Flexural Rigidity Research Articles

This paper concerns the study of the multidirectional drape and bending rigidity of clothing packages combined with three types of adhesive inserts. The aim of this research was to investigate the effect of introducing seams of differentiated complexity to clothing packages consisting of cotton fabric and adhesive inserts. The adhesive inserts were differentiated according to their mass per square meter. Three kinds of seams differing by the number of bent and sewn layers were introduced into packages, and two techniques of bonding, differentiated by the sequence of operations, were applied. The results of the influence of bonding technique on the bending rigidity and multidirectional drape for packages with seams and those without them are discussed. All of the tests carried out were aimed at answering the question of how seam introduction and its complexity (the number of sewn layers) influence the bending rigidity and drapeability of clothing packages in order to facilitate clothing technologists in the proper selection of appropriate adhesive inserts for the engineered design of clothing products.

We present a general method to compute canonical averages for physical models sampled via quantum or classical quadratic unconstrained binary optimization (QUBO). First, we introduce a histogram reweighting scheme applicable to QUBO-based sampling constrained to specific intervals of an order parameter, e.g., physical energy. Next, we demonstrate that the scheme can accurately recover the density of states, which in turn allows for calculating expectation values in the conjugate ensemble, e.g., at a fixed temperature. The method can thus be used to advance the state-of-the-art characterization of physical systems that admit a QUBO-based representation and that are otherwise intractable with real-space sampling methods. A case in point are space-filling melts of lattice ring polymers, recently mapped in QUBO form, for which our method reveals that the ring catenation probability is nonmonotonic with the bending rigidity. Published by the American Physical Society 2025

As tactile sensors, antennae must be flexible and responsive while maintaining shape and control of the structure. We evaluated the geometric and mechanical properties of cricket antennae, which we treat as bending cantilever beams. Flexural rigidity (EI) is the mechanical property that most significantly controls bending behavior. We determined that the flexural rigidity decreases steeply (proximal to distal) by evaluating the quasistatic bent shapes in response to obstacle contact at different points along the antennae. This steep decrease in flexural rigidity causes the antennae to bend readily only near the obstacle contact, in contrast to the curvature of a beam with uniform properties and cross-section (which bends closer to the base). This flexural rigidity gradient in the antennae is consistent with the morphology: a decreasing second moment of area calculated from the measured taper and the diminishing wall (cuticle) thickness. Cricket antennae recovered from a single localized perturbation quickly and with minimal to no oscillation, suggesting behavior close to critical damping (fastest return without oscillations). Bending primarily occurred in the portion of the flagellum near the obstacle contact, reducing the length of the flagellum that participated in the oscillating behavior (natural frequency ∼11 Hz). Forced sinusoidal vibrations generated a resonance frequency of ∼30 Hz with imperceptible movement in the proximal part of the flagellum while the distal part vibrated. The results suggest that tapering of an elongated mechanosensor may facilitate a rapid return to its original shape without oscillation, which is an advantageous attribute that may also inform biomimetic applications.

Multilayer three-dimensional (3D) fabrics are gaining importance due to their unique properties, which are significantly influenced by the interlocking pattern and govern their end-use applications, particularly in protective textiles requiring higher through-the-thickness mechanical characteristics. This research focuses on developing 3D woven structures with novel orthogonal through-the-thickness interlocking patterns: warp interlocked (WP-IL), weft interlocked (WT-IL), and hybrid interlocked (HB-IL) by using warp and weft yarns simultaneously for interlocking fabric layers. Various performance characteristics, including air permeability, thermal conductivity, compression resistance, bending rigidity, tensile strength, and puncture resistance, were evaluated to assess the influence of fabric structure. Statistical analysis using One-way ANOVA was conducted to determine the significance of the interlocking pattern on these properties. The results indicate that weft interlock structures exhibit the highest air permeability due to their greater porosity, whereas hybrid interlock and warp interlock structures show 20.7% and 18% lower air permeability, respectively, due to their reduced structural porosity. Thermal conductivity results suggest no significant differences in insulation properties among the structures. Hybrid interlock fabrics demonstrate superior compression resistance and tensile strength, with 26.2% higher tensile strength than warp interlock structures and 12.3% higher than weft interlock structures in the warp direction, owing to the balanced distribution of binding yarns. In contrast, warp interlock structures exhibit the lowest bending rigidity in the weft direction, making them more flexible. Additionally, hybrid interlock structures provide the highest puncture resistance, while weft interlock structures show the lowest resistance due to their increased porosity. These findings highlight the critical role of fabric architecture in determining both comfort and mechanical properties, providing valuable insights for selecting optimal 3D woven structures in applications requiring specific performance attributes.

Biohybrid actuatorsexploit the contraction of biological components(muscle cells) to produce a force. In particular, bottom-up approachesuse tissue engineering techniques, by coupling cells with a properscaffold to obtain constructs undergoing contraction and guaranteeingactuation in biohybrid devices. However, the fabrication of actuatorsable to recapitulate the organization and maturity of native muscleis not trivial. In this field, quasi-two-dimensional (2D) substratesare raising interest due to their high surface/thickness ratio andthe possibility of functionalizing their surface. In this work, wefabricated micropatterned thin films made of poly(styrene–butadiene–styrene)(SBS) doped with barium titanate nanoparticles (BTNPs) for fosteringmyogenic differentiation. We investigated material concentrationsand fabrication process parameters to obtain thin microgrooved filmswith an average thickness below 1 μm, thus featured by a relativelylow flexural rigidity and with an anisotropic topography to guidecell alignment and myotube formation. The embodiment of BTNPs didnot significantly affect the film’s mechanical properties.Interestingly, the presence of BTNPs enhanced the expression of myogenicdifferentiation markers (i.e., MYH1, MYH4, MYH8, and ACTA1). The resultsshow the promising potential of SBS thin films doped with BTNPs, openingavenues in the fields of biohybrid actuation and skeletal muscle tissueengineering.

During skeletal aging, the bone remodeling cycle becomes dysregulated when bone resorption by osteoclasts outpaces bone formation by osteoblasts. Bone matrix mineralization by osteoblasts is an energy demanding process, and our lab seeks to better understand the fuel selectivity and utilization of energetic precursors by osteoblasts during age-related bone loss. Previous data from our lab underscored the importance of fatty acids as an energy source for bone formation in young (3 month) mice as mice deficient for carnitine palmitoyltransferase 2 (Cpt2flox/flox; Ocn-Cre), an obligate enzyme in mitochondrial long chain fatty acid beta-oxidation, exhibited lower trabecular bone volume than littermate controls. However, the impact of fatty acid catabolism during skeletal maturity and advanced aging remains unknown. To begin this study, we reanalyzed a publicly-available RNAseq dataset (GSE72815) comparing gene expression in human bone biopsies from young and geriatric female participants. A general pattern of increased expression of genes involved in fatty acid catabolism was evident in aged samples with the expression of SLC27a1, SLC27a5, and SLC27a6, involved in fatty acid uptake, being significantly up-regulated. These results were confirmed by qPCR analysis of RNA isolated from young (4 month) and aged (20 month) mouse femoral bone, and further supported by the increased fatty acid uptake in osteoblast cultures isolated from aged mice relative to young mice. To determine the significance of the shift towards increased fatty acid utilization in aging bone, we examined the skeletal phenotype of Cpt2 knockout mice and control littermates at 6 or 20 months of age. In contrast to the phenotype of 3-month-old Cpt2 knockout mice, bone mineral density was comparable to controls in male mutants at 6 months of age, then trended higher in the mutants at 20 months of age. MicroCT suggested the increase in BMD was due to a significant increase in cortical thickness at the femoral mid-diaphysis. In line with this finding, femurs from mutant mice exhibited increased bending rigidity and failure load. Because cellular senescence is a hallmark contributing to aging phenotypes, we examined the effect of senescent burden on the bone microenvironment in aged Cpt2 KO compared to controls. Reduced expression of cell cycle inhibitor CDKN2A, as well as senescent associated secretory phenotype (SASP) genes suggest an impact on senescent load in femoral bone due to the attenuation of lipid catabolism. These data suggest fatty acid oxidation has distinct age-dependent effects on osteoblast function and skeletal homeostasis, and disruption of this catabolic pathway could alter the senescent phenotype contributing to age-related bone loss. NIH DK099134 and NIH AR077533 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Observation of increasing bending rigidity of graphene with temperature

Nanoparticles, such as viruses, can enter cells via endocytosis, a process by which the cell membrane wraps around them. The role of nanoparticle size and shape on endocytosis has been well studied, but the biophysical details of how extracellular proteins on the cell membrane surface mediate uptake are less clear. Motivated by recent discoveries regarding extracellular vimentin in viral and bacterial uptake and the structure of coronaviruses, we construct a computational model with a cell-like and virus-like construct containing filamentous protein structures protruding from their surfaces. We study the impact of these additional degrees of freedom on viral wrapping. The cell surface is modeled as a deformable sheet with bending rigidity, and extracellular vimentin as semiflexible polymers, or extracellular components (ECC), placed randomly on the sheet. The virus is modeled as a deformable shell that also has explicit, freely rotating spike filaments on its surface. Our results indicate that cells with optimally populated filaments are more susceptible to infection as they take up the virus more quickly and utilize a relatively smaller area of the cell surface. At optimal ECC density, the cell surface forms a fold around the virus, which is faster and more efficient at wrapping than localized crumples. Additionally, cell surface bending rigidity aids in the generation of folds by increasing force transmission across the surface. Changing other mechanical parameters, such as the stretching stiffness of filamentous ECC or virus spikes, can result in localized crumple formation on the cell surface. We conclude with the implications of our study on the evolutionary pressures of virus-like particles, with a particular focus on the cellular microenvironment. Published by the American Physical Society 2025

Biomechanics of the implant-supported full arch fixed complete denture manufactured by milling and injection techniques: An experimental and FEA study.

Abstract This paper explores a novel methodology for identifying prestress force (and bending rigidity) from the perspective of static deflection methods and derives an incremental beam–column equation (iBCE) by elucidating the mechanisms underlying the long‐ and short‐term behaviors, with particular emphasis on a physical system that disregards long‐term deflections, including self‐weight and equivalent lateral loads. It allows for the scaling of measurements from the real world to the corresponding nondimensional form of the physical system. The methodology begins by constructing the non‐homogeneous terms of the equations using parameters and variables observed in the real world. Subsequently, utilizing second‐order theory induced by incremental loads during step loading, the decoupling and identification of prestress force and bending rigidity are accomplished. The identification algorithm is constructed by integrating the nondimensional form of the iBCE with physics‐informed neural networks. Without any additional regularization, the rationality and adaptability of this methodology are validated by nine examples that exhibit no nonlinear relations. A comprehensive series of systematic studies indicates that high accuracy can be achieved with the decoupled algorithm. This accuracy is possible when one mechanical parameter, such as bending rigidity or prestress force, is known and utilized to identify the remaining parameter. When both mechanical parameters are unknown, investing more in training costs enables the inverse identification of multiple parameters. Even with a 1% noise level, reasonable accuracy in the decoupling and identification of two mechanical parameters can be achieved. This methodology avoids the traditional limitations associated with solving the forward and inverse problems of incremental differential equations and transcendental equations.

The use of polyester and polyamide fabrics for parachute constructions has a great advantage because, in comparison with classical silk-based parachutes, they are more durable and suitable for absorbing higher mechanical shocks. Because polyester and polyamides are thermoplastics, they are sensitive to sudden increases in temperature due to mechanical shocks and high-speed friction. It is known that the local surface temperature of these parachute fabrics may exceed the melting point of the canopy for a short time period during parachute opening, which would have irreversible effects on parachute functionality and could lead to catastrophic parachute rupture. The main aim of this article is to enhance the surface heat resistance of the parachute fabrics from polyamide and polyester filaments through surface coating combined with super-fine TiO2 particles and silanization. This coating is also selected to increase the frictional heat loss and enhance the mechanical stability of parachute fabrics constructed from polyamide and polyester filaments. The changes in air permeability, bending rigidity, and friction of surface-coated parachute fabrics are evaluated as well. The new method based on laser irradiation by a pulsed laser is used for the prediction of these fabrics’ short-time surface thermal resistance.

Abstract This paper presents a novel approach to designing and manufacturing a composite sandwich panel with circular-shaped core. The sandwich panel is reinforced with silica nanoparticles (SNPs) and filled with polyurethane (PU) foam. The mechanical properties of the sandwich panels are then evaluated through a three-point bending (TPB) test. The study investigates the impact of various parameters, including the core’s length and height, the weight percentage (wt.%) of SNPs, and the PU foam, on the structure’s flexural strength. Additionally, the fracture surface of specimens is studied by scanning electron microscopy analyses. In order to validate the findings, a TPB test of the sandwich panel was simulated using ABAQUS software. The obtained results were then compared to the experimental data, revealing a favorable level of agreement between the two. The research findings indicate that incorporating SNPs within a specific range significantly improves flexural strength. Specifically, adding SNPs up to 3% results in an approximate 37% increase in flexural strength. However, the addition of 4 wt.% SNPs causes a decrease of about 13% in the strength of the sandwich panel. Furthermore, the geometry of the core plays a crucial role in controlling the flexural strength and rigidity of the panel. Increasing the core length and height decreases flexural strength by 52% and 31%, respectively. Moreover, the study reveals that the inclusion of PU foam in the sandwich panel, despite a slight increase in weight, significantly enhances flexural strength by about 54% and delays its ultimate failure. Eventually, the hybrid specimen exhibits a flexural strength approximately 70% greater than the pure foamless sandwich panel.

Alcohols influence the shape of the cells. To elucidate this phenomenon and understand the influence of alcohols on the mechanical properties of cell membranes such as bending rigidity, it is essential to investigate their effects on lipid bilayers. In this study, we explored the impact of short- and medium-chain alcohols on the bending rigidity and thickness of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers in the fluid phase. We employed various techniques, including vesicle fluctuation analysis, small-angle X-ray scattering, and differential scanning calorimetry. Experimental observations were further validated and interpreted using atomistic molecular dynamics simulations. Our results demonstrate that alcohols ranging from ethanol to octanol reduce the main phase transition temperature (Tm), bending rigidity (κ), and thickness of the bilayer (DHH). Decanol and dodecanol, on the other hand, increase Tm without significantly affecting κ and the bilayer thickness. Our study conclusively shows that alcohols shorter than decanol induce a negative chain length mismatch condition, leading to disorder and enhanced interdigitation in DMPC membranes, resulting in membrane thinning and softening. In contrast, decanol, whose chain length matches that of the lipid, enhances lipid chain order and reduces their interdigitation, resulting in no alteration in the bending rigidity and membrane thickness.

Purpose The aim of this study is to investigate the effect of alkaline treatment of jute/polyester interwoven fabric with different concentration levels (0, 2, 4, 6%) on some properties such as the weight changes, water adsorption time, moisture content, vertical wicking, bending and tensile properties. Design/methodology/approach The plain weave jute/polyester fabric was interwoven using jute and filament polyester yarns in the warp direction (1:1 ratio) and jute yarns in the weft direction using a shuttle weaving machine. Jute/polyester fabrics were treated with different concentrated solutions of NaOH (0–6% w/v) in an aqueous medium with soaking time of 60 min at room temperature. After soaking, jute/polyester fabrics were washed with deionized water twice. Jute/polyester fabrics were then. After drying, jute/polyester fabrics were kept in a desiccator for the following tests. To compare the properties of untreated and treated samples, some properties were evaluated. Findings The results indicated a decrease in weight and bending rigidity with increasing NaOH concentration. In general, alkali treatment of jute/polyester interwoven fabrics improved the handle properties, moisture content and wicking capabilities, but this treatment decreased the tensile strength of the fabric. Originality/value Study of the effect of alkaline hydrolysis on jute/polyester interwoven fabrics This treatment will have dual effects on the fabric, namely, the changing of jute fibers and the hydrolysis of the polyester component.

Deflection control in Reinforced Concrete (RC) beams is a fundamental aspect of structural engineering. Most contemporary design codes estimate deflection using the effective moment of inertia formula, which remains largely consistent across various standards. However, an alternative and more precise approach involves computing deflection through the double integration of the moment-curvature relationship along the beam's length, offering superior accuracy but requiring significantly higher computational effort. This study evaluates deflection predictions obtained through experimental testing, conventional code-based calculations, and the moment-curvature double integration method. The findings demonstrate a strong correlation between the experimental data and the results from moment-curvature integration, whereas deflection estimates based on code formulations tend to be overly conservative. Therefore a comprehensive parametric study was performed, considering key parameters such as tensile and compressive reinforcement ratios, and span-to-depth ratio. Based on the study's findings, an empirical model is proposed to determine the effective moment of inertia, offering improved accuracy in deflection predictions while maintaining computational efficiency in RC beam analysis.

Yielding of amorphous glasses and gels is a mechanically driven transformation of a material from the solid to liquid state on the experimental timescale. It is a ubiquitous fundamental problem of nonequilibrium physics of high importance in material science, biology, and engineering applications such as processing, ink printing, and manufacturing. However, the underlying microscopic mechanisms and degree of universality of the yielding problem remain theoretically poorly understood. We address this problem for dense Brownian suspensions of nanoparticles or colloids that interact via repulsions that induce steric caging and tunable short-range attractions that drive physical bond formation. In the absence of deformation, these competing forces can result in fluids, repulsive glasses, attractive glasses, and dense gels of widely varying elastic rigidity and viscosity. Building on a quiescent microscopic theoretical approach that explicitly treats attractive bonding and thermally induced activated hopping, we formulate a self-consistent theory for the coupled evolution of the transient and steady state mechanical response and structure as a function of stress, strain, and deformation rate over a wide range of high packing fractions and attraction strengths and ranges. Depending on the latter variables, under step rate shear the theory predicts three qualitatively different transient responses: plasticlike (of two distinct types), static yielding via a single elastic-viscous stress overshoot, and double or two-step yielding due to an intricate competition between deformation-induced bond breaking and decaging. A predictive understanding of multiple puzzling experimental observations is achieved, and the approach can be extended to other nonlinear rheological protocols and soft matter systems.

Locomotor adaptation in the hominoid clavicle through ontogeny.

High-frequency acoustic devices based on two-dimensional (2D) materials are emerging platforms to design and manipulate the spatiotemporal response of acoustic waves for next-generation sensing and contactless actuation applications. Conventional actuation methods, however, cannot be applied to all 2D materials, are frequency-limited or influenced by substrate interactions. Therefore, a universal, high-frequency, on-chip actuation technique is needed. Here, we demonstrate that surface acoustic waves (SAWs) can efficiently actuate suspended 2D materials by exciting suspended graphene membranes with high-frequency (375 MHz) Rayleigh waves and mapping the resulting vibration field with atomic force acoustic microscopy (AFAM), enabling direct visualization of wave propagation without substrate interference. Acoustic waves traveling from supported to suspended graphene experience a reduction in acoustic wavelength from 10 μm to ∼2 μm due to the decrease in effective bending rigidity, leading to a decrease in wave velocity on suspended graphene. By varying the excitation frequency through laser photothermal actuation (0-100 MHz) and SAW excitation (375 MHz), we observed a phase velocity change from ∼160 m/s to ∼700 m/s. This behavior is consistent with the nonlinear dispersion of acoustic waves, as predicted by plate theory, in suspended graphene membranes. The geometry and bending rigidity of the membrane thus play key roles in modulating the acoustic wave pattern and wavelength. This combined SAW actuation and AFAM visualization scheme advances the understanding of acoustic transport at the nanoscale limit and provides a route toward the manipulation of localized wavefields for on-chip patterning and transport over 2D materials surfaces.

This paper introduces a method for accurately estimating cable tension, combining the energy approach with the cable’s mode shape. The method simultaneously accounts for the bending rigidity of the cable and the rotational stiffness at both ends. Rayleigh’s energy-based method is applied to analytically derive a formula for cable tension, while the mode shape is approximated using a nonlinear regression analysis algorithm. The accuracy of the method is validated through comparison with available experimental data. The approach is applied to the An Dong Extradosed Bridge in Vietnam, demonstrating its effectiveness in evaluating cable forces for similar bridge structures. Notably, a significant difference of up to 13.13% in cable forces is observed when considering the rotational stiffness at cable ends, highlighting the importance of this factor in structural analysis.

Fracture fixation with standard locked plates can suppress interfragmentary motion beneficial for secondary bone healing. To address this limitation, dynamic fracture fixation plates have been developed which seek to maintain bending and torsional rigidity while providing controlled axial micromotion. This article provides a comprehensive systematic review of the history and current state of proposed dynamic plating technologies to better inform future development. 59 records (51 articles, 8 patents) describing 26 unique dynamic plating devices were identified across three literature and patent databases using PRISMA review guidelines. Concepts were grouped into one of 9 engineering approach categories, including plates that incorporate sliding mechanisms, elastic inserts, lattice structures, and mechanically compliant flexures, among others. Devices are compared in their technological characteristics, ranges of axial motion, stiffnesses, and levels of development. Despite many dynamic technologies demonstrating good healing results experimentally and clinically, widespread clinical adoption has not occurred. Some explanations for this are provided, including production costs for complex designs and the current co-existence of both rigid and flexible fixation approaches. Overall, dynamic plating offers a promising area of innovation to address the ongoing concerns of non-union rates associated with standard locked plating of long bone fractures.