Flexural Rigidity Research Articles

The increasing traffic congestion in East Jakarta, particularly at the Cakung intersection, prompted the construction of the Cakung Flyover, designed with a prestressed concrete box-girder system. However, field observations revealed several serviceability issues, including hairline cracks (0.10–0.28 mm), vertical deflections of 18–25 mm, and a 30.5 % reduction in effective prestress compared with theoretical design values. This research aimed to analyze prestress losses and their structural implications through an integrated analytical–empirical approach combining field measurements, theoretical modeling, and validation using SAP2000 and MATLAB simulations. The results showed that the box-girder section (A = 5.65 m², Wa = 5.43 m³, Wb = 2.76 m³) exhibited satisfactory flexural rigidity but experienced frictional losses at tendon angular deviations, particularly near anchorage zones. The tropical environment—average temperature 33 °C and relative humidity 85–90 %—accelerated creep, shrinkage, and relaxation in the 7-wire low-relaxation strands. Consequently, measured prestress losses were 1.3–1.6 times higher than those predicted by standard codes. This study confirms that tropical humidity significantly amplifies prestress degradation and highlights the need for climate-specific calibration of SNI 2847:2019 coefficients. The research contributes a calibrated correlation between tendon eccentricity (eₛ ≈ 1.195 m), deflection, and stress relaxation, enabling more accurate prediction and control of structural performance. The proposed framework provides practical guidelines for tendon configuration, prestress monitoring, and maintenance strategies for prestressed concrete flyovers in humid tropical regions such as Jakarta.

Acrylic coating is applied to fabrics in order to improve their aesthetic properties as well as their physical performance. In this study, the effects of the acrylic coating process applied to woven fabrics with different structural parameters on various surface (roughness and friction coefficient) and physical performance (permeability and handle) properties of the fabrics were investigated. From the results obtained, a general decrease in the surface roughness parameters and friction coefficients of the fabrics was observed after the acrylic coating process, and these reduction rates were affected by the weave structure of the base fabric and the fabric's structural parameters. A decrease in air permeability, water vapor permeability, and thermal resistance values of acrylic-coated fabrics was observed; in addition, in terms of handle properties, the bending rigidity values increased, and crease recovery angle values decreased.As a result of this study, it was observed that the fabric surfaces after the acrylic coating gained smoother and lower friction coefficient properties, and by taking into account other physical performance properties such as permeability and handle properties of fabrics after coating, it could contribute to the determination of fabric structural parameters to be taken into consideration in the selection of the base fabric to be coated for the desired area of use.

The locking compression plate (LCP) supports bridge plating in complex fractures or osteoporotic bones, promoting secondary bone healing via callus formation while preserving blood supply by maintaining a gap between the plate and bone. However, the high stiffness of LCP constructs may inhibit interfragmentary motion, leading to suboptimal callus formation or atrophic non-union. To address this problem, Singapore General Hospital (SGH) has developed a technique to introduce dynamization into locking plate systems. Our first study compared the stiffness of locking compression plate (LCP) constructs with and without elongated figure-of-8 holes of the similar diameters drilled into the near cortex. Drilling these holes reduced axial stiffness by 16% but did not affect bending stiffness or maximum strength under axial or bending loads. The findings suggest that elongated holes in the near cortex alter axial stiffness without compromising overall construct strength or fatigue performance. In the second study, we investigated the effect of eccentric over-drilling the near cortex in locked plate constructs with holes of varying diameter to reduce stiffness and enhance fracture healing. The technique was found to decrease axial stiffness by 34.2% and significantly reduced bending and torsional rigidity, while maintaining construct strength. Thus, this cost-effective method allows controlled compression across the fracture site, offering a practical solution to “dynamize” locked plates and promote better healing without the need for complex or expensive implant modifications. The advantage of these studies was that we used standardised sawbone models instead of cadavers to limit differences in terms of anatomical variations and mechanical quality of the bone. However, the main limitation of our studies is that the mechanical properties of the bone-implant construct which is dependent on fracture healing was not accounted for. Dynamic locking screws (DLS) has been introduced with the aim to enhance secondary bone healing by allowing controlled axial micro-motion but often failed due to design issues causing unpredictable stiffness, excessive or insufficient motion, and mechanical complications like screw loosening or breakage. These challenges ultimately limited their clinical reliability and adoption. In contrast, we believe our technique is simple to implement during surgery and does not require any modifications to the implant.

This study investigates the quantitative analysis of stiffness and softness properties of sports jersey fabrics. Four 100% polyester microfibre sports jersey fabrics, which are mini mesh, polar eyelet, eyelet, and interlock fabrics, were tested under controlled laboratory conditions. One-way ANOVA and Tukey's post-hoc statistical analysis showed significant differences in wale and course directions among the fabric types (p < 0.05). Eyelet fabric exhibited the highest softness properties while also demonstrating structural stiffness, with bending lengths of 0.89 cm (wale) and 0.88 cm (course), and flexural rigidity of 19.29 mg·cm (course). Despite its soft tactile feel, these values indicate resistance to bending. In contrast, the polar eyelet demonstrated the least resistance to bending, with the lowest bending length of 0.65 cm in both directions. Mini mesh fabric showed the highest pliability, having the lowest flexural rigidity of 7.00 mg·cm, making it the least stiff fabric overall. The study highlights that fabric mass per unit area, thickness, and structural design significantly influence tactile properties. This paper provides the importance of tactile properties in fabric selection for optimizing athlete comfort in sportswear.

Lattice structures have been widely studied in various fields due to their lightweight and high-energy absorption capabilities. In this study, we propose the use of lattice structures in the design of sports protective equipment for contact sports athletes. A total of six specimens were additively manufactured either with a bending-dominated rhombic dodecahedron (RD) structure or stretch-dominated re-entrant (RE) structure. Elastic resin was used to investigate the specimens’ compressive strength and energy absorption, impact reduction, and flexural properties in comparison with those of conventional foam and rigid polyethylene (PU). Despite having a lower relative density, the RE structure exhibits greater stiffness, showing up to 40% greater hardness and averaging 30.5% higher bending rigidity compared with the RD structure. However, it unexpectedly shows less stability and strength under uniaxial loading, which is 3 to 6 times weaker when compared with the non-auxetic RD structure. Although conventional PU has higher loading than 3D-printed lattices, the lattice shows excellent bendability, which is only 1.5 to 3 times stiffer than that of foam. The 3D-printed lattice in this study shows an optimal improvement of 43% in terms of impact absorption compared with foam and a 2.3% improvement compared with PU. Amongst the six different unit cell dimensions and structures studied, the RD lattice with a cell size of 5 mm is the most promising candidate; it has superior elasticity, compressive strength, and impact resistance performance whether it is under low- or high-impact conditions. The findings of this study provide a basis for the development of 3D-printed lattice sports protective chest equipment, which is more comfortable and offers improved protection for contact sports players.

Optimizing solution-processed nanosheet networks for electronic applications requires understanding the relationship between nanosheet dimensions, network morphology, and electrical properties. Here, we fabricate graphene nanosheets with both low- and high-aspect-ratios using liquid-phase exfoliation (LPE) and electrochemical exfoliation (EE), respectively. Spray-coated networks of both nanosheet types display distinct morphological and electrical properties. High-resolution 3D imaging shows that low-aspect-ratio LPE nanosheet networks display a disordered, porous structure with point-like junctions. Conversely, high-aspect-ratio EE graphene forms low-porosity networks with highly aligned nanosheets with large-area conformal junctions. Electrical measurements demonstrate that EE networks achieve lower resistivity and reduced percolation thicknesses due to reduced junction resistances and improved nanosheet alignment. We propose a theoretical model linking nanosheet bending rigidity, aspect ratio, and junction formation, highlighting the critical role of nanosheet flexibility in enabling conformal junctions. Furthermore, by size-selecting both nanosheet types, we measure the dependence of network resistivity on nanosheet thickness. LPE networks show increasing resistivity with thickness, whereas EE networks exhibit decreasing resistivity. We develop a simple model linking these behaviors to point-like and planar junctions respectively and quantify the size-dependence of both nanosheet and junction resistance for both cases. Unexpectedly, data analysis using this model predicts the EE nanosheets to be more conductive than the LPE ones, a fact confirmed by THz spectroscopy. This study establishes the importance of nanosheet aspect ratio and flexibility in governing network morphology and electrical performance. Our findings provide key insights for developing high-performance, solution-processed 2D material networks for future electronic devices.

Transition metal dichalcogenide (TMD) nanotubes, particularly those of molybdenum disulfide (MoS2), exhibit exceptional optoelectronic, superconducting, and mechanical properties, rendering them highly promising for diverse advanced applications. Despite this potential, the controlled synthesis of small-diameter, single-walled TMD nanotubes, especially MoS2, remains a significant challenge, primarily due to their high bending rigidity. Here, we provide direct atomic-scale evidence for the spontaneous transformation of bilayer MoS2 nanoribbons into fully closed single-walled nanotubes within the confined environment of carbon nanotubes (CNTs). By employing atomic-scale high-resolution transmission electron microscopy (HRTEM), nanobeam electron diffraction (NBED), annular dark-field scanning transmission electron microscopy (ADF-STEM), and electron energy-loss spectroscopy (EELS), we identify a cooperative mechanism involving simultaneous axial rotation and out-of-plane bending of the bilayer nanoribbons. This coupled motion facilitates seamless edge reconstruction, ultimately leading to the formation of defect-free, fully closed single-walled MoS2 nanotubes. Quantitative geometric reconstruction and strain analyses, supported by density functional theory (DFT) calculations, reveal that although the transformation induces radial, axial, and shear strains (dominated by radial bending strain), spontaneous interlayer Mo-S edge bonding provides crucial energetic stabilization for the resulting tubular structure. Statistical analysis of multiple transformation events confirms the necessity of this coupled mechanism, which inherently generates interlayer twist and results in exclusively chiral nanotubes, predominantly with diameters between 4.1 and 4.9 nm. Our findings elucidate a deterministic, self-limiting transformation pathway driven by coupled axial rotation and bending, providing a strategy for potentially controlling the structure (chirality and diameter) of quasi-one-dimensional TMD nanotubes for future nanoelectronics, photonics, and energy applications.

Abstract Constant-torque compliant joints are able to maintain a quasi-constant torque over a defined range of rotations, while minimizing backlash, friction, and wear. However, comparing different design solutions remains a challenging task, due to the variety of materials, dimensions, and fabrication technologies. In this article, a comparison criterion based on the maximum stress value that occurs in the flexure during the deflections is presented. The maximum stress criterion provides a standardized framework for evaluating the performance of different joints, in terms of maximum output torque, regardless of their material properties, footprint, and flexural rigidity. The criterion highlights the shapes that generate the lowest stress values and that can be exploited to produce the highest torque outputs. The criterion is elucidated considering different flexure designs and used to compare the compliant joints presented in the literature.

The wrapping of nano- and microparticles is a fundamentally important pathway for their cellular uptake and depends on the physicochemical properties of both particle and membrane. Polymeric gels are a versatile class of materials whose elastic properties can be tuned in a wide range from ultrasoft to hard by changing the density of cross-linkers. Using spring networks for the microgels and triangulated surfaces for the membranes, we study microgel wrapping with computer simulations. The interplay of microgel and membrane deformation is controlled by the competition between microgel elasticity and membrane bending rigidity. Compared with hard particles, the range of adhesion strengths for which partial-wrapped states are stable is enlarged. Volume and surface area of partial-wrapped microgels can be significantly reduced compared with those of free microgels. Understanding microgel wrapping can help us to design polymeric particles for biomedical applications, e.g., as membrane markers and targeted drug delivery vectors.

Adaptable hydrogel bioelectronics that sustain long-term, uninterrupted operation are critical for early disease diagnosis and personalized health care. However, conventional hydrogel electrodes suffer from mechanical fragility, rapid dehydration, freezing, and poor comfort because of thickness-induced interfacial gaps. We report a 2.7-micrometer-thick robust, permeable, and antifreezing hydrogel electrode for high-quality 8-day electrophysiological monitoring under everyday scenarios. The ultrathin electrode is fabricated using gelatin hydrogels with temperature-controlled phase change properties reinforced by nanomesh while incorporating lithium chloride, and a binary solvent achieves antifreezing and antidehydration characteristics. The design minimizes flexural rigidity, resulting in high interfacial adhesion energy with human skin, and enhances gas (air, oxygen, and carbon dioxide) permeance and water vapor transmission rate. Consequently, the ultrathin hydrogel electrode exhibits high biocompatibility, superior wear comfort, and minimized motion and sweat artifacts, enabling reliable, uninterrupted, wireless health monitoring over eight consecutive days across various real-life activities and adaptation to cold environments.

Compositional asymmetry is a defining feature of cellular membranes, controlling permeability, protein activity, cholesterol dynamics, and shape remodeling. This asymmetry can create a stress imbalance, with the two leaflets experiencing opposing tensions, though direct experimental measurement of leaflet stress remains challenging. Such a stress imbalance can compress one leaflet and trigger a fluid-to-gel phase transition, which reduces membrane fluidity and markedly increases bending rigidity. These phenomena raise a key question of how membranes respond mechanically before crossing the transition threshold, a regime that remains relevant to biological functions. Here, we combine extensive all-atom and coarse-grained molecular dynamics simulations to examine how stress asymmetry modulates membrane structure and mechanics near the transition point. Using POPE and DLPC bilayers as model systems, we find that moderate asymmetry induces transient gel-like domains that continuously form and dissolve, amplifying undulations and lowering bilayer rigidity. Beyond the gelation threshold, the trend reverses and the bilayer stiffens, resulting in a non-monotonic dependence of rigidity on asymmetry. Moreover, our results reveal distinct curvature preferences of fluid and gel phases. Extending this analysis to a multicomponent bacterial outer membrane, we demonstrate that stress asymmetry can trigger transient gel-like domain formation even in complex lipid mixtures. This provides a proof of principle that differential stress modulates membrane mechanics by inducing either softening or stiffening, complementing the effects of molecular composition. Our findings elucidate how cells might exploit the stress-curvature-phase coupling to tune membrane rigidity under near-physiological conditions.

This study experimentally investigates the use of stainless-steel woven wire mesh (SSWWM) as a patch material for repairing damaged glass fibre-reinforced (GFR) composite laminates. The effects of several factors on the three-point bending (3PB) behaviour of the parent laminate were examined, including the repair method (the plugging of open hole and the external patch repair), the mesh count of the SSWWM, and the number of SSWWM layers. According to the findings, all parameters considered in this study play a pivotal role in 3PB behaviour. Employing SSWWM as a patch material can recover 66.02–129.2% of the undamaged 3PB failure load, depending on the repair method, mesh count of the SSWWM, and number of SSWWM layers. Overall, decreasing the mesh count and increasing the number of SSWWM layers and applying an external patch repair method yield better results in terms of failure load and patch efficiency. This can be attributed to the increased wire diameter, improved bending rigidity, and better load distribution over a wider area. The SSWWM bridges the damaged zone, ensuring effective load transfer between the patch and parent laminate while preventing crack propagation. Utilising SSWWM as a patch material provides a quick, reliable solution for damage scenarios in engineering applications.

The mechanically extracted fibres from water hyacinth stems/petioles are used to produce a needle-punched nonwoven structure. The fibre yield is around 5%, and the length of fibres ranges between 37 cm and 60 cm. 83% of water hyacinth fibre dissolves in 59.5% H2SO4. The fibre fineness, as calculated, is 5.6 tex, with a low bundle strength (1.5 g/tex) and specific flexural rigidity of 0.94 cN-mm2/tex2. The scanning electron microscopic image of alkali-treated fibre shows the sign of fibre splitting, and the removal of hemicellulose and lignin is confirmed through the Fourier Transform Infrared Spectroscopic study of alkali-treated fibre. The energy dispersive X-ray spectrometer identifies the presence of different compositional elements. The produced nonwoven has excellent water absorbency (∼ 777%), which increases with an increase in sodium hydroxide dose level up to 10%. The sectional air permeability is higher (23-27%) for various concentrations of alkali treatment compared to untreated samples.

Post-buckling properties of cold-formed steel thin-walled C-sections with improved-flanges of flexural rigidity

Magnetic torque-based method for quantifying the flexural rigidity of microfibers

This study examines the effect of stone washing and elastane protectants on thermal and low-stress mechanical properties of denim fabric. Stone washing has a significant effect on fabric properties resulting in increased thermal conductivity, shear stiffness, and work of compression while decreasing air permeability and tensile strength and bending rigidity. Increased washing time from 30 to 60 minutes further enhances these effects. Notably, the addition of elastane protectants during stone washing mitigated various adverse effects of stone washing by maintaining fabric comfort properties while improving the mechanical properties. Specifically, these protectants limited the increase in thermal conductivity, preserving potential fabric comfort. Furthermore, while stone washing improved water vapor permeability, the introduction of elastane protectants showed negligible changes to this property. Overall, the findings highlight the key role of careful selection of washing time and elastane protectant in tailoring the denim fabric properties to achieve desired comfort and mechanical performance. This study is also addressing the Sustainable Development Goals, SDG 9 (Industry, innovation and infrastructure) by exploring methods to reduce damage during denim production, potentially leading to resource efficiency.

This study investigates the Burmister problem for a nanosized elastic layer under normal, tangential, and couple tractions, incorporating surface effects within the framework of classical couple stress theory. By integrating Gurtin–Murdoch and Steigmann–Ogden surface elasticity models, we derive a semi-analytical solution using stress function formulation and Fourier integral transforms, numerically evaluated via Gauss–Legendre quadrature. Comprehensive parametric analyses reveal significant surface effects on force stresses, displacements, and couple stresses near the layer’s top surface. Both surface models mitigate singularities in stresses and displacements compared to classical theory, with the Steigmann–Ogden model achieving greater reduction under normal loading due to its bending rigidity. Under tangential loads, it smooths fields but yields slightly higher magnitudes than the Gurtin–Murdoch model. Couple traction induces nonzero surface stresses and alters displacement profiles, with Steigmann–Ogden reducing subsidence displacement more effectively. However, couple stress singularities persist, with surface effects playing a secondary role. As layer thickness increases, solutions converge to the half-plane case, with stresses converging faster than displacements. These findings highlight the critical role of surface mechanics in nanoscale structures, offering insights for designing robust nanomaterials in engineering applications. The results underscore the Steigmann–Ogden model’s superior regularization of elastic fields, advancing the understanding of surface effects in couple stress layers.

The interplay between polymer dynamics and molecular crowding is a crucial aspect of many biological and synthetic systems. In this study, we employ coarse-grained molecular dynamics simulations to investigate the translocation of a polymer through a nanopore under varying crowding conditions. The crowders are modelled as rigid rods of different lengths, and their influence on translocation probability and time is systematically analyzed by varying the area fraction (ϕ), crowder length (L), and bending rigidity (kθ). We find that increasing ϕ leads to a significant reduction in translocation probability, with longer and more rigid crowders imposing a stronger steric hindrance, thereby amplifying the entropic barrier. Translocation time follows a non-monotonic trend, suggesting a competition between entropic compression and active pushing from the crowders. These findings highlight how crowding geometry and rigidity influence polymer transport, with implications for biological processes such as DNA translocation and applications in synthetic nanopores. However, limitations arise due to the lack of explicit hydrodynamic interactions and the idealized nature of crowder-polymer interactions.

An analytical method is developed to evaluate the modal density of a fluid-loaded stiffened plate with a damping layer. The effects of the damping layer, ribs, and fluid load on the structure’s equivalent bending rigidity and surface density are analyzed. The vibration equation is obtained by applying the Hamilton principle, and the modal density is calculated by counting modes in the specific band. The modal density calculation method for both ribbed-type plates and uniform-type plates is verified through numerical simulation. The increase in the number of ribs has made the rib-off frequency at which the effect of the ribs can be neglected become higher, since the wavelength needs to be shorter when the ribbed plate can be treated as a uniform-type plate. The introduction of the damping layer has slightly increased the modal density compared to the uniform plate. In contrast, the introduction of fluid load has dramatically increased the modal density of the corresponding base plate in the low-frequency domain, and the effect of the fluid load can be ignored in the high-frequency domain.

Considering the inelasticity properties of eccentric compression columns of reinforced concrete, a uniform equivalent rigidity reduction factor is provided in specifications. As many factors affect the elastoplastic flexural rigidity of reinforced concrete columns and owing to load increase, some concrete tension zones crack, resulting in a lower flexural rigidity of concrete columns, however, the uniform equivalent rigidity coefficient cannot reflect this change rule. To investigate the change rule of flexural rigidity of reinforced concrete columns when considering the deflection second-order effect of compression columns, by testing reinforced concrete eccentric compression columns, a trilinear calculation model is established that can reflect the change rule of elastoplastic flexural rigidity of reinforced concrete columns by analyzing the relationship between bending moment and curvature. Additionally, a formula to calculate the elastoplastic flexural rigidity reduction factor of a reinforced concrete eccentric compression column is obtained via linear regression. This formula can reflect the effects of concrete cracking, axial compression ratio, eccentricity, and reinforcement ratio on the flexural rigidity of concrete columns, as well as predict the flexural rigidity reduction of existing reinforced concrete columns.