Tension Forces Research Articles

Needleless graft preparation for anterior cruciate ligament reconstruction with 4-strand semitendinosus autograft: a biomechanical in vitro study using a porcine model

BackgroundRuptures of the anterior cruciate ligament (ACL) are common injuries. Reconstruction using autologous grafts is recommended to prevent further damage and functional impairment. Grafts are usually prepared with stabilizing sutures. The aim of this study was to evaluate if a 4-strand semitendinosus autograft preparation technique is non-inferior to conventional preparation techniques with regard to maximum tensile strength threshold.MethodsFresh porcine flexor tendons were used as specimens in this study. Four different preparation techniques for quadruple-folded tendons were compared. Group 1 three suture FiberWire® (n = 20) and Group 2 one suture FiberWire® (n = 20) using Krakow stitches, Group 3 (n = 10) using SPEEDTRAP® and piercing the autograft and 4 (n = 9) using SPEEDTRAP® without piercing the autograft for preparation. Biomechanical tensile testing included 50 sinusoidal cycles of preloading between 50 and 150 N at 1 Hz and load-to-failure was measured at 20 mm/min.ResultsFailure at the maximum load occurred at the filament for all samples, whereas failure of the suture/tendon interface was not observed. Load-to-failure was significantly higher in Group 1 (711 ± 91 N) than in all other groups. When comparing groups 2–4 load-to-failure was significantly higher in Group 2 (347 ± 24 N) than in Group 3 (258 ± 25 N, p < 0.02) but not than in Group 4 (325 ± 26N).ConclusionIn all 4 Groups the load to failure was higher than the maximum tension force on the construct that will be applied by hand (182N). Therefore, the needleless preparation technique seems to be a valuable alternative to conventional techniques for the insertion of the graft into the joint during joint-near tibial fixation technique.

Secondary Reconnection Between Interlinked Flux Tubes Driven by Magnetic Reconnection With a Short X‐Line

AbstractA three‐dimensional particle‐in‐cell simulation is performed to study secondary reconnection between two interlinked flux tubes produced by neighboring guide field reconnection x‐lines. The reconnecting magnetic fields of this secondary reconnection is enhanced toward the diffusion region, agree well with that in observations. The magnetic field pileup is attributed to the upstream magnetic tension force, that smashes the flux tubes into each other. We propose that the primary reconnection x‐line length is a key parameter to determine the formation of interlinked flux tubes and secondary reconnection therein. Interlinked flux tubes will form only if the x‐line is short; when the x‐line is long enough, the regular flux ropes are formed instead. The critical x‐line length to form interlinked flux tubes is determined by the distance between two neighbor x‐lines and the magnetic shear angle of the primary reconnection. The results provide a novel scenario of secondary reconnection generation during three‐dimensional reconnection.

Numerical Simulation of Anchor Pullout and Shear Tests Using a Regularized Damage Model

The prediction of the mechanical behavior of anchorage plates in reinforced concrete is crucial for ensuring equipment reliability, particularly in sensitive installations. This paper employs finite element analysis to forecast the experimental outcomes of anchor pullout and shear tests. In this article, a regularized damage model is proposed to simulate the effects of loads transmitted to the concrete by the anchor rod. Specifically, a modified Mazars model is introduced, incorporating an “energetic” regularization in both tension and compression. The model is validated for a single anchor rod under tension and subsequently for a complete anchorage system subjected to both tension and shear forces. Various failure modes, such as concrete cone cracking or steel rupture, are accurately represented, alongside the overall anchorage strength. This approach, thus, faithfully reproduces the mechanical behavior of anchorage plates, ensuring equipment robustness under diverse loading conditions.

TwoPhaseInterTrackFoam: an OpenFOAM module for Arbitrary Lagrangian/Eulerian Interface Tracking with Surfactants and Subgrid-Scale Modeling

We provide an implementation of the unstructured Finite-Volume Arbitrary Lagrangian / Eulerian (ALE) Interface-Tracking method for simulating incompressible, immiscible two-phase flows as an OpenFOAM module. In addition to interface-tracking capabilities that include tracking of two fluid phases, an implementation of a Subgrid-Scale (SGS) modeling framework for increased accuracy when simulating sharp boundary layers is enclosed. The SGS modeling framework simplifies embedding subgrid-scale profiles into the unstructured Finite Volume discretization. Our design of the SGS model library significantly simplifies adding new SGS models and applying SGS modeling to Partial Differential Equations (PDEs) in OpenFOAM. Program summaryProgram Title: twoPhaseInterTrackFoamCPC Library link to program files:https://doi.org/10.17632/6b49wb7fvd.1Developer's repository link:https://gitlab.com/interface-tracking/twophaseintertrackfoamreleaseLicensing provisions: GPLv3Programming language: C++Nature of problem: Two-phase flow problems involving surface-active agents (surfactants), variable surface tension force and very sharp boundary layers.Solution method: An OpenFOAM implementation of the Arbitrary Lagrangian / Eulerian Interface Tracking method.

Fundamental Study for Slip Resistance Improvement of High-Strength Bolted Joints Subjected to Shear and Tension

AbstractThe objective of this study was to refine the slip resistance formulas for high-strength bolted joints subjected to combined shear and tension forces. Traditional formulas typically assume that the prying force generated at the contact surface does not contribute to the slip resistance. To explore the influences of the prying force on slip resistance, a trial design was conducted based on the Specifications for Highway Bridges and Recommendation for Design of High Strength Tensile Bolted Connections for Steel Bridges, with variations in parameters such as bolt diameter, bolt pitch, joint flange thickness, and joint flange material. Additionally, numerical analyses were performed to validate the design methodology incorporating prying force. The trial design results demonstrated that the slip capacity improved when the prying force was considered, especially in cases where the external force direction ranged between 27.6 and 90 degrees. The maximum observed improvement in slip capacity was a factor of 1.2. Moreover, the slip resistance of joints with thinner flanges was enhanced when prying force effects were accounted for. This increase in slip capacity due to prying force was further corroborated through fine element method (FEM) simulations. Finally, the findings suggest the potential for enhancing joint compactness and slip resistance.

Bubble-driven heater dynamics in saturated pool boiling

Exploring energy within boiling system is becoming an effective way to enhance heat transfer nowadays. Novel bubble-driven heater has great potential to achieve it. However, heater dynamics in this technique are crucial but unclear in previous studies. Here, boiling on a movable suspended heater with the same density of liquid was simulated to investigate heater dynamics and corresponding mechanisms in detail. Smaller departure diameter and higher frequency were found on movable heater. Periodical up-down motion was observed and the upward movement only occurred at high heat fluxes. Up-down motion contributed to small dry spot diameter and rapid cold liquid supply. The mechanism of different motion over entire bubble cycle was investigated for the first time. Heater moved downwards due to evaporation momentum force (Fe) and add mass force (Fa) during the initial bubble growth stage with expanding triple line, moved upwards due to surface tension force (Fs) during bubble growth period with nearly constant triple line, and it moved downwards again due to Fa when bubble departed. Fa and Fe which impeded bubble departure before were found benefit departure by induced movable heater. Heater manipulation mechanism was found and our study would benefit the design of smart and automatic heater.

Study on Error Influence Analysis of an Annular Cable Bearing-Grid Structure

Manufacturing errors of cable length, external node coordinates and tension force by the passive tension method are inevitable, which will inevitably affect the prestressing of cable bearing-grid structures, while existing studies lack the error analysis of error influences in this area. This paper proposes a method for analyzing random errors in constructing annular cable bearing-grid structures. An error control index and a normal distribution-based random error model, considering the impact of cable and ring beam length errors on cable force, were established afterwards. Taking the roof of the Qatar Education City Stadium as an example, the influence of the length errors of the radial cable, ring cable, and outer pressure ring beam on the structural cable force and stress level was analyzed, and the coupling error effect analysis was carried out. The results show that ring cable force and radial cable force are less affected by the length error of each other’s cables, while they are more affected by the length error of the outer ring beam. Stress levels exhibit greater sensitivity to outer ring beam errors compared to cable length errors. As the error limits of outer ring beam increase, radial and ring cable error ratios and outer ring beam stress errors also rise.

A consistent, volume preserving, and adaptive mesh refinement-based framework for modeling non-isothermal gas–liquid–solid flows with phase change

This work expands on our recently introduced low Mach enthalpy method (Thirumalaisamy and Bhalla 2023) for simulating the melting and solidification of a phase change material (PCM) alongside (or without) an ambient gas phase. The method captures PCM’s volume change (shrinkage or expansion) by accounting for density change-induced flows. We present several improvements to the original work. First, we introduce consistent time integration schemes for the mass, momentum, and enthalpy equations, which enhance the method stability. Demonstrating the effectiveness of this scheme, we show that a system free of external forces and heat sources can conserve its initial mass, momentum, enthalpy, and phase composition. This allows the system to transition from a non-isothermal, non-equilibrium, phase-changing state to an isothermal, equilibrium state without exhibiting unrealistic behavior. Furthermore, we show that the low Mach enthalpy method accurately simulates thermocapillary flows without introducing spurious phase changes. To reduce computational costs, we solve the governing equations on adaptively refined grids. We investigate two cell tagging/untagging criteria and find that a gradient-based approach is more effective. This approach ensures that the moving thin mushy region is always captured at fine grid levels, even when it temporarily falls within a subgrid level. We propose an analytical model to validate advanced computational fluid dynamics (CFD) codes used to simulate metal manufacturing processes (welding, 3D printing). These processes involve a heat source (like a laser) melting metal or its alloy in the presence of an ambient (inert) gas. Traditionally, studies relied on artificially manipulating material properties to match complex experiments for validation purposes. Leveraging the analytical solution to the Stefan problem with a density jump, this model offers a straightforward approach to validating multiphysics simulations involving heat sources and phase change phenomena in three-phase flows. Lastly, we demonstrate the practical utility of the method in modeling porosity defects (gas bubble trapping) during metal solidification. A field extension technique is used to accurately apply surface tension forces in a three-phase flow situation. This is where part of the bubble surface is trapped within the (moving) solidification front.

Development of a Shoelace Tensile Testing System and Investigation into the Effects of Different Running Speeds on Shoelace Tensile Variation

AbstractThis study investigated the validity and sensitivity of a custom-made shoelace tensile testing system. The aim was to analyze the distribution pattern of shoelace tension in different positions and under different tightness levels during running. Mechanical tests were conducted using 16 weights, and various statistical analyses, including linear regression, Bland-Altman plots, coefficient of variation, and intraclass correlation coefficient, were performed to assess the system’s validity. Fifteen male amateur runners participated in the study, and three conditions (loose, comfortable, and tight) were measured during an upright stance. The system utilized VICON motion systems, a Kistler force plate, and a Photoelectric gate speed measurement system. Results showed a linear relationship between voltage and load at the three sensors (R2 ≥ 0.9997). Bland-Altman plots demonstrated 95% prediction intervals within ± 1.96SD from zero for all sensors. The average coefficient of variation for each sensor was less than 0.38%. Intraclass correlation coefficient values were larger than 0.999 (p&lt;0.0001) for each sensor. The peak tension of the front shoelace was greater than that of the front and middle when the shoelace was loose and tight. The rear shoelace had the highest tension force. The study also found that shoelace tension varied throughout the gait cycle during running. Overall, this research provides a novel and validated method for measuring shoelace tensile stress, which has implications for developing automatic shoelace fastening systems.

A Framework for Evaluating the Reasonable Internal Force State of the Cable-Stayed Bridge Without Backstays

The synchronous construction of the pylon and cables of a cable-stayed bridge without backstays has the characteristics of a short construction period and reduced support costs. However, it also increases the difficulty of construction control, making the reasonable completion state of the bridge more complex. To investigate the impact of various load parameters on the structural state of a cable-stayed bridge without backstays during the synchronous construction process, and to ensure a rational final bridge state, this study proposes an assessment framework for evaluating the internal forces of the bridge. The framework initially uses the response surface method to establish explicit equations relating the control indicators of the bridge’s final state to various load parameters. Subsequently, through sensitivity analysis, the degree of influence of each load parameter on the structural response of the cable-stayed bridge without backstays is examined. The most sensitive factors are identified to create a bridge parameter influence library, which helps reduce computational costs. Based on this, a method for controlling construction errors and predicting cable forces is proposed. This method utilizes the pre-established bridge parameter influence library, combined with the internal force state of the bridge at the current construction stage, to accurately predict the tension force of the stay cables in the subsequent stage, thereby ensuring a rational final bridge state. The framework is ultimately validated through a case study of the Longgun River Bridge to assess its rationality and effectiveness.

Microsurgical vascular suture

Anastomosis of two vessels by end-to-end or end-to-side suturing to create an uninterrupted blood flow between the two vessels. Transplantations; replantations; vascular trauma. Active infections in the area to be vascularized or surgical site; large differences in caliber between the vessels; hypercoagulability; extensive tissue damage. First, clamping, cleaning and flushing of the vessel ends; adaptation of the vessel ends using end-to-end or end-to-side anastomosis, using an end-to-side anastomosis if an existing vessel axis should not be interrupted; creation of the anastomosis using asingle button suture or continuous suture technique; careful avoidance of puncturing the posterior wall and exact adaptation of the vessel ends without leaks; release of the blood flow and examination of the anastomosis. Postoperative avoidance of traction, tension, pressure and shear forces on the anastomosis; regular blood flow checks of the revascularized tissue or flap; sufficient anticoagulation. An atraumatic and gentle suturing technique is abasic requirement for asuccessful anastomosis. Special suturing techniques can improve the anastomosis of fragile vessels.

Influence of rope fastening on the spectrum of its natural transverse vibrations

According to the previously developed method, which takes into account the bending stiffness of steel ropes during their transverse oscillation, the ropes of the pedestrian bridge ‘Lovers’ in the city of Tyumen were investigated. The obtained values of tension forces and bending stiffness were within the expected range. The high variation of bending stiffness values forced to pay attention to the accuracy of the initial values of rope lengths, which were obtained from the photograph. To measure the rope lengths, a method of nodal harmonic registration was proposed, but the results obtained by this method were higher than the values obtained from the photograph. The evaluation of measurement errors did not explain this overestimation, which led to the necessity to revise the solution of the differential equation of transverse oscillations. It turned out that previously only its partial solution was considered, assuming a hinged rope attachment, whereas it is cantilevered and has a bending reaction. Taking this feature into account by introducing an additional boundary condition allowed to improve the calculation model and explain the overestimation of the rope length in the method of nodal harmonics.Taking into account the nature of the rope attachment allowed us to introduce a generalised parameter s, which takes zero value for rigid cantilever attachment, and is equal to one for articulated attachment. Then the stiffness weakening inside the anchorage will be manifested by the growth of the parameter s and can be detected by the results of the oscillation spectrum registration.

Modified Use of the Component Method to Get More Realistic Force Distribution in Joints of Steel Structures

According to the EN 1993-1-8 Standard, the moment resistance of end-plated connections can be calculated with the use of the component method. In this, a pair-of-force defines the moment resistance. The magnitude and the location of the compression force can be accurately identified. The tension force part is usually the resultant of parallel forces appearing in line with the bolt rows. Following the rules of manual calculation and using a mechanical finite element model, where each component is modelled with spring elements, in some—easily identifiable—cases, leads to different force distribution. The simplifications defined in the Standard provide a longer arm for the same force, and because of this, larger moment resistance at the expense of safety. In this work, an alternative calculation method will be presented that provides the same force values in each bolt row, as the mechanical model of the connection, without constructing the finite element model.

An active energy management distributed formation control for tethered space net robot via cooperative game theory

The current studies for Tethered Space Net Robot (TSNR) typically treat the tension force induced by the net as a disturbance and employ passive suppression for compensation. However, these approaches not only result in excess fuel consumption but also overlook the intrinsic nature of the net dynamics. When one Maneuverable Unit (MU) maneuvers, it generates a tension force on the net that is transmitted to other MUs. This force not only affects the control accuracy of other MUs but also has a positive effect. In this paper, an Active Energy Management Distributed Formation Control (AEMC) strategy is proposed to reveal this kind of interaction and maximize its advantage. Firstly, an energy recovery framework is established, allowing each MU can effectively utilize the tension force due to the net. Specifically, a neural network estimator is designed to capture the hysteresis relationship in which MUs influence each other by transmitting forces through the net. Furthermore, to achieve the cooperative completion of tasks, a game based control scheme is proposed to optimize the control input and tension force collectively. Through prediction and optimization, MUs actively manage their impacts on each other, thereby controlling the influence of tension force on the tracking errors of others. Finally, numerical simulations are conducted to showcase the effectiveness of the proposed approach.

Non-intrusive experiments on coupled bubble dynamics and heat transfer during nucleate boiling under varying pressure conditions

The experimental investigation is concerned with the dynamics of single vapor bubble and heat transfer during nucleate boiling under varying pressure conditions, encompassing both atmospheric and sub-atmospheric levels. Utilizing high-speed rainbow schlieren deflectometry, a non-intrusive imaging technique for visualizing and quantifying the flow field variables in the fluid medium, this research examines the influence of operating pressure on some of the important parameters pertaining to boiling phenomenon such as bubble size, shape, and detachment mechanisms. The observations show that a decrease in pressure leads to the formation of larger bubbles, which, in turn, alters their growth mechanism. These changes in bubble behavior have a significant influence on the various forces acting on the growing bubble as well as on the associated heat transfer rates. The analysis provides insights into the complex interplay between buoyancy, surface tension, growth and contact pressure forces. Change in pressure significantly impacts these forces, influencing bubble dynamics. Moreover, the study presents a quantitative analysis of the whole field temperature distribution and heat transfer rates throughout the boiling process. Results reveal a strong dependence of thermal field on the working pressure, with higher pressures leading to more uniform temperature distributions. Evaporative component of heat transfer from the bubble base and convective heat transfer from the superheated layer are identified as the dominant mechanisms. Natural convection initially dominates, decreases post-nucleation, and increases upon bubble departure due to the fluid quenching effects.

Assessment of the free shear boundary condition in a capillary meniscus via molecular dynamics

Computational fluid dynamics models often employ the free shear boundary condition at free surfaces, a result from the continuity of the stress and the large viscosity contrast at liquid–gas interfaces. This study leverages nonequilibrium molecular dynamics simulations to investigate the validity of the free shear boundary condition on the exposed surface of a liquid meniscus at the nanoscale. The primary objective is elucidating the fundamental mechanisms and behavior of fluid interactions within a capillary meniscus formed between two carbon nanotubes (CNTs) in shear-driven flow. Shear-driven flow simulations were conducted by varying the velocity of a solid slab to induce different shear rates in the adjacent water molecules. The results demonstrate, for the first time, negligible shear at the free surface, supporting the free shear assumption from the nanoscale point of view. A force balance analysis reveals that capillary and surface tension forces dominate within the meniscus, dictating its shape and stability. Meniscus deformation was observed and primarily attributed to interatomic interactions between water molecules and CNTs, driven by a combination of short-range repulsive forces and van der Waals attractions. The minimal contribution from shear forces suggests that interatomic forces, rather than applied shear stress, are the primary drivers of the meniscus deformation. These findings offer valuable insights into fluid behavior and a sound fundamental analysis of the free shear boundary condition at the nanoscale.

A general model for spin coating on a non-axisymmetric curved substrate

We derive a generalised asymptotic model for the flow of a thin fluid film over an arbitrarily parameterised non-axisymmetric curved substrate surface based on the lubrication approximation. In addition to surface tension, gravity and centrifugal force, our model incorporates the effects of the Coriolis force and disjoining pressure, together with a non-uniform initial condition, which have not been widely considered in existing literature. We use this model to investigate the impact of the Coriolis force and fingering instability on the spreading of a non-axisymmetric spin-coated film at a range of substrate angular velocities, first on a flat substrate, and then on parabolic cylinder- and saddle-shaped curved substrates. We show that, on flat substrates, the Coriolis force has a negligible impact at low angular velocities, and at high angular velocities results in a small deflection of fingers formed at the contact line against the direction of substrate rotation. On curved substrates, we demonstrate that, as the angular velocity is increased, spin-coated films transition from being dominated by gravitational drainage with no fingering to spreading and fingering in the direction with the greatest component of centrifugal force tangent to the substrate surface. For both curved substrates and all angular velocities considered, we show that the film thickness and total wetted substrate area remain similar over time to those on a flat substrate, with the key difference being the shape of the spreading droplet.

Comparative Analysis of Flexural Properties of Bamboo-Glass Hybrid FRP Composites: Influence of Water Absorption

Hybrid fibers are crucial in the self-propelled vehicle industry, with bamboo-glass fiber composites playing a significant role. Bamboo fibers, in particular, feature numerous tiny gaps that enhance their properties and performance. Hence there is a possibility for the absorption of moisture content from the atmosphere when compared to the relevant fibers. These setbacks can be rectified in various ways. Apart from that these fibers are very friendly to echo systems, can degrade quickly, and are flexible in their property. The major drawbacks of most of the fibers are, that they get easily affected by bacteria and fungus when they get soaked and wetted. But as far as the bamboo fibers are concerned they have a high resistance to these attacks. Therefore these materials can be preferred for external use such as engine guards of vehicles. The bamboo fiber in the glass hybridized polyethylene composite is alkali-treated to enhance the adherence of these materials. The high interpenetration of the resin into the fiber surface reduces the contact of this fiber especially the bamboo’s direct reach to the atmosphere. In this work, this hybrid material is preferred for doing a two-wheeler engine safety guard or a protective cover to protect the engine from the external natural compressive or the tensional forces acting on the engine when moves forward along with the vehicle. So, there is a necessity for measuring the flexural strength of the material, whether it will be suitable for this assigned work and also the stiffness of the material is obtained through the flexural modulus curve. Apart from this though these materials are placed in the outdoor sector, these materials can get in contact with external climatic conditions such as rain, dust, and moisture due to cold climatic conditions. This leads to the need for conducting the water absorption test. The test was conducted separately to obtain the water absorption coefficient as well as flexural test before and after water absorption to obtain any deviation if any after water absorption. The test was conducted in the open atmosphere at room temperature for both water absorption and flexural test. The results were tabulated and compared. The comparative study shows that only negligible deviation in property due to water absorption of the hybrid composite is observed.

Research on the reliability of wire web in diamond multi-wire saw slicing photovoltaic monocrystalline silicon wafer

Diamond multi-wire slicing technology is the main method for producing the solar cell substrate based on monocrystalline silicon. To reduce the production cost and increase the production efficiency during the sawing process, the diameter of the diamond saw wire is becoming thinner, and the sawing speed is getting faster, which leads to an increasingly prominent problem of saw wire breakage during the slicing process. To understand the breaking characteristics of diamond saw wire and evaluate the reliability of the saw wire during the sawing process, the tensile testing of saw wires was carried out in this paper. And based on the Weibull function, the breaking force was analyzed statistically. A maximum tension force model for the saw wire during the sawing process was established. And based on the maximum tension force model and Weibull reliability function, the influence of various process parameters on the reliability of the wire web was analyzed. The results indicated that as the usage time of the saw wire increases, the breaking force gradually decreases and stabilizes. Compared to the fresh saw wire, the reliability of the used saw wires is significantly reduced. As the abrasive distribution density and the wire speed increases, the reliability of the wire web gradually increases. Conversely, as the feed speed and the pretension of the saw wire increase, the reliability of the wire web gradually decrease. The results of this paper provide a theoretical approach for assessing the reliability of diamond saw wire web during the sawing process. It also provides guidance for optimizing process parameters to enhance the reliability of the wire web.

Optimizing Electron‐Beam Photothermal Pyrolysis Parameters for Enhanced Molecular Biodegradability of Polyvinyl Chloride Plastics

AbstractPolyvinyl chloride (PVC), a synthetic plastic notable for harmful emissions during deterioration, has potential to be molecularly adjusted by photo‐oxidative ultraviolet degradation. This research investigates the influence of electron beam irradiation and near‐infrared photothermal treatment utilizing gold nanoparticles to establish the optimized molecular weight and beam time exposure for biodegradable PVC properties while maintaining a minimum tensile strength as measured through the ratio of peak tension force by cross sectional area. PVC powder samples with number‐average molecular weights ranging from 20.0 to 90.0 kDa and varying exposure times of a 100 kGy electron beam from 80 to 115 ms are employed for the study. Outcomes from PVC irradiation reveal the optimal parameters for inducing biodegradability in samples: an e‐beam exposure duration of 95 ms applied to PVC powder with a sample molecular weight of 20.0 kDa. Analysis of the ratio of number average molecular weight and weight average molecular weight demonstrates that shorter irradiation durations result in lower molecular weights and molecular weight is directly proportional to Tg and crystallinity. Future work aims to scale up the procedure to industrial applications and investigate the treatment's applicability to a variety of thermoplastics.