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In this research, a laminate was produced by assembling five textile layers. These layers were a coated double-sided knitted structure, a non-woven fabric, a hydrophilic membrane that was thermally assembled to a surface veil, and an open-work knitted fabric. The laminated textile's breathability, windproofness, and waterproofness were evaluated. The multi-layered fabric was windproof, and its water vapor permeability was 347.297 g m-2 s-1 (CV= 8.902%). Its resistance to water penetration was equal to 117.68 Schmerber (CV = 7.81%). The assembled fabric's mechanical properties were also evaluated. Young's modulus values were equal to 2 MPa (CV= 8.613%) and 1.6 MPa (CV= 8.349%) for both fabric directions. Its flexural rigidity was 5056.659 mg cm and its surface total deformation was lower than 450 µm when measured under 20, 40, 60, and 80 mN loads. Based on the results obtained, it was concluded that the developed multi-layered fabric could be used to produce raincoats and jackets to protect the wearer from light rain and drizzle. [ABSTRACT FROM AUTHOR]

This paper presents a numerical investigation of the flexural behavior of timber beams externally strengthened with carbon-fiber-reinforced polymer (CFRP) sheets. At first, the accuracy of linear elastic and elastic-plastic models in predicting the behavior of bare timber beams was compared. Then, two modeling approaches (i.e., the perfect bond method and progressive damage technique using the cohesive zone model (CZM)) were considered to simulate the interfacial behavior between FRP and timber. The models were validated against published experimental data, and the most accurate numerical procedure was identified and subsequently used for a parametric study. The length of FRP sheets varied from 50% to 100% of the total length of the beam, while different FRP layers were considered. Moreover, the effects of two strengthening configurations (i.e., FRP attached in the tensile zone only and in both the tensile and compressive zones) on load-deflection response, flexural strength, and flexural rigidity were considered. The results showed that elastic-plastic models are more accurate than linear elastic models in predicting the flexural strength and failure patterns of bare timber beams. In addition, with increasing FRP length, the increase in flexural strength ranged from 10.3% to 52.9%, while no further increase in flexural strength could be achieved beyond an effective length of 80% of the total length of the beam. Attaching the FRP to both the tensile and compressive zone was more effective in enhancing the flexural properties of the timber beam than attaching the FRP to the tensile zone only. [ABSTRACT FROM AUTHOR]

• A model is proposed to predict the response of tracks and belts to vibrations. • A generalised Zener model captures flexural rigidity and damping of tracks and belts. • Models with 3 to 5 Maxwell-elements successfully simulate selected rubber tracks. • The spring-damping properties of tracks and belts are identified by cyclic bending. • A new test stand is developed to test tracks and belts under cyclic bending. In the article, a model for predicting the energy losses caused by the flexural vibrations of rubber tracks, rubber belts, and rubber-bushed metal link-tracks for off-road vehicles is proposed, and a test stand and an experimental procedure are developed to identify the mechanical parameters of this model. The track or belt is represented by a chain of discrete rigid links connected by revolute joints, and a discrete spring-element is placed in parallel with multiple Maxwell-elements in each joint to capture the flexural rigidity and damping of the real track or belt. The mechanical parameters of the joint are found by testing real tracks or belts under cyclic bending. The models consisting of three, four, or five Maxwell-elements per joint are the most successful in predicting the response of a sample rubber track to cyclic bending. The spring-damping properties of tracks and belts identified with the method discussed herein can be applied in simulation studies on the interaction of tracked vehicles and soil. Furthermore, vehicle elements such as rubber bushings for suspension systems, rubber torsion springs, and oil-filled and rubber torsion dampers can be tested with this method to find their spring-damping properties required by vehicle dynamics simulations. [ABSTRACT FROM AUTHOR]

Basic magnesium sulfate cement concrete (BMSC) was invented in 2013, which has many merits: excellent mechanical performance, good toughness and good crack resistance. But the mechanical performance of BMSC beams laid in the harsh weather for a long time is not known. The mechanical properties of six corroded reinforced BMSC beams were studied for applying this new concrete to practical engineering. It can be found that there is no rust crack before loading test. The bearing capacity of corroded reinforced BMSC beam laid in the harsh environment for two years, especially in the weather of long-term freeze-thaw cycles and acid rain, degraded by 11.9 % and the bending rigidity degraded by 17.0 %. Based on the attenuation of steel corrosion and deterioration of BMSC after the harsh exposure, the model of bearing capacity and cracking load of the corrosion-damaged BMSC beam is proposed. This paper is helpful to the application of BMSC members in the area of harsh environments.

The paper aims to develop a unified modeling to analyze the free vibrations and buckling of laterally functionally graded material columns. The columns of rectangular cross-section, in which the mass density and Young's modulus vary along the depth as a power-law function, were considered. The differential equation governing a mode shape of a deformed column was derived with the relevant boundary conditions, including the effect of rotatory inertia. The computation results for the natural frequencies and buckling load were compared well with those available in the open scientific literature. The effects of geometrical and material properties on natural frequencies and buckling loads with the mode shapes are highlighted. [ABSTRACT FROM AUTHOR]

A diaphragm is an essential component of a T-girder bridge. Evaluating the influence of various truss diaphragms (TDs) on the structural behavior and load distribution factor of T-girder bridges assists in bridge design and strengthening. In this study, a series of experiments and simulations were conducted to investigate the strengthening effect of two types of TDs (i.e., triangle-TDs and K-TDs) based on a small-scale T-girder bridge model. Formulas for the flexural rigidity of the two types of TDs were proposed and verified by using rigid-joint girder methods, experiments, and simulations. Then, taking the K-TD as an example, the calculation method for the stiffness of the truss was analyzed and derived based on rigid-joint girder and graphic multiplication methods. The results showed that K-TDs had a better strengthening effect than triangle-TDs. The deflection and strain of the K-TD-strengthened T-girder bridge were reduced by 21% and 16%, respectively, compared with those of the triangle-TD-strengthened bridge. The formulas for flexural rigidity were proposed and used to calculate the load distribution factor. The maximum error of the calculated load distribution factor was 16% compared with the simulation and experimental results. Moreover, the calculation method for the stiffness of the K-TDs was analyzed and obtained. Deterioration of multigirder bridges is getting worse due to the increasing traffic load and insufficient maintenance. Adding diaphragms to the existing bridges can improve the load distribution of multigirder bridges and reduce the maximum load of the girders. This work evaluated the influence of two types of truss diaphragms (triangle truss diaphragm and K truss diaphragm) on the load distribution of a T-girder bridge, and the results showed that the two types of truss diaphragms can reduce the maximum deflection and strain in the T-girder bridge effectively. The flexural rigidity formulas for the two types of truss diaphragm were proposed and proved to be accurate by comparing with experiments and finite-element methods. Moreover, the truss stiffness of the K truss diaphragm was derived by a graphic multiplication method. These formulas can be used by bridge engineers for new bridge designing or existing bridge strengthening in practical engineering. [ABSTRACT FROM AUTHOR]

An attempt has been made to develop cotton-treated fabrics to be used as home textile and decorative products inside the room, which can adsorb carbon dioxide and thus reduce indoor air pollution. Cotton fabric has been treated with bentonite clay, aerosol fumed silica and zeolite separately, and then evaluated for adsorption of CO2 gas using newly developed NITRA fabric gas adsorption efficiency testing equipment. It is found that the fabric treated with a 4% concentration of bentonite clay, 3% concentration of aerosol fumed silica, and 2% concentration of zeolite adsorbs 23.62%, 28.04%, and 21.35% of CO2 respectively in 24 h. Treated samples are also tested for various physical properties like breaking strength, flexural rigidity, etc. [ABSTRACT FROM AUTHOR]

This paper presents a numerical investigation of the flexural behavior of timber beams externally strengthened with carbon-fiber-reinforced polymer (CFRP) sheets. At first, the accuracy of linear elastic and elastic-plastic models in predicting the behavior of bare timber beams was compared. Then, two modeling approaches (i.e., the perfect bond method and progressive damage technique using the cohesive zone model (CZM)) were considered to simulate the interfacial behavior between FRP and timber. The models were validated against published experimental data, and the most accurate numerical procedure was identified and subsequently used for a parametric study. The length of FRP sheets varied from 50% to 100% of the total length of the beam, while different FRP layers were considered. Moreover, the effects of two strengthening configurations (i.e., FRP attached in the tensile zone only and in both the tensile and compressive zones) on load-deflection response, flexural strength, and flexural rigidity were considered. The results showed that elastic-plastic models are more accurate than linear elastic models in predicting the flexural strength and failure patterns of bare timber beams. In addition, with increasing FRP length, the increase in flexural strength ranged from 10.3% to 52.9%, while no further increase in flexural strength could be achieved beyond an effective length of 80% of the total length of the beam. Attaching the FRP to both the tensile and compressive zone was more effective in enhancing the flexural properties of the timber beam than attaching the FRP to the tensile zone only.

Bleaching and softening of the hard fiber “Coir” renders it suitable for use in the coir industry, which presently adopts various chemical treatment processes that are not eco-friendly. The present study aims at treatment of coir fibers with Averrhoa bilimbi for enhanced bleaching and softening. The quality of the treated fibers with respect to physical and chemical characterization viz. variation in lignin content, flexural rigidity to assess the degree of softness, light fastness, tensile strength and brightness index has been carried out. The treated fibers displayed remarkable increase in brightness index from 9.45 to 11.19. Removal of surface projections on the coir fiber upon treatment is evident from Scanning Electron Microscope images. These surface changes can be attributed to the fiber softening.

Coir fiber has been pretreated using liquid ammonia and further subjected to phosphorylation for enhancing fire retardancy using a mixture of phosphoric acid and phosphorus pentoxide. Enhancement in fire retardancy was observed with reduced water absorption and without inducing any degradative effects on its physical properties. SEM images revealed the surface modifications induced by pretreatment and the surface became more smooth after phosphorylation indicating the adherance of the phosphorylation compounds added, on to the surface. The flammability characteristics, such as reduction in time of burning from 182 to 50 s, no smoke without afterglow when burnt are the major observations. Horizontal flammability tests showed a 66% reduction in burning rate of phosphorylated coir samples. Thus, proving it as an economically viable flame retardant treatment method which suits coir fiber as an efficient substrate for various applications.

An investigation of Poisson’s ratio of a series of spun bonded non-woven fabrics, differing in areal density, number of layers, testing directions and finishes, is reported. The Poisson’s ratio value is found to be higher with increase in the number of layers of spun bonded fabric assembly of fabrics of same Grams per Square Metre (GSM). The contraction in cross direction is higher than in the machine direction. Since spun bonded non-woven fabrics are anisotropic in nature, the Poisson’s ratio values range from 0 to 0.728 for the various extension levels that have been considered depending on the direction of action of the tensile force in the machine (MD) and cross directions (CD). The relationship between Young’s modulus & bending rigidity is poor. Flexural rigidity and Young’s modulus in machine direction are higher than in cross direction. [ABSTRACT FROM AUTHOR]

Phosphorylation reduced the burning rate of coir fiber samples by 66%, which implies that phosphoric acid/ phosphorus pentoxide at a concentration of 5% is an effective method for imparting fire retardancy in coir fibers. The advantageous outcome of phosphorus compounds as flame retardants over halogenated compounds includes high flame retardant efficiency, environmental friendly and less emission of hazardous gases. Keywords: Coir fiber; fire retardancy; flexural rigidity; flammability; breaking stress; tablet test; ; ; ; ; ; EN Coir fiber fire retardancy flexural rigidity flammability breaking stress tablet test ZH 7445 7453 9 11/21/22 20221220 NES 221220 Introduction Natural fibers are hair-like structures originated from plants or animals, having the advantages of low-density, economical and ecofriendly. Burning rate of raw, pretreated and phosphorylated samples Tablet test Pretreatment and phosphorylation reduces the time of burning of coir fiber sample as indicated in Table 3. [Extracted from the article]

Bleaching and softening of the hard fiber "Coir" renders it suitable for use in the coir industry, which presently adopts various chemical treatment processes that are not eco-friendly. The present study aims at treatment of coir fibers with Averrhoa bilimbi for enhanced bleaching and softening. The quality of the treated fibers with respect to physical and chemical characterization viz. variation in lignin content, flexural rigidity to assess the degree of softness, light fastness, tensile strength and brightness index has been carried out. The treated fibers displayed remarkable increase in brightness index from 9.45 to 11.19. Removal of surface projections on the coir fiber upon treatment is evident from Scanning Electron Microscope images. These surface changes can be attributed to the fiber softening. [ABSTRACT FROM AUTHOR]

The control performances of inerter-based dampers on stay cables, usually governed by relevant damper parameters (such as inertance, stiffness, and damping coefficients), are sensitive to parameter variation around the optimal range. Further given these inerter-based dampers amplify the vibration amplitude at the damper location, the effects of cable's flexural rigidity, which is often ignored in previous studies, are examined in this study. The results suggest an approximate 10% increase in all three design parameters (i.e., inertance, stiffness, and damping coefficients) is required to achieve optimal control compared with the case ignoring the flexural rigidity. In addition, the potential combination of inerter-based dampers with negative stiffness elements is also discussed in this study, which offers a more flexible layout and enhances multi-mode cable vibration control performance. Consequently, the tuning procedures are updated, and the revised optimal tuning formulas taking account of both the cable's flexural rigidity and the introduction of negative stiffness are presented in this paper. [ABSTRACT FROM AUTHOR]

This paper presents the use of Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method to determine the optimum time, NaOH concentration, and temperature for reduction in lignin content, reduction in flexural rigidity, and tenacity of the coir yarns using box-behnken design. Optimum conditions for better properties are obtained from the ramp graphs. The results indicate that the TOPSIS method is appropriate for solving the multi-criteria optimization of the process parameters based on ranking system. The optimal value for time, concentration, and temperature are 3 h, 5% NaOH, and 80°C based on the defined criteria.

This study proposes an innovative method for structural health monitoring of simply supported PCI girder bridges based on dynamic strain and edge computing. Field static and dynamic load tests were conducted on a bridge consisting of a span with newly replaced PCI girders and numerous spans with old PCI girders. Both the static and dynamic test results showed that the flexural rigidity of the old PCI girders decreased significantly due to deterioration. To improve the efficiency of on-site monitoring data transmission and data analysis, this study developed a smart dynamic strain gauge node with the function of edge computing. Continuous data with a sampling frequency of 100 Hz were computed at the sensor node. Among the computed results, only the maximum dynamic strain data caused by the passage of the heaviest vehicle within 1 min were transmitted. The on-site monitoring results indicated that under routine traffic conditions, the dynamic strain response of the new PCI girder was smaller than that of the deteriorated PCI girder. When the monitored dynamic strain response has a tendency to magnify, attention should be paid to the potential prestress loss or other deterioration behaviors of the bridge. [ABSTRACT FROM AUTHOR]

Abstract Background Microtubules (MTs) are highly dynamic tubular cytoskeleton filaments that are essential for cellular morphology and intracellular transport. In vivo, the flexural rigidity of MTs can be dynamically regulated depending on their intracellular function. In the in vitro reconstructed MT-motor system, flexural rigidity affects MT gliding behaviors and trajectories. Despite the importance of flexural rigidity for both biological functions and in vitro applications, there is no clear interpretation of the regulation of MT flexural rigidity, and the results of many studies are contradictory. These discrepancies impede our understanding of the regulation of MT flexural rigidity, thereby challenging its precise manipulation. Results Here, plausible explanations for these discrepancies are provided and a new method to evaluate the MT rigidity is developed. Moreover, a new relationship of the dynamic and mechanic of MTs is revealed that MT flexural rigidity decreases through three phases with the growth rate increases, which offers a method of designing MT flexural rigidity by regulating its growth rate. To test the validity of this method, the gliding performances of MTs with different flexural rigidities polymerized at different growth rates are examined. The growth rate-dependent flexural rigidity of MTs is experimentally found to influence the pattern formation in collective motion using gliding motility assay, which is further validated using machine learning. Conclusion Our study establishes a robust quantitative method for measurement and design of MT flexural rigidity to study its influences on MT gliding assays, collective motion, and other biological activities in vitro. The new relationship about the growth rate and rigidity of MTs updates current concepts on the dynamics and mechanics of MTs and provides comparable data for investigating the regulation mechanism of MT rigidity in vivo in the future. Graphic Abstract

The biomechanics of embryonic notochords are studied using an elastic membrane model. An initial study varying internal pressure and stiffness ratio determines tension and geometric ratios as a function of internal pressure, membrane stiffness ratio, and cell packing pattern. A subsequent three-point bending study determines flexural rigidity as a function of internal pressure, configuration, and orientation. Flexural rigidity is found to be independent of membrane stiffness ratio. Controlling for number and volume of cells and their internal pressure, the eccentric staircase pattern of cell packing has more than double the flexural rigidity of the radially symmetric bamboo pattern. Moreover, the eccentric staircase pattern is found to be more than twice as stiff in lateral bending than in dorsoventral bending. This suggests a mechanical advantage to the eccentric WT staircase pattern of the embryonic notochord, over patterns with round cross-section., (Copyright © 2023. Published by Elsevier B.V.)

In Egypt, large quantities of coarse granite wastes are produced annually during the quarrying operations of granite rocks. This waste represents a potentially useful source of material for a variety of applications such as a filler material in epoxy granite composite material. In this work a new eco-friendly composite material studied as a substitute for machine tools traditional materials, like cast iron, to produce better efficiency with lower cost. This study aims to investigate the mechanical properties of granite epoxy composite by using the local epoxy (kemapoxy 150) and the granite residues in the Egyptian quarries. The investigated processing variable was epoxy content, and the mechanical characterization ware carried out by compressive and flexural tests according to the ASTM standard method B. Commercially available, Aswan red granite was procured, crushed, and sieved to three size ranges from 0.150 to 8 mm, respectively. Epoxy ratios of 80:20, 85:15 have been used with granite aggregate size mix with small, medium, and coarse size proportions of 50:25:25 respectively for preparing the specimens with granite granular size range (0.150-8) mm. The results show that Epoxy granite composite with granite to epoxy ratio of 80:20% wt. induced the highest compressive strength (72.15 MPa) while the composite with the ratio of 85:15% wt. induced the highest flexural strength (20.1 MPa). Epoxy granite composite show superior results with respect to cement concrete, polyester concrete, and natural granite.

Basalt fiber characterized by high corrosion resistance and relatively low production cost has been increasingly employed in concrete constructions worldwide. However, few studies focused on the flexural performance of basalt fiber reinforced concrete (BFRC) structural members. In this work, constitutive models for the compressive and tensile behavior of BFRC were firstly validated using experimental results. Then, analytical methods for the calculation of the flexural capacity, the moment of inertia of the cracked transformed section, the effective flexural rigidity of steel-reinforced basalt FRC (RBFRC) beams, and concrete-basalt FRC (RC-BFRC) composite beams were proposed. The analytical results indicate that the ultimate moment and maximum deflection at the mid-span under service load agree well with the experimental results, which is meaningful for guiding the design of structural members with BFRC. [ABSTRACT FROM AUTHOR]

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]

The emergence of soft robots with "flexible motion" is expected to be improved by incorporating flexible energy harvesting technology and electronic devices with excellent biocompatibility. Therefore, it is important to improve the design and performance of the device itself, according to the soft adherend to which the device is applied. In this study, we outline the design of flexible devices from a mechanical viewpoint and introduce our recent achievements. [ABSTRACT FROM AUTHOR]

Flexible jointed-panel structures play a significant role in the entire service cycle of spacecraft, but they also bring serious vibration problems to the spacecraft orbit control. The bidirectional flexible jointed-panel structure installed on the large-scale spacecraft considered in this paper may produce large-amplitude vibration. To investigate the nonlinear vibration of such a flexible structure, a nonlinear dynamic model with a lower degree of freedom should be established analytically. Thus, the global mode functions of such a complex structure should be extracted first. Taking the eigenfunctions of beams as basis functions, the Rayleigh-Ritz method is developed to extract the analytic global mode functions for bidirectional flexible jointed-panel structures. As a typical example, the cruciform flexible jointed-panel structures made up of six isotropic rectangular panels are investigated, and the dynamic model for the transverse vibration of the structure is established. Numerical results are conducted to illustrate the validation of the proposed modeling process by comparing the natural frequency and global modes obtained by the developed approach with those obtained from the finite element method. Then, the influence of parameters on the inherent properties of the structure is discussed, and an effective method to increase the fundamental frequency of the structure is proposed. [ABSTRACT FROM AUTHOR]

Abstract Embroidery through computer aided semi-automatic machines is one of the most widely used option for the surface ornamentation of apparel fabrics at present. Since the embroidery process includes addition of certain amount of embroidery-threads depending upon the design motif, it is quite obvious that basic physical and functional properties of fabric are subject to change. It is therefore important to develop an algorithm or empirical equation for proper prediction of the properties of the embroidered fabric, relevant to its required end-use in apparel industry. In this context, an effort has been made to determine a prediction equation through linear multiple regressions for the prediction of longitudinal stiffness of embroidered fabric in terms of flexural rigidity in warp direction of the base fabric, considering the input parameters as warp-way flexural rigidity of the base fabric, breaking load and linear density of the embroidery thread, stitch density, average stitch length and average stitch angle of the embroidery design. The final Prediction model is statistically verified taking new embroidery samples of different varieties. It is found that the model can predict with a very satisfactory level of accuracy. Also, the influences of the embroidery parameters in this context have been analyzed through the corresponding regression coefficients and the three dimensional (3D) surface curves. Stitch density has been emerged as the most influential parameter, followed by the stitch length and the stitch angle.

This study proposes a soft pneumatic actuator with adhesion (SPAA) consisting of a top fluidic-driven elastic actuator and four bottom adhesive pads for adhering to large cylinders. Finite element models were developed to investigate the bending properties under positive air pressure and the effect of "rib" height on the flexural rigidity of the SPAA. A synchronous testing platform for the adhesive contact state and mechanics was developed, and the bending curvature and flexural rigidity of the SPAA were experimentally measured relative to the pressure and "rib" height, respectively, including the adhesion performance of the SPAA with different rigidities on large cylinders. The obtained results indicate that the SPAA can continuously bend with controllable curvature under positive air pressure and can actively envelop a wide range of cylinders of different curvatures. The increase in the "rib" height from 4 to 8 mm increases the flexural rigidity of the SPAA by approximately 230%, contributing to an average increase of 54% in the adhesion performance of the SPAA adhering to large cylinders. The adhesion performance increases more significantly with an increase in the flexural rigidity at a smaller peeling angle. SPAA has a better adhesion performance on large cylinders than most existing soft adhesive actuators, implying that is more stable and less affected by the curvature of cylinders. To address the low contact ratio of the SPAA during adhesion, the optimization designs of the rigid–flexible coupling hierarchical and differentiated AP structures were proposed to increase the contact ratio to more than 80% in the simulation. In conclusion, this study improved the adhesion performance of soft adhesive actuators on large cylinders and extended the application scope of adhesion technology. SPAA is a basic adhesive unit with a universal structure and large aspect ratio similar to that of the human finger. According to working conditions requirements, SPAAs can be assembled to a multi-finger flexible adhesive gripper with excellent maneuverability. [ABSTRACT FROM AUTHOR]

This study focuses on the flexural properties of the layered wall structures of plastic tanks produced by rotational molding technology. The aim was to assess the possibility of replacing the homogeneous walls of rotationally cast large-volume underground tanks with structural walls for stability and warpage prevention. The possibilities of material saving by combining lightweight and non-lightweight tank wall layers were investigated. By applying the engineering theory of bending inhomogeneous layered walls, the flexural rigidity values of the walls of the tanks of different structures were determined. The values of the flexural rigidity of the tank wall samples produced by rotomolding technology were determined experimentally. Moreover, a comparison of the calculated and experimentally determined flexural rigidity values of the layered walls and optimization of these structures was carried out. In the case under study, it was theoretically and experimentally confirmed that the optimum ratio of compact layer thickness versus total wall thickness is given by the resulting value: t1OPT = 0.189 h. [ABSTRACT FROM AUTHOR]

This study proposes an innovative method for structural health monitoring of simply supported PCI girder bridges based on dynamic strain and edge computing. Field static and dynamic load tests were conducted on a bridge consisting of a span with newly replaced PCI girders and numerous spans with old PCI girders. Both the static and dynamic test results showed that the flexural rigidity of the old PCI girders decreased significantly due to deterioration. To improve the efficiency of on-site monitoring data transmission and data analysis, this study developed a smart dynamic strain gauge node with the function of edge computing. Continuous data with a sampling frequency of 100 Hz were computed at the sensor node. Among the computed results, only the maximum dynamic strain data caused by the passage of the heaviest vehicle within 1 min were transmitted. The on-site monitoring results indicated that under routine traffic conditions, the dynamic strain response of the new PCI girder was smaller than that of the deteriorated PCI girder. When the monitored dynamic strain response has a tendency to magnify, attention should be paid to the potential prestress loss or other deterioration behaviors of the bridge.

This study proposes a soft pneumatic actuator with adhesion (SPAA) consisting of a top fluidic-driven elastic actuator and four bottom adhesive pads for adhering to large cylinders. Finite element models were developed to investigate the bending properties under positive air pressure and the effect of “rib” height on the flexural rigidity of the SPAA. A synchronous testing platform for the adhesive contact state and mechanics was developed, and the bending curvature and flexural rigidity of the SPAA were experimentally measured relative to the pressure and “rib” height, respectively, including the adhesion performance of the SPAA with different rigidities on large cylinders. The obtained results indicate that the SPAA can continuously bend with controllable curvature under positive air pressure and can actively envelop a wide range of cylinders of different curvatures. The increase in the “rib” height from 4 to 8 mm increases the flexural rigidity of the SPAA by approximately 230%, contributing to an average increase of 54% in the adhesion performance of the SPAA adhering to large cylinders. The adhesion performance increases more significantly with an increase in the flexural rigidity at a smaller peeling angle. SPAA has a better adhesion performance on large cylinders than most existing soft adhesive actuators, implying that is more stable and less affected by the curvature of cylinders. To address the low contact ratio of the SPAA during adhesion, the optimization designs of the rigid–flexible coupling hierarchical and differentiated AP structures were proposed to increase the contact ratio to more than 80% in the simulation. In conclusion, this study improved the adhesion performance of soft adhesive actuators on large cylinders and extended the application scope of adhesion technology. SPAA is a basic adhesive unit with a universal structure and large aspect ratio similar to that of the human finger. According to working conditions requirements, SPAAs can be assembled to a multi-finger flexible adhesive gripper with excellent maneuverability.

This study focuses on the flexural properties of the layered wall structures of plastic tanks produced by rotational molding technology. The aim was to assess the possibility of replacing the homogeneous walls of rotationally cast large-volume underground tanks with structural walls for stability and warpage prevention. The possibilities of material saving by combining lightweight and non-lightweight tank wall layers were investigated. By applying the engineering theory of bending inhomogeneous layered walls, the flexural rigidity values of the walls of the tanks of different structures were determined. The values of the flexural rigidity of the tank wall samples produced by rotomolding technology were determined experimentally. Moreover, a comparison of the calculated and experimentally determined flexural rigidity values of the layered walls and optimization of these structures was carried out. In the case under study, it was theoretically and experimentally confirmed that the optimum ratio of compact layer thickness versus total wall thickness is given by the resulting value: t1OPT = 0.189 h.

Aquatic vegetation is an important component of coastal and riverine environments and plays a significant role in shaping their evolution. The extent and nature of eco-hydraulic interaction depends upon the geometric and biophysical properties of the vegetation which affect the drag force and vegetation reconfiguration. Such vegetation properties commonly vary along each stem. However, this variability has not received significant attention in previous models. Here, we present a biomechanical model, based upon local parameterization of stem properties which can represent variable rigidity stems. The model is validated for straight and curved beams before being applied to experimental data using surrogates with variable thickness and Young's modulus. Finally, the model is applied to saltmarsh vegetation data. The results for saltmarsh vegetation show that using stem-averaged properties may result in errors in predicted drag force of up to 26% and highlights the need to consider the reconfiguration of variable rigidity stems. [ABSTRACT FROM AUTHOR]

This paper presents the use of Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method to determine the optimum time, NaOH concentration, and temperature for reduction in lignin content, reduction in flexural rigidity, and tenacity of the coir yarns using box-behnken design. Optimum conditions for better properties are obtained from the ramp graphs. The results indicate that the TOPSIS method is appropriate for solving the multi-criteria optimization of the process parameters based on ranking system. The optimal value for time, concentration, and temperature are 3 h, 5% NaOH, and 80°C based on the defined criteria. [ABSTRACT FROM AUTHOR]

The performance of a table tennis racket is often stipulated using an unique standard for the manufacturer. However, the performance criteria for restitution characteristics still have been unclear due to lack of qualitative evaluation by each manufacturer. For metal baseball bats, a formula that can easily estimate the coefficient of restitution (COR) for the bat has been proposed. Similarly, it is important to establish a method that can control the COR at the design stage for table tennis rackets. In this study, first, to understand the restitution characteristics of the table tennis ball used in the official game, an impact test was conducted on a pseudo-rigid wall at low to high velocity. Then, for 15 types of rackets, the COR of the racket body (with and without rubber) was measured. Additionally, the natural frequency and flexural rigidity of the racket body without rubber were measured. Furthermore, these experimental data revealed relationships between the COR and both of the impact velocity and natural frequency of the racket. A formula for the COR was derived similar to that for a baseball bat, and developed by considering the flexural rigidity. The effect of rubber on the COR was also investigated. Consequently, the effects of ball’s impact velocity, racket’s natural frequency and racket’s flexural rigidity on the COR of the racket were clarified. From these results, an equation that can estimate and control the COR of the racket at the design stage was developed.

Ultra-lightweight sheets with excellent deformability are required for the development of new air vehicles, as well as greener conventional vehicles. Carbon fiber reinforced plastic (CFRP) has a high specific rigidity and strength but is too expensive to be used in general machine parts. Using CFRP enhances the properties of the material itself. Furthermore, developing the usage of the material also makes the mechanical properties higher. The purpose of this paper is to combine both methods and produce a material with better rigidity and deformability. The new structure was proposed considering the moment of inertia of area. This structure was excellent not only in terms of rigidity but also in the moldability of the core. In addition, the effects of the structure dimensions on the moldability, bonding strength and flexural rigidity were determined using finite element (FE) analysis and experiments. By comparing the results of the FE analysis conducted under pure bending conditions with three-point bending experiment, it was found that the FE analysis of pure bending fails to predict the three-point bending stiffness because the shear stress has a significant effect on the experimental measurements. By modifying the model from pure bending to three-point bending, the experimental results were well reproduced by the 3D FE analysis. [ABSTRACT FROM AUTHOR]

Multilayer laminated beams, comprised of alternating stiff and soft layers, are widely used in flexible electronics and photonics. These structures exhibit complex mechanical behaviors that deviate from the Euler–Bernoulli beam theory under conditions of extreme inter-layer modulus mismatch. Extending beyond prior studies on trilayer beams, we present an analytical framework for laminated beams with arbitrary number of layers subjected to various bending conditions, and validate our theory with finite element analysis. We define an equivalent flexural rigidity, exploring its dependence on position and deformation, and systematically examine the impact of the number of layers, applied deformation, layer properties, and the layer aspect ratio. • The extreme modulus in a multilayer laminated beam can trigger the shear-lag effect. • The shear-lag effect makes the beam softer than the Euler–Bernoulli beam theory. • A dimensionless number was found to control the discrepancy from the Euler-Bernoulli beam theory. • Membrane strain saturates with increasing layer number. • Equivalent flexural rigidity scales linearly with layer number when layer number is large. [ABSTRACT FROM AUTHOR]

Background: Modular connections in total hip arthroplasty (THA) offer surgical advantages, but can contribute to implant fretting and corrosion due to micromotion at the head-stem interface. Previous studies implicated lower flexural rigidity as a key contributing factor to THA corrosion and fretting, but none associated flexural rigidity with direct histological evaluation or magnetic resonance imaging (MRI) outcomes. The purpose of this study was to determine how implant flexural rigidity is associated with MRI imaging metrics and histopathological outcomes in patients who have a failed THA., Methods: Patients requiring revision THA surgery underwent preoperative MRIs with 3-dimensional multispectral imaging techniques to suppress metal artifacts. The MRI images were graded for adverse local tissue reactions. For each hip, trunnion flexural rigidity was measured from the retrieved femoral stem, and a periprosthetic tissue sample was retrieved and evaluated using semiquantitative histology. Generalized linear models and analyses of variance were used to assess associations between flexural rigidity and MRI and histology outcomes., Results: A total of 106 THA stems were retrieved (46 women and 60 men, age: 68 years (range, 60 to 73 years). After adjustment for length of implantation, flexural rigidity was negatively correlated with histologic aseptic lymphocyte-dominant vasculitis-associated lesion severity (β = -26.27, P = .018), Fujishiro lymphocyte grading (β = -13.4, P = .039), perivascular lymphocyte layers (β = -17.8, P = .022), the grade of tissue organization (β = -22.5, P = .009), the presence of diffuse synovitis (β = -66.5, P = .003), and the presence of lymphoid aggregates (β = -75.9, P = .022). No association was found between MRI metrics and flexural rigidity., Conclusions: Among these implants, decreased trunnion stiffness was associated with increased histologic features of adverse host-mediated soft tissue reactions., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In this paper, the governing equation of chloride diffusion in reinforced concrete square piles is presented. The deterioration process of a pile caused by chloride-induced reinforcement corrosion is analyzed. The time-varying degradation coefficient of the flexural rigidity of piles induced by reinforcement corrosion is obtained. The time-varying failure probability and reliability index under the displacement failure criterion are calculated by using the Monte Carlo simulation method. The sensitivity of the coefficient of variation (COV) and mean value of the significant parameters for the time-varying probability density function (PDF) curves is analyzed. The results indicate that the degradation coefficient of the flexural rigidity and the reliability index decrease with increasing service time, while the failure probability increases with increasing service time. The peak value of the PDF curve of the pile head displacement decreases as the COV of the lateral load, soil elastic modulus and mean value of the lateral load and bending moment increase. The displacement of the pile head corresponding to the peak value increases substantially with increasing lateral load and bending moment, and decreases significantly with increasing soil elastic modulus and concrete elastic modulus. [ABSTRACT FROM AUTHOR]

Testing methods are required for estimating prestress losses in Prestressed Concrete (PC) girder-bridges. They mainly include destructive approaches which cause significant damages. Conversely, dynamic nondestructive methods are unsuitable. Given these findings, a novel method for identifying residual prestress force in simply supported PC girder-bridges was implemented. Following the vertical load application in a three-point bending, the method estimates the prestress force by measuring the vertical deflection at a quarter or, alternatively, at the midspan of the PC girder-bridge. The method also requires information regarding its flexural rigidity. Particularly, the initial tangent Young's modulus must be evaluated by compression tests on cores drilled at its quarter and midspan cross-sections after three-point bending. In absence of the geometric and/or material properties, the flexural rigidity can be estimated according to free vibrations. Secondly, the method comprises a reference solution, or a finite element model of the PC girder-bridge, in which the prestress force is unknown. Thirdly, the measured deflection becomes a parameter of the prestress force identification process. Accurate identifications are obtained when the deflection, under a higher vertical load, was precisely measured and the flexural rigidity was determined using reference solution and initial tangent Young's modulus. In this article, the novel method was simulated on a simply supported PC beam-bridge subjected to time-dependent prestress losses for ≈9.5 months in the laboratory. [ABSTRACT FROM AUTHOR]