Flexural Rigidity Research Articles

Snap-through dynamics of buckled flexible filaments in a side-by-side configuration

The flow-induced snap-through dynamics of side-by-side buckled flexible filaments in a uniform flow were investigated using the penalty immersed boundary method. We systematically examined the effects of gap distance and bending rigidity on the filament's motion and energy harvesting performance. Four distinct modes were observed as we varied the aforementioned parameters: the dual equilibrium mode, the dual streamwise oscillation mode, the single snap-through oscillation (STO) mode, and the dual STO mode. We analyzed the corresponding wake patterns associated with each of these modes. A phase transition from out-of-phase to in-phase motion was observed at low gap distances and bending rigidities. At lower gap distances, the interaction between two filaments was pronounced, leading to a co-motion of the filaments and enhanced elastic energy. This interaction decreased as the gap distance increased. Filaments in the 2STO mode exhibited significantly higher strain energy compared to the other modes. The elastic energy was concentrated at the rear part of the filaments and increased with higher gap distances and bending rigidities. Considering both energy harvesting efficiency and space utilization rate, a gap distance equal to 1 exhibited the best performance.

Giant organelle vesicles to uncover intracellular membrane mechanics and plasticity

Tools for accessing and studying organelles remain underdeveloped. Here, we present a method by which giant organelle vesicles (GOVs) are generated by submitting cells to a hypotonic medium followed by plasma membrane breakage. By this means, GOVs ranging from 3 to over 10 µm become available for micromanipulation. GOVs are made from organelles such as the endoplasmic reticulum, endosomes, lysosomes and mitochondria, or in contact with one another such as giant mitochondria-associated ER membrane vesicles. We measure the mechanical properties of each organelle-derived GOV and find that they have distinct properties. In GOVs procured from Cos7 cells, for example, bending rigidities tend to increase from the endoplasmic reticulum to the plasma membrane. We also found that the mechanical properties of giant endoplasmic reticulum vesicles (GERVs) vary depending on their interactions with other organelles or the metabolic state of the cell. Lastly, we demonstrate GERVs’ biochemical activity through their capacity to synthesize triglycerides and assemble lipid droplets. These findings underscore the potential of GOVs as valuable tools for studying the biophysics and biology of organelles.

Unlocking the superior flexibility and enhanced catalytic oxidation performance of CoTiO3 nanofibrous membranes through zirconium doping

The development of continuous CoTiO3 (CTO) fibers with prominent catalytic oxidation activity, tunable fibrous structures, and improved recyclability is appealing for application in efficient organic wastewater treatment; however, inescapable flaws remain, such as their inherent brittleness and adverse operability. Herein, a facile and effective strategy is proposed for the fabrication of flexible and mechanically robust CTO nanofibrous membranes through a combination of element doping and sol–gel-assisted electrospinning. Compared with pristine CTO fibers, the resulting zirconium-doped CoTiO3 (ZCTO) nanofibrous membranes displayed remarkably enhanced flexibility and tensile mechanics, which were attributed to their lower crystallinity, smaller grain size, and fewer fiber surface defects. The developed ZCTO fibrous membrane demonstrated exceptional resistance to bending fatigue, retaining a polymer-like bending rigidity of approximately 25 mN even after undergoing 200 reciprocating bending cycles. Furthermore, the incorporation of zirconium into CTO clearly had an advantageous effect on the formation of oxygen vacancies, thereby enhancing the surface adsorption of peroxymonosulfate (PMS), accelerating the electron transfer process, and weakening the peroxy bonds. The tetracycline degradation efficiency of the ZCTO fibers remained at 81.4% within 10 min after 5 continuous cycles. Benefiting from their robust mechanical properties and excellent catalytic activity, the fabricated membranes demonstrated outstanding dynamic catalytic performance under gravity-driven conditions. More importantly, the reported strategy might be adopted and extended to develop a wide range of ceramic fibers with enhanced flexibility and mechanics for catalytic oxidation.

Homogenization Model for Multistable Honeycomb Metastructures with Beam-like Behavior

Reduced order models facilitate initial design space investigations and enable assessing the benefits of compliant structures utilized for shape adaptability. This work presents a simple model to determine the flexural rigidity of a beam-like, multistable metastructure used as a spar in a hybrid spanwise morphing wing. The model considers the more complex metabeam as a homogeneous beam described by Euler-Bernoulli beam theory with an equivalent flexural rigidity. The analytical model's validity is established by comparing the obtained static and dynamic responses to finite element simulations. A closed-form expression of the flexural rigidity is then given, drawing from the multistable honeycomb's material properties and the metabeam’s geometry. The model's limitations are addressed by examining several specific cases of the metabeam’s morphed configurations and a more complex metabeam structure.

Effects of two types of surface treatments on the structural elasticity of human fingernails.

The human nail has a three-layered structure. Although it would be useful to quantitatively evaluate the changes in deformability of the nail due to various surface treatments, few studies have been conducted. The effects of two types of surface treatment-a chemically acting nail softener and a physically acting nail strengthener-on the deformability of human fingernails were investigated. The Young's modulus of each plate of the nail samples before and after softening treatment was determined by nanoindentation. The Young's modulus of the strengthener was determined by conducting a three-point bending test on a polyethylene sheet coated with the strengthener. Young's modulus decreased in order from the top plate against the softening treatment time, and the structural elasticity for bending deformation (SEB) of the nail sample, which expresses the deformability against bending deformation independent of its external dimensions, decreased to 60% after 6h of treatment. The Young's modulus of the nail strengthener was 244.5MPa, which is less than 10% of the SEB of the nail. When the nail strengthener was applied to the nail surface, the SEB decreased to 73%, whereas the flexural rigidity increased to 117%. Changes in nail deformability caused by various surface treatments for softening and hardening were quantitatively evaluated successfully.

Folding of a growing hyperelastic sheet in a viscous fluid

Understanding the growth-induced deformation of soft materials in viscous environments is important for a variety of problems in nature and engineering. Here, we focus on the fluid–structure interaction of a hyperelastic sheet growing in an incompressible Newtonian fluid in the Stokes flow regime. We develop a computational framework for simulating this problem, where the isogeometric boundary integral method is used with the Kirchhoff–Love shell formulation and elastic–plastic decomposition of the deformation gradient tensor. We quantify the relative effects of the growth rate, the sheet bending rigidity, and the fluid viscosity on the fold formation and development of the growing sheet. Our results suggest that the viscous resistance to in-plane deformation promotes fold formation, whereas the viscous resistance to out-of-plane deformation suppresses fold development. We also investigate the effects of the thickness and aspect ratio of the rectangular sheet. Finally, we compare the growth- and prestrain-induced deformations to find a common behavior of sheets under viscous environments.

Numerical evaluation of dimension effects of cold-drawn shape memory alloy crimped fiber on pullout resistance

A finite-element (FE) pullout model was developed and validated by a previous experimental pullout test of cold-drawn shape memory alloy (SMA) crimped fiber. Then, how the crimped fiber dimensions, such as the diameter, wavelength, embedded wave, and wave depth, influence its pullout behavior is investigated. The FE results indicate that the fiber diameter must be large enough to produce a good flexural rigidity. The recommended diameter is about 1.0 mm. However, it should note that the pullout resistance is not improved much for thicker fiber. The short wavelength is more effective than the long one because of the higher maximum pullout stress and the more peak points. The more embedded waves produce the higher pullout resistance; however, the increasing pullout resistance is slowed down when the maximum pullout stress exceeds the yield strength. A 5-embedded wave is proposed to produce a reasonable pullout resistance whereas satisfying the economically used material. Finally, deep-crimped fiber generates a higher pullout resistance than shallow-crimped fiber. Based on the effect of the dimensions on the pullout behavior, an optimum dimensions concept is proposed for crimped fiber.

Phase field model for multi-material shape optimization of inextensible rods

We derive a model for the optimization of the bending and torsional rigidities of non-homogeneous elastic rods. This is achieved by studying a sharp interface shape optimization problem with perimeter penalization, that treats both rigidities as objectives. We then formulate a phase field approximation of the optimization problem and show the convergence to the aforementioned sharp interface model via $\Gamma$-convergence. In the final part of this work we numerically approximate minimizers of the phase field problem by using a steepest descent approach and relate the resulting optimal shapes to the development of the morphology of plant stems.

Flexural behavior of the corrugated steel-concrete composite structures with the polyurethane concrete (PUC)

The use of polyurethane concrete (PUC) with a high compressive strength together with a corrugated steel plate (CSP) with a high tensile strength can improve the bending capacity of the corrugated steel-concrete composite structures. Although the PUC is lighter than normal concrete, its compressive, tensile, and bond strengths are much higher. In the paper, two groups of corrugated steel-concrete composite structure specimens with the PUC were designed, and the positive and negative bending capacities of the composite structure specimens were tested by a symmetrical four-point loading test and compared with that of the composite structure specimens using the normal concrete. The test results show that the bending capacity and deformation property of the composite structure specimens with the PUC are greatly improved compared with those using the normal concrete. Compared with the positive and negative bending capacities of the corrugated steel-normal concrete composite structure specimens, the composite structure specimens using PUC in the compression zone increased by 137.88 % and 136.42 %, while the corrugated steel-PUC composite structure specimens increased by 311.69 % and 283.39 %. Since the PUC has high bond strength, the test results of the negative flexural rigidity of the corrugated steel-PUC composite structure specimens were evaluated higher than the derived theoretical results. The test results of the corrugated steel-normal concrete composite structure specimens and the composite structure specimens using PUC in the compression zone are consistent with the theoretical results. In addition, using the PUC in the compression zone greatly improves the negative bending performance of the composite structure.

Interaction of surface water waves with partial porous structure and floating elastic plate in the presence of sea wall

ABSTRACT This study proposes a model composed of either bottom-standing porous structure (BSPS) or surface-piercing porous structure (SPPS) in combination with an elastic plate (EP) placed at a distance from one another to protect a sea wall. The study uses the governing equation and the boundary conditions to coin a system of equations, and the system of equations is solved to identify the hydrodynamics coefficients. Further, it is noticed that length, frictional coefficient, porosity of the porous structure, and flexural rigidity of EP play a crucial role in reducing the force on the sea wall, water elevation and plate deflection. The SPPS exhibits a nearly 60% reduction in wall force coefficient due to a 50% increase in wave-damping when compared to BSPS for k 0 H = 0.85. These results are crucial for developing floating structures that can resist harsh wave environments and minimize the effects of waves close to the shore.

Asymmetry in linear measurements and cross-sectional geometry in the humerus during ontogeny.

Adult upper limb asymmetry is used to reconstruct behavior. However, the developmental trajectory of asymmetry in bone length, cross-sectional geometry (CSG), and joint dimensions is poorly understood. This study examines the development trajectory of humeral asymmetry and if asymmetry in bone length, joint size, and CSG develop in concert. Linear measurements of bone length and metaphyseal/epiphyseal breadth, bending rigidity (Imax and Imin), and cross-sectional shape (Imax/Imin) at 30%, 50%, and 70% of bone length were acquired from 3D models of humeri from four skeletal samples of prehistoric hunter-gatherer populations (n = 82). Dental age cohorts were used to assess ontogenetic trends. Percent absolute (%AA) and directional (%DA) asymmetry were calculated for paired measures. Percentage of matching direction of asymmetry across variables and correlation analysis tested relationships between variables. Within the total pooled sample, Imax shows the highest %AA and %DA, followed by shape and linear dimensions. Asymmetry is lowest in neonates and increases with age, particularly %DA of Imax in mid-proximal sections. Correlations among variables are low to moderate and strongest between Imax measures. Matching direction of asymmetry between variables is low and generally increases with age. Higher correlations with age in CSG likely indicate greater responsiveness to mechanical loading. Low correlations in magnitude of asymmetry and side dominance suggest independence in the development of asymmetry between maximum rigidity, shape, and linear measures. Differences in how asymmetric loading affects the ontogeny of linear and CSG variables may account for the heterogeneous development of asymmetry.

Changes in limb bone diaphyseal structure in chimpanzees during development.

This study tests if femoral and humeral cross-sectional geometry (CSG) and cross-sectional properties (CSPs) in an ontogenetic series of wild-caught chimpanzees (Pan troglodytes ssp.) reflect locomotor behavior during development. The goal is to clarify the relationship between limb bone structure and locomotor behavior during ontogeny in Pan. The latex cast method was used to reconstruct cross sections at the midshaft femur and mid-distal humerus. Second moments of area (SMAs) (Ix, Iy, Imax, Imin), which are proportional to bending rigidity about a specified axis, and the polar SMA (J), which is proportional to average bending rigidity, were calculated at section locations. Cross-sectional shape (CSS) was assessed from Ix/Iy and Imax/Imin ratios. Juvenile and adult subsamples were compared. Juveniles and adults have significantly greater femoral J compared to humeral J. Mean interlimb proportions of J are not significantly different between the groups. There is an overall decreasing trend in diaphyseal circularity between the juvenile phase of development and adulthood, although significant differences are only found in the humerus. Juvenile chimpanzee locomotion includes forelimb- and hindlimb-biased behaviors. Juveniles and adults preferentially load their hindlimbs relative to their forelimbs. This may indicate similar locomotor behavior, although other explanations including a diversity of hindlimb-biased locomotor behaviors in juveniles cannot be ruled out. Different ontogenetic trends in forelimb and hindlimb CSS are consistent with limb bone CSG reflecting functional adaptation, albeit the complex nature of bone functional adaptation requires cautious interpretations of skeletal functional morphology from biomechanical analyses.

Study on the Effect of Terminalia chebula Softening Treatment on Physical and Mechanical Properties of the Banana Fabric

ABSTRACT The demand for environmentally friendly clothing and fabrics continues to increase globally. Banana fiber is a sustainable fiber known for its high tensile strength. It can be effectively blended with cotton and various synthetic fibers to develop versatile fabrics. The fiber’s abrasive texture is a major problem, making it difficult to wear and limiting its application in the apparel industry. The study focuses on the utilization of Terminalia chebula, an organic material, as a softening agent to address these concerns and maintain the environmentally friendly nature of the banana fabric. The experiment involved treating the banana fabric with different concentrations (20%, 40%, and 60%) of Terminalia chebula solution. The physical, comfort, and mechanical properties of the treated fabric are evaluated and compared to those of the untreated fabric. The results demonstrate that Terminalia chebula treated fabric has better comfort (both bending rigidity and stiffness) Notably, the treated fabric shows a substantial improvement in crease recovery and drapability. However, no effective improvement was found in tensile and seam strength. In addition, the study explores the potential of T. chebula as a multifunctional textile finish, making a valuable contribution to the growth of sustainable and eco-friendly textile finishing methods.

Elastic medium and torsional spring effects on the nonlocal dynamic of functionally graded porous nanotubes

In this study, Eringen’s nonlocal elasticity theory that applies the small size effects in functionally graded porous nanotubes embedded in an elastic matrix is discussed. The material properties of functionally graded porous nanotubes are taken into account to vary over the radius direction with a rule of mixture. The free torsional vibration relation according to nonlocal elasticity theory, via Hamilton’s principle, is obtained and an eigenvalue solution is constructed for the free torsional vibration response of the presented work. The presented analytical model is validated by comparing the calculated mathematical results for homogeneous nanotubes with rigid and non-rigid boundary conditions. Special attention is given to deformable boundary conditions, porosity coefficient, material grading coefficient and also to the influence of elastic medium on the free torsional vibration frequencies. In this paper, it has been proven that the influence of length, elastic medium, elastic torsional spring rigidities, material grading and porosity coefficients on the vary in the torsional vibration frequency of the functionally graded nanotube is not small.

103 A Bifurcation Model Predicts Intravascular Catheter Herniation When Using Transradial Access in Neuroendovascular Procedures

INTRODUCTION: The speed and safety of acute ischemic stroke interventions can be improved with catheter-based revascularization performed via the transradial access versus the traditional transfemoral access. A critical source of delay and procedural failure is a phenomenon known as herniation where the catheter system suddenly buckles and deviates from the intended endovascular pathway as the surgeon attempts to track one device over or through another around a tight bend. METHODS: Recent modeling work suggests that herniation is associated with a bifurcation in strain energy. We hypothesized that herniation could be predicted by modeling the strain energy stored in a catheter based on its flexural rigidity and the vascular anatomy. To test our hypothesis, we developed a computational model using finite element analysis and an experimental benchtop model using 3D-printed patient-specific aortic arches. Our mathematical model was validated in vivo using observational data derived from patient and porcine endovascular surgeries. RESULTS: Vascular geometry and flexural rigidity were used to derive the bifurcation condition and predict catheter stability versus instability (herniation). Catheter instability criterion was predictive of herniation in our computational model (sensitivity 100.0%, PPV 93.5%, NPV 100.0%); experimental ex vivo model (sensitivity 92.3%, PPV 89.6%, NPV 90.0%); patient in vivo model (sensitivity 100.0%, PPV 80.0%, NPV 100.0%); and porcine in vivo model (sensitivity 100%, PPV 100%, NPV 100%). CONCLUSIONS: We validated a predictive model of catheter herniation based upon the hypothesis that bifurcation in strain energy drive the phenomenon. Key factors in the model are the curvature of the vascular pathway and the flexural rigidity of the coaxial devices. Results suggest that strategic selection of catheters and wires based on their known flexural rigidity can be used to prevent the bifurcation in strain energy that causes herniation.

Neutral Surface Position of a Circular Plane Plate with Radial Ribs

Abstract This paper establishes the neutral surface position of a circular plane plate with radial nervures, considering anisotropic structures theory. The nervures have a constant thickness and linear variable high along the length. At the same time this paper presents the cylindrical flexural rigidity of a such structure. The obtained theoretical data represent a development of a plate study with constant thickness and height nervures, assembled on a single face. The effect of welding on global rigidity of the plate is neglected. A numerical example of such a plate is made.

Evidence of crustal flexure induced by fluvial incisions

Fluvial erosion of the Earth's crust creates valleys ranging from hundreds of meters to a few kilometers wide. The resulting unloading is supported by the flexural rigidity of the continental lithosphere. As a result, the bending of the lithosphere around individual river valleys is usually imperceptible in the landscape, specially in tectonically quiescent environments. However, in the Recôncavo-Tucano-Jatobá (RTJ) basins, an elongated Cretaceous rift located in northeastern Brazil, there is evidence of upward bending of sedimentary strata at the edges of the river valleys, where parts of the syn- and post-rift Late Cretaceous sedimentary layers were eroded. To assess whether the flexural response of the lithosphere due to fluvial erosion is able to explain the observed bending along the RTJ basins, we conducted a series of numerical experiments to evaluate the amplitude and wavelength of the lithospheric flexure achieved in the thermomechanical scenarios for the lithosphere, while imposing the observed amount of denudation derived from field data. We conclude that the wavelength and amplitude of the flexural behavior of the lithosphere obtained in the numerical scenarios are consistent with the observed bending only when the upper crust is partially decoupled from the lithospheric mantle, a configuration observed when the lower crust has a low effective viscosity. We propose that a combination of thermal and lithological factors contributed to induce the lithospheric decoupling, including heating of the lower crust due to magmatic underplating and the blanket effect created by the thick sedimentary layer preserved along the rift. Additionally, we propose that the flexural response of the lithosphere to individual river incisions is only noticeable in the continental lithosphere when the flexural rigidity of the lithosphere is low, with an effective elastic thickness (Te) ≲5 km.

New Displacement Method for Free Embedded Cantilever Walls in Sand

In the current literature, there is no practical formula to calculate the horizontal displacement of cantilever walls. To fill this gap, in the present study, eight formulae for the estimation of wall displacement were developed based on 431 FE wall model configurations. Each formula considers factors such as the wall height, embedment depth, surcharge load, unit weight, internal friction angle, elastic modulus of the surrounding soil, and flexural rigidity of the wall. The FE model, which was used in the development of the formula, was also validated against a physical laboratory study. In addition, the outputs obtained from the formulae were compared with the results of two laboratory studies and a real site study. Finally, a parametric study was performed to estimate the influence of formula input parameters on wall displacement.

Ultra-Thin GaAs Single-Junction Solar Cells for Self-Powered Skin-Compatible Electrocardiogram Sensors.

GaAs thin-film solar cells have high efficiency, reliability, and operational stability, making them a promising solution for self-powered skin-conformal biosensors. However, inherent device thickness limits suitability for such applications, making them uncomfortable and unreliable in flexural environments. Therefore, reducing the flexural rigidity becomes crucial for integration with skin-compatible electronic devices. Herein, this study demonstrated a novel one-step surface modification bonding methodology, allowing a streamlined transfer process of ultra-thin (2.3µm thick) GaAs solar cells on flexible polymer substrates. This reproducible technique enables strong bonding between dissimilar materials (GaAs-polydimethylsiloxane, PDMS) without high external pressures and temperatures. The fabricated solar cell showed exceptional performance with an open-circuit voltage of 1.018V, short-circuit current density of 20.641mAcm-2, fill factor of 79.83%, and power conversion efficiency of 16.77%. To prove the concept, the solar cell is integrated with a skin-compatible organic electrochemical transistor (OECT). Competitive electrical outputs of GaAs solar cells enabled high current levels of OECT under subtle light intensities lower than 50mWcm-2, which demonstrates a self-powered electrocardiogram sensor with low noise (signal-to-noise ratio of 32.68dB). Overall, this study presents a promising solution for the development of free-form and comfortable device structures that can continuously power wearable devices and biosensors.

A Comparison of the Physical Properties Between Merino Wool and Camel Hair Through Discriminant Analysis

ABSTRACT The applicability of camel hair is still conditioned by a gap in the knowledge about this raw material, which in turn hinders its supply chain, commercial possibilities, and the value that the product reaches in the market. The present research compares the physical-mechanical properties of Canarian camel hair versus Merino sheep wool, the world’s most popular proteinic fabric material, using a discriminant canonical analysis. The attributes that maximized differences between both types of animal-origin fibers were related to average fiber diameter, fineness, length staple, and residual dirt. Although slightly shorter than sheep wool, camel hair can reach a prominent fabric quality and spinning performance given its greater average diameter and its lower variation within small fragments along the snippet, as well as the higher distance from the tip to the finest point in the staple, which is an indicator for the breaking point. Such characteristics are known to increase bending rigidity during the manufacturing process. Residual dirt may be associated with the low-input, extensive exploitation of camels. The present paper provides a reference for maturing pre-process and manufacture techniques for the further valorization of camel hair in the present-day textile industry and, thus, engages income opportunities for this livestock production.