Tension Distribution Research Articles

Predictive reliability assessment of suction caissons for moored floating systems

A procedure for assessing the predictive reliability of suction caissons under inclined loads from mooring lines of floating systems is developed. It considers the randomness of the maximum dynamic tension in the mooring lines during extreme sea states. Parameters of the probability distribution of the maximum dynamic line tension are expressed as function of the uncertain extreme sea-state variables employing response surfaces. Line tensions from catenary and taut-leg mooring models are considered for the response surfaces. Reliability analyses are performed at the mudline, so that loading and caisson capacity can be considered statistically independent. Load capacity is modeled using the plastic limit method considering suction caissons in normally consolidated clays and response surfaces for capacity are generated in terms of geotechnical variables. A nested reliability formulation is presented employing an auxiliary limit state function which is solved numerically applying FORM. The influence of geotechnical variables on the predictive failure probability is studied. Also, the effect of accounting for parameter uncertainty in the loading on the reliability assessment of suction caissons is evaluated.

A study on the influence of a surface-contacting spinning strand on yarn appearance during sirofil spinning

Ring spun yarn hairiness can be reduced by such methods as spinning with a contact surface and Z-twisting the staple strand in a “left diagonal” yarn path (denoted as LDP). Actually, the LDP method already exists in sirofil spinning technology. In this study, mechanism analysis of controlling and trapping staple fibers is conducted theoretically for sirofil spinning with a contact surface. Analysis reveals that contacting with a rubber surface leads to deformation of the straight sirofil spinning strand; this can better the tension and twist distribution on the right-hand component of the sirofil spinning triangle to improve LDP sirofil yarn appearance. Related experiments are also carried out to validate the theoretical analysis. Online pictorial investigation confirms the deformation of the straight sirofil composite yarn once it contacts with a rubber surface. Experimental results show that the lower weight loss and smoother appearance are bestowed upon LDP sirofil yarn spun with a rubber contact surface, which agrees well with corresponding theoretical analysis.

Integrated analysis of drag embedment anchor installation

During installation of drag embedment anchors (DEAs), the anchor, tensioned mooring line and anchor-handling vessel interact with each other and make up an integrated system. This paper presents an integrated quasi-static model for the anchor, line and vessel for use in simulating the installation of DEAs by moving vessels or stationary vessels. The differences in the anchor׳s kinematic trajectory, line profiles and tension distributions for these two installation methods were analyzed. The examples indicate that there is a line length for each installation method that optimizes the installation efficiency. The effects of different types and lengths of lines, different types of soil behavior and different fluke–shank angles are also considered in the practical suggestions given for DEA installation.

A Calculation Method Based on Tension Distribution and Temperature Compensation for Sliding Cables

The calculation of sliding cable is difficult because it can dynamically pass through prescribed nodes and the length is variable. In order to solve the above problem, a calculation method based on tension distribution and temperature compensation for sliding cables was put forward. At first, the sliding cable was supposed to be fixed cable and the internal force of each cable segment was calculated. Then, the unbalanced tensions between neighboring cable segments were distributed to make the tensions equal. And then different temperatures were applied to the corresponding cable segments, which could cause temperature stress to compensate the unbalanced tensions between the initial calculated tensions and distributed tensions. At last the calculation was carried on again after applying the temperature to each cable segment. Moreover, an example was presented to verify the precision and validity of this method. The results show that the calculation method based on tension distribution and temperature compensation for sliding cables is effective.

Quasi-elastic laser scattering for measuring inhomogeneous interfacial tension in non-equilibrium phenomena with convective flows.

An inhomogeneous distribution of interfacial tension can induce different types of non-equilibrium spontaneous motion at the interface by convective flow, or by the solutal Marangoni effect. Several applications of the quasi-elastic laser scattering (QELS) method used to study these effects are presented here. The relationship between the interfacial tension and the non-equilibrium phenomena has been verified experimentally for each application. In a water/nitrobenzene oscillatory system with continuous surfactant addition to the interface, the local adsorption of surfactants at the interface has been demonstrated and shown to be strongly related to the presence of electrolytes. In a donor/membrane/acceptor system, the dual-beam QELS method shows that surfactant adsorption at the membrane/acceptor interface is responsible for oscillations in the electric potential. The differences in the adsorption/desorption behavior of metal complex catalysts between air/liquid and liquid/liquid interfaces were considered in the propagating chemical waves of the Belousov-Zhabotinsky reaction. We successfully measured the distribution of interfacial tension around a self-propelled camphor boat and an alcohol droplet floating on an aqueous phase, and compared the mechanisms of their motion.

계측기반모델에 의한 사장케이블의 장력 평가

본 연구는 교량의 상시계측자료인 고유진동수 및 고유모드를 기준으로 계측기반모델을 구성하고, 구조해석을 수행하여 교량 공용상태에서 사장케이블 장력평가를 수행하였다. 케이블 설치 위치에 따라 하중유형별 케이블 장력이 다르다는 것을 알 수 있다. 고정하중과 활하중에 의한 케이블 계측장력은 케이블 설치위치에 따라 차이가 크지 않으나 설계하중을 적용한 해석결과보다 큰 값을 나타낸다. 계측기반모델에 대한 케이블장력분포는, 설계모델에 대한 장력보다 크지만, 계측장력과 유사한 분포를 나타낸다. 그러므로 장기거동을 고려하여 사장교 케이블설계는 계측기반모델의 해석결과를 반영할 필요가 있다. 이를 위하여 많은 계측자료를 이용한 장기거동 분석연구가 요구된다. This study presents the recomposition of MBM (measurement-based model) using natural frequencies and modes from the usually measured data, and the evaluation of cable tension in service from the analysis results upon MBM of existing CSB (cable stayed bridge). The cable tension is shown to be different according to the position attached to cable and loading type. The measured cable tensions are not different distinctly according to position attached cable under dead and live loads, but larger than those under design loads. The distribution of cable tension calculated upon the MBM is similar to those of measured tension although the former is more than those of cable tension upon the design model. Considering to long-term behaviors of cable, therefore, the design of cable in CSB needs to apply the analysis results on MBM. For this purpose, future study needs lots of measured data and MBM is used to analyze the long-term behavior of cable in CSB.

Theoretical study of spinning triangle with fiber concentric circular cones arrangement at front nip line

Spinning triangle is a critical region in the spinning process of staple yarn, which geometry influences the mechanical performances of fibers in the spinning triangle and determines the physical performance of spun yarns directly. Taking appropriate measures to reduce the spinning triangle and improve the qualities of yarn has attracted great interesting recently. In these modified ring spinning systems, the fibers in the spinning triangle are not arranged in the same plane, but arranged in concentric circular cones at front nip line, such as compact spinning, in which a fiber-converging device is installed on ring spinning frame, and the fiber bundle can be condensed before twisting in order to reduce the spinning triangle. Therefore, in this paper, a new theoretical model of fiber tension distribution in the spinning triangle with fiber concentric circular cones arrangement at front nip line is proposed based on the principle of minimum potential energy firstly. Then, corresponding residual torque within a yarn caused by the fiber tension is given. Finally, as an application of the proposed method, taking the spinning triangle in Ne40 cotton yarn 3-line rollers compact spinning as an example, the fiber tension distributions in the spinning triangle both with and without fiber buckling and corresponding residual torque within a yarn are numerically simulated, and the results are compared with those from earlier model. Furthermore, the properties of spun yarns produced by compact spinning system and ring spinning system are evaluated and analyzed.

Development of Looper Shape Meter and Verification Test Results in Hot Rolling

The harder and thinner strips, such as high strength steel and so on, have been needed to be rolled. When the rolled strip becomes thinner and harder, the unstable state rolling and tail end pinching might occur and so the strip shape measurement during rolling is strongly required under the condition that tension is applied to the strip. Visual-type shape meter, which has been already used, could not measure the strip shape when tension is applied to the strip. Looper Shape Meter, hereinafter referred as LSM, has been developed which could measure the strip shape under the tension. LSM is installed between mill stands and consists of 7 segment rolls along the width direction and a segment roll has two torque meters. LSM could accurately measure the tension distribution along the width direction without hysteresis and is protected with purge air and internal cooling system against severe environment in hot rolling. In order to verify the performance of LSM, the verification test was carried out in laboratory and production line. As a result, enough durability and good results of measured strip shape are obtained. LSM is easily replaced with existing conventional looper and it is expected that LSM contributes to the stable rolling and improve the productivity of rolling.

Stoichiometry of cytochromes and oxygen tension in skeletal muscles of marine fish

The character of oxygen tension distribution and peculiarities of cytochromes stoichiometry in skeletal muscles of bottom and pelagic species of marine fish were compared. It is shown, that the limitation of muscle activity increases the number of hypoxic zones in the muscle tissue. The mitochondrial electron-transporting chain then obtain the uncompensated type of organization, expressed in the increase of the share of the terminal complex aa3 on the background of general reduction of cytochromes content in the muscles. The reaction is of an adaptive character and can be implemented by pelagic fish species in conditions of experimental hypokinesia.

Simultaneous Measurement of Surface Tension and Its Gradient around Moving Camphor Boat on Water Surface

Abstract The distribution of surface tension on the front and rear sides of a camphor boat continuously moving on an aqueous-phase camphor solution was observed by the time-resolved quasi-elastic laser scattering method. The uniform motion of the boat was induced by a difference in the surface tension between the front and rear sides. A surface-tension gradient developed along the rear side, resulting in Marangoni convection that decelerated the boat.

A finite element modeling technique for an aquaculture net with laboratory measurement comparisons

The escape of fish from an aquaculture facility can be considered a threat to wild populations. Openings in the containment net can occur from stresses induced by inadequate attachments, abrasion or fish bite. The objective of this work involves the development of a net finite element model (FEM) with focus on a representation of the Raschel net structure. An approach is taken with a combination of FEM simulations and laboratory tests. Material and geometric properties of a net were obtained from peer-reviewed literature, standards and complemented with tensile testing. FEM simulations of a net pen system were performed under operational conditions to approximate tensions within the net. The distribution of tension in the net panel was considered a two-dimensional problem dependent on mesh construction. Elongation experiments were conducted with orthogonal loading to measure planar deflections. A FEM of the net panel was then built with a focus on the net structure, loaded and results compared with laboratory data. The results showed that the construction details influence loaded deflections. Next, holes were made in the model by removing trusses representing twine sections, loaded and strain values compared with measurements obtained from laboratory tests with the same holes in the net panel.

Surface Tension Gradient around an Alcohol Droplet Moving Spontaneously on a Water Surface

The surface tension gradients in the front and rear sides of a 1-hexanol droplet exhibiting self-propelled motion were compared by a time-resolved quasi-elastic laser scattering method. The velocity of the alcohol droplet strongly correlated to the difference of the inverse of the recovery distances of the surface tensions between the front and rear sides. This result indicates that the spontaneous alcohol droplet motion is governed by an imbalance in the Marangoni convection flow, induced by an asymmetric surface tension distribution.

Theoretical study of fiber tension distribution at Solospun spinning triangles

Spinning triangle is a critical region in the spinning process of staple yarn. Its geometry influences the distribution of fiber tension in the spinning triangle and affects the properties of spun yarns. Taking appropriate measures to influence the spinning triangle geometry and improve the quality of yarn has attracted great interesting recently. Solospun technology is one of the most important representatives, which is implemented by dividing ring spinning triangle into several small primary triangles and one final triangle using a Solospun roller. Therefore, theoretical study of fiber tension distributions at Solospun spinning triangles is presented in this paper. First, a theoretical model of the fiber tension distributions in Solospun spinning triangles is given by using the principle of minimum potential energy. Second, the relationships between fiber distributions and spinning triangle parameters are analyzed theoretically. Especially, the effects of horizontal offset of the twisting point to triangle symmetric axis of nip line d on fiber tension distributions are discussed and numerical simulations are given. Finally, the properties of spun yarns are evaluated and analyzed by using the simulation results.

Review of distribution of fiber tension at the spinning triangle

In the ring spinning process, the spinning triangle plays an important role in the quality and efficiency of yarn spinning. The distribution of fiber tension at the spinning triangle is important. In this study, models such as energy methods, energy methods using false twist, and finite element method are applied. The model parameters on the distribution of fiber tension in the symmetric and asymmetric spinning triangle with a uniform distribution of single fiber, uniform distribution of fiber types, and distribution buckling fibers in the spinning triangle are analyzed. The results show that there is an increase in the distribution of fiber tension in symmetric spinning triangle. Fibers, depending on their position in the spinning triangle, have different tensions. In single fibers in the twist point, the tension of the fiber bundle is maximum, the fiber tension is less, and the compression force of the fiber bundle is greater. The spinning triangle shape is effective on the distribution of fiber tension.

Influence of Tapered and External Hexagon Connections on Bone Stresses Around Tilted Dental Implants: Three‐Dimensional Finite Element Method With Statistical Analysis

The purpose of this study is to analyze the tension distribution on bone tissue around implants with different angulations (0°, 17°, and 30°) and connections (external hexagon and tapered) through the use of three-dimensional finite element and statistical analyses. Twelve different configurations of three-dimensional finite element models, including three inclinations of the implants (0°, 17°, and 30°), two connections (an external hexagon and a tapered), and two load applications (axial and oblique), were simulated. The maximum principal stress values for cortical bone were measured at the mesial, distal, buccal, and lingual regions around the implant for each analyzed situation, totaling 48 groups. Loads of 200 and 100 N were applied at the occlusal surface in the axial and oblique directions, respectively. Maximum principal stress values were measured at the bone crest and statistically analyzed using analysis of variance. Stress patterns in the bone tissue around the implant were analyzed qualitatively. The results demonstrated that under the oblique loading process, the external hexagon connection showed significantly higher stress concentrations in the bone tissue (P <0.05) compared with the tapered connection. Moreover, the buccal and mesial regions of the cortical bone concentrated significantly higher stress (P <0.005) to the external hexagon implant type. Under the oblique loading direction, the increased external hexagon implant angulation induced a significantly higher stress concentration (P = 0.045). The study results show that: 1) the oblique load was more damaging to bone tissue, mainly when associated with external hexagon implants; and 2) there was a higher stress concentration on the buccal region in comparison to all other regions under oblique load.

Traction Force Microscopy Based on an Active Cable Network Model

Generation of mechanical force is essential for the function of tissue cells, for example during migration, wound healing or rigidity sensing. The traction field of adherent cells can be measured on soft elastic substrates using traction force microscopy (TFM). However, mathematical reconstruction of traction fields effectively requires inversion of the long-ranged elastic equations and therefore is an ill-posed inverse problem. Moreover measurement of the traction pattern alone does not tell us how force is distributed inside the cell. To improve the robustness, resolution and scope of conventional TFM, we have developed a new procedure called model-based TFM (MBTFM). We estimate the distribution of intracellular tension from elastic substrate data by minimizing the difference between the experimentally measured displacement field and the predictions of a detailed theoretical model based on active cable networks. Previously this type of model has been successfully used to predict cell shapes on micropatterned substrates. For MBTFM, we consider not only active network contraction, but also contributions of various types of contractile bundles modeled as contractile one-dimensional line element embedded into the network. Subsequent computer simulations of network contraction and parameter optimization allow us to estimate the most likely distribution of tension over various contractile structures and adhesion sites.

Theoretical Analysis of Membrane Tension in Moving Cells

Lateral tension in cell plasma membranes plays an essential role in regulation of a number of membrane-related intracellular processes and cell motion. Understanding the physical factors generating the lateral tension and quantitative determination of the tension distribution along the cell membrane is an emerging topic of cell biophysics. Although experimental data are accumulating on membrane tension values in several cell types, the tension distribution along the membranes of moving cells remains largely unexplored. Here we suggest and analyze a theoretical model predicting the tension distribution along the membrane of a cell crawling on a flat substrate. We consider the tension to be generated by the force of actin network polymerization against the membrane at the cell leading edge. The three major factors determining the tension distribution are the membrane interaction with anchors connecting the actin network to the lipid bilayer, the membrane interaction with cell adhesions, and the force developing at the rear boundary due to the detachment of the remaining cell adhesion from the substrate in the course of cell crawling. Our model recovers the experimentally measured values of the tension in fish keratocytes and their dependence on the number of adhesions. The model predicts, quantitatively, the tension distribution between the leading and rear membrane edges as a function of the area fractions of the anchors and the adhesions.

On the Minimum Cable Tensions for the Cable-Based Parallel Robots

This paper investigates the minimum cable tension distributions in the workspace for cable-based parallel robots to find out more information on the stability. First, the kinematic model of a cable-based parallel robot is derived based on the wrench matrix. Then, a noniterative polynomial-based optimization algorithm with the proper optimal objective function is presented based on the convex optimization theory, in which the minimum cable tension at any pose is determined. Additionally, three performance indices are proposed to show the distributions of the minimum cable tensions in a specified region of the workspace. An important thing is that the three performance indices can be used to evaluate the stability of the cable-based parallel robots. Furthermore, a new workspace, the Specified Minimum Cable Tension Workspace (SMCTW), is introduced, within which all the minimum tensions exceed a specified value, therefore meeting the specified stability requirement. Finally, a camera robot parallel driven by four cables for aerial panoramic photographing is selected to illustrate the distributions of the minimum cable tensions in the workspace and the relationship between the three performance indices and the stability.

Active Regulation of Cellular Membrane Tension

Cell membrane tension plays a critical rule in a variety of cellular activities, including membrane protein signaling, cell motility and cell blebbing. The specific mechanical environment of eukaryotic cells may result the spatially dependent membrane tension, which is crucial to actin filaments activity. In this work, we will start with simple fluid model to estimate lipid membrane tension in terms of active contractile interaction of actin filaments and polymerization/depolymerization rate. We includes the case of suspended cells and lamellipodium-membrane tension at cells resting on 2D substrates. The simple mechanical model will give us an overall scene of membrane tension distribution at specific order of magnitude, including the surface tension gradient, which cannot be measured by conventional experiment. Membrane tension also actively controls cell membrane blebbing. We also discuss the case of cell motility. We purpose the jet propulsion is the main mechanism for cell moving. The fluid field around the cell imposes an unique mechanical environment to the cell, which we will further demonstrate surface tension distribution and membrane net flow due to the spatially variant tension.

Identification of tension distribution of thin plate using vibration characteristics (Validations of identification accuracy by experiment)

Identification of tension distribution of thin plate using vibration characteristics (Validations of identification accuracy by experiment)