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With the increasing demands of ultra‐large space antennas, on‐orbit assembly stands out as a promising solution. However, this achievement necessitates the reconfiguration design of the whole antenna structure to maintain structural integrity and stability. In light of this challenge, a novel rapid design method is proposed for the unit configuration of modular‐assembled antennas in this paper. The method utilizes an inscribed regular hexagon, which is positioned within a horizontal topological circle. The hexagon is subsequently projected onto a spinning paraboloid, resulting in the creation of unit nodes that conform to the shape of the paraboloid. The configuration of the unit topology is then determined based on the arrangement of these nodes. By using the method, two units of space‐assembled antennas are designed. The topology design of the cable network is carried out for the modular unit. The pretensions of the cables are calculated. The results of the case study reveal that the developed modular units fulfill the requirements of the on‐orbit‐assembly antenna structure and can solve the engineering application difficulties of this type of antenna. [ABSTRACT FROM AUTHOR]

In this study, the mechanical behavior of novel fully grouted cable rock bolts made of basalt fiber–reinforced polymer (BFRP) was investigated, which included pullout and double-shear joint behavior. Three BFRP cables were prepared: (1) single-tendon; (2) untwisted multiple-tendon; and (3) twisted multiple-tendon. In the pullout tests, the effects of cable type, borehole diameter, and encapsulated length were studied. However, the influence of the pretension load level was focused on in the double-shear joint tests. The results suggested that an overly thick grout annulus significantly reduced the pullout strength and stiffness. For the BFRP cable with multiple tendons, the initial pullout stiffness was enhanced compared with the BFRP cable with a single tendon due to better interfacial bonding with the grout. In the double-shear joint tests, the pretension of the cable significantly improved the shear capacity and stiffness. With an enhancement in the confinement from pretension, the partial failure of the grout at an early stage could be prevented. The parallel and twisted-tendon BFRP cable rock bolts had larger failure displacements than the single-tendon cable. This analytical study found that a pullout analytical model available in the literature was accurate when back-calculating the stress conditions along the rock bolt. The predicted shear capacity of the rock joint showed good agreement with the experimental values. A parametric study indicated that the joint shear capacity was sensitive to the tensile and shear strengths of the cable but was irrelevant to the cable moduli. Considering the effectiveness of pretension and creep safety for BFRP, a suitable range for the pretension load was suggested. Practical Applications: This study attempts to promote the use of novel, fully grouted cable rock bolts made of basalt fiber–reinforced polymer (BFRP) materials in geotechnical engineering applications. Different types of cable rock bolts are produced, which include single-tendon, untwisted multiple-tendon, and twisted multiple-tendon cables. In the pullout tests, the untwisted multiple-tendon cable exhibited the highest pullout capacity, because of its better interfacial bonding with the grout. From the double-shear joint tests, the pretension of the cable could significantly improve the shear capacity and stiffness. In general, the BFRP cable rock bolts could have a competitive mechanical behavior compared with the steel rock bolts. The respective analytical models for pullout and double-shear joint specimens have proved to be accurate for predicting the mechanical responses of the cable rock bolts. These concise but reliable analytical models could allow researchers and designers to better utilize these novel cable rock bolts in potential applications. [ABSTRACT FROM AUTHOR]

Roller chain drives are frequently applied in a variety of machinery for mechanical motion and power transmission. The roller engagement location on the sprocket tooth contour and the resulted contact behavior is governed by the wear of components and pretension of the chain. Therefore, the influence of extension of chain resulted from wear and pretension of chain on contact behavior was investigated numerically using explicit dynamics module of ABAQUS software. The contact angles evaluated from the numerical simulation were assessed relative to those obtained from the basic rigid body analytical formulation. The chain elongation of 3% increased the maximum contact force up to 52% during engagement with the driver sprocket. The contact force raised to 400% when the pretension in the chain drive was increased from 200 to 1000 N, leaving the force distribution pattern unaltered. The optimal design of a steel sprocket is realized through equivalent static finite element contact analysis of a sprocket engaged with 3% extended roller chain. The dynamic finite element analysis in conjunction with topology optimization reduced the weight of the sprocket by 24%. [ABSTRACT FROM AUTHOR]

This study explores the stiffness enhancement in textile composites using four different fiber types: carbon, Kevlar, Vectran, and high-tenacity polyester (HTP). Pretension levels of 0.2, 2, 5, and 10 N were applied. A setup was developed to measure fiber stiffness. Results indicate that carbon fiber consistently demonstrates the highest stiffness across all pretenstionlevels, attributable to its high tensile strength and modulus. Kevlar fiber, although initially less stiff than carbon, exhibits the most substantial increase in stiffness, particularly between 5 and 10 N of pretension, reaching a peak stiffness of 33.8 at 10 N. Vectran fiber shows a gradual increase in stiffness, surpassing HTP but slightly lagging behind carbon and Kevlar. The rates of yarn-specific bending stiffness increase were measured as 0.168 for HTP, 0.054 for carbon fiber, 0.173 for Kevlar fiber, and 0.191 for Vectran fiber. The study highlights the importance of understanding how yarn pretension affects the bending stiffness of yarn-polymer composites, which is crucial for advancements in textile engineering. It was found that variations in the bending stiffness of HTP and carbon fibers significantly impacted the composite bending stiffness more than Vectran and Kevlar fibers under pretension during composite formation. High-stiffness yarns were less influenced by increasing pretension during composite fabrication. The study suggests utilizing yarn pretension to control the stiffness of textile/polymer composites and proposes individually tensioning and pultruding fibers or yarns in the polymer matrix before composite formation. A specialized setup for achieving this during the protrusion process is recommended. [ABSTRACT FROM AUTHOR]

Copyright of Themis: Revista de Derecho is the property of Themis Asociacion and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wetting of a liquid droplet on another liquid substrate is governed by the well-known Neumann equations. The present work aims to develop an explicit modified version of the Neumann equations for axisymmetric wetting of a liquid droplet on a highly stretched elastic membrane of non-zero bending rigidity. An explicit modified form of the Neumann equations is derived to determine the two contact angles, which is reduced to Young's equation for a liquid droplet on a rigid membrane or to the Neumann equations for a liquid droplet on another liquid substrate. Further implications of the modified Neumann equations are examined by comparison with some previous results reported in the recent literature, particularly considering the ranges of material and geometrical parameters of the liquid droplet-membrane system which have not been recently addressed in the literature. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Direito GV is the property of Fundacao Getulio Vargas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Filament yarn is one of the most widely used soft strands in the textile industry; it exhibits excellent flexibility and is capable of being used in various productions, including knitting, weaving, braiding, sewing, and embroidery. The inherent complex interlacement between fibers, including twist, entanglement, and yarn geometry, often exhibits a nonlinear response to external loads. In addition, the interlacement of fibers also introduces difficulties when accurately measuring the flexural property of multi-filament yarn. In particular, the flexural rigidity of the yarn strongly influences the quality of end products when incorporated into novel textile technologies. In this paper, we developed a three-point bending instrument and a method for measuring the flexural rigidity of filament yarn. A representative point obeyed from Coplan's construction on the bending constitutive curve was determined to obtain pure flexural rigidity. Furthermore, the bending process and deformations across cross-sections of filament yarns were discussed. The research provides new physical insights into the yarn bending property with the consideration of eliminating the sub-deformation variabilities. The work also paves the way for the accurate and quick measurement of the flexural rigidity of high length-to-width ratio soft materials by a three-point bending method. [ABSTRACT FROM AUTHOR]

A quench boiler is the key equipment in ethylene production for the rapid cooling of high-temperature cracking gas. In the boiler, heat transfer is occurs between the hot cracking gas passing through the inner heat exchange tubes with an average temperature of 385 °C and cold water (or boiler water) passing through the inner heat exchange tubes with an average temperature of 350 °C. Required for double-pipe heat transfer, special tubesheets formed by welding flat-round tubes side by side are difficult to design, as no suitable design code is available. The thermal expansion difference between the inner heat exchange tubes and the jacketed tubes could lead to high thermal stress on the tubesheet. In this study, we investigated the effects of pretension or prestretching of the heat exchange tubes on stress distribution and strength assessment of the flat-round tubesheet in a quench boiler under two dangerous load conditions. Results show that without prestretching the heat exchange tubes, the flat-round tubesheet cannot pass the strength assessment. Prestretching the heat exchange tubes is necessary, and a pretension of 9 mm is most suitable. The magnitude of the pretension of the heat exchange tubes should be determined based on the thermal expansion difference between the inner heat exchange tubes and the jacketed tubes, with consideration of the strength improvement of the flat-round tubesheet. [ABSTRACT FROM AUTHOR]

In this paper, a newly developed test method to evaluate the influence of corrosion on pretension and fatigue of bolted connections is presented, suitable from size M36 to M72. A first preliminary series of M30 property class 10.9 bolts were tested to validate the individual test setup steps and to detect challenges and improvement. Pretension load tests, static load tests and fatigue load tests were performed while monitoring stresses on a small number of bolts. The method presented is used to compare different coatings for bolts, like Hot‐dip galvanized coatings and zinc flake coatings, as well as nano‐coatings. To create a realistic approach on offshore corrosion and loading conditions, the bolts will be preloaded in a clamping device resembling the ring flange of an offshore wind tower segment. In a next step, the bolts are corroded in a climate chamber, using the salt spray test or condensation test. Following the corrosion process, the bolts are tested for fatigue without loosening the nut and damaging the thread. Before corrosion and after the fatigue test, 3D surface scans are made to document the corrosion process and to create numerical models of the corroded surface. The method presented offers a new way to evaluate fatigue, pretension and corrosion effects, which is validated on bolts M30 property class 10.9. In close future, the test method is used for larger series of corroded M36 property class 10.9 bolts, having different coating systems applied. [ABSTRACT FROM AUTHOR]

The unique properties along with ease of manufacturing make short fiber reinforced polyamide 66 composites ideal for sprockets used in low positive power transmission. An explicit dynamic finite element simulation of short fiber reinforced polyamide 66 composite sprocket—roller chain drive was carried out. The sprocket was approximated as a plane stress body and roller was considered as a rigid circle. The contact force extracted from the numerical simulation was validated with the analytical results for a standard chain. The deviations in the pitch of the chain produced a varied dynamic contact behavior in terms of a distinct contact width and pressure distribution pattern. The position of maximum contact shear stress altered from subsurface to surface due to low contact normal stress and associated slip. The variation in the chain pitch (up to 3%) affected the peak force of driver sprocket significantly (up to 41%). The increase of pretension of roller chain from 100 to 300 N induced the rise in contact force of driver sprocket up to 169% without changing the pattern. [ABSTRACT FROM AUTHOR]

Tendon drive is used for transmission design in applications ranging from wearable rehabilitation and surgical robots to industrial robots. For their efficient operation, one of the principal design requirements is to have adequate tension in the tendon element. This paper introduces a novel mechanism for tension adjustment using a secondary cable-pulley arrangement via a lever mechanism. An adjustment in a tension spring applies a force in the tendon element meant for the transmission of remote centre-of-motion (RCM) mechanism for medical robotic application. Thereafter, the current work presents the kinematic and force analyses of the proposed concept along with a series of plots of various mechanism parameters. The variation of these parameters is in good agreement with the physical motion of the devised mechanism. As compared to the conventional methods of tension adjustment, the proposed concept is a better solution for problems that arise due to low manufacturing tolerances and the need for independent tension adjustment in a multi degrees-of-freedom tendon driven RCM mechanism. In the preferred embodiment, it is proposed to use cables (wire-ropes) as tendon elements to drive a mechanically constrained double-parallelogram-based RCM mechanism which is extensively used for Minimally Invasive Surgery. From this implementation, it is learnt that the presented mechanism can be implemented in several configurations. However, this paper presents the preferred embodiment only which meets the demand, of invariant tendon length, of the RCM mechanism under consideration. An initial prototype is made from acrylic sheets, PLA material, and standard elements (like bearings, pulleys, aluminum pins, 0.5 mm stainless-steel wire-rope, etc.) using laser micromachining and 3D printing. [ABSTRACT FROM AUTHOR]

Copyright of Principia Iuris is the property of Universidad Santo Tomas, Seccional Tunja and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In coal mining roadway support design, the working resistance of the rock bolt is the key factor affecting its maximum support load. Effective improvement of the working resistance is of great significance to roadway support. Based on the rock bolt's tensile characteristics and the mining roadway surrounding rock deformation, a mechanical model for calculating the working resistance of the rock bolt was established and solved. Taking the mining roadway of the 17102 (3) working face at the Panji No. 3 Coal Mine of China as a research site, with a quadrilateral section roadway, the influence of pretension and anchorage length on the working resistance of high-strength and ordinary rock bolts in the middle and corner of the roadway is studied. The results show that when the bolt is in the elastic stage, increasing the pretension and anchorage length can effectively improve the working resistance. When the bolt is in the yield and strain-strengthening stages, increasing the pretension and anchorage length cannot effectively improve the working resistance. The influence of pretension and anchorage length on the ordinary and high-strength bolts is similar. The ordinary bolt's working resistance is approximately 25 kN less than that of the high-strength bolt. When pretension and anchorage length are considered separately, the best pretensions of the high-strength bolt in the middle of the roadway side and the roadway corner are 41.55 and 104.26 kN, respectively, and the best anchorage lengths are 1.54 and 2.12 m, respectively. The best anchorage length of the ordinary bolt is the same as that of the high-strength bolt, and the best pretension for the ordinary bolt in the middle of the roadway side and at the roadway corner is 33.51 and 85.12 kN, respectively. The research results can provide a theoretical basis for supporting the design of quadrilateral mining roadways. [ABSTRACT FROM AUTHOR]

In the last 2 decades, many ancillary structures have collapsed, with several instances traceable to loose anchor nuts. According to a quality assurance inspection conducted by the Virginia Department of Transportation (VDOT) in 2012, approximately 30% of the anchor nuts on the inspected ancillary structures across the state of Virginia were found to be loose. The exact cause of the loose anchor nuts is not known; however, one theory is that specified tightening procedures were not properly followed or were not adequate. Currently, a turn-of-the-nut method is used for the tightening of anchor nuts on double-nut moment connections at the base of ancillary structures. This research reviewed current tightening procedures for anchor nuts on ancillary structures. The relationship between three critical tightening parameters—applied torque, nut rotation, and pretension in the rod—was examined. One hundred galvanized steel anchor rods of five different diameters and three different grades were tested. The experimental tests serve as a benchmark to validate the current tightening procedures, as well as to recommend changes. [ABSTRACT FROM AUTHOR]

Introduction: Due to the small weight and large flexibility, membrane structures are prone to vibration under external excitation. Furthermore, it may affect the normal function of membrane structures. Objectives: In view of the limitation of traditional perturbation method and small deflection theory in solving strongly nonlinear vibration problem of membranes. an improved multi-scale method is proposed in this paper to investigate the characteristics of strongly nonlinear vibration of membrane. Methods: Firstly, based on the large deflection theory of membrane and the improved multi-scale method, the strongly nonlinear damped vibration control equation of membrane with consideration of geometrical non-linearity is solved. Then, the analytical expressions of the frequency and displacement functions of the strongly nonlinear vibration of membranes are obtained, which are compared with the numerical results. Furthermore, the vibration characteristics of the membrane under the initial displacement are explained together with the experimental results. Results and Conclusion: The results show that the improved multi-scale method is more suitable for solving the strongly nonlinear vibration of membranes than the traditional perturbation method, since the accuracy is higher. Therefore, such a discovery exhibit exposes a more accurate theoretical method for the vibration control and design of membranes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bolt preload is a critical parameter in bolted connections with a strong influence on their general structural behavior. Traditional bolt preload estimation methods are sensitive to the surface conditions of the fastening elements while more accurate measuring methods might require significant modifications of the connection, such as embedded sensors. In this study, a novel contactless bolt preload monitoring method based on Digital Image Correlation measurements of the bolt elongation was developed. A fixed bolted setup was designed to validate the optical measurements with laser triangulation and three-dimensional point tracking, while the bolt preload was monitored with an embedded load cell. Two M16 bolt classes, 8.8 and 10.9, and multiple bolt lengths were evaluated. The bolt preload and displacement results correlated well with the available bolt theoretical models and an accurate preload estimation was possible. An analysis on the method resolution demonstrates that better resolutions are achieved with slender and long bolts. The method resolution is estimated to be under 2.25% and 1.8% of the recommended bolt preload value for each bolt class, respectively. [ABSTRACT FROM AUTHOR]

Bolted connections are used all over the world in almost every engineering application. It is an established fact that these joints get loosened when subjected to dynamic loadings. The objective of this paper is to develop an experimental setup to investigate loosening of bolted joints and its analytical study for establishing the role of the washer subjected to dynamic loading. Experiments were carried out over bolted joint subjected to shear loading with various test variables, including pretension/torque values ranging from 20 N-m, 22.5 N-m and 25 N-m, and number of load cycles ranging from 30,000 to 300,000 cycles. Several tests as per DOE were performed. These tests were carried out following 3 washer conditions: NW-No Washer; PW-Plain Washer; and SW-Spring Washer. The results were represented in terms of slackening/loosening angle with respect to torque/pretension and load cycles. A mathematical model is also developed between angle of loosening, load cycle and pretension. Analysis of this test was performed; contour and surface plots were analyzed. A new mathematical equation was proposed and validated based on the experimental outcomes. The study concludes that washers play a very vital role in preventing loosening failures of bolted joints. [ABSTRACT FROM AUTHOR]

Documented evidence shows that anchor nut loosening on highway ancillary structures has been a problem in the transportation industry since at least the 1990s. There have been reported cases in the past, where loose anchor nuts were found to be partially responsible for the failure of ancillary structures. Resonant vibrations in ancillary structures as a result of variable frequency winds are believed to be one of the potential causes of loose anchor nuts. The current research primarily focused on investigating the effect of wind-induced vibrations on the loosening of anchor nuts in double-nut moment connections in ancillary structures. The research involved large-scale vibration testing of a traffic signal on the basis of vibration stress results from a 4-month field monitoring program. The purpose of the large-scale testing was to establish the relationship between the number of vibratory cycles, rod pretension, and nut loosening. A small-scale vibration test was also performed to validate the large-scale testing results. The testing results showed that anchor rods tightened in a double-nut moment connection above a pretension of 38 MPa (5.5 Ksi) do not experience nut loosening under vibrations. [ABSTRACT FROM AUTHOR]

Viewing both ethics and aesthetics as reflections of the social, cultural sociologists fail to thoroughly account for the complex interrelations between these realms. This article explores this relationship through a study of 'farterism', a discursive category that emerged in Israel during the 1990s and is used to denounce vain pretence. Not only do aesthetic surfaces operate as emotionally-laden shortcuts to deeper layers of ethical meaning, the very act of aesthetic judgement is moralized, subjected to normative regulation. The article analyses the use of 'farterism' in the lay evaluation of architecture, restaurants and films, while reconstructing its implied ethic of aesthetic, 'the hedonistic ethic of authenticity'. I discuss this ethic's philosophical-cultural roots (including the performative contribution of critical social science) and the continuities between its application in cultural evaluation and in wider moral contexts. The pattern that emerges in the data relies on the Emperor's New Clothes tale: uncovering the hidden influence of the social on the aesthetic is at the centre of the normative regulation of aesthetic judgement. This allows laypersons to challenge cultural hierarchies shaped by cultural fields, experts and markets, and denounce them as corrupted by the social. [ABSTRACT FROM AUTHOR]

This article experimentally studied the sliding behaviour of high-strength bolted connections. A total of 14 specimens varying in types of hole and bolt diameters were designed and tested under ambient temperature and target temperature of 130°C and 200°C, respectively. The experimental results show that the pretension in the bolts increases with the increase in temperature below 200°C. After 200°C, the pretension reverses and starts to decrease. It was found that the reverse temperature depended on the relative thermal expansion of the steel plates and bolts. The model of temperature-dependent thermal expansion coefficients given by Australian standard AS 4100 is in good agreement with the test results. The friction coefficient increases with the increase in temperature. The friction coefficients of connections with slot holes increase by 12% at 200°C compared with that at ambient temperature. At the same temperature, the friction coefficients of connections with slot holes are found to be 12% lower than that of connections with standard holes. [ABSTRACT FROM AUTHOR]

In order to research the morphology and mechanical properties of submarine cable during laying operations, a semi-analytical approximation of a two-dimensional in-plane mechanical behavior along ocean depth during laying operations is presented, with considering the coupling effect of submarine cable's tension, self-weight and the sea buoyancy. In the analysis, the mechanics equilibrium equations, that is a set of non-linear differential equations of a short section of submarine cable are established with using Newton's laws of motion, which is comprehensively considering submarine cable elevation angle, configuration and tension change during laying operations and analyzing in-plane mechanical behavior of submarine cables. Through numerical simulation calculation in numerical examples, the submarine cable's tension almost varies linearly with the water depth and the effect of payout rate on submarine cables during laying operations relative to submarine cable self-weight, cable ship velocity, and the pretension is negligible. [ABSTRACT FROM AUTHOR]

Copyright of Bautechnik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new concept was developed to accelerate the construction of highway bridge bents, to improve their seismic resilience, and to make them more durable. On-site construction activities are accelerated by precasting the columns and cap beams and by using socket connections at the bottoms of the columns and grouted connections at the top. Unbonded pretensioning of the columns increases both the bridge's seismic resilience (through improved recentering) and its durability (through reduced cracking), whereas precasting improves quality control. Previous researchers have incorporated unbonded posttensioning into structural systems to reduce postearthquake residual displacements, but pretensioning is preferable in terms of construction convenience, speed, and quality control. Epoxy coating also adds corrosion resistance to the pretensioned strands. Two cantilever concrete subassemblies, representing the top and bottom connections for a column, were subjected to constant axial load and cyclic lateral loading. The tests demonstrated that the new system recenters better than does a comparable RC column. Furthermore, the inelastic action was restricted to the columns, thereby validating the capacity protection of the connection regions. [ABSTRACT FROM AUTHOR]

Prestressed stayed steel columns experience loss of strength and stiffness when exposed to fire conditions. This paper presents results from experimental studies on the behavior of prestressed stayed circular steel columns under fire conditions. Two full scale prestressed stayed steel columns were tested by subjecting the columns to simultaneous gravity (mechanical) loading and fire conditions. In these fire tests, the varied parameters include load level and level of prestressing. Cross sectional temperatures, axial deformations, as well as fire resistance during the fire tests were recorded and measured. The results indicate that prestressed stayed steel columns undergo various failures modes under different combinations of load and prestress ratios. Specifically, load level significantly influence the fire response of prestressed stayed steel columns with higher load level leading to higher contraction and lower fire resistance. [ABSTRACT FROM AUTHOR]

Prestressed (PS) strands are widely used to develop prestressed concrete (PSC) and are stronger than other types of structural steel used in the construction industry. Because of their high strength, PS strands are more effective for use in structures than other materials. Recently, high-strength 2,400-MPa PS strands have been developed and are being considered as an alternative to conventional 1,860-MPa PS strands. However, there have been no reports of research or proposed regulations for pretensioned 2,400-MPa strands in PSC. In this study, 28 PSC beams were fabricated by using 2,400-MPa PS strands, and the transfer length of the PSC was measured. Experiments were performed to evaluate several parameters such as the compressive strength of concrete, steel-fiber volume ratio, and stirrup reinforcement along with different de-tensioning methods in order to determine their effects on the transfer length. In addition, the transfer length with the 2,400-MPa PS strands was measured and compared with the transfer length predicted by previously proposed models. [ABSTRACT FROM AUTHOR]

Critical sociology suggests that taste judgments are not independent of the social, as actors use them to claim social value. This article demonstrates that this critical perspective has gained currency among laypersons, transforming everyday struggles over cultural evaluation. I discuss the new discursive category ‘farterism’, which emerged in Israel in the 1990s to denounce vain pretence and became ubiquitous in everyday evaluation. I analyse online user-generated reviews on films and restaurants alongside broadsheet newspaper articles to explore how this category is used in different contexts by different actors, which aesthetic surface characteristics are most associated with it and why, and how farterism critique reshapes the relationship between lay judgments and established market (prices) and field/art-world (status) hierarchies. Farterism critique is often used to fend off symbolic violence, but cultural elites use it too, despite their interest. I discuss the implicit ethic behind farterism critique, and its connections with recent transformations of capitalism. [ABSTRACT FROM AUTHOR]

This article presents an experimental study on the moment-resisting capacity and stiffness of the proposed pre-stressed tube bolted connection. High-strength bolts with tubes were used as fasteners in such connections. A series of monotonic and reversed cyclic loading tests were conducted with T-shaped glulam beam-to-column connections. The strength, stiffness, ductility, and energy dissipation property of the pre-stressed tube bolted connections were obtained and compared with traditional bolted connections. Meanwhile, the effect of self-tapping screw reinforcement on increasing the structural performance of the pre-stressed tube bolted connection was also investigated. The results showed that the initial rotational stiffness of pre-stressed tube bolted connection improved significantly as a result of the friction between steel tubes and steel plate together with the tight-fitting of tubes and timber holes. The ultimate moment-resisting capacity and ductility of the pre-stressed tube bolted connection were also increased when self-tapping screws were applied. [ABSTRACT FROM AUTHOR]

Copyright of Pensamiento Jurídico is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Suture pretension during tendon repair is supposed to increase the resistance to gap formation. However, its effects on the Bunnell suture technique are unknown. The purpose of this study was to determine the biomechanical effects of suture pretension on the Bunnell and cross-lock Bunnell techniques for tendon repair. Methods: Eighty porcine hindlimb tendons were randomly assigned to four different tendon repair groups: those repaired with or without suture pretension using either a simple Bunnell or cross-lock Bunnell technique. Pretension was applied as a 10 % shortening of the sutured tendon. After measuring the cross-sectional diameter at the repair site, static and cyclic biomechanical tests were conducted to evaluate the initial and 5-mm gap formation forces, elongation during cyclic loading, maximum tensile strength, and mode of failure. The suture failure mechanism was also separately assessed fluoroscopically in two tendons that were repaired with steel wire. Results: Suture pretension was accompanied by a 10 to 15 % increase in the tendon diameter at the repair site. Therefore, suture pretension with the Bunnell and cross-lock Bunnell repair techniques noticeably increased the resistance to initial gap formation and 5-mm gap formation. The tension-free cross-lock Bunnell repair demonstrated more resistance to initial and 5-mm gap formation, less elongation, and higher maximum tensile strength than the tension-free Bunnell repair technique. The only difference between the tensioned cross-lock Bunnell and tensioned Bunnell techniques was a larger resistance to 5-mm gap formation with the cross-lock Bunnell technique. Use of the simple instead of cross-lock suture configuration led to failure by suture cut out, as demonstrated fluoroscopically. Conclusion: Based on these results, suture pretension decreases gapping and elongation after tendon repair, and those effects are stronger when using a cross-lock, rather than a regular Bunnell suture. However, pretension causes an unfavorable increase in the tendon diameter at the repair site, which may adversely affect wound healing. [ABSTRACT FROM AUTHOR]

Piezoelectric actuation is widely used for the active vibration control of smart structural systems, and corresponding research has largely focused on linear electromechanical devices. This paper investigates the design and analysis of a novel piezoelectric actuator that uses a piezoelectric cantilever beam with a loading spring to produce displacement outputs. This device has a special nonlinear property relating to converting between kinetic energy and potential energy, and it can be used to increase the output displacement at a lower voltage. The system is analytically modeled with Lagrangian functional and Euler-Lagrange equations, numerically simulated with MATLAB, and experimentally realized to demonstrate its enhanced capabilities. The model is validated using an experimental device with several pretensions of the loading spring, therein representing three interesting cases: a linear system, a low natural frequency system with a pre-buckled beam, and a system with a buckled beam. The motivating hypothesis for the current work is that nonlinear phenomena could be exploited to improve the effectiveness of the piezoelectric actuator's displacement output. The most practical configuration seems to be the pre-buckled case, in which the proposed system has a low natural frequency, a high tip displacement, and a stable balanced position. [ABSTRACT FROM AUTHOR]

One of the most attractive applications of composite materials is their use as confining devices for concrete columns, which may result in remarkable increases of strength and ductility. The current investigation focuses on the modeling of reinforced concrete columns passively or actively confined by composites, under axial load. Furthermore, the research highlights the effectiveness and modeling of ultra high extension capacity fiber ropes implemented as external confining reinforcement so as to upgrade ductility and strength of concrete columns. It concerns columns of square cross-section with plain or steel reinforced concrete. The novel confining technique uses composite rope made of polypropylene fibers as passive or pretensioned reinforcement while it presents linear elastic behavior up to failure and is applied by hand. It may enable confined columns to dissipate enormous amounts of earthquake induced energy through concrete deformation. The proposed constitutive model is compared against available experimental results involving circular or square columns with passive or active FRP confinement. [ABSTRACT FROM AUTHOR]

Flex fatigue behaviour of plastic optical fibres (POFs) with the diameters of 0.2 and 0.3 mm under different pretensions is measured with fatigue life curve by flexometer. The fatigue sensitivity coefficient is calculated by the linear fitting curve of normalised stress versus logarithm of bending cycles. The residual modulus is investigated during the flex fatigue processes. The results exhibit the exponential relationship between applied pretension and numbers of bending cycles at break. It is indicated that the flex fatigue of POFs might be sensitive with high swing angle or swing speed. There is an evident loss of modulus for two POFs with pretensions of 4 and 10% of ultimate tensile strength during 10-times bending cycles. The values of residual modulus of two POFs almost keep constant after 10-times bending cycles. [ABSTRACT FROM AUTHOR]

The allowable compressive stress of the pretensioned precast concrete members at transfer is the most important factor for determining its bed staying time at the Precast Concrete (PC) factory, and it consequently has a large influence on the productivity of pretensioned PC members. The current design code provisions have specified the allowable compressive stresses of concrete at prestress transfer in an empirical manner, and it was simply expressed only as the function of concrete compressive strength at the time of transfer. In contrast, the Strength Design Method (SDM) can theoretically determine the allowable compressive stresses of pretensioned concrete members considering the effect of influential factors, such as eccentricity ratio of tendons, sectional types, level of prestressing forces, and size of concrete section. In this study, a SDM based approach was proposed to simplify the calculation process of the SDM for the each type of concrete cross-section. In addition, four rectangular pretensioned concrete specimens were fabricated and tested to investigate their allowable prestress. It appeared that ACI318-11 and EC2-02 code models provided unsafe estimations on the allowable compressive stress of pretensioned concrete members with the low eccentricity ratios but excessively conservative results for those with high eccentricity ratios. The SDM and the simplified SDM proposed in this study showed reasonable accuracy and safety margin on the allowable compressive stresses of the pretensoined concrete specimens at prestress transfer. [ABSTRACT FROM AUTHOR]

The elastane-core-spun yarns are hard to be controlled because of the absence of specific tests. Therefore, this study is aims to determine the appropriate conditions to test the mechanical behaviour in term of tensile and relaxation tests. In the present study, cotton-covered elastane-core-spun yarns were used with the same twist factor and various elastane draft values. The analytical results showed that the pretension necessary to deploy the elastic-core-spun yarn increases while the elastane draft increases. Moreover, the elastane ratios have an important effect on the yarn properties for different tests, especially the tensile and the relaxation tests. Besides, the experimental conditions such as the extension rate and the specimen length have a great influence on the mechanical properties. [ABSTRACT FROM AUTHOR]

This study is concerned with a new method to apply consistent and known pretension to silicone rubber membranes intended for micro air vehicles. Pretension has a marked effect on the static and dynamic responses of membrane wings and controls the overall deflections, as such control and measurement of the membrane pretension are important. The technique developed employs thermal expansion to set the pretension and digital image correlation to assess the resulting spatial strain field. Two different frame geometries were fabricated to evaluate the technique. For open-cell frames, the pretension was not uniform, whereas it was for closed-cell frames. Results show developed full-field stress and strain fields as a function of membrane attachment temperature and frame geometry along with experimental iterations to prove repeatability. The membranes can be stretched to a specific pretension according to the temperature at which it adheres to frames. [ABSTRACT FROM PUBLISHER]

Copyright of Revista del Instituto Colombiano de Derecho Procesal is the property of Instituto Colombiano de Derecho Procesal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Modern structural concrete members have become longer and slender, and the prestressed concrete method is an efficient way for sufficiently satisfying the strength and serviceability requirements of such members. Particularly, pretensioned concrete members are typically produced as a precast system that can reduce the construction time and waste significantly by minimizing on-site work. Thus, the pretensioned precast concrete structure is an effective method that can meet both environmental and economic demands in international society. Productivity of the pretensioned members, however, is significantly influenced by the timing of releasing prestress, because prestressing forces can be transferred when the target compressive strength of early age concrete is attained. Unfortunately, the allowable compressive stress at transfer specified in current design code provisions may not be reliable in some practical situations, and those stress limits were determined by empirical methods without a theoretical basis. To overcome such problems, a reasonable estimation equation for allowable compressive stress at transfer was proposed in this paper using extensive analyses based on the Strength Design Method (SDM), in which the eccentricity ratio of the tendon, the sectional size and shape, the level of prestress, and the self-weight moment were considered. The allowable releasing compressive stresses specified in international design codes and based on the proposed equation were compared to test results collected from literature. These comparisons indicated that the allowable stresses specified in current design codes provided unconservative evaluation results for pretensioned members with low eccentricity ratios and conservative results for those with high eccentricity ratios, while the proposed equation reasonably evaluated the allowable compressive stresses of pretensioned members with rectangular, tee, and inverted tee sections. [ABSTRACT FROM AUTHOR]

The results of an experimental investigation of round concrete columns confined by a wound basalt filament yarn are presented. Basalt is an attractive material for strengthening purposes due to its low cost coupled with a good mechanical performance, especially at high temperatures. It is shown that the basalt FRP confinement provides a considerable strengthening effect. The winding equipment employed in this study has the ability to set a desired pretension force of the yarn and thereby to produce a prestressed confinement. It is found that the prestressed confinement notably delays the onset of intense internal cracking of concrete. [ABSTRACT FROM AUTHOR]

A cable-stayed bridge is built by following a construction sequence of different subsequent stages that imply changes of the geometric configuration, restraints and consequently stress and strain patterns. A study is presented about stay stressing sequences in cable-stayed bridges with composite deck for the case of construction made by the cantilever method. Initial cable forces are found through partial elastic schemes of construction stages. Different stay stressing procedures are implemented and a comparison between them is proposed in order to evaluate the differences in terms of deformed shape and internal force distribution of the deck and the pylon. Results can be useful to give practical suggestions to designers, when they have to deal with stay stressing sequences of composite cable-stayed bridges. [ABSTRACT FROM AUTHOR]

Copyright of Discusiones Filosóficas is the property of Universidad de Caldas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The applied pretension on the conductor and support condition during coil fabrication has a great effect on the stress state of the coil. Otherwise, the thermal contraction properties of mandrels and coils would cause residual thermal stress during cool down. A combined homogeneous cylinder method was used to analyze the mechanical performance of winding process for the condition of no mandrel support. A finite-element model of solenoid was created to calculate the stress of winding process and cool down. The mandrel support conditions of fixed support at ends of former and radial support along the whole inner surface of former were researched. Mechanical behaviors of one coil used for a 9.4-T magnetic resonance imaging magnet during winding process and cool down were studied based on the aforementioned approach. [ABSTRACT FROM AUTHOR]

Surgical robot instruments are driven by using cable-pulley structure. The elasticity at cable-pulley structure causes slack effect of cable. Elastic region of cable must be compensated for preventing the slack. The surgical instrument inputs a pretension for compensation at cable's elastic region. Therefore pretension is an important factor in the design of a surgical instrument. However, the pretension is related with friction force which is affected by normal force at the driving shaft pulley. The shaft and contact surface of the pulley consist of sliding bearing structure. Typically, the friction coefficient in the sliding bearing structure is determined by the Petroff equation. The pressure of Petroff equation is related to the denominator of the equation. Therefore increasing normal force brings about an effect which decreases friction coefficient. Eventually, in theoretically, that means the pretension can be increased to infinity to decrease friction coefficient. However actual result comes out different. Therefore in this paper, the friction analysis method according to a pretension is proposed and an experiment method for the analysis of the friction is introduced. The correlation between pretension and friction is estimated by the analysis. The estimated result is compared with the experiment one and is analyzed. Also finally this paper suggests an appropriate pretension for surgical robot instrument by the friction analysis result. [ABSTRACT FROM AUTHOR]

The purpose of this document is to study the application of Tensegrity principles on tensile textile constructions, which is one of points of the PhD Thesis that the author is writing under the tutorship of Prof. Josep Ignasi Llorens and Prof. Ramon Sastre, professors at the Polytechnic University of Catalunia. This work studies the basic concept of Tensegrity unit, its classification according a previous researcher (Anthony Pugh) and the author's contribution, focused on new generations of forms. Through the geometry and computer software, another typology and a constructive simple method is developed, bearing in mind, some aspects as important as system pretension to find its balance. The objective principal is to contribute in a particular way to the application of the tensegrity in architectural spaces, in this case sports spaces through a new proposal that generates an external ring in tensegrity with a central dome, free of any interior support, by formfinding a diamond membrane pattern with discontinuous struts in a double layer that find their equilibrium through the tension of the membrane. In the following examples one can observe that traditional tensegrity tendons are replaced by membranes Fig 1, which is the main contribution of this work that finds geometry and its constructive method of the different prototypes with the help of software like AutoCAD and WinTess (a software development by Ramon Sastre), which verifies the structural equilibrium. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental investigation of concrete columns confined by wound pretensioned epoxy-impregnated carbon filament yarns. The yarn winding equipment, with the ability to set the desired pretension force and thereby to produce confined concrete specimens with different initial lateral pressure, was developed at the Institute of Polymer Mechanics. It is shown that the pressure in creases the axial stress at which intense internal cracking of concrete develops. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to investigate the effects of pretension on work and power output of the muscle-tendon complex during dynamic elbow flexion under several submaximal and maximal conditions. The subjects were 10 healthy female students. Randomized trials from 0% to 100% maximal voluntary contraction (MVC) pretension (PT) at 60° elbow flexion were conducted. After about 3 s of static PT, subjects maximally flexed the elbow joint to 90° using a quick release method. The weight was individually selected for each subject to provide an optimal load for the development of maximal power. A Hill-type model was utilized to analyze the performance of the elbow muscle-tendon complex (MTC). PT 0, 30, 60 and 90% MVC data were used for comparison, and all data were expressed as the mean and standard deviation. Multiple paired comparisons between the value of PT 0% MVC and that of the other PT levels were performed post-hoc using Dunnett’s method. The work of the series elastic component (SEC) increased gradually with the PT level because elastic energy was stored in the PT phase. However, the work of the contractile component (CC) decreased gradually with an increase in PT level. Moreover, the work of the MTC also decreased, closely related to the CC work decrement. The phenomenon of CC work decrement was caused by force depression and was not related to either the force-length or force-velocity relationships of the CC. EMG activity (agonist and antagonist) showed no significant differences. Muscle geometry changes or intracellular chemical shifts may have occurred in the PT phase. [ABSTRACT FROM AUTHOR]