Effect Of Tensile Force Research Articles

A modified dynamic relaxation form-finding method for general tensegrity structures with inextensible tensile members

In tensegrity structures, there may exist tensile members with very low elongation. This type of tensile member is almost inextensible under the effect of tensile force and cannot effectively utilize length change to calculate axial force, posing challenge in form-finding. In this paper, a modified dynamic relaxation (DR) form-finding method for general tensegrity structures with inextensible tensile members is presented. The method considers the compressive members as rigid bodies and establishes pseudo-dynamic equation that incorporate both forces and torques. The existence of inextensible tensile members constrains on the motion of rigid bodies, the mobility analysis via screw theory can decompose the wrenches acting on the rigid bodies into their degrees of freedom space. Through iterative processes, rigid compressive members movement towards equilibrium poses under the action of unbalanced wrenches within the permissible range of mobilities. Numerical examples demonstrate the effectiveness of the proposed method in form-finding of classic tensegrity, general tensegrity, and clustered tensegrity.

A Study of the Performance Degradation of Conductive Threads Based on the Effects of Tensile Forces and Repeated Washing.

In recent years, after the ongoing success in the creation of portable electronic devices, an increasing effort has been put in creating wearable devices capable of sensing multiple parameters while being imperceptible to the user. A field that has recently gained attention due to this is that of textile electronics. For this purpose, one of the most commonly used materials is conductive threads, capable of sustaining an electrical connection, while at the same time being part of a garment. As research on the performance and stability of such threads is scarce, the aim of this work is to study the effects of tension on readily available conductive threads and to verify their suitability and reliability for e-textile applications. After testing seven commercially available threads, this study demonstrates that the nominal parameters provided by the manufacturers are not in line with experimentation, and that both embroidery and washing have an impact on their performance.

Biphasic Force-Regulated Phosphorylation Site Exposure and Unligation of ERM Bound with PSGL-1: A Novel Insight into PSGL-1 Signaling via Steered Molecular Dynamics Simulations.

The PSGL-1-actin cytoskeleton linker proteins ezrin/radixin/moesin (ERM), an adaptor between P-selectin glycoprotein ligand-1 (PSGL-1) and spleen tyrosine kinase (Syk), is a key player in PSGL-1 signal, which mediates the adhesion and recruitment of leukocytes to the activated endothelial cells in flow. Binding of PSGL-1 to ERM initials intracellular signaling through inducing phosphorylation of Syk, but effects of tensile force on unligation and phosphorylation site exposure of ERM bound with PSGL-1 remains unclear. To answer this question, we performed a series of so-called “ramp-clamp” steered molecular dynamics (SMD) simulations on the radixin protein FERM domain of ERM bound with intracellular juxtamembrane PSGL-1 peptide. The results showed that, the rupture force of complex pulled with constant velocity was over 250 pN, which prevented the complex from breaking in front of pull-induced exposure of phosphorylation site on immunoreceptor tyrosine activation motif (ITAM)-like motif of ERM; the stretched complex structure under constant tensile forces <100 pN maintained on a stable quasi-equilibrium state, showing a high mechano-stabilization of the clamped complex; and, in consistent with the force-induced allostery at clamped stage, increasing tensile force (<50 pN) would decrease the complex dissociation probability but facilitate the phosphorylation site exposure, suggesting a force-enhanced biophysical connectivity of PSGL-1 signaling. These force-enhanced characters in both phosphorylation and unligation of ERM bound with PSGL-1 should be mediated by a catch-slip bond transition mechanism, in which four residue interactions on binding site were involved. This study might provide a novel insight into the transmembrane PSGL-1 signal, its biophysical connectivity and molecular structural basis for cellular immune responses in mechano-microenvironment, and showed a rational SMD-based computer strategy for predicting structure-function relation of protein under loads.

FEATURES OF EXTERNAL ROD-CONTROLLED FIXATION IN CALCANEAL FRACTURES

A device for transosseous osteosynthesis of rod type and a technique of external fixation have been developed, which will allow to provide with high degree of efficiency a positive clinical result of reposition of all types of intra−articular calcaneus fractures. The proposed device, based on the apparatus Ilizarov details, as well as technique of osteosynthesis have their own peculiarities, namely the technical ability to use a removable repotent node to perform the reposition of all types of calcaneus fractures. We have used the modified method of closed one−moment instrumental reposition. Own practical experience and observations allowed us, depending on the nature of the destruction of posterior articular facet and types of its displacement, to assert the possibility of using a closed one−time instrumental reposition. The essence consists in distraction surgery, where the main mechanism of indirect reposition is the effect of tensile forces in a certain sequence on surrounding fracture of damaged ligaments, i.e. so−called the effect of ligamentotaxis. According to this method, 6 surgical procedures were performed. In all cases, the use of the proposed device intraoperative repositioning of the posterior articular surface of the heel bone and restoration of the Böhler's angle were considered satisfactory, even with significant destruction. Technical capabilities enables the conclusion about recommending this for surgical treatment of intra−articular fractures of a heel bone. It is advisable to continue research in the specified patient category to confirm the effectiveness of new, minimally invasive surgical intervention. Further improvement and implementation of surgery of intra−articular fractures of calcaneus will improve both the medium and long−term results. Key words: calcaneus, fractures, transosseous osteosynthesis.

The effect of two-parameter of Pasternak foundations on the oscillations of composite pipelines conveying gas-containing fluids

The effect of two-parameter of Pasternak foundations on the oscillations of composite pipelines conveying a two-phase slug flow is studied in the paper. To analyze the oscillations of the pipelines conveying gas-containing fluid, a viscoelastic model of the theory of beams and a model of Pasternak foundation are used. The Boltzmann-Volterra hereditary theory of the viscoelasticity is used to describe the viscoelastic properties of the pipeline material and earth foundation. A computational algorithm has been developed for solving problems of calculating the oscillatory processes in the pipelines conveying a two-phase gas-containing flow. On the basis of the computational algorithm developed, a set of applied computer programs has been created, which makes it possible to carry out numerical studies of pipeline oscillations. The effect of the flow rate of gas and liquid phases, the effect of tensile forces in the longitudinal direction of the pipeline, Pasternak foundations parameters, the parameters of singularity in the heredity kernels on the oscillations of the pipeline made of composite materials are numerically investigated. It is found that an increase in the length of the gas bubble zone leads to a decrease in the critical velocity of a two-phase slug flow.

Collapse resistance of RC beam–slab subassemblies due to column loss at large deflections

This paper proposes an energy-based method to theoretically determine the collapse resistance of reinforced-concrete (RC) beam–slab subassemblies subject to a middle column loss at large deflection. It considers the contributions to internal energy dissipation due to extension of rebar in the slab and beams, the additional resultant bending moment from membrane forces in the slab and catenary tensile forces in beams, and the sectional bending moment at plastic hinges of beams and along yield lines of slabs. Furthermore, the effect of tensile forces on the sectional bending moment of the slab and beams is also accounted for. The effectiveness and accuracy of the proposed method are validated against available test results. The proposed method is found to produce accurate predictions on the collapse resistance of the subassemblies, as well as capture the main feature of mechanism of the subassembly at large deflections. It is concluded that the energy dissipation due to the extension of rebar and additional resultant bending moment significantly contribute to the resistance of subassemblies at large deflections. The interaction between membrane forces and bending moment of the beam and slab sections has a detrimental effect on the collapse resistance. Neglecting this effect will overestimate the collapse resistance for the subassembly.

Effect of Tensile Force on Magnetostrictive Sensors for Generating and Receiving Longitudinal Mode Guided Waves in Steel Wires

When the longitudinal mode guided waves based on magnetostrictive effect were employed to inspect the bridge cables, we found that there was a large difference in the signal’s amplitude of the same specification cable under different tensile force. This difference would affect the test results and the identification of defects. It is necessary to study the effect of tensile force on the signal for the reliability of detection. Firstly, the effective field theory is employed to take the force as an additional bias magnetic field. Then, the effect of the tensile force on generating and receiving longitudinal mode guided waves based on magnetostrictive effect is obtained by the relationship between the bias magnetic field and the magnetostrictive coupling coefficient. Finally, the experiment of the magnetostrictive sensor is carried out on a Φ5 mm steel wire under different force. The experimental results are in good agreement with the theoretical results. The results show that the existence of the tensile force would change the operation point for generating and receiving the longitudinal mode guided waves based on magnetostrictive effect, which associated with the coupling coefficient. In order to obtain the optimal conversion efficiency for the force state wire and cable, the applied bias magnetic field should be set smaller than the bias magnetic field for the force-free state.

Technique of studying thermal diffusivity of metallics in different directions in a field of centrifugal accelerations and forces

Study of the thermal diffusivity of metallics in a field of centrifugal accelerations and forces is essential for aerospace engineering. Characteristics of thermal diffusivity of materials are used in calculations of thermal state of blades and disks of turbine rotors. An original technique and a device on semiconductors have been developed for determination of thermophysical characteristics of materials on an acceleration bench using a vacuum chamber, under centrifugal forces and accelerations. Presented are results on nonstationary heating of heat conductors in the radial and circumferential directions in a field of centrifugal forces and accelerations. Analysis of experimental results shows that the thermal diffusivity of heat conductors grows with rotational speed as compared with a static state without rotation. The thermal diffusivity phenomenon of concern has two components: from centrifugal acceleration and from centrifugal tensile load. From experimental data on the effect of tensile forces it follows that the second component is small. Thus, said thermal diffusivity growth is strongly associated with increase in the velocity of electron drift in ametal under centrifugal acceleration forces.

Observation of ultrasonic guided wave propagation behaviours in pre-stressed multi-wire structures

Ultrasonic guided wave (UGW) is a promising technique for nondestructive testing of pre-stressed multi-wire structures, such as steel strand and wire rope. The understanding of the propagation behaviours of UGW in these structures is a priority to applications. In the present study, first the properties of the UGW missing frequency band in the pre-stressed seven-wire steel strand is experimentally examined. The high correlation between the observed results and the previously published findings proves the feasibility of the magnetostrictive sensor (MsS) based testing method. The evolution of missing frequency band of UGW in slightly tensioned steel strand is discussed. Two calibration equations representing the relationship between the missing band parameters and the tensile force are given to derive a new tensile force measurement method, which is capable of measuring an incremental of stress of approximately 3MPa. Second, the effects of tensile force on the UGW propagation behaviours in three types of complicated steel wire ropes are alternatively investigated based on the short time Fourier transform (STFT) results of the received direct transmission wave (DTW) signals. The observed inherent missing frequency band of the longitudinal mode UGW in the pre-stressed steel wire rope and its shifting to a higher frequency range as the increases of the applied tensile force are reported for the first time. The influence of applied tensile force on the amplitude of the DTW signal and the unique UGW energy jump behaviour observed in a wire rope of 16.0mm, 6×Fi(29)+IWRC are also investigated, despite the fact that they cannot yet be explained.

Tensile force on human macrophage cells promotes osteoclastogenesis through receptor activator of nuclear factorκB ligand induction.

Little is known about the effects of tensile forces on osteoclastogenesis by human monocytes in the absence of mechanosensitive cells, including osteoblasts and fibroblasts. In this study we consider the effects of tensile force on osteoclastogenesis in human monocytes. The cells were treated with receptor activator of nuclear factorκB ligand (RANKL) to promote osteoclastogenesis. Then,expression and secretion of cathepsin K were examined. RANKL and the formation of osteoclasts during the osteoclast differentiation process under continual tensile stress were evaluated by Western blot. It was also found that -100kPa or lower induces RANKL-enhanced tartrate-resistant acid phosphatase activity in a dose-dependent manner. Furthermore, an increased tensile force raises the expression and secretion of cathepsin K elevated by RANKL, and is concurrent with the increase of TNF-receptor-associated factor6 induction and nuclear factor κB activation. Overall, the current report demonstrates that tensile force reinforces RANKL-induced osteoclastogenesis by retarding osteoclast differentiation. The tensile force is able to modify every cell through dose-dependent in vitro RANKL-mediated osteoclastogenesis, affecting the fusion of preosteoclasts and function of osteoclasts. However, tensile force increased TNF-receptor-associated factor6 expression. These results are in vitro findings and were obtained under a condition of tensile force. The current results help us to better understand the cellular roles of human macrophage populations in osteoclastogenesis as well as in alveolar bone remodeling when there is tensile stress.

Tensile forces applied on a cell-embedded three-dimensional scaffold can direct early differentiation of embryonic stem cells toward the mesoderm germ layer.

Mechanical forces play an important role in the initial stages of embryo development; yet, the influence of forces, particularly of tensile forces, on embryonic stem cell differentiation is still unknown. The effects of tensile forces on mouse embryonic stem cell (mESC) differentiation within a three-dimensional (3D) environment were examined using an advanced bioreactor system. Uniaxial static or dynamic stretch was applied on cell-embedded collagen constructs. Six-day-long cyclic stretching of the seeded constructs led to a fourfold increase in Brachyury (BRACH-T) expression, associated with the primitive streak phase in gastrulation, confirmed also by immunofluorescence staining. Further examination of gene expression characteristic of mESC differentiation and pluripotency, under the same conditions, revealed changes mostly related to mesodermal processes. Additionally, downregulation of genes related to pluripotency and stemness was observed. Cyclic stretching of the 3D constructs resulted in actin fiber alignment parallel to the stretching direction. BRACH-T expression decreased under cyclic stretching with addition of myosin II inhibitor. No significant changes in gene expression were observed when mESCs were first differentiated in the form of embryoid bodies and then exposed to cyclic stretching, suggesting that forces primarily influence nondifferentiated cells. Understanding the effects of forces on stem cell differentiation provides a means of controlling their differentiation for later use in regenerative medicine applications and sheds light on their involvement in embryogenesis.

Comparisons of a Polymer in Confinement versus Applied Force

The similarities and differences between geometric and tensile constraints on polymers have not been fully investigated. Here we use theory (blob models) and simulations to present a comprehensive comparison between polymers in these two situations. For a polymer in good solvent, the effect of tensile force f on extension in the Pincus regime is similar to the effect of cylindrical confinement in the de Gennes regime after mapping the characteristic length kBT/f to the cylindrical diameter D, where kBT is the thermal energy. However, the comparison of the effects of tension and confinement on extension is lacking when kBT/f and D are less than the thermal blob size b, referred to as extended Pincus regime and extended de Gennes regime, respectively. In the extended Pincus regime, force can still segregate the ideal-coils with the size of ∼kBT/f, resulting in the scaling of extension L∥ ∼ (kBT/f)−1. In the extended de Gennes regime, excluded volume interaction is not sufficient to segregate the ideal-coils...

Finite Element Analysis for Cyclic Behavior of Exposed Type of Column Bases Subjected to Tensile Force

This paper presents the results of analytical studies on exposed type of column bases, which were carried out to investigate the effect of tensile force on cyclic behavior of column bases. The cyclic behavior of the column bases subjected to tensile force ratio n &gt; -0.4 is stable. While, in the column bases subjected to tensile force ratio n &lt; -0.6, the deformation of base columns progresses with increasing severely under a constant amplitude.

Reverse effect of tensile force on sidewall curl for materials with tensile/compressive strength difference

Sidewall curl occurring by the removal of tool surfaces after forming is one adverse phenomenon that should be effectively reduced in sheet metal forming operations. Among several process parameters controlling sidewall curl, a constraint tensile force is widely used along with attainable formability by introducing blank holder and drawbead. The classic but common knowledge is that sidewall curl is suppressed for conventional sheet metals as the constraint tensile force increases. Interestingly, however, for magnesium alloy sheets that have unusual asymmetry in tension and compression it has been recently reported that springback increases as the tensile force increases within a specific range of tension. The major deformation in the sidewall usually consists of bending and unbending under tensile force. Therefore, this unique stress-strain response of sheet materials with strength-differential, including magnesium alloys, should be considered for an accurate estimation of sidewall curl. In the present study, a semi-analytical bending/unbending theory incorporating characteristic constitutive behavior of magnesium alloys was developed to evaluate the moment-curvature relationship for various levels of constraint tensile forces. The present analysis proved that the reverse effect of constraint tensile force on sidewall curl was caused by the lower resistance to plastic yielding in compression with proper combination of applied tensile force.

2019 張力がアクチンフィラメントの分子間相互作用に及ぼす影響(OS20.細胞・生体分子の計算バイオメカニクス(5),オーガナイズドセッション)

2019 張力がアクチンフィラメントの分子間相互作用に及ぼす影響(OS20.細胞・生体分子の計算バイオメカニクス(5),オーガナイズドセッション)

Effect of tensile force on expression of PTHrP and thickness of hypertrophic zone in organ-cultured mouse spheno-occipital synchondroses

Objective Responses of spheno-occipital synchondroses to direct tensile stress have not been identified before. This study was, therefore designed to evaluate expression of PTHrP, and thickness of hypertrophic zone in spheno-occipital synchondroses in response to such stress, using mouse in vitro model. Methods Spheno-occipital synchondroses together with adjacent structures were excised from fifty-five 2-day-old mice that were randomly assigned to 6 control and 5 experimental groups for 5 experimental periods ( n = 5). In the experimental groups, tensile force of 0.2 g was applied across the synchondroses, using helical springs. In 5 control groups, the springs were made inactive. Both groups were then cultured for 6, 24, 48, 72 h and 7 days. Another control group was cultured without any springs for 7 days to compare with natural growth of the synchondroses from a group of five 9-day-old mice. Alcian blue-PAS staining was used to study growth of the synchondroses; immunohistochemical staining to identify PTHrP and type X collagen expression. The area of PTHrP expression and thickness of hypertrophic zone, demarcated by type X collagen expression, were measured. Results Quantitative analysis showed that PTHrP expression increased significantly at hour 24 of the force application in the experimental group ( p < 0.05), then reduced from hour 24 to 72 with a significant drop from hour 24 to 48 ( p < 0.01); and the thickness of hypertrophic zone significantly increased at hour 48 ( p < 0.01). Conclusions Our findings suggested that the growth of spheno-occipital synchondroses could be modified by tensile stress; and a light continuous force could enhance its growth, as evidenced by an increase in PTHrP expression and thickness of hypertrophic zone.

Effect of tensile force on the expression of IGF-I and IGF-I receptor in the organ-cultured rat cranial suture

Insulin-like growth factors (IGFs) play an important role in the regulation of bone metabolism. In this study, we investigated changes in the expression of IGF-I and IGF-I receptor and cell proliferation when a continuous tensile force was applied to the cranial suture of cultured rat calvaria. The parietal bones with the midsagittal suture were removed from male Wistar rats (19-days old), cultured for 24h, and divided into two groups. In the experimental group, tensile force (3 x 10(-3)N) was applied by helical springs to the midsagittal suture, whereas helical springs with no tension (0 N) were set in the control group. The tensile force significantly increased the expression of both IGF-I mRNA and protein (P < 0.05). By using in situ hybridisation, we also confirmed that IGF-I and IGF-I receptor mRNAs were localized in osteoblast-like and fibroblastic cells subjected to the tensile force. Also, this force stimulated the proliferation of osteoblast-like and fibroblastic cells in calvaria, without affecting their alkaline phosphatase activity. These results indicate that a tensile force applied to a cranial suture can cause an increase in the production of IGF-I and IGF-I receptors in osteoblast-like and fibroblastic cells, and this increase in IGF-I may cause the proliferation of the cells in an autocrine or paracrine manner.

Effects of tensile forces on the expression of type III collagen in rat interparietal suture

The aim was to investigate the direct contribution of mechanically induced stress to synthesized type III collagen in the interparietal suture. Twenty 4-week-old male rats were used as experimental animals. An activated expansion spring was placed across the interparietal suture. After expansion, the parietal bones including the suture were dissected and immunostained for type I and III collagens. Also, a three-dimensional model of the interparietal suture was developed to analyze stress during expansion. The localization of type III collagen in the suture was dependent upon the duration of expansion. Although the control suture exhibited no or little reactivity for type III collagen, it was observed as early as 15 h of expansion in the cambial layers, and was distributed throughout the suture at 50 h of expansion. The time-dependent distribution of type III collagen was fully consistent with that of tensile stresses calculated by the use of a three-dimensional finite-element model. It was concluded that the increases in tensile stress are associated with the synthesis of type III collagen in the suture.

Tensile water transport in a porous gel.

A Monte Carlo simulation model, which incorporates the effect of tensile forces as well as diffusion, is proposed to explain the behavior of water transport in a saturated porous gel. The algorithm is able to account for the puzzling moisture profiles, which were first observed by conventional magnetic resonance imaging and, more recently, by Overhauser imaging.