WG) constructed from a periodic array of single-crystal cubic-silicon carbide (3C-SiC) coupled micromechanical resonators, with an exceptional dynamic range exceeding 92 dB. The PnC design comprises 50 periodic cells, enabling the propagation of flexural mechanical waves in high-frequency and very-high-frequency bands, featuring a broad PnC bandgap spanning approximately 24–27.5 MHz. Furthermore, the 3C-SiC PnC WG exhibits excellent characteristics, including a high group velocity of 350 m/s and a low transmission loss of 0.69 dB/mm, enabling efficient guidance and support for mechanical waves across extended distances before reaching the noise level of the device. These attributes of the PnC WG, as demonstrated in this study, may open possibilities for the development of device platforms with applications in on-chip signal processing, sensing, and quantum transducer technologies. [ABSTRACT FROM AUTHOR]

Constitutive models are essential for describing the mechanical behavior of materials under high temperatures and pressures, among which the Steinberg–Guinan (SG) model is widely adopted. Recent work has discovered a peculiar dual anomaly of compression-induced softening and heating-induced hardening in the elasticity of compressed vanadium [Phys. Rev. B 104, 134102 (2021)], which is beyond the capability of the SG model to describe. In this work, a modified SG elasticity constitutive model is proposed to embody such an anomalous behavior. Elemental vanadium is considered as an example to demonstrate the effectiveness of this improved model in describing the dual anomalies of elasticity. This new SG elasticity model can also be applied to other materials that present an irregular variation in the mechanical elasticity and are important to faithfully model and simulate the mechanical response of materials under extreme conditions. [ABSTRACT FROM AUTHOR]

An extension of a constitutive law for 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is proposed with a focus on the calibration of a crystal plasticity law. TATB, a highly anisotropic energetic molecular crystal used in explosive formulations, can be subjected to high-pressure and high-temperature conditions, either under high strain-rate deformation or shock loading. The existing thermodynamically consistent model, fully informed by molecular dynamics (MD) simulations, includes nonlinear elasticity as well as a phase-field by reaction pathway formalism under large strain for the modeling of TATB behavior upon pressure as well as its well-known twinning–buckling deformation mechanism. However, it has been observed that TATB single crystal can accommodate large deformations through dislocation-mediated plasticity, a feature not included in the mesoscale model. In the present work, we take advantage of the microscopic flow surface, previously computed through MD calculations, to calibrate a crystal plasticity law, extending the capability of the continuum model currently limited to low velocity impacts and moderate strain rate. Indeed, the microscopic flow surface, defined as a 3D stress-at-first-defect-nucleation contains all information about TATB single crystal mechanical response under directional shear loading, including twinning, buckling, and plastic events. The calibration process uses differential evolution optimization to calibrate TATB basal and transverse slip systems critical stresses to reproduce the microscopic flow surface. Finally, the response of a TATB single crystal to directional loading is investigated in order to evaluate the new model. [ABSTRACT FROM AUTHOR]

This work presents a 3D quantum mechanics based model to address the physics at band structure crossing/anti-crossing points in full band Monte Carlo (FBMC) simulations. The model solves the Krieger and Iafrate (KI) equations in real time using pre-computed coefficients at k -points spatially sampled within the first Brillouin zone. Solving the KI equations in real time makes this model applicable for all electric fields, which enables its use in FBMC device simulations. In this work, a two-level refinement scheme is used to aggressively sample regions in proximity to band crossings for accurate solutions to the KI equations and coarsely sample everywhere else to limit the number of k -points used. The presented sampling method is demonstrated on the band structure of silicon but is effective for the band structure of any semiconductor material. Next, the adaptation of the fully quantum KI model into the semi-classical FBMC method is discussed. Finally, FBMC simulations of hole transport in 4H silicon carbide with and without the KI model are performed. Results along different crystallographic directions for a wide range of electric fields are compared to previously published simulation and experimental values. [ABSTRACT FROM AUTHOR]

Based on the variational field theory framework, we extend our previous mean-field formalism [Y. A. Budkov and A. L. Kolesnikov, JStatMech 2022, 053205.2022], taking into account the electrostatic correlations of the ions. We employ a general covariant approach and derive a total stress tensor that considers the electrostatic correlations of ions. This is accomplished through an additional term that depends on the autocorrelation function of the local electric field fluctuations. Utilizing the derived total stress tensor and applying the mechanical equilibrium condition, we establish a general expression for the disjoining pressure of the Coulomb fluids, confined in a pore with a slit-like geometry. Using this equation, we derive an asymptotic expression for the disjoining pressure in a slit-like pore with non-electrified conductive walls. Present theory is the basis for future modeling of the mechanical stresses that occur in electrode pores with conductive charged walls, immersed in liquid phase electrolytes beyond the mean-field theory. [ABSTRACT FROM AUTHOR]

Van der Waals (vdW)-layered materials, such as graphite, exhibit unique mechanical properties owing to their structural and mechanical anisotropies. This study reports the development of a mechanical model that reproduces the characteristics of the nonlinear and reversible bending deformation of vdW-layered materials, while taking into account the microscopic mechanism of the discrete interlayer slips. The vdW-layered material was modeled as a stack of interacting discrete deformable layers (semi-discrete layer model), and the interlayer interaction was modeled using a cohesive zone model that reproduced the localized interlayer slip. Using the finite-element method, out-of-plane bending deformation analyses were performed on the cantilevers of the highly oriented pyrolytic graphite (HOPG) and MoTe2, and the validity of the model was verified by comparing it with the experimental results. The model accurately reproduced the loading and unloading behaviors in the experiments for the submicron HOPG cantilevers or the large nonlinear and reversible deformation with a hysteresis loop. Furthermore, the model reproduced well the characteristics of the bending experiments for the micro-MoTe2 cantilevers, or the intermittent decrease in stiffness during the loading process and deformation restoration during the unloading process. These results demonstrated that the designed semi-discrete layer model can be universally applied to reproduce the bending deformation characteristics of a variety of vdW-layered materials and can be employed to effectively elucidate the underlying deformation mechanisms. [ABSTRACT FROM AUTHOR]

Structural integrity and robustness are key parameters to evaluate microfabrication techniques. Bending and collapsing of 2D/3D microstructures are commonly noted in solvent-involved procedures, e.g., liquid-based post-treatment in wet-etching, lithography, and Two Photon Polymerizations (TPPs). Such structural failures are caused by excessive solution-imposed capillary forces, where multiple kinds of liquids may intensively participate. Current pieces of the literature focus on the mechanical one-axis models to illustrate their deformation process. To date, there exists an emerging demand for dual-axis models to satisfy rapidly developed micro/nano-engineerings. Here, utilizing polymer micro-pillars distributed in a square array as an illustration example, a dual-axis beam-sway model is proposed considering the influences of structure arrangement as well as the solvent. Specifically, a simplified criterion for judging structural stability is identified. For verifications, the TPP-based experimental data show excellent consistency with model predictions. All in all, the extended model offers reliable guidance for the fabrication of delicate structures and further benefits the optimization of related microfabrication processes. [ABSTRACT FROM AUTHOR]

In this paper, we apply a theoretical model for fluid state thermodynamics to investigate simulated water in supercooled conditions. This model, which we recently proposed and applied to sub- and super-critical fluid water [Zanetti-Polzi et al., J. Chem. Phys. 156(4), 44506 (2022)], is based on a combination of the moment-generating functions of the enthalpy and volume fluctuations as provided by two gamma distributions and provides the free energy of the system as well as other relevant thermodynamic quantities. The application we make here provides a thermodynamic description of supercooled water fully consistent with that expected by crossing the liquid–liquid Widom line, indicating the presence of two distinct liquid states. In particular, the present model accurately reproduces the Widom line temperatures estimated with other two-state models and well describes the heat capacity anomalies. Differently from previous models, according to our description, a cluster of molecules that extends beyond the first hydration shell is necessary to discriminate between the statistical fluctuation regimes typical of the two liquid states. [ABSTRACT FROM AUTHOR]

Rock burst disasters severely restrict the safe and efficient mining of coal. The fundamental cause of their occurrence is the concentration of stress within the coal mass. Stress monitoring in coal seam drilling is widely used as an effective method for rock burst monitoring. However, how to scientifically and reasonably set the critical values of early warning indicators that match the conditions of each mine has always been a key issue restricting the accurate prediction of rock burst by the drilling stress method. This paper adopts a method combining theoretical analysis and field practice to conduct research on the critical values of drilling stress early warning indicators. Based on perturbation response instability theory, a mechanical model for the occurrence of impact ground pressure has been established. Based on the instability theory of disturbance response, a mechanical model for the occurrence of impact ground pressure has been established, leading to the derivation of the expression for the near-field critical stress of impact ground pressure events. The theoretical formula for the critical value of drilling stress early warning indicators was obtained based on the difference between the critical stress of rock burst occurrence and the actual stress in the roadway. This formula includes the mechanical parameters of the coal mass and its propensity for rock burst, roadway support stress, mining depth, stress concentration coefficient, and the initial installation pressure of the stress gauge. They can be determined by the geological and mining technical conditions of each mine. This theoretical formula breaks the uniformity of the critical values for stress warning indicators in various mine drill holes, allowing each mine to scientifically determine its critical value based on its own conditions. This theoretical method has been applied to a high-stress mine in Shanxi, China, and the critical values of drilling stress early warning indicators were obtained. When the monitored stress exceeded the critical value, dynamic phenomena of anchor rod and cable fractures occurred in the roadway roof. The distribution of microseismic events also shifted towards the warning area, and the microseismic monitoring indicators reached the warning values. This confirmed the engineering feasibility of the critical values for drilling stress early warning indicators determined by the theoretical method. [ABSTRACT FROM AUTHOR]

The viability of hydrogen storage in bedded salt caverns hinges on understanding the geomechanical challenges posed by the anisotropic stress states and complex geology of such environments. This study presents a comprehensive geomechanical analysis focusing on a proposed cavern within the Carribuddy Formation in Western Australia, characterized by its interbedded salt layers. This paper introduces a new geomechanical workflow, encompassing 1D and 3D modeling techniques to provide detailed changes of mechanical properties and stress state in interbedded salt formation allowing to identify the initial optimal operational pressures for underground hydrogen storage. Initial 1D models evaluated mechanical properties and in-situ stresses, while subsequent 3D simulations, enriched by data from neighboring wells, detailed the stress, strain, and displacement responses of the cavern walls to internal pressure changes. The analysis pinpointed an initial safe gas pressure range between 3000 and 4000 psi, attributing this margin to the robust characterization of the mechanical and in-situ stress of the formation. Our findings underscore the significance of high-resolution geomechanical modeling in identifying initial optimal operational pressures for hydrogen storage in salt caverns, ensuring both safety and structural integrity. • Integrated 1D and 3D models assess hydrogen storage in salt caverns. • Cavern within Carribuddy Formation exhibits initial safe pressure of 3000–4000 psi. • High-resolution models are crucial for understanding geomechanical behavior. • Study emphasizes the formation's robustness and stress resilience. • Findings guide optimal operational pressures for safety and integrity. [ABSTRACT FROM AUTHOR]

When porous materials are subjected to compressive loads, localized failure chains, commonly termed anticracks, can occur and cause large-scale structural failure. Similar to tensile and shear cracks, the resistance to anticrack growth is governed by fracture toughness. Yet, nothing is known about the mixed-mode fracture toughness for highly porous materials subjected to shear and compression. We present fracture mechanical field experiments tailored for weak layers in a natural snowpack. Using a mechanical model for interpretation, we calculate the fracture toughness for anticrack growth for the full range of mode interactions, from pure shear to pure collapse. The measurements show that fracture toughness values are significantly larger in shear than in collapse, and suggest a power-law interaction between the anticrack propagation modes. Our results offer insights into the fracture characteristics of anticracks in highly porous materials and provide important benchmarks for computational modeling. Porous materials such as snow can collapse under compression, forming anticracks. The authors show that anticrack fracture modes vary with loading direction and find a mechanism that suggests that cracks grow more easily under compression than under shear, advancing stability models for porous materials. [ABSTRACT FROM AUTHOR]

As a mature non-destructive testing technology, near-infrared (NIR) spectroscopy can effectively identify and distinguish the structural characteristics of wood. The Wood Defect One-Dimensional Visual Geometry Group 19-Finite Element Analysis (WD-1D-VGG19-FEA) algorithm is used in this study. 1D-VGG19 classifies the near-infrared spectroscopy data to determine the knot area, fiber deviation area, transition area, and net wood area of the solid wood board surface and generates a two-dimensional image of the board surface through inversion. Then, the nonlinear three-dimensional model of wood with defects was established by using the inverse image, and the finite element analysis was carried out to predict the elastic modulus of wood. In the experiment, 270 points were selected from each of the four regions of the wood, totaling 1080 sets of near-infrared data, and the 1D-VGG19 model was used for classification. The results showed that the identification accuracy of the knot area was 95.1%, the fiber deviation area was 92.7%, the transition area was 90.2%, the net wood area was 100%, and the average accuracy was 94.5%. The error range of the elastic modulus prediction of the three-dimensional model established by the VGG19 classification model in the finite element analysis is between 2% and 10%, the root mean square error (RMSE) is about 598. 2, and the coefficient of determination (R2) is 0. 91. This study shows that the combination of the VGG19 algorithm and finite element analysis can accurately describe the nonlinear defect morphology of wood, thus establishing a more accurate prediction model of wood mechanical properties to maximize the use of wood mechanical properties. [ABSTRACT FROM AUTHOR]

Metals manufactured by selective laser melting (SLM) with different directions exhibit different mechanical properties. This study conducted dynamic and static mechanical tests using a universal testing machine and split-Hopkinson bar (SHPB). The mechanical properties of 18Ni300 with 0° and 90° build directions manufactured by SLM were compared, and the micro-structure properties of the two build directions were analysed by metallographic tests. The Johnson–Cook (J-C) constitutive model was fitted according to the experimental results, and the obtained constitutive parameters were verified by numerical simulations. The results revealed that the constitutive model could predict the mechanical properties of 18Ni300 in a dynamic state. The build direction had little influence on the mechanical properties in a static state, but there was a significant difference in the dynamic state. The difference in the dynamic compressive yield strength of the 18Ni300 material manufactured by SLM with two build directions was 9.8%. The SLM process can be improved to produce 18Ni300 with uniform mechanical properties by studying the reasons for this difference. [ABSTRACT FROM AUTHOR]

In this article, arrestment of an aircraft by a hydraulic twister based system is modeled and reduced to simple design charts. We are primarily interested in performance parameters like maximum deceleration, run-out distance, and maximum tape force. We first present a simplified mechanical model for the system. Some analytical progress is possible with the governing nonlinear differential equation, yielding expressions for velocity and acceleration in terms of displacement. The system has only two nondimensional parameters. This allows us to present simple design charts for the performance parameters. The same approach is extended to secondary performance parameters namely maximum jerk and the time at which maximum deceleration occurs. We choose some practical parameter sets and demonstrate the use of our charts. These charts can be used for design calculations and quick performance prediction of an arresting gear design for different weight classes of aircraft and practical initial velocities. [ABSTRACT FROM AUTHOR]

A friction coefficient of tire model for cornering simulation is generally set inductively to be consistent with experimental results. However, the inductively set friction coefficients have no clear relationship with the viscoelasticity of the rubber, so they cannot be used in the design of rubber formulations to obtain the desired friction coefficient. In this study, we propose a new tire mechanical model for cornering simulation that includes a friction coefficient deductively derived from the viscoelasticity of rubber based on the Persson's multiscale friction theory. In this model, the contact pressure, sliding velocity, and lateral stress distributions are calculated based on an elliptical contact patch. Because the proposed model analytically connects the lateral force with the viscoelasticity of rubber, it is applicable to rubber design for achieving the targeted cornering properties. The validity of the model was experimentally verified using an internal drum machine with quartz piezoelectric sensors on an aluminium road segment. With appropriate parameter settings, the friction coefficient distribution in the length direction calculated by the proposed model agreed well with the experimental results compared to the elliptical contact patch tire model. [ABSTRACT FROM AUTHOR]

Summary: The aim of this study is to clarify the essential means of describing the characteristics of foods represented by texture terms using a model based on the mechanical properties of foods. Seven texture terms were identified, and the mechanical properties of gel‐like samples were determined using elasticity and rupture tests. The Blatz, Sharda and Tschoegl (BST) equation was applied to the stress‐strain curve of the samples, and the elastic parameter E and the nonlinear index n were calculated. The evaluation model of the score obtained from the sensory test for each texture term was developed using E and n, rupture stress, and rupture depth. The model demonstrated the contribution of each variable to the texture term. Moreover, a single correlation was investigated between each specific term for the texture and each mechanical parameter, respectively. These results confirmed that some of the impressions given by the texture terms did not match the actual mechanical properties of foods. [ABSTRACT FROM AUTHOR]

The mechanical behaviour of Fibre-reinforced sands (FRS) has been extensively studied, presenting improved mechanical properties compared to unreinforced soils. Many models have been developed to predict its general stress-strain behaviour. However, the use of double-phase models in FRS is still incipient. Double-phase models are advantageous because they can simulate the whole FRS and the behaviour of its individual components, soil skeleton and reinforcement. This paper uses a modified model for Municipal Solid Waste to reproduce the FRS mechanical response. Introducing a new hardening parameter and a dilatant zone allowed the model to reproduce FRS dilatancy. The model's variables are easily understood, allowing the reproduction of the mechanical behaviour of FRS formed by sands with void ratios ranging from 0.610 to 0.917 and mean grain size from 0.29 to 0.83 mm. The fibres' lengths varied from 12.5 to 51 mm. The results of triaxial and hollow cylinder torsional tests under different stress paths had their main characteristics (peak strength, post-peak behaviour, dilatancy and reinforcement effectiveness) well captured by the model. Predicted and experimental FRS's deviator stress usually differ by less than 15% and the model performance is equivalent or superior to other available models, even requiring fewer input parameters. [ABSTRACT FROM AUTHOR]

Despite vast research on the utilisation of coal ashes in cement mortars, many studies lack a comprehensive evaluation of properties related to mortar for masonry and plaster work. This study investigate properties like workability, compressive strength, drying shrinkage, tensile bond strength and adhesive strength through a systematic replacement of river sand by pond ash in cement mortars. Volumetric mix proportions of 1:3, 1:4, 1:5 and 1:6 (cement: sand) were considered, where river sand was replaced in the range of 20–100% by pond ash. At 30% pond ash content, properties like the compressive strength, tensile bond strength and adhesive strength improved in the range of 21–30%, 13–20% and 14–24%, respectively, for all mix proportions. At 60% pond ash content, these strength properties were comparable with those of control mixes and found suitable for mortars for masonry works. However, the drying shrinkage increased with an increase in pond ash content. At 30% pond ash content, drying shrinkage increased in the range of 26–40% for all mix proportions. The thermogravimetric analysis (TGA) showed that mixes with pond ash demonstrated reduced portlandite content compared to the control mixes, resulting in the formation of secondary C-S-H gel. Simple regression models were developed based on experimental results to establish the relationships between different properties. Based on coefficient of determination (R2), variance inflation factor (VIF) and Durbin–Watson statistics, relationships between the strength and shrinkage properties were very well quantified to be used by researchers and practitioners. Utilisation of pond ash as partial replacement of river sand in mortars proved to be a useful step towards achieving circular economy at the same time reducing threat to depletion of limited natural resources. [ABSTRACT FROM AUTHOR]

Base-cutting is essential in sugarcane harvesting, and violent collisions between the base-cutter and stalk can cause stubble damage. Therefore, it is necessary to study the base-cutting mechanism to reduce stubble damage. Based on the mechanical analysis method, this study analysed the base-cutting process of sugarcane vascular bundles and stems from fibber and macro perspectives, respectively. In addition, the base-cutting process was simulated based on Discrete Element Method, and field experiments were conducted to validate the analysis results. The tensile length function L (z) of the vascular bundle was derived from a fibber perspective. A mechanical model of the cutting force on the entire stem was obtained from a macro perspective. From the equations, it can be found that the kinematic parameters of the base-cutter have a significant influence on the cutting force. The simulation test revealed that the cutting force increased sharply when the blade was cut into stems, and the maximum cutting force reached 146.9N. Field tests were conducted to explore the relationship between these factors and the stubble damage rate. To decrease the damage rate to a smaller level, the single-factor test results showed that the forward speed of harvester, rotational speed of disc, and cutting depth should be controlled in the range of 0.8–1.4 m s−1, 600–1000 r·min−1, and 60–120 mm, respectively. The response surface test showed that the order of the effect of each factor on stubble damage was forward speed > rotational speed > cutting depth. The lowest stubble damage rate was 6.20% when the forward speed, rotational speed of disc, and cutting depth were 1.4 m s−1, 800 r·min−1, and 79.07 mm, respectively. After experimental field verification, the damage rate met the harvesting standard. • Under-the-ground base-cutting mechanism and processes were revealed in this study. • Tensile length function and mechanical model were got in different perspectives. • The soil around root-soil composite can decrease damage of stubble during cutting. • The maximum cutting force reached to 146.9N when blade completely cut into stem. • The optimal parameters of factors and interaction were explored by field tests. [ABSTRACT FROM AUTHOR]

To date, the traffic-induced dynamic behavior of geosynthetic-encased stone column-supported embankments (GESC) under traffic cyclic loads accompanied by embankment consolidation has not been well studied. Three-dimensional (3D) coupled mechanical and hydraulic modeling is performed using FLAC3D, which considers the fluid flow during the lifespan of three stages: (1) embankment construction (EC): (2) consolidation (C) under embankment surcharge; and (3) cyclic loading (CYC). During the simulation, excess pore pressure, stress concentration, settlement, and lateral displacement are monitored, and the total settlement and lateral displacement could be easily obtained by accumulating the components of the three stages. Parametric analyses are conducted on the reinforcement forms and cyclic loading characteristics that include the dynamic stress amplitude and loading frequency. The ordinary stone (OSC) and GESCs could reduce the settlement and lateral displacement during each stage by improving the strength of the foundation and accelerating drainage consolidation; however, GESCs outperform the columns without geoencasement. In addition, the stress concentration ratio under embankment filling decreased with the increase in the dynamic stress amplitude and loading frequency, which led to the increase in the percentage of the cyclic loading-induced settlement to total settlement. [ABSTRACT FROM AUTHOR]

Thermomechanical coupling effects, which are almost inevitable in materials processing, are particularly notable in NiTi shape memory alloy (SMA). Understanding the dynamic mechanical properties of NiTi SMA at high temperatures and high strain rates is important to reveal its cutting mechanism. In the present work, the split Hopkinson pressure bar experiments under different temperatures and strain rates are carried out. The dynamic mechanical behaviors are discussed from both macro- and microperspectives. The results indicate that nonlinear deformation behaviors of Ni50.8Ti SMA strongly depended on strain rates and temperatures. The influence mechanisms of temperature and strain rate on the nonlinear deformation of Ni50.8Ti SMA are clarified in detail. Moreover, a constitutive model for nonlinear deformation of Ni50.8Ti SMA is established to depict the dynamic characteristics. This is helpful to study the thermomechanical effects on the Ni50.8Ti SMA during machining. [ABSTRACT FROM AUTHOR]

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In the western mining region, weakly cemented rock layers above the coal seams often lead to frequent catastrophic accidents during mining due to their instability. To address this, this paper analyzes the movement characteristics of surrounding rock in the recovery roadway and the effectiveness of from nearby large coal pillar roadways. A mechanical model for the failure of weakly cemented roadways was established, and numerical simulations were used to verify the feasibility of leaving small coal pillars along soft, thick coal seams. Additionally, existing measurements were used to evaluate the impact of leaving small coal pillars on the deformation of the surrounding rock in the recovery roadway. The results show that after changing the coal pillar retention to 5 m in the 130,205 working face of the Yangchangwan mining area, the roadway is in a low-stress zone, with minimal surrounding rock deformation, meeting safety requirements for production. [ABSTRACT FROM AUTHOR]

Ultra-precision measurement and manufacturing need high-precision machines, just as a photolithography machine needs air bearings. In gas lubrication, the use of compound restrictors with recesses has been widely proven to be an effective method to improve stiffness, which directly affects the accuracy of the machine. However, determination of the structural parameters of recesses is lacking in theoretical models. This paper has established a mechanical property model for a small-scale guideway, which can respond to the variation in force caused by micron-level changes in the recesses' depth. To meet the requirements of high positioning accuracy and movement accuracy, this paper puts forward a high-stiffness guideway without an air tube. In order to improve rotational stiffness and determine the structural parameters of recesses, this paper found a guideway with the optimal gradient depth of recesses. Both AFVM (adaptive finite volume method) research and experimental results show that the gradient depth of recesses could significantly improve the rotational stiffness of guideways without air tubes. [ABSTRACT FROM AUTHOR]

In recent years, the construction of new railway tunnels worldwide has become increasingly challenging due to larger cross-sections, deeper burial depths, higher in situ stress, and more complex geological conditions. During both construction and operation, some tunnels have encountered significant issues with floor heave. This paper begins by identifying the primary causes of deformation and instability in tunnel floor structures through an investigation and statistical analysis. It then examines floor heave across more than 20 railway lines, summarizing the types, generation mechanisms, and mechanical models associated with this issue. Additionally, extensive survey data indicate that tunnel floor heave is most likely to occur in gently inclined thin-layered rock masses. Therefore, using a tunnel passing through the plate suture zone in such a rock mass as a case study, numerical simulations, theoretical analyses, and on-site monitoring were conducted. This study systematically analyzed the influence of single and multiple factors, as well as the mechanical behavior of the support system, on tunnel floor heave in gently inclined thin-layered surrounding rock. Furthermore, several key models were proposed: a tunnel floor heave estimation and load formula based on a mechanical model, a dynamic relationship between surrounding rock support force and tunnel floor heave using the Nishihara model, a tunnel floor settlement estimation formula based on deformation statistics, and a tunnel floor heave energy prediction model utilizing the B-P neural network algorithm. These conclusions have been validated and widely applied in practical engineering, providing a robust theoretical foundation and technical support for future tunnel construction. [ABSTRACT FROM AUTHOR]

The rock–lining interaction significantly affects the stability and safety of a tunnel in service. In this study, a mechanical model is proposed to explore the rock–lining interaction under hydrostatic pressure. The model takes into account the alterable mechanical property (such as the elastic modulus) of the lining in the rheological rock mass, which may be subjected to inner surface pressure along the radial direction of the highway tunnel. The alterable elastic modulus is assumed as a power function of the radius. The analytical solutions of this model are first verified by comparison with existing solutions and corresponding results are obtained by numerical simulation. Then, systematic parametric investigations are carried out to analyze the influence of the main model parameters on the radial deformation of the rock–lining interface and the normalized supporting pressure provided by the lining. The research conclusions obtained by this study can offer some valuable references for the safety evaluation of a tunnel in service. [ABSTRACT FROM AUTHOR]

To overcome the deficiencies of large particle radius, strict vibration conditions, and low kinetic energy exchange rate of traditional particle dampers, it is proposed to organically combine the rack and pinion inerter device with a stacked single particle damper (SSPD) to form a novel stacked single particle‐inerter damping system (SSPIS). Based on a detailed analysis of the force state of particles at various stages, the vibration damping mechanism of SSPIS is analyzed, and a mechanical model of a single‐degree‐of‐freedom (SDOF) structure equipped with an SSPIS is established. The numerical simulation and analysis process of SSPIS is provided, and a parametric design method of inerter device based on the structural performance requirements is proposed. The accuracy of the theoretical mechanical model and numerical simulation analysis process of SSPIS is verified through shaking table tests of a single‐story steel frame, and the actual damping control effect of SSPIS on the controlled structure is investigated. Both test and theoretical results show that the numerical simulation analysis process of SSPIS is clear and accurate, and the mechanical model of the SSPIS‐SDOF structural system is highly accurate. The inerter device in SSPIS can significantly improve the momentum exchange efficiency between particles and structures, and SSPIS could adaptively adjust the particle radius size on demand compared with the traditional particle dampers, with a high damping frequency band, and can realize good damping control effect under the earthquake with various types of sites, which has expansive engineering application scenarios. [ABSTRACT FROM AUTHOR]

The energy-dissipation mechanism of an external replaceable mild steel energy dissipater suitable for self-centering hybrid connections under repeated tensile and compressive loads was investigated. The effects of the slenderness ratio and energy consumption section diameter on the bearing ability, energy-dissipation capacity, displacement ductility and stiffness degradation of the dissipater were also evaluated. The research results showed that when the hysteretic curve of the energy-dissipation device is full, the slenderness ratio has a great influence on the overall performance of the energy-dissipation device. The ratio of the end diameter of the dissipater to the weakening section should not be less than 4/3. The energy-consuming devices have good-displacement ductility, up to 4.97. Simplified models of the dissipater-force mechanism were established. Two stress stages of the replaceable mild steel energy dissipater under cyclic tension–compression loading were defined. A parametric model of the hysteresis curve under cyclic tension–compression loading was established via theoretical calculations and experiments. [ABSTRACT FROM AUTHOR]

A mechanical model and numerical method for the simultaneous analysis of Reissner–Mindlin shells with geometries implied by a continuous set of level sets (isosurfaces) over some three‐dimensional bulk domain is presented. A three‐dimensional mesh in the bulk domain is used in a tailored FEM formulation where the elements are by no means conforming to the level sets representing the shape of the individual shells. However, the shell geometries are bounded by the intersection curves of the level sets with the boundary of the bulk domain so that the boundaries are meshed conformingly. This results in a method which was coined Bulk Trace FEM before. The simultaneously considered, continuously embedded shells may be useful in the structural design process or for the continuous reinforcement of bulk domains. Numerical results confirm higher‐order convergence rates. [ABSTRACT FROM AUTHOR]

This work is devoted to a theoretical and numerical study of the dynamics of a two-phase system vapour bubble in equilibrium with its liquid phase under translational vibrations in the absence of gravity. The bubble is initially located in the container centre. The liquid and vapour phases are considered as viscous and incompressible. Analysis focuses on the vibrational conditions used in experiments with the two-phase system SF $_6$ in the MIR space station and with the two-phase system para-Hydrogen (p-H $_2$) under magnetic compensation of Earth's gravity. These conditions correspond to small-amplitude high-frequency vibrations. Under vibrations, additionally to the forced oscillations, an average displacement of the bubble to the wall is observed due to an average vibrational attraction force related to the Bernoulli effect. Vibrational conditions for SF $_6$ correspond to much smaller average vibrational force (weak vibrations) than for p-H $_2$ (strong vibrations). For weak vibrations, the role of the initial vibration phase is crucial. The difference in the behaviour at different initial phases is explained using a simple mechanical model. For strong vibrations, the average displacement to the wall stops when the bubble reaches a quasi-equilibrium position where the resulting average force is zero. At large vibration velocity amplitudes this position is near the wall where the bubble performs only forced oscillations. At moderate vibration velocity amplitudes the bubble average displacement stops at a finite distance from the wall, then large-scale damped oscillations around this position accompanied by forced oscillations are observed. Bubble shape oscillations and the parametric resonance of forced oscillations are also studied. [ABSTRACT FROM AUTHOR]

Adhesives can be made by patterning surfaces with discrete adhesive elements. Nature uses this approach to provide animals with highly adaptive and robust approaches towards gaining an effective grip on surfaces. The mechanism of patterned surface adhesion involve many different attachment principles, adhesive site interactions, and probabilistic effects, the interplay of which is not understood. This limits our ability to design patterned surface adhesives for engineering applications. In this work, we quantify how a mechanically patterned adhesive based on passive mushroom-shaped elements performs. We explore a range of surface design features and model the mechanical adhesion dynamics with an approach based on the fiber bundle model (FBM). We find that the fiber bundle model can be used to rationalize the observations after modifying it to capture the initial non-linear force response of the adhesives. Additionally, we investigate the behavior of the system's elastic energy and damage energy, as it is stretched under strain-controlled conditions. Our experimental data indicates that the elastic energy has a maximum that appears after the macroscopic strength (σc), corresponding to strains where a full rupture of the system can no longer be prevented. Moreover, we observed that below the maximum of the constitutive curve σc, the elastic energy consistently exceeds the damage energy. Finally, we found that the derivative of the elastic energy has a maximum, which always appears before σc. Therefore, the derivative of the elastic energy would serve as a reliable signal of upcoming catastrophic failure in experiments under stress-controlled conditions. [ABSTRACT FROM AUTHOR]

AbstractUnderstanding mechanical degradation is crucial for successful polymer flooding. In this study, the effects of stretching velocity, pore-throat ratio, polymer concentration, and migration distance on the mechanical degradation of HPAM were studied using a pore-throat model. Additionally, the contribution of tensile degradation at the entry point of the pore-throat model to the overall mechanical degradation was assessed through extrapolation. The experimental results indicate that tensile degradation at the entry point is the primary cause of the mechanical degradation, and its contribution is positively related to the flow rate. The mechanical degradation correlates positively with the stretching velocity (0.41 ∼ 6362s−1), pore-throat ratio (6 ∼ 60), and polymer concentration (500 ∼ 2200mg/L). Moreover, higher flow rate amplify the effects of changes in polymer concentration and pore-throat ratio on mechanical degradation. As the migration distance increases, the mechanical degradation initially increases and then stabilizes in the pore-throat model, whereas in the sand-packed model, the mechanical degradation continues to increase with increasing migration distance. This study enhances our understanding of polymer mechanical degradation and offers insights for developing strategies to reduce mechanical degradation and improve polymer-enhanced oil recovery. [ABSTRACT FROM AUTHOR]

The Aqueous environment impairs the mechanical performance of carbon fiber‐reinforced polymers (CFRPs) and decreases the durability of engineering structures made of CFRPs primarily by degrading the resin matrix. Hence, the objective of this study is to investigate and accurately predict the influence of hydrothermal aging on the epoxy and its carbon fiber reinforced polymer (CFRP). Particularly, this work developed a modeling method that combined Fick's model, empirical aging model and elastoplastic constitutive model to predict the mechanical behavior of hydrothermally aged epoxy matrix. After the experimental characterization, this epoxy modeling method demonstrated its predictive capability on the mechanical response of the deteriorated epoxy under different hydro‐thermal‐salt conditions, with the mean absolute percent error (MAPE) of approximately 4.61%. Furthermore, the transverse compressive behavior of unidirectional (UD) CFRPs could be predicted by using the representative volume element (RVE) model with the degraded matrix behavior predicted via this epoxy modeling method. Integrated with this CFRP modeling, results from mechanical tests and fracture analysis further demonstrated that the hydrothermal aging effect on the transverse compressive performance of the UD CFRPs was dominated by the deterioration of their resin matrix. Therefore, this study demonstrates the feasibility of the finite element analysis (FEA) for mechanical aging of the epoxy matrix and its CFRP under hydrothermal conditions via employing the proposed integrated modeling method. Highlights: Degradation of epoxy polymer under hydro‐thermal‐salt aging conditions.Integrated model to predict mechanical response of hydrothermally aged epoxy.RVE model to predict the mechanical behavior of hydrothermally aged CFRP.Hydrothermal aging on the transverse compressive behavior of UD CFRP. [ABSTRACT FROM AUTHOR]

Lujo virus (LUJV) is a human pathogen that was the cause of a deadly hemorrhagic fever outbreak in Africa. LUJV is a divergent member of the Arenaviridae with some similarities to both the "Old World" and "New World" serogroups, but it uses a cell-entry receptor, neuropilin-2 (NRP2), that is distinct from the receptors of OW and NW viruses. Though the receptor binding domain of LUJV has been characterized structurally, the overall organization of the trimeric spike complex and how NRP2 is recognized in this context were unknown. Here, we present the structure of the membrane-embedded LUJV spike complex determined by cryo-electron microscopy. Analysis of the structure suggested that a single NRP2 molecule is bound at the apex of the trimeric spike and that multiple subunits of the trimer contact the receptor. The binding of NRP2 involves an intriguing arginine-methionine interaction, which we analyzed using quantum mechanical modeling methods. We compare the LUJV spike structure with the only other available structure of a complete arenaviral spike, which is the Lassa virus. The similarities and differences between them shed light on Arenavirus evolution, inform vaccine design, and provide information that will be useful in combating future Arenavirus outbreaks. The Lujo virus is a deadly human pathogen. Here, Eilon-Ashkenazy et al. determine the structure of the viral spike complex and elucidate key aspects of its function. [ABSTRACT FROM AUTHOR]

This article presents a proportional-integral sliding mode control (PI-SMC) approach for a two-mass variable speed wind turbine (VSWT) system. Most studies on wind turbines typically focus mainly on the electromagnetic part of the generators, or even on the high-speed part, considering the shaft stiffness as negligible. However, the generator torque is actually driven by the aerodynamic torque, and a two-mass system like the one studied here plays the role of a transmission element for this power. To address this challenge, the problem of low power generation resulting from wind speed variability is tackled by designing a PI-SMC control law, capable of controlling the mechanical turbine model that optimizes power and torque by tracking the maximum power point (MPPT) for rotational speed and aerodynamic power. To validate the developed theoretical results, an application of the wind turbine system is simulated in Matlab/Simulink, for a particular case. The control used is capable of satisfying the dynamic performance of the systems. [ABSTRACT FROM AUTHOR]

In the design and upkeep of canals in areas of seasonal permafrost, resistance to frost heave is a critical factor for ensuring the stability of water conveyance canals. Mechanical modeling is the key to frost heaving‐resistant design. In this study, the theory of elastic thin plates was used to build a mechanical model of frost heaving damage to rectangular canals. The model's plausibility was confirmed using a prototype canal as an example, and the canal's deformation, internal force, and stress distribution were examined. The findings demonstrate that, compared to beam theory, the internal forces and deformations computed by the model are not evenly distributed along the plate width; the base slab and side walls both saw their greatest deformations in the middle portion and two‐fifths from the canal's top, respectively; at the junction of the two, the bending moments and tensile stresses are maximum and distributions are consistent; transverse moments should be used as control moments in the structural design of canals, and stick feet should be placed at junctions to stop damage. In addition, the maximum normal frost heaving force and optimal thickness that four various canals can withstand were estimated, and the results were biased in favor of safety. The calculation's results can serve as a theoretical guide for antifreeze design concrete rectangular canals in places that experience seasonal freezing. [ABSTRACT FROM AUTHOR]

AbstractSensitive marine clays (SMCs) often pose considerable problems in the construction of embankments for transportation structures. In this study, extensive mechanical, microstructural, and monitoring experiments were carried out to evaluate the evolution of mechanical properties of SMCs stabilized via Deep Mixing Method. The results indicate that unconfined compressive strength and secant modulus increase with curing time. A significant improvement in mechanical properties is observed at early ages. Higher binder contents produce higher mechanical properties after same curing period. However, excess binder content does not provide significant improvement effects. The addition of ground granulated blast furnace slag (GGBFS) results in higher mechanical properties after long-term curing, and the enhancing degree is more evident with a higher proportion of GGBFS. But the situations are reversed at young age due to the “retarding effect” of GGBFS. These observations are also supported by results of physical properties, mercury instruction porosimetry, suction monitoring, and X-ray diffraction analyses. In addition, predictive models are established based on elastic-plastic theory and binder hydration model. The developed models are implemented in COMSOL Multiphysics and validated against experimental results. A good agreement is observed between experimental and predicted results which confirms the ability of developed models to predict the mechanical characteristics. [ABSTRACT FROM AUTHOR]

We present a corrosion internal state variable (ISV) damage model based upon the integrated computational materials engineering (ICME) hierarchical multiscale paradigm. Structure–property experiments for magnesium alloys were used where the only inputs were the volume fractions of each element of the periodic table. This macroscale ISV corrosion model finds its basis in Horstemeyer's mechanical damage model, which includes three separate ISVs for damage nucleation, growth, and coalescence, as well as Walton's inclusion of corrosion, which introduces five new ISVs for pit nucleation, growth, and coalescence, along with general corrosion and intergranular corrosion. While Walton's corrosion ISVs are phenomenological in nature, herein we develop a multiscale physical basis for the corrosion ISVs. The parameters for the macroscale corrosion ISVs were garnered from the mesoscale Butler–Volmer equations. Pure magnesium with differing amounts of aluminum were used in corrosion tests to exemplify the different pitting, general corrosion, and intergranular corrosion rates, and the macroscale ISV model was calibrated with said data, in which the only inputs to the model are the volume percentages of the elements magnesium and aluminum. Although magnesium alloys were used to motivate and calibrate the model, the model is abstract enough to possibly capture other material systems as well. [ABSTRACT FROM AUTHOR]

This study introduces a novel method for particle abrasion derived from fundamental natural phenomena and mechanical principles, allowing precise control over the degree of abrasion and more accurately mimicking natural processes. The method's validity is confirmed using a specific shape index. Through conventional triaxial tests, the mechanical behavior of granular aggregates with varying degrees of abrasion was analyzed. The findings indicate that increased particle abrasion leads to a decrease in the average coordination number and sliding amount, while the rotation amount increases. This suggests an inverse relationship between the degree of abrasion and the structural stability and interlocking of the particle aggregate. The fabric anisotropy of the system is mainly attributed to the anisotropy of the contact normal force, which decreases as particle abrasion increases. The partial stress ratio of the particle system is influenced by fabric anisotropy and remains independent of particle shape. Additionally, the internal friction angle may be overestimated in conventional triaxial tests. [ABSTRACT FROM AUTHOR]

The structured sand presents significant interparticle bonding and anisotropy, resulting in significant differences in the physical and mechanical properties from the pure sand. This study proposes a new surrogate model based on the concept of multi‐fidelity residual neural network (MR‐NN) as an alternative to DEM simulation for predicting the mechanical behaviours of structured sand with different initial anisotropy and saving largely computational costs. The model is initially trained using low‐fidelity (LF) data to focus on capturing the main underpinning correlations between macroscopic mechanical parameters with inter‐particle properties and anisotropic state variables (i.e., microscopic fabric and tilting angle of sand), where the LF data are generated from previously proposed anisotropic macro‐micro quantitative correlation. Subsequent training on sparser high‐fidelity (HF) data is used to calibrate and refine the model with HF data generated from DEM simulations for anisotropic structured sand. Feedforward neural network (FNN) is adopted as the baseline algorithm for training models. The macroscopic anisotropic parameters of structured sand predicted by the surrogate model are compared with DEM simulations to examine its feasibility and generalization ability. Furthermore, the robustness of the surrogate model is examined by discussing the effect of LF data on the performance of MR‐NN. The superiority of the MR‐NN is further verified by comparing the performance of the trained MR‐NN with the one‐shot trained FNN based on the same HF data. All results demonstrate that the proposed surrogate model can provide a fast and accurate simulation of the anisotropic parameters of structured sand. [ABSTRACT FROM AUTHOR]

Reasonably determining the failure characteristics of coal seam floor with varying dip angles can provide a theoretical basis for the prevention and risk assessment of groundwater outbursts. Mechanical models of two types of coal seam floors (horizontal and inclined) were established by considering the effect of mining and confined water pressures, and the relationship between the vertical failure range and strata dip was theoretically analyzed. The mining failure zone of the floor strata with different angles above a confined aquifer was numerically simulated, and the risk of groundwater outbursts was further quantified using an improved water-inrush coefficient method. A comparison between the theoretical and simulation results revealed differences in the failure characteristics between the horizontal and inclined coal seam floors. The vertical failure range of the horizontal floor exhibits a "spoon-shaped" pattern along the strike whereas a symmetrical "inverted saddle-shaped" pattern along the dip direction. Compared with the horizontal floor, the vertical failure range of the inclined floors along the dip direction exhibits an evident asymmetry, presenting an inverted saddle shape with "upper shallow and lower deep". The maximum floor failure depth first increases and then decreases with increasing strata dip. Under the same mining distance, the floor strata with a dip angle range of 20–30° are more prone to groundwater outburst. The research results are expected to provide valuable references for the management of groundwater outburst disasters. [ABSTRACT FROM AUTHOR]

Understanding tendon mechanical properties, such as stiffness and hysteresis, can provide insights into injurymechanisms. This research addresses the inconsistency of previously reported in-vivo and in-vitro tendon hysteresis properties. Although limited, our preliminary findings suggest that in-vivo hystereses (Mean ± SD; 55% ± 9%) are greater than in-vitro hystereses (14% ± 1%) when directly comparing the same tendon for the same loading conditions in a sheep model in-vivo versus within 24 h post-mortem. Overall, it therefore appears that the tendon mechanical properties are affected by the testing environment, possibly related to differences in muscle-tendon interactions and fluid flow experienced in-vivo versus in-vitro. This communication advocates for more detailed investigations into the mechanisms resulting in the reported differences in tendon behaviour. Overall, such knowledge contributes to our understanding of tendon function towards improving modelling and clinical interventions, bridging the gap between in-vivo and in-vitro observations and enhancing the translational relevance of biomechanical studies. [ABSTRACT FROM AUTHOR]

Summary: In this study, a viscoelastic damper (VED) employing an additional amplification device is proposed to enhance the stiffness as well as energy dissipation. The mechanical model of the amplified viscoelastic damper (AVED) is developed and the amplification efficiency is explored. The mechanical behaviors of AVED and the traditional VED are experimentally investigated. By adopting a leverage system, the stiffness and the dissipated energy of AVED are significantly improved and the amplification factors are confirmed. Meanwhile, the seismic responses and structural damages are addressed through a numerical study on a frame attached to the AVEDs and VEDs. The AVED reinforced building employing fewer dampers has close seismic responses compared with VED reinforced building. Furthermore, the installation of AVEDs significantly reduces the risk of structural damage. [ABSTRACT FROM AUTHOR]

Droplet sorting and enrichment, as a prominent field within microfluidic technology, represent a pivotal stage in the manipulation of droplets and particles. In recent times, droplet sorting methods based on lab-on-disk (LOD) have garnered significant interest among researchers for their inherent merits, including high throughput, ease of operation, seamless device integration, and independence from supplementary driving forces. This study introduces a centrifugal force-driven microfluidic chip comprising spiral microchannels. The chip incorporates microhole arrays along the sidewall of the spiral channels, enabling size-based sorting and enrichment of microdroplets under the influence of multiple forces. Firstly, a comparative analysis was performed to assess the influence of the separation port structure and rotational speed on efficiency, and a mechanical modeling approach was employed to conduct kinetic analyses of droplet behavior during instantaneous separation. Those findings demonstrated a good agreement with the experimental results at ω < 100 rpm. Subsequently, sorting experiments on homogeneous droplets indicated that repetitive sorting could increase the recovery ratios, RT(α), of high-concentration droplets (20.7%) from 35.3% to over 80%. We also conducted a sorting experiment on three-component homogeneous-phase emulsions using a serially connected chip array, and the sorting throughput was 0.58 mL min−1. As a result, the RT(α) for 60 and 160 μm droplets were 99.4% and 88.9%, respectively. Lastly, we conducted elution experiments and dual-sample sorting on a single chip, and the fluorescence results demonstrated that this study provided an efficient and non-cross-contaminating sorting method for non-homogenous phase multi-sample microreactor units. [ABSTRACT FROM AUTHOR]

Knitting interloops one-dimensional yarns into three-dimensional fabrics that exhibit behaviour beyond their constitutive materials. How extensibility and anisotropy emerge from the hierarchical organization of yarns into knitted fabrics has long been unresolved. We seek to unravel the mechanical roles of tensile mechanics, assembly and dynamics arising from the yarn level on fabric nonlinearity by developing a yarn-based dynamical model. This physically validated model captures the mechanical response of knitted fabrics, analogous to flexible metamaterials and biological fibre networks due to geometric nonlinearity within such hierarchical systems. Fabric anisotropy originates from observed yarn–yarn rearrangements during alignment dynamics and is topology-dependent. This yarn-based model also provides a design space of knitted fabrics to embed functionalities by varying geometric configuration and material property in instructed procedures compatible to machine manufacturing. Our hierarchical approach to build up a knitted fabric computationally modernizes an ancient craft and represents a first step towards mechanical programmability of knitted fabrics in wide engineering applications. [ABSTRACT FROM AUTHOR]

Verification, validation, and uncertainty quantification is generally recognized as a standard for assessing the credibility of mechanical models. This is especially evident in biomechanics, with intricate models, such as knee joint models, and highly subjective acquisition of parameters. Propagation of uncertainty is numerically expensive but required to evaluate the model reliability. An alternative to this is to analyze the worst-case models obtained within the specific bounds set on the parameters. The main idea of the paper is to search for two models with the greatest different response in terms of displacement-load curve. Real-Coded Genetic Algorithm is employed to effectively explore the high-dimensional space of uncertain parameters of a 2D dynamic knee model, while Radial Basis Function surrogates reduce the computation by orders of magnitude to near real-time, with negligible impact on the quality. It is expected that the studied knee joint model is very sensitive to uncertainty in the geometrical parameters. The obtained worst-case knee models showcase unrealistic behavior with one of them unable to fully extend, and the other largely overextending. Their relative difference in extension is up to 35% under ±1 mm bound set on the geometry. This unrealistic behavior of knee joint model is confirmed by the large standard deviation obtained from a classical sampling-based sensitivity analysis. The results confirm the viability of the method in assessing the reliability of biomechanical models. The proposed approach is general and could be applied to other mechanical systems as well. [ABSTRACT FROM AUTHOR]