Force Distribution Research Articles

Analytical Modelling of Plasma Actuator-Induced Flow Control on a NACA 0015 Aerofoil

Plasma actuators function as quick, lightweight solutions for aerofoil airflow control through non-moving parts. The majority of Dielectric Barrier Discharge (DBD) actuator research relies on Computational Fluid Dynamics (CFD), but this paper demonstrates an analytical solution through MATLAB-based modelling. The use of a Gaussian plasma body force distribution relies on the voltage, frequency, and shape of the actuator to predict its effects on airflow using thin-aerofoil theory. The model shows that lift coefficient changes based on actuator placement and strength can produce lift increases of up to 15% during stall conditions. The analytical results match experimental data from published research regarding lift improvement and the best actuator placement positions. The research demonstrates that analytical methods provide fast guidance for designing plasma actuators, particularly when used during initial development stages or limited-resource research settings.

Analysis on Distribution and Evolution of Fiber Contact Force in the Fiber Assembly of Equal Size Fiber Under Triaxial Compression

ABSTRACT Fiber is similar to a long rod-shaped particle; the fiber assembly can be regarded as an assembly of fibrous particles (cotton, flax, and hemp). For the first time, we used PFC software to simulate fiber assembly compression. To analyze the contact force among fibers in the fiber assembly with equal-sized fibers, the fiber assembly with three different fiber arrangements was designed by the PFC software to simulate the contact force among fibers. We found that the contact force among fibers forms a three-dimensional force network in fiber assembly by point or line contact. The contact number among fibers gradually increases, and many point and line contacts connect to form a dense fiber contact force network with compression. The fiber arrangement significantly impacts its compression force, and the axial load of the fiber assembly under triaxial compression plays a dominant role; the effect of other directions is secondary. Some fiber indices, such as diameter and elastic modulus, significantly impact the pressure of fiber assembly.

A fractal gripper with switchable mode for geometry adaptive manipulation

Despite thriving development in academic and practical scenarios, multi-joint underactuated manipulators is still struggling with grasp stability, especially in case of heavy or irregular-shaped objects. A gripper with fractal morphology is invented to improve the grasping capacity of multi-joint underactuated manipulators. Combining the adaptivity of fractal geometry and the principle of lever, the invented fractal gripper achieves superior grasping capacity. The self-recovery feature is realized by resilient design to activate the function of continuous robust grasping and improve the grasping efficiency. Besides, the grasped objects can be held softly owing to the contact force redistribution and pressure re-equilibrium. Meanwhile, the fractal finger is wrapped by elastic polymer to ensure a safe and secure grasp. Fractal gripper with switchable mode promote its applicability. In the fingertip pressure experiments, we tested the fractal gripper and demonstrated its ability to stably envelop complex objects while ensuring even force distribution. Well-designed grab experiments with objects of diverse shapes and sizes demonstrate the multi-scale adaptability and superior grasping stability of the fractal gripper. Our study brings a transformative design paradigm to integrate traditional machine design with mathematical and mechanical principles, which meets critical requirements from a broader field of practical scenarios, such as dealing with irregular heavy objects in everyday housework, agricultural harvesting and underwater operations.

Analysis of the Influence of Arc Transition Oil Cavity Structure on the Performance of High-Speed Gear Hobbing Machine Hydrostatic Spindle

This study investigates the influence of arc transition oil cavity structure on the load-bearing characteristics of hydrostatic oil films in high-speed gear hobbing machine spindles under high-stroke conditions. By establishing fluid simulation models of oil cavity structures with different arc radii (r=0.5, 1.0, 1.5, and 2.0 mm), the effects of parameters such as eccentricity and stroke speed on oil film pressure and shear force distribution were systematically analyzed. The results demonstrate that the arc transition oil cavity structure significantly enhances the load-bearing capacity and lubrication performance of the hydrostatic oil film. Specifically, the structure with an arc radius of r=2.0 mm exhibits the most uniform pressure distribution, the lowest maximum pressure and shear force, and optimal performance. While eccentricity has a minor impact on pressure distribution, increasing eccentricity raises pressure on the eccentric side and slightly reduces it on the opposite side. At an eccentricity of 0.5, slight shear force concentration occurs on the eccentric side. Under high stroke speeds (1.0–2.0 m/s), both oil film pressure and shear force increase with speed, but the r=2.0 mm cavity structure remains the most stable, with no significant expansion of shear force concentration zones. Optimizing the oil cavity structure and employing higher supply pressure effectively improves the lubrication performance and operational stability of the hydrostatic spindle, providing theoretical and practical guidance for the design of high-speed gear hobbing machine spindles.

Calculation of the t-shaped shank of the steam turbine rotor blade

The broad possibilities of the developed approach [8, 9, 11, 12] are illustrated by the solution of a new practically important task related to specific design developments. The most important load-bearing elements of the rotors of steam turbines are the blade shanks. This paper presents the calculation of the T-shaped shank, which is affected by the forces caused by the rotation of the rotor. They consist of the surface load blade distributed over the area of the root section of the blade and mass forces distributed over the volume of the shank. but along some of its central parts. This leads to an uneven distribution of contact forces along the axis along the shank. The results of the calculation allow us to draw the following conclusions that in the case of a uniform load, the determination of stresses can be carried out within the framework of a flat setting, since this leads to a relatively small (five, eight percent) error compared to the spatial setting. Taking into account the uneven nature of the load distribution along the length of the shelf allows you to significantly clarify the level of maximum stresses in comparison with a flat problem. Thus, the value of the intensity of tangential stresses increased by more than thirty percent and exceeded the yield strength of the material. The results of the calculation of the shank beyond the elastic properties of the material are presented in this work and reflect the development of the zone of plastic deformations in the plane Z3'=0. By studying the influence of the geometric parameters of the shank, it was found that a decrease in the level of plastic deformations can be achieved by simultaneously increasingthe radiusthe gap and the width of the shelf.

Comparative analysis of the stress state of a bolted joint based on an analytical approach using SFEM and experimental results

The main types of connections are welded, riveted, and bolted. Bolted connections have many advantages over other types of connections, namely: high manufacturability, reliability, and speed of installation work, so we will further consider various approaches to modeling bolted connections. One of the most crucial and important points in the design of a structure is the calculation of the connection elements of the components, since the reliability of the structure as a whole depends on the accuracy and reliability of the calculation results. For a wide range of tasks, the finite element method (FEM) is often used in calculations; this numerical method has proven to be one of the most common and versatile. When calculating elements of assemblies such as bolts, rivets, etc., simplified design schemes are usually used, but this approach does not allow for a complete analysis of the distribution of forces. For a complete analysis, it is necessary to create detailed spatial models, which in turn leads to the need to solve systems of high-order equations. To increase the efficiency of the FEM, it is necessary to combine it with the method of distribution of unknowns, as a result, the resulting approach is called the semi-analytical finite element method (SFEM). The bolt, bolt head, and nut were modeled by spatial elements, and the bolt tension was modeled by a load from uniform heating. The obtained results of the stress-strain state using the finite element method and the semi-analytical finite element method allow us to conclude that there is a slight difference in the stress distribution in the spatial formulation of the FEM and SFEM with experimental data and allowed us to identify a rational approach to modeling bolt tension.

Analytical and Numerical Investigation of Internal Force Distribution in “Pile-Wall” Structures Based on Finite Difference Method

The “pile-wall” structural system involves the use of conventional temporary retaining piles as part of the underground structure during its operational phase. While this approach has been implemented in engineering practice, there is a significant research gap regarding the theoretical and numerical understanding of the internal force distribution and load-sharing characteristics of the “pile-wall” system, especially in relation to the reinforcement bars used as connection nodes at the interface between the retaining piles and basement walls. This study addresses this gap by proposing a composite structural model that integrates an elastic foundation beam with a continuous beam to simulate the mechanical behavior of the “pile-wall” system. A finite difference equation and computational method are developed to analyze the internal forces and displacements in the system during two key stages: excavation and completion of the basement wall construction. The analytical solutions are validated through comparison with finite element simulations, which show a high degree of consistency between the results. The main contributions of this study include the development of a reliable calculation method for analyzing “pile-wall” internal forces and providing new insights into the load-sharing mechanisms of the system. These findings contribute to a deeper understanding of the mechanical behavior of the “pile-wall” structure and offer a solid theoretical foundation for its broader application in engineering design.

The effect of carrying a school bag, the distribution of force and plantar pressure during the gait of children with different levels of physical activity.

BackgroundCarrying a school bag is often a necessary activity for children and children perform it during everyday productive activities.ObjectiveOf the research is to examine the impact of carrying a school bag on the distribution of force and plantar pressure during the gait of children with different levels of physical activity.MethodsThe prospective comparative study included 150 students aged 11-12 from Banja Luka. According to the protocol, each group of subjects walked at average and maximum speed on flat and 5% inclined terrain. For research purposes, the Physical Activity Questionnaire PAQ-C (The Physical Activity Questionnaire for Older Children), measurement of anthropometric parameters, school bag characteristics and Zebris tape (Zebris Medical GmbH, Germany) were used for gait analysis.ResultsModerately active and especially low active subjects show a significant increase in maximal force and maximal pressure values. Changes in antero-posterior variability are also related to the position of the bag in inactive subjects, in whom this parameter is lower if the bag is worn in the highest position, up to 5 cm from the seventh cervical vertebra (Mdn1 to 5 cm). = 5.05, M dn2 from 5-10 cm = 14.15, M dn3 over 10 cm = 13.20 χ 2 (2) = 7.95, p = 0.019, ε 2 = 0.16.ConclusionsExternal load did not lead to a change in dynamic parameters in highly active subjects, except for an increase in the maximum force on certain parts of the foot, when the subjects carried their own bag.

The Analysis of Plastic Forming in the Rolling Process of Difficult-to-Deform Ti + Ni Layered Composites.

The article presents the results of experimental studies on the symmetrical and asymmetrical rolling process of composite laminate sheets consisting of difficult-to-deform Ti and Ni materials. Composite sheets joined by explosive welding were used for the tests. The aim of the research was to determine the impact of plastic shaping conditions in the rolling process on the quality and selected functional properties of the materials constituting the layered composite. The rolling process was carried out cold on a duo laboratory rolling mill with a roll diameter of 300 mm. During the rolling process, the influence of the rolling process conditions on the distribution of metal pressure forces on the rolls was determined, as well as the shear strength and microstructural studies of the joint area of the layered composites. As part of the conducted considerations, residual stress tests were carried out using the Barkhausen noise method. The scientific aim of the presented work was to determine the optimal conditions for the plastic processing of multi-layer Ti-Ni sheets. The results presented in the work allowed for determining the most favorable conditions for the rolling process.

Failure mode of single shear and double shear porous panel with different rotation angles

Abstract This article utilized polylactic acid (PLA) material combined with fused deposition modeling (FDM) technology to fabricate porous structural panels with regular hexagons of varying rotation angles as the basic configuration. A method was utilized quasi-static tensile experiment and finite element simulation analysis. The influence of rotation angle on the shear force distribution and load-bearing capacity of single and double shear porous structural panels were explored. The results showed that layup sequence affected the force on the inter-layer interface, and an appropriate layup angle can optimize the stress distribution and reduced the risk of inter-layer failure. The double-shear structure had strong bearing capacity and stability. For applications that require high shear resistance, the 15° configuration should be considered.

Kajian Analisis Struktur Gedung 2D dengan Ketidakberaturan Vertikal Menggunakan Metode Nonlinear Pushover

Multi-story buildings with vertical irregularities often experience uneven load distribution, which can affect the structural performance under lateral loads, particularly seismic forces. Vertical irregularities, such as varying column and beam dimensions between floors, can lead to significant increases in displacement and deformation on the upper floors compared to the lower floors. Therefore, it is crucial to evaluate the impact of vertical irregularities on the structure's behavior to ensure building safety. This study aims to analyze the impact of vertical irregularity on the behavior of multi-story buildings using the nonlinear pushover method. The analysis was performed using SAP2000 software to assess the structural capacity to withstand lateral loads, particularly seismic loads. The results show a significant linear relationship between story displacement and lateral forces (R² = 0.8898), as well as the impact of vertical irregularities that increase story drift and story drift ratio on the upper floors. The increase in story drift ratio exceeding the earthquake design standard limits may affect the stability of the structure. Furthermore, this study reveals that vertical irregularity can cause significant differences in forces on columns and beams between the lower and upper floors, increasing the risk of structural failure. Based on these findings, it is recommended to consider vertical irregularities in the design of multi-story buildings, accounting for a more uniform distribution of forces throughout the building to ensure structural resilience against seismic loads.

Hotel underground parking garage renovation project: finite element analysis of deep excavation induced effects

The soil disturbance caused by deep excavation of adjacent buildings will have adverse effects on building foundation. This will threaten the stability of superstructure and engineering safety. In this paper, a three-dimensional finite element model is established by taking the renovation project of underground parking garage near a hotel as an example. The calculated results of the model agree well with the measured data, which verifies the validity of the model. On this basis, the construction mechanical behavior of deep excavation of adjacent buildings is studied. The research content mainly includes the stress and deformation characteristics of soil and structural members. The results show that the stress and deformation characteristics of soil and structural members are sensitive to the excavation depth of deep excavation. It increases with the increase of excavation depth. The vertical displacement of soil at the bottom of deep excavation is mainly uplift. When the excavation is completed, the maximum uplift value is 26.9 mm. The displacement of strip foundation is mainly settlement. The maximum vertical displacement of the foundation of buildings A and B is − 5.2 mm and − 10.98 mm, respectively. In general, the vertical displacement of column foot shows the deformation law of “slope”. The maximum displacements of diaphragm wall 1 and 2 are 6.09 mm and − 6.56 mm respectively. The maximum values of XX direction stress and YY direction bending moment are − 494.2 kN/m and − 746.1 kN m/m, respectively. The axial force of the internal support is mainly pressure. The maximum value is − 1225.9 kN. The total maximum axial force shows a trend of “increasing”. When the excavation is completed, the total maximum axial force is − 2748.3 kN. The deformation and internal force distribution of soil and structural members at the bottom of deep excavation have obvious spatial characteristics. The closer to the center of the deep excavation, the greater the value. Therefore, attention should be focused and necessary measures should be taken.

Management of Pile End Sediment and Its Influence on the Bearing Characteristics of Bored Pile

In order to study the influence of pile end sediment on the bearing characteristics of bored piles, the on-site bearing capacity test was conducted on a single pile. A mathematical model of bearing capacity and the settlement response of a single pile considering sediment effects and a finite element model of a single pile with pile end sediment were established. In addition, the influence of sediment thickness on the bearing capacity of bored piles was systematically analyzed. The results show that the compaction of sediment at the pile end could significantly improve the ultimate bearing capacity of the single pile. Compared with the single pile that did not consider the compaction of the sediment at the pile end, the load required to reach the ultimate bearing capacity of the pile after compaction of the sediment increases by 900 KN. The settlement of the pile under a maximum vertical load increases with an increase in the thickness of the sediment. The influence of sediment thickness on axial force transmission is mainly reflected in the linear to nonlinear transformation of axial force distribution from low to high during the process of load. The slight decrease in axial force at the bottom of the pile could also be caused by the increase in the thickness of sediment. The increase in sediment layer thickness means that the transfer efficiency of the pile end resistance decreases. However, with an increase in load, the compression effect of the pile end sediment becomes obvious, which will further change the distribution of load between the pile side resistance and the pile end resistance.

Influence of Different Supporting Structures on Supporting Deformation of Long and Deep Foundation Pit of Railway

In this study, the influence of different pile diameters and supporting materials on deformation characteristics of long and deep foundation pit supporting structure of railway is systematically analyzed by finite element simulation method. The research results show that the lateral displacement of diaphragm wall exceeds the safety limit of 20mm due to the lack of cross-sectional stiffness of 800mm diameter protective piles, while the displacement control effects of 1000mm and 1200mm diameter protective piles are similar, but the latter has poor economic benefits. In the selection of supporting materials, the influence of concrete bracing or steel bracing on lateral displacement of protective piles is not significant, but steel bracing has more advantages in controlling vertical displacement of deep bracing. It is also found that the diagonal brace and corner reinforcement structure can effectively restrain the corner displacement of foundation pit, and increasing the pile diameter to 1000mm can significantly enhance the restraint of soil around the pile and improve the internal force distribution of the structure. Comprehensive technical and economic analysis shows that the composite supporting scheme with 1000mm diameter protective pile and steel support can not only meet the requirements of deformation control, but also have good engineering economy, which can be used as the optimal supporting scheme for similar long and deep foundation pit projects.

Force distributions associated with different elastic traction methods for maxillary dentition distalization by clear aligners: an in-vitro study

ObjectiveThe aim of this study was to examine the distribution patterns of orthodontic and reactive forces on each tooth during dentition distalization using clear aligners (CAs), and to assess the impact of different elastic traction methods.Materials and methodsThree sets of aligners for maxillary dentition distalization were fabricated, targeting different tooth movements: simultaneous distalization of the first molars and second premolars; simultaneous distalization of the first premolars and canines; and simultaneous retraction of incisors. An in vitro orthodontic simulator, consisting of 14 three-dimensional sensors, was used to evaluate mechanical changes in each tooth. The orthodontic and reactive forces exerted by aligners, along with additional pulling forces from 1/4 inch 3.5oz elastic using different elastic traction methods (with hooks or buttons), were measured and subjected to comparative analysis.ResultsThe initial orthodontic force exerted by CAs varied across different teeth, ranging from 1.52 N to 6.77 N. Concurrently, the primary anchorage teeth experience reactive forces within a range of 1 N to 6.48 N. While the traction force on these teeth generally remained significantly smaller, staying below 0.6 N. The traction force exerted via hooks decayed to 84.3% and was primarily concentrated on the canines, whereas traction force applied via buttons transmitted approximately 96.1% and was more readily distributed to other teeth.ConclusionElastic traction is not sufficient to completely counteract the initial reactive forces produced by the deformation of CAs. It is advisable to use stronger elastics or extend aligner wear time to ensure sufficient anchorage protection. Utilizing traction with buttons can reduce mechanical loss and enhance the transmission of traction force to other teeth.

Research on Adhesion Performance of Track Monomer with Bionic Structure.

Goats can walk freely and flexibly in complex environments such as concave and convex or soft ground. And their flexible spine has functions such as adjusting balance and providing auxiliary power during movement, while the limbs only have support functions. The spine has an adjustable and decisive role in the pressure on the sole of the hoof of the goat. Therefore, the goat spine was taken as the bionic prototype, the three-dimensional force distribution of the goat body space was analyzed, and the optimal spinal space curve was explored, combined with the goat gait cycle. Based on the study of spinal curve arrangement and placement, the spinal curve was stretched along the grouser length direction. The soil contact surface structure of the track monomer was constructed based on functional simulation. And the bionic structure of the track monomer with superior adhesion performance was explored. The results of simulation analysis and soil tank test both showed that the attachment performance of bionic structure was better than that of an ordinary structure. It showed that adding bionic curves to the contact surface of the track monomer could significantly improve the adhesion performance, and the bionic structure with a single bionic curve arranged on the complete contact surface of the track monomer had the best adhesion performance. Moreover, the adhesion of the optimal track monomer bionic structure was increased by 19.22 N compared with an ordinary structure in the soil tank test, which verified the superiority of the track monomer bionic structure design. It provides a new method and a new idea for improving the adhesion performance of tracked vehicle in hilly areas.

Analysis of the Influence of Bearing Plate Position on the Uplift Bearing Capacity of Low-Header CEP Single-Pile Foundations

This study investigates the impact of the bearing plate position on the uplift bearing capacity of low-header concrete expanded pile (CEP) foundations using the ANSYS finite element simulation method. Nine models of low-header CEP single piles with varying bearing plate positions are constructed. Incremental loading is applied to obtain relevant data, including load–displacement curves for vertical tensile forces, displacement contours, and shear stress distributions. The study analyzes the characteristics of load–displacement curves under different loading conditions, the axial force distribution along the pile shaft, the failure state of the surrounding soil, and how the uplift bearing capacity varies with changes in the bearing plate position. Based on the findings, a calculation model for the uplift bearing capacity of low-header CEP single-pile foundations is proposed. Given that the uplift bearing capacity decreases to varying degrees depending on the bearing plate position, the slip-line theory from previous studies is applied to refine the corresponding calculation formula for uplift bearing capacity. The results from the ANSYS finite element simulation confirm that the bearing plate position significantly influences the uplift bearing performance of low-header CEP single-pile foundations. The uplift bearing capacity increases with the distance between the bearing plate and the low header, reaching a peak before decreasing beyond a certain threshold. Considering the influence of the bearing plate position on bearing capacity, the affected area of soil beneath the foundation, and the time required for the system to enter its working state, the optimal bearing plate position is found to be at a distance of d1 = 4R0 to 5R0 from the top of the pile.

Microtubule-driven cell shape changes and actomyosin flow synergize to position the centrosome.

The regulation of centrosome position is critical to the alignment of intracellular structures with extracellular cues. The exact nature and spatial distribution of the mechanical forces that balance at the centrosome are unknown. Here, we used laser-based nanoablations in adherent cells and found that forces along microtubules were damped by their anchoring to the actin network, rendering them ineffective in moving the microtubule aster. In contrast, the actomyosin contractile network was responsible for the generation of a centripetal flow that robustly drives the centrosome toward the geometrical center of the cell, even in the absence of microtubules. Unexpectedly, we discovered that the remodeling of cell shape around the centrosome was instrumental in aster centering. The radial array of microtubules and cytoplasmic dyneins appeared to direct this reorganization. This revised view of the respective roles of actin and microtubules in centrosome positioning offers a new perspective for understanding the establishment of cell polarity.

Group Effects of Energy Pipe Piles Embedded in Layered Transversely Isotropic Soils Due to Thermo‐Mechanical Loading

ABSTRACTEnergy pile technology is an environmentally sustainable and economically viable solution to achieve building thermal comfort. Energy pipe piles offer advantages over solid piles due to their inner hollow space, allowing for the installation of heat exchange tubes and optimization of backfill materials. Although the activation of an energy pile group can significantly promote the heat exchange performance for satisfying the energy demand of upper structures, there is currently no efficient calculation method available for the energy pipe pile group. Hence, this paper utilizes the coupled boundary element‐finite element method to investigate behaviors of energy pipe pile groups embedded in layered transversely isotropic soils, aiming to guide optimal design and accelerate application promotion. The proposed method's validity is confirmed through field tests and finite element simulations. Parametric analyses indicate that the reduction of pile thickness weakens the group effect, and the induced tensile forces in pipe piles under cooling conditions should be paid more attention when the pile spacing is large and the soil is stiff. Besides, a stiff bearing stratum minimizes the overall settlement and facilitates the uniform axial force distribution within energy pipe pile groups.

Pressure Inside Hadrons: Criticism, Conjectures, and All That

The interpretation of the energy-momentum tensor form factor \(D(t)\) of hadrons in terms of pressure and shear force distributions is discussed, concerns raised in the literature are reviewed, and ways to reconcile the concerns with the interpretation are indicated. Abstract Published by the Jagiellonian University 2025 authors