Force Distribution Research Articles

Effect of Rectangular Dimensions on Elastic Deformation in PMMA Using Reflection Photoelasticity

The deformation and distribution of force were investigated in different-sized rectangular shapes of polymethyl methacrylate (PMMA). The experiment involved inducing stress-strain on the surface of each sample based on a point loading of 688 N, followed by observation of the isochromatic fringe order and strain distribution using reflection photoelasticity. The samples were tested vertically between the clamps inducing the point loading. It was found that the fringe order and strain value depended on the sample size (different vertical heights and horizontal widths, with a constant thickness). The maximum strain and fringe order for the contact points on the samples decrease in the vertical direction from the contact point to the center and in a horizontal direction from the center to the edge of the sample. Based on a constant height and different widths of samples, the lowest width had the highest fringe order (4). Based on a constant width of the sample and different heights, the lowest sample height had the highest fringe order (5.5) and a microstrain value of 1,100. Therefore, the smaller the width or height of a sample, the greater the extent of deformation and distribution of force into the sample’s area.

Mediated Interactions Between Two Impurities Immersed in Bose-Einstein Condensates

Abstract We consider two pointlike static impurities without direct interaction immersed in three-dimensional Bose-Einstein condensates (BEC) at zero temperature. By solving the Gross-Pitaevskii (GP) equation in a perturbative manner, we calculate the ground state energy in the region where atom-impurity interaction is assumed to be weak. We obtain analytical expression for the spatial distribution of atom number density and effective force between these two impurities. The effective force is found to be closely related to the strength of atom-impurity interaction strength and the relative distance between these two impurities. Two critical relative distances between two impurities are found. The first one corresponds to the vanishing of the perturbed energy with impurities but the effective force between the two impurities still exists. At the second critical value, the energy of impurities changes with the atom-impurity linearly, otherwise it changes with the atom-impurity quadratically.

Analysis the Mechanical Response of Tunnels Under the Action of Vertical Jacking in Shield Construction and Research on Reinforcement

This research examines the effects of vertical jacking construction on the mechanical behavior of shield tunnels. Model tests simulating vertical jacking were performed utilizing a purpose-built apparatus to quantify the reaction forces generated by the diffusion block during the jacking operation. A systematic analysis was conducted on the mechanical responses of shield tunnel lining segments and their interconnecting joints. Utilizing Particle Flow Code (PFC) methodology, a deformation prediction model specifically tailored for vertical jacking conditions was formulated. Correlating simulation results with experimental measurements quantified the sensitivity of tunnel deformation to grouting reinforcement, enabling the identification of an optimal reinforcement zone. Key findings reveal that the jacking reaction force distribution exhibits pronounced nonlinearity: a substantial increase precedes failure, followed by rapid post-failure reduction and eventual stabilization in advanced jacking stages. Tunnel convergence deformation evolves through four distinct phases: significant growth, rapid attenuation, gradual diminution, and final stabilization. The primary zone of influence encompasses the opening ring and its two adjacent rings. Jacking induces longitudinal bending deformation, with maximum joint opening occurring at the opening ring. Abrupt longitudinal load fluctuations cause dislocation between the opening ring and neighboring rings. Internal segment stresses exhibit initial tensile and compressive increases followed by subsequent relaxation. Externally applied grouting reinforcement effectively attenuates jacking-induced tunnel deformation. An optimal reinforcement range was determined at the 60° position relative to the segment springline, substantially lowering resource consumption and construction risks compared to conventional reinforcement strategies. These outcomes furnish theoretical underpinnings and technical benchmarks for optimizing engineering design and facilitating the implementation of vertical jacking technology.

Establishing a switchable dual-mode membrane bioreactor with functionalized PAC-MnOx filters to treat manganese-contaminated groundwater: autocatalytic manganese removal cycle, improved shear force distribution and rapid startup

Establishing a switchable dual-mode membrane bioreactor with functionalized PAC-MnOx filters to treat manganese-contaminated groundwater: autocatalytic manganese removal cycle, improved shear force distribution and rapid startup

Optimization of Trailing-Edge Unloading for Lambda-Wing UAV Using B-Spline Trailing-Edge Twist Method

As a commonly used configuration for advanced unmanned aerial vehicles (UAVs), the flying-wing configuration suffers from pitching moment trimming issues due to the lack of horizontal tail. The UAV either needs to unload lift at the trailing edge or needs to increase the wingtip twist angle at the cost of losing the lift-to-drag ratio. The commonly used methods for solving pitching moment trimming issues are compared and analyzed in this paper, and it is found that the method of trailing-edge twist has advantages under cruising lift coefficient. Furthermore, a trailing-edge twist deformation parameterized model that can deform multiple critical sections is designed with relevant grids. The multi-objective genetic algorithm is used to optimize the parameterized model and obtain the optimized results. Through comparative analysis, it is found that the optimized trailing-edge twist model has an advantage in distributing the pitching moment. By optimizing the distribution of aerodynamic forces and moments, cruise trim is achieved with only a 1.43% cost to the cruise lift-to-drag ratio compared to the initial model.

Numerical Continuation Applied to Automotive Wiper Blades

This paper presents an application of numerical continuation to a lumped parameter model of an automotive wiper blade. The presented model includes considerations of a real contact force distribution of a wiper blade that is calculated through finite element analysis, as well as the nonlinear freeplay that is a common feature of movable joints which is captured through a cubic function. Performing bifurcation analysis allows the model’s parameter space to be mapped and qualitative assessments of the dynamics to be made; with the identified regions in the parameter space corresponding to transitions of stability of the presented model. Key quantities that can be related back to shaping of the contact distribution are studied, which include the wiper blade stiffness, total load, loading asymmetry, and a consideration of blade wrap.

CUTTING FORCE DISTRIBUTION IN TANGENTIAL TURNING OF 42CRMO4 ALLOY STEEL: INFLUENCE OF HIGH CUTTING SPEEDS AND HIGH FEED RATES

This study investigates the cutting force distribution during tangential turning of 42CrMo4 alloy steel under high cutting speeds and high feed rates. The experiments were conducted by varying cutting speed (200 and 250 m/min), feed rate (0.3 and 0.8 mm/rev), and depth of cut (0.1 and 0.2 mm). The major cutting force, feed directional force, and thrust force components were measured, and their maximum values and relative ratios were analysed. The results indicate that both cutting speed and feed rate have a significant influence on the magnitude and distribution of the cutting force components. Higher cutting speeds generally led to a reduction in cutting force values, while increased feed rates resulted in higher force magnitudes and altered force ratios. The obtained data contribute to a better understanding of the cutting mechanics in tangential turning, supporting process optimization and the selection of appropriate cutting parameters for improved machining performance.

Research on the Optimisation of Enterprise Human Resource Management Based on the Perspective of Labour Economics

[1] Zhu Li. Research on optimization of enterprise human resource management based on the perspective of labour economics[J]. Chinese Science and Technology Journal Database (Full Text Edition) Economic Management, 2023(4):3. [2] Qin Fushun. Discussion on effective measures to strengthen human resources management in enterprises under the perspective of labour economics[J]. Enterprise reform and management, 2024(6):87-89. [3] Gao Fengyu. Research on human resource management based on labour economics[J]. 2024(12):116-118. [4]Lu Shuping. ‘An analysis of human resource management under the perspective of labour economics.’ Journal of Science and Technology Economy v.28;No.705.07(2020):232-232. [5]Xia Peng. Research on the optimal distribution of new urban labour force in Henan Province under the perspective of economy and water resources [D]. Henan University,2023.

Numerical Investigation of the Pull-Out and Shear Mechanical Characteristics and Support Effectiveness of Yielding Bolt in a Soft Rock Tunnel

Conventional bolts frequently fail under large deformations due to stress concentration in soft rock tunnels. In contrast, yielding bolts incorporate energy-absorbing mechanisms to sustain controlled plastic deformation. This study employed FLAC3D to numerically investigate the pull-out, shear, and bending behaviors of yielding bolts, evaluating their support effectiveness in soft rock tunnels. Three-dimensional finite difference models incorporating nonlinear coupling springs and the Mohr–Coulomb criterion were developed to simulate bolt–rock interactions under multifactorial loading. Validation against experimental pull-out tests and field measurements confirmed the model accuracy. Under pull-out loading, the axial forces in yielding bolts decreased more rapidly along the bolt length, reducing stress concentration at the head. The central position of the maximum load-bearing capacity in conventional bolts fractured under tension, resulting in an hourglass-shaped axial force distribution. Conversely, the yielding bolts maintained yield strength for an extended period after reaching it, exhibiting a spindle-shaped axial force distribution. Parametric analyses reveal that bolt spacing exerts a greater influence on support effectiveness than length. This study bridges critical gaps in understanding yielding bolt behavior under combined loading and provides a validated framework for optimizing energy-absorbing support systems in soft rock tunnels.

Assessment of Uneven Wear of Freight Wagon Brake Pads

This study deals with the problem of uneven wear of brake pads of wagons caused by a set of structural, dynamic, technological and operational factors. It has been found that an uneven distribution of the brake pad pressure force leads to higher maintenance costs and lower braking efficiency. The main causes of uneven wear are worn kinetostatic units, differences in the geometric parameters of pads, and imperfections in the lever transmission design. A method for optimizing the distribution of the pressure force using weight coefficients and the Lagrange function has been developed; it reduces the uneven wear of brake pads to 8–10% compared to that of a typical wagon bogie brake system, which is 20–35%. The experiments conducted have shown that for a mileage of 74,400 km and with the air distributor in empty mode, the wear of the pads is 19.6–28 mm, while in the loaded mode it amounts to 27.53–38.04 mm. The stress state of brake pads was determined with consideration of the weight coefficients. It was found that for abnormal wear of brake pads, their strength is not observed. The strength of the wheel when interacting with an abnormally worn pad has also been assessed. The resulting stresses are 1.5% higher than those that occur when the wheel interacts with the pad with nominal dimensions. The results of the research will contribute to the database of developments to be used for designing of modern structures of tribotechnical pairs of rolling stock and increasing the efficiency of railway transport.

Spindle Orientation Regulation Is Governed by Redundant Cortical Mechanosensing and Shape-Sensing Mechanisms.

Spindle orientation (SO) plays a critical role in tissue morphogenesis, homeostasis, and tumorigenesis by ensuring accurate division plane positioning in response to intrinsic and extrinsic cues. While SO has been extensively linked to cell shape sensing and cortical forces, the interplay between shape- and force-sensing mechanisms remains poorly understood. Here, we reveal that SO is governed by two parallel mechanisms that ensure redundancy and adaptability in diverse cellular environments. Using live-cell imaging of cultured cells, we demonstrate that the long prometaphase axis (LPA) is a superior predictor of SO compared to the long interphase axis, reflecting adhesive geometry and force distribution efficiently at prometaphase. Importantly, we uncover a pivotal role for focal adhesion kinase (FAK) in mediating cortical mechanosensing to regulate SO in cells undergoing complete metaphase rounding. We show that in cells with complete metaphase rounding, FAK-dependent force sensing aligns the spindle with the major force vector, ensuring accurate division. Conversely, in cells retaining shape anisotropy during mitosis, a FAK-independent shape-sensing mechanism drives SO. These findings highlight a dual regulatory system for SO, where shape sensing and force sensing operate in parallel to maintain division plane fidelity, shedding light on the mechanisms that enable cells to adapt to diverse physical and mechanical environments.

Research on static seating comfort of the Chinese population under different seat angle design parameters

IntroductionThis study aimed to deepen the understanding of seating comfort for the Chinese population by developing a human finite element (FE) model.MethodsThis model was integrated with a specific vehicle seat FE model to construct a comprehensive human-seat FE model, and the mechanical responses of the human body were analyzed under varying seat angles. Body pressure distribution, intervertebral disc stress and strain, and vertebral body stress were examined to study the relationship between the internal reactions of the human body and surface contact conditions.ResultsThe results indicate that when the seat is flipped, the trends of disc stress, average pressure, and contact area are consistent, and the maximum strain closely aligns with the maximum pressure. When the backrest is adjusted, lumbar spine stress and surface pressure exhibit similar trends, while disc stress, strain, and the 1-SPD value show consistent patterns.DiscussionThe study concludes that increasing the backrest angle does not necessarily enhance comfort. Moreover, the stress variations in the thoracic and lumbar spines correlate with spinal angle alterations, suggesting that spinal angle can serve as a reliable indicator of stress conditions. Finally, the study highlights the correlation between spinal force and body pressure distribution, underscoring the utility of body pressure distribution metrics as a valuable proxy for understanding spinal responses.

Finite element modeling of asymmetric expansion using ATOZTM expander

Asymmetric dentoskeletal expansion is one of the common complications associated with rapid palatal expansion (RPE), often leading to functional and aesthetic concerns. This study investigates the biomechanical performance of ATOZ™ expander using finite element method, with a focus on addressing asymmetrical expansion through expander design modifications. A 3D skull model incorporating teeth and sutures were reconstructed, and two scenarios were analyzed. Model I featured symmetrical suture maturation (stage B), and Model II with asymmetrical suture maturation, particularly more mature zygomatic sutures on the right side (Stage C). Five expander configurations were evaluated in each model. A 0.3 mm total displacement (0.15 mm per side) was applied parallel to the midpalatal suture. Results showed that in Model I, configurations 1, 2, and 3 resulted in relatively symmetrical expansion, while configurations 4 and 5 introduced asymmetry. In Model II, all configurations except configuration 4 demonstrated significant asymmetrical expansion toward the less mature left side. Configuration 4, which included one-sided dental support on the left, was found to redistribute forces and minimize asymmetry. The number of micro-implants had minimal impact on expansion outcomes, while dental support substantially influenced force distribution. These findings suggest that the ATOZ™ expander, especially when configured with one-sided dental support, offers a non-surgical solution to compensate for asymmetrical sutural resistance. This approach may improve clinical outcomes in patients exhibiting unilateral suture maturity and could help reduce the need for surgical intervention such as SARPE.

Finite element modeling of asymmetric expansion using ATOZTM expander.

Asymmetric dentoskeletal expansion is one of the common complications associated with rapid palatal expansion (RPE), often leading to functional and aesthetic concerns. This study investigates the biomechanical performance of ATOZ™ expander using finite element method, with a focus on addressing asymmetrical expansion through expander design modifications. A 3D skull model incorporating teeth and sutures were reconstructed, and two scenarios were analyzed. Model I featured symmetrical suture maturation (stage B), and Model II with asymmetrical suture maturation, particularly more mature zygomatic sutures on the right side (Stage C). Five expander configurations were evaluated in each model. A 0.3 mm total displacement (0.15 mm per side) was applied parallel to the midpalatal suture. Results showed that in Model I, configurations 1, 2, and 3 resulted in relatively symmetrical expansion, while configurations 4 and 5 introduced asymmetry. In Model II, all configurations except configuration 4 demonstrated significant asymmetrical expansion toward the less mature left side. Configuration 4, which included one-sided dental support on the left, was found to redistribute forces and minimize asymmetry. The number of micro-implants had minimal impact on expansion outcomes, while dental support substantially influenced force distribution. These findings suggest that the ATOZ™ expander, especially when configured with one-sided dental support, offers a non-surgical solution to compensate for asymmetrical sutural resistance. This approach may improve clinical outcomes in patients exhibiting unilateral suture maturity and could help reduce the need for surgical intervention such as SARPE.

Design and safety assessment of a novel GFRP lattice-rubber sandwich anti-collision island: Full-scale real-vehicle crash test

Fiber-reinforced polymer (FRP) composites have garnered significant interest in impact protection engineering owing to their exceptional mechanical properties and energy dissipation capabilities. Conventional reinforced concrete anti-collision islands, characterized by inherent rigidity and inadequate energy absorption, frequently induce catastrophic structural failures and occupant injuries during vehicular collisions. This investigation proposes an innovative GFRP lattice-rubber sandwich structure to enhance impact mitigation performance. Experimental evaluations through hammer impact testing revealed substantial force attenuation, with peak impact forces measuring 307.34 kN (3 m) and 364.64 kN (6 m), demonstrating 72.8% and 68.3% reductions compared to conventional concrete counterparts (970.37 kN and 1344.44 kN, respectively). Full-scale real-vehicle crash test further validated the system’s efficacy, exhibiting limited superficial damage in the composite layer alongside markedly reduced vehicular structural deformation. Data indicated compliance with occupant safety thresholds, as evidenced by controlled dummy acceleration profiles and force distribution metrics. The observed temporal decoupling between vehicular and anti-collision island acceleration maxima (Δt = 0.24s) substantiates the energy dissipation mechanism through controlled elastomeric deformation, effectively prolonging impact duration while mitigating peak load intensity. The findings provide experimental support for the application of GFRP-lattice structures in highway anti-collision Islands, demonstrating their promising prospects for engineering applications.

Load transfer mechanism of corroded rockbolt grouted structures under low strain rate: Experimental and theoretical analysis

This paper explores the engineering failure of corroded rockbolt grouted structures under dynamic disturbance. Through indoor testing, the influence of a low strain rate on the load transfer behaviour is examined to elucidate the bond-slip mechanism. The load transfer principle is used to construct the load transfer equation of rockbolt considering the effects of strain rate and corrosion, and the distributions of axial force and shear stress in corroded rockbolt are analysed under low strain rates. The results indicate that, at high temperature, the corrosion rate of the rockbolt accelerates, and the cracks at the grouted interface expand rapidly, which makes the rockbolt change failure mode. Under a given load, a higher corrosion degree accelerates the axial force decay rate and makes the distribution of the interface shear stress more uneven. The axial force and shear stress of the rockbolt tend to increase with the strain rate, which increases the load transfer efficiency of the rockbolt and makes it more likely to enter the softening phase. The established load transfer model realistically expresses the effects of corrosion and low strain rate on the load transfer mechanism during rockbolt pull-out, and the test results verify the veracity of the model.

Efficient prediction of aerodynamic forces in rarefied flow using convolutional neural network based multi-process method

Abstract The direct simulation Monte Carlo (DSMC) is a widely used approach for studying aerodynamics effects of rarefied flows, but it is highly time-consuming and may exhibit statistical fluctuations. In this study, we propose an efficient aerodynamic prediction method based on convolutional neural networks (CNNs) to further explore the application of deep learning in improving the efficiency of DSMC for calculating the aerodynamics of rarefied flows. The method includes centroid aerodynamics forces prediction (CFP) and surface aerodynamic forces distribution prediction (SFP), both of which are trained using a dataset of free molecular flow around obstacles derived from DSMC simulations. The SFP is designed to bridge the gap between flow field and surface forces, with two characteristics extraction methods developed specifically for this purpose. Additionally, two data preprocessing methods are designed to suppress the statistical noise inherent in DSMC simulations. Both CFP and SFP have demonstrated optimal performance in terms of accuracy and resistance to overfitting, achieving considerable predictive accuracy. The SFP exhibits a significant speedup, enabling real-time prediction of aerodynamic distributions from flow field. The results demonstrate that the proposed CNN-based approach offers a promising solution for the efficient calculation of aerodynamic forces in rarefied flows, and provide a robust foundation for ongoing development.

Enhancing Gait Biomechanics in Persons With Stroke: The Role of Functional Electrical Stimulation on Step-To-Step Transition.

Stroke often causes muscle weakness, reduced motor control, and gait abnormalities, such as foot drop and propulsion deficits, which impair weight transfer and walking efficiency. Traditional interventions such as ankle-foot orthoses and botulinum toxin address these impairments but often fail to activate the muscles involved in propulsion. Functional electrical stimulation (FES) has shown potential to enhance muscle activation and gait speed, but its effects on biomechanical parameters, particularly on step-to-step transitions, remain insufficiently explored. A randomized crossover design included 18 individuals with stroke who walked with and without functional electrical stimulation (FES). Kinematic data and ground reaction forces (GRF) were recorded to evaluate step-to-step transitions. Outcome measures included the minimum vertical velocity (Vvmin) of the center of mass (CoM) and the force ratio (FRatio) between the back foot (Fback) and front foot (Ffront). FES significantly reduced the force ratio (FRatio) (p<0.001), indicating improved force distribution toward the back foot. The minimum vertical velocity (Vvmin) of the center of mass (CoM) occurred earlier with FES (0.470±0.032) compared with No FES (0.513±0.033; p<0.001), demonstrating enhanced control of CoM redirection during gait. FES applied to specific lower limb muscles improved critical biomechanical gait parameters, including enhanced force distribution and better control of the center of mass (CoM). These findings suggest that FES can optimize gait mechanics, particularly during step-to-step transitions, and improve walking efficiency in individuals with stroke. Further research is needed to assess its long-term effects and explore its integration into rehabilitation protocols. The study was registered with Clinical Trials.gov (NCT06237972).

Integration of Soil Shear Strength Analysis with Wave Force Calculations to Optimize Coastal Slope Stability

Coastal regions face significant challenges due to the dynamic interplay between waves and soil slopes, which can lead to instability and erosion. This study investigates the stability of coastal slopes under wave-loading conditions by integrating soil shear strength analysis with wave-induced forces calculation. The simplified slope stability analysis method serves as the framework for assessing slope stability, while wave characteristics such as height, period, and direction are considered to calculate driving forces induced by waves. Soil shear strength parameters, including cohesion and friction angle, are incorporated to determine the resisting forces within the soil mass. An example scenario illustrates the calculation process, demonstrating how wave shear stress and soil shear strength interact to influence slope stability. This research found that wave parameters such as height, period, and direction had a significant influence on the magnitude of the driving force acting on the coastal slope. The distribution of wave pressure and wave forcing is also described, showing a significant increase in pressure at certain depths. This research resulted in the integration of soil shear strength with calculations of forces caused by waves, which greatly influenced the stability of coastal slopes. This research shows that soil with higher shear strength has better resistance to forces caused by waves. Coastal slopes with a FoS value of more than 1 are considered stable, while slopes with a FoS of less than 1 indicate instability and potential failure. At a certain depth, driving forces are dominant, which increases the potential for slope failure. The main innovation of this research is the approach that combines hydrodynamic analysis with geotechnical analysis to assess coastal slope stability, the simplified slope stability method approach from Bea and Audibert (1981) to calculate FoS on coastal slopes, and the use of Historical Data and Numerical Modeling forForce Evaluation Wave.

ESMAC Best Paper 2024: Defining exoskeleton aim matters: Simulating optimal assistive moments with explicit objectives using bilevel optimization.

ESMAC Best Paper 2024: Defining exoskeleton aim matters: Simulating optimal assistive moments with explicit objectives using bilevel optimization.