Bending Displacement Research Articles

Finite element analysis shows minimal stability difference between individualized mini-hemilaminectomy-corpectomy and partial lateral corpectomy in a dog model.

Use finite element analysis to evaluate the biomechanical effects of spinal decompression procedures in healthy Beagle dogs, comparing individualized mini-hemilaminectomy-corpectomy (iMHC), mini-hemilaminectomy, partial lateral corpectomy (PLC), and hemilaminectomy. A finite element model of the L1-L2 functional spinal unit was generated using CT data. For each decompression model, loads were applied in 0.2-Nm steps (maximum, 2.0 Nm) in 6 directions: flexion, extension, right and left lateral bending, and right and left axial rotation. The L1 spinous process tip displacement angle was quantified numerically. Among the 4 techniques, mini-hemilaminectomy exhibited the smallest displacement angles across all directions. Hemilaminectomy exhibited the largest displacement angles in extension, flexion, right rotation, and left rotation across all techniques. Left and right lateral bending displacement angles were marginally larger for iMHC than for hemilaminectomy at 0.4 Nm; however, at 2.0 Nm, displacement angles were similar. Mini-hemilaminectomy minimizes functional spinal unit instability to the greatest extent. Hemilaminectomy is more unstable than iMHC and PLC in flexion, extension, and rotation. Mini-hemilaminectomy-corpectomy and PLC are more unstable than hemilaminectomy in lateral bending, with iMHC being slightly more unstable than PLC or nearly equal. Mini-hemilaminectomy minimizes instability to the greatest extent in cases of ventrolateral spinal compression. In cases of ventral spinal compression, iMHC may be preferable to PLC for providing equivalent stability without impeding spinal cord visualization, but both techniques can cause instability depending on loading direction, so careful attention to postoperative instability is necessary when excessive vertebral body resection is involved.

Ti3C2T x MXene Based Electro-Ionic Soft Actuator with Potential for Wearable Finger Straps.

Soft electro-ionic actuators have received extensive research and attention due to their advantages such as low voltage response and adjustable deformation. However, they have not been able to enter the actual industry application like traditional rigid actuators; one of the reasons may be that the kinematic properties of actuators have been less studied. The electro-ionic actuator based on Ti3C2T x MXene-CNT/PPy electrode prepared in this paper shows good bending displacement (18.8 mm) and strain (0.63%) under 4 V voltage. In this article, the overlapping nature and exponential function relationship of the actuator end-point trajectories are preliminarily discussed, and the morphology change and cubic polynomial function relationship of the actuator body are considered. Moreover, in application, a novel proof-of-concept model of smart wearable finger straps is proposed. This study is a unique attempt and is hoped to provide a new research perspective in the field of soft electro-ionic actuators.

Coupling CFD model and FEM model to investigate the impact of debris flows on a low-rise building

This study integrates a hydrodynamic model with a structural analysis model to investigate the behavior of a reinforced concrete (RC) frame building under the influence of various hydrodynamic variables, such as debris flow materials, flow intensity, and flow direction. The impact force generated during the first phase of fluid-structure interaction is significantly larger around (20 ÷ 30) % than that in the steady phase, resulting in a substantially bigger maximum value of bending moment (Mmax) and displacement (δ) in every RC column. An increase in flow intensity and solid concentration leads to a larger impact load, resulting in higher values of Mmax and δ. Furthermore, the flow that passes through the porous exterior of the house poses a greater risk than the flow that affects the non-porous side of the house. By comparison with two Vietnamese standards of bending moment and displacement, all columns of the target building are susceptible to collapse in all scenarios when taking into account the bending moment. Nevertheless, in relation to the key threshold of displacement, the building is likely to remain secure.

Flexible Thermoelectric and Piezoelectric Hybrid Energy harvester by Adopting a Multifunctional Cellulose-based Composite Film

Thermoelectric (TE) and piezoelectric (PE) energy harvesting are the most advantageous conversion mechanisms for converting energy generated by the human body into electrical energy, respectively. However, the development of a hybrid energy harvester is essential for achieving high energy conversion efficiency since a single energy harvester cannot convert enough energy. Herein, we present a flexible TE-PE hybrid energy harvester (f-TPHEH) based on a self-assembled single film consisting of Bi2Te2.7Sn0.3 particles, BaTiO3 nanoparticles, and cellulose. The fabricated f-TPHEH exhibited a maximum TE output power of 18.47 nW and a PE instantaneous output of 13.5 nW under integrated thermal and bending conditions (ΔT = 40 K, bending displacement = 7 mm). We conducted a theoretical analysis using multiphysics simulation based on finite element analysis to support the experimental measurements of the fabricated f-TPHEH. In addition, to demonstrate the mechanical stability of the cellulose matrix-based f-TPHEH, a durability test was performed up to 5,000 cycles of bending deformation. This study presents a method for developing the flexible hybrid energy harvester using a low-cost and simple fabrication process.

Achieving excellent properties of laser tailor-welded thin Al-Si coated press-hardened steel joint via controlling dilution rate

In laser tailor welded traditional 25 μm thick Al-Si coated press-hardened steel (PHS), a lot of ferrite was easily formed in the weld, so filling with expensive high-alloys wire is usually necessary. In this work, a new thin Al-Si coated PHS with 18 μm thickness was laser tailor welded, and a cheap low alloy wire was attempted to fill into the weld to via control the dilution rate. At a high dilution rate of 94%, the weld contained a ferrite fraction of 38%, resulting in the fracture occurring in the weld during tension and bending. At a medium dilution rate of 85%, the ferrite fraction in the weld decreased to 18%, obtaining excellent tensile and bending properties. The tensile strength and elongation of the joint reached 1528 MPa and 5.6%, respectively, with fracture being in the base metal (BM). The maximum bending load and displacement were 1291 N and 7.0 mm, respectively, and cracks initiated and propagated in the BM. This is attributed to the small amount of ferrite and stress concentration in the narrow weld. At a low dilution rate of 76%, the ferrite reduced to 6%, and the bending cracks initiated and propagated in the BM. However, the tensile specimen fractured in the weld, which should be related to the relatively low C concentration and the stress concentration at the weld toe due to the weld reinforcements.

Experimental and theoretical research on deformation monitoring of distributed piezoelectric inclinometer tube

To improve horizontal displacement monitoring in geotechnical engineering, researchers have focused on developing distributed, automated, and cost-effective inclinometers capable of long-term monitoring. However, existing technologies cannot fully satisfy these requirements. This study proposes a novel piezoelectric inclinometer tube that incorporates a sensor-enabled piezoelectric geocable (SPGC), which was mounted along the surfaces of three tubes made of different materials. The distributed strain along the inclinometer tube was measured using the impedance–strain effect of the SPGC, and a deflection curve was obtained. The results of the failure test showed that the piezoelectric inclinometer tube remained within its measurement range before breaking. Furthermore, the placement of the SPGC on the outer surface of the tube demonstrated superior monitoring effectiveness under bending deformation, providing qualitative insights into the deformation and fracture behavior of the tube. Loading and unloading tests demonstrated excellent reproducibility of strain in the piezoelectric inclinometer tube. Among the tested materials, the inclinometer tube made of acrylonitrile butadiene styrene exhibited acceptable elasticity, large bending displacement, and a high strain transfer rate, making it ideal for monitoring significant deformations in rock and soil. A linear calibration equation was established for the normalized impedance change–strain relationship of the piezoelectric inclinometer tube through calibration tests. Furthermore, a theoretical model was derived to convert the normalized impedance change to the deflection of the piezoelectric inclinometer tube using the finite difference method. Theoretical and experimental values were significantly consistent, with strain and deflection measurement accuracies of 10 με and 0.1 mm, respectively, and an average calculation error of less than 4%. These results are expected to improve the distributed monitoring of horizontal displacement in rock and soil.

Aerodynamics of a three-dimensionally deformed rigid wing

A flexible wing with a large aspect ratio emerges in many modern engineering applications (e.g. solar planes and super large wind turbine blades) and its interaction with incident flow differs markedly from conventional fluid–structure interactions (FSI), exhibiting frequently a large three-dimensional (3D) deformation. Yet, there is little information on how such deformation may change wing aerodynamics. This work investigates the aerodynamic performance of deformed and cantilever-supported NACA0012 rigid wings with an aspect ratio of 9, using ANSYS Fluent with the SST-κ-ω turbulence model at a chord-length-based Reynolds number Rec of 1.5 × 105. Numerical simulation is validated experimentally. The wing tip bending displacement is up to 4.14c, and the maximum twisted angle is up to 7°. The angle α of attack varies from 0° to 20° at mid span of the wing. It has been found that the torsional deformation can significantly advance the local flow separation, reattachment, bubble length, and transition from laminar to turbulence, resulting in a drop in the critical angle αcr of attack, at which the separation bubble size reaches the maximum. Accordingly, the lift and drag coefficients increase, as well as the bending and pitching-up moments, though the stall is advanced due to a change in local α. The tip vortex is also enhanced, inducing strong downwash postponing the separation bubble on the wing and resulting in redistributed force near the wing tip that increases markedly the local bending moment but decrease the local pitching-up moment. On the other hand, the bending deformation tends to produce an effect opposite to the torsion on the flow structure and causing little change in the lift coefficient, though reducing the induced drag and moments appreciably. With both deformations in place, the torsion overwhelms the bending in general in terms of its impact upon aerodynamics and flow structures, the latter acting to cancel at least partially the effect of the former.

A semi-analytical method using auxiliary sine series for vibration and sound radiation of a rectangular plate with elastic edges

This paper proposes an efficient semi-analytical method using auxiliary sine series for transverse vibration and sound radiation of a thin rectangular plate with edges elastically restrained against translation and rotation. The formulation, constructed by two-dimensional sine and/or cosine series, can approximately express the bending displacement, and calculate vibration and sound radiation under excitation of point force, arbitrary-angle plane wave, or diffuse acoustic field with acceptable accuracy. It is also applied for baffled or unbaffled conditions. A post-process program is developed to predict vibrating frequencies and modes, mean square velocity spectrum, and sound transmission loss via reduced-order integrals of radiation impedances. The method is validated by experiment and simulation results, demonstrating accurate and efficient computation using a single program for transverse vibration and sound radiation of a plate under different elastic boundary conditions and different excitations. Formulas given in this paper provide a basis for the code development on transverse vibration and sound radiation analysis of thin plates.

Modeling of visco-electro-elastic responses of PZT-based functionally graded beam benders

The modeling of the visco-electro-elastic behavior of functionally graded beam benders with PZT constituents is accomplished via a hierarchical framework that is based on the homogenization technique for composite layers and the laminate theory for a composite laminate. The representation of a bulk PZT constituent is based on linear visco-electro-elastic constitutive equations. The resulting bending displacements of PZT-graded bimorph and multimorph are obtained under the assumption of the Euler–Bernoulli beam. The experimental data of the bending displacements versus applied voltage are compared with the predictions for a bimorph and a multimorph, resulting in a good agreement. The responses of a bender to a complete cycle of applied voltage are shown in order to reveal the critical hysteretic actuation due to the presence of a visco-electro-elastic PZT material in a functionally graded piezoelectric beam bender which is made by functionally graded piezoelectric materials.

A Jacobi-Ritz Approach for Aeroelastic Analysis of Swept Distributed Propulsion Aircraft Wing

Abstract This paper presents a Jacobi-Ritz approach for conducting flutter and divergence analysis of a complex distributed propulsion aircraft wing like NASA X-57. The general orthogonal Jacobi polynomials are used to approximate the bending displacement and torsional rotation angle in the Ritz method based structural and aeroelastic analysis. The Jacobi polynomials satisfy the orthogonality condition using weight functions which are easily modified to satisfy different essential and natural boundary conditions. Compared to simple polynomials, Jacobi polynomials can eliminate the well-known ill-conditioning numerical issues when considering higher-order polynomials. The Jacobi-Ritz method is also found to alleviate mode switching often encountered in tracking the changes of modes with the varying airspeed. The Jacobi-Ritz method is later used to investigate the flutter and divergence speeds under distributed propulsor mass and their locations, nonuniform aerodynamic model in the presence of multiple propulsors, and the sweep angle. Results show that placing the distributed propulsors on the wing's leading edge increases the flutter speed even though the bending and torsion modal frequencies are decreased compared to those of the wing without propulsors. The presence of pods for the middle high-lift motors causes an extra aerodynamic moment which reduces the flutter speed. Parametric studies also show that the divergence speed is lower than the flutter speed for a uniform and straight distributed propulsor wing. Using swept-back wing configuration and placing the tip propulsor near the wing's leading edge can help to increase both flutter and divergence speeds.

Study on microstructure evolution and deformation behavior of Mg– Zn base alloy pipes during hot bending

The strong basal fiber texture of magnesium (Mg) alloy pipes usually leads to poor secondary forming performance. In this study, Mg–2Zn-0.4Ce-0.4Mn (ZME) and Mg–2Zn-0.4Ce-0.4Mn-0.2Ca (ZMEX) pipes were prepared. Compared with the ZME pipe, the ZMEX pipe with a weaker initial texture exhibits excellent bending performance, with a peak load displacement (PLD) of 14.5 ± 0.5 mm and a total energy absorption (TEA) of 142.9 ± 1.7 J. The difference in bending performance between the two pipes is related to the deformation mechanism during hot bending. In the hardening stage, the deformation of the compression zone (CZ) of the two pipes is mainly ETW nucleation, and the overall proportion of twin grains is similar. However, in the tensile zone (TZ), the deformation of the ZME pipe is mainly prismatic slip, while the weak initial texture of the ZMEX pipe leads to the deformation dominated by both prismatic and multiple pyramidal slips, resulting in a higher hardening rate. In the softening stage, the deformation behavior in the CZ and TZ of both pipes tends to be similar. In addition, it is revealed that the softening phenomenon of both pipes after the bending displacement reaches PLD is caused by discontinuous dynamic recrystallization (DDRX) driven by high-density dislocations accumulated in the later CZ and TZ. The research on the microstructure evolution and deformation mechanism of Mg alloy pipe during bending deformation carried out in this study is of great significance for optimizing its secondary forming controllability and further expanding its application.

Bending motion induced by near-infrared laser irradiation of polymer films made by UV-curable liquid crystalline monomer containing gold-coated fine particles

Polymer films made by UV-curable liquid crystalline (LC) monomer have both characters of the external stimulus responsiveness of LC and flexibility of polymer chains. Therefore, polymer film made by UV-curable LC monomer are expected as soft actuators. By incorporating photothermal conversion materials in polymer film, the macro shape of film can be controlled by light irradiation. In this study, a polymer film made by UV-curable LC monomer containing gold-coated fine particles was prepared and its bending motion induced by near-infrared laser irradiation was studied. When the film is irradiated with near-infrared laser, it bends. We also investigated the dependence of the concentration and distribution of gold-coated fine particles in the film, and irradiation time and intensity for the bending displacement.

Intensity modulation of orthogonally polarized laser with two weak light reinjection beams of the bifurcated sub-cavity

This paper proposes a specially designed laser cavity with two reinjected beams to achieve coupled self-mixing interference. Based on the orthogonally polarized laser, a wave plate is employed to construct the bifurcated sub-cavity, and the oscillating laser mode splits into two. Under the domination of the sub-cavity, both the intensity and frequency of the orthogonally polarized beams exhibit near-sinusoidal modulation with a certain phase difference. The modulated intensity also has a long period envelope if the sub-cavity is tuned with pitch angle. Thus, it has potential to acquire the extension and bending displacement of such key components in a space-borne instrument.

Geometrically nonlinear analysis of plates and shells by a cell-based smoothed CS-MITC18+ flat shell element with drilling degrees of freedom

A development of a 3-node triangular flat shell element to analyze geometric nonlinearity of plate and shell structures is presented in this study. The proposed flat shell element has 6 degrees of freedom per node, including the drilling rotational ones, by using the Allman-type approximations for the in-plane displacements and the bending displacement approximations enriched by a cubic shape function at the bubble node located at the element's centroid. The geometrically nonlinear behaviors are described by the von Karman's large deflection assumption. The membrane and bending strains of the presented flat shell elements are averaged over sub-triangular elements based on the cell-based smoothed (CS) technique. To attenuate the shear locking phenomenon, the transverse shear strains are re-interpolated following the mixed interpolation of tensorial components (MITC) technique designed for the 3-node triangular degenerated shell elements enriched by a cubic bubble function (MITC3+). Combined with the Newton-Raphson iterations and load increments predicted by the arc-length method, the suggested 3-node triangular flat shell elements, namely the CS-MITC18+ element, can analyze moderately geometrical nonlinearity, including the snap-thought and snap-back behaviors, of various plates and shells with the different shapes, thickness, and boundaries. The numerical investigations show that the load-displacement curves provided by the CS-MITC18+ flat shell elements well agree with other references.

Evolution of Long-Term Load Reduction Using Borrowed Soil

AbstractThe effectiveness of load-reduction techniques often diminishes due to creep behavior observed in geomaterials, as loess backfill is used, the load reduction rate of high-filled cut-and-cover tunnels (HFCCTs) after creep will decrease by 10.83%, posing a threat to the long-term stability of deeply buried structures such as HFCCTs. Therefore, a geotechnical solution is crucial to ensuring sustained effectiveness in load-reduction strategies over time. This study utilizes a finite-difference method to examine three promising measures for mitigating creep effects. Our analysis focuses on the time-dependent changes in earth pressure atop the cut-and-cover tunnel (CCT) and the internal distribution of cross-sectional forces, including bending moment, shear force, axial force, and displacement. Results indicate that the creep behavior of load-reduction materials significantly influences the internal force distribution. Furthermore, sustained load reduction is achieved when utilizing low-creep materials like dry sandy gravel as backfill soil, which needs to be borrowed from other sites. Additionally, integrating concrete wedges with load-reduction techniques facilitates a more uniform stress distribution atop CCTs.

Ultrahigh Electrobending Deformation in Lead-Free Piezoelectric Ceramics via Defect Concentration Gradient Design.

Recent breakthroughs in defect-engineered lead-free piezoelectric ceramics have reported remarkable electrostrain values, surpassing the limit of lattice distortion. This has aroused wide concern on bending deformation and the associated underlying mechanism. Herein, via designing lead-free piezoelectric ceramics with varying volatilization characteristics, it is uncovered that the ultrahigh electrobending deformation is primarily attributed to a large strain gradient induced by unevenly distributed defect dipoles. In 0.5 mm thick Sr/Sn co-doped potassium sodium niobate ceramics featuring volatile K/Na elements, the inherent bipolar electrostrain value can reach 0.3% at 20kV cm-1 due to the existence of defect dipoles, while the gradient distribution of defect dipole generates significant bending displacement, amplifying apparent electrostrain value to 1.1%. Notably, nonvolatile Ba0.99TiO2.99 ceramic with homogeneous defect dipole distribution does not present electrobending. Of particular interest is that the electrobending phenomenon can be observed through introducing a defect dipole gradient into barium titanate ceramic. A monolayer ceramic with defect dipole gradient can generate large tip displacement (±1.5mm) in cantilever structure, demonstrating its promising potential in precise positioning. This study delves into the underlying mechanism driving electrobending deformation and its impact on the apparent electrostrain measurement in defect-engineered piezoelectric ceramics, providing fresh perspectives for the development of piezoelectric bending actuators.

Design and optimization analysis of pylon open lower corbel

This study, centered around the engineering context of the Wuxue Yangtze River Bridge, addresses the challenge of significant temperature-induced secondary internal forces in the short lower tower column. A novel open lower corbel tower scheme is proposed as a solution. Firstly, comprehensive finite element models are established for both the open lower corbel pylon scheme and the traditional lower continuous beam pylon scheme. These models are employed for finite element analysis to derive bending moments and displacements of the bridge pylon under various loads, including permanent, vehicle, temperature, and wind loads. Subsequently, considering internal force distribution and stiffness, a comparative assessment is made between the open lower corbel cable pylon scheme and the traditional lower continuous beam cable pylon scheme. The findings reveal that the open corbel structure bridge pylon exhibits lower transverse bending moment values under the influence of permanent load, vehicle load, temperature load, and wind load. This reduction is advantageous for mitigating the issue of significant temperature-induced secondary internal forces in the bridge pylon. Additionally, the transverse bridge stiffness of the open lower corbel cable pylon scheme is found to be on par with that of the lower continuous beam cable pylon scheme. Moreover, topology optimization of the original corbel design is accomplished using the relative density method. The computational results demonstrate that the corbel’s stress and deformation under vertical loads meet code requirements. These research findings offer valuable insights for the design and construction of similar projects.

Multifunctional and Electronically Conjugated Triazine Framework for Superior Electro‐Ionic Artificial Muscles

AbstractElectro‐ionic artificial muscles, consisting of a configuration where an electrolyte membrane is flanked by two active electrodes, have emerged as transformative components in the field of soft robotics. Despite this, the current actuation performance falls short for many practical applications, because most existing electrode materials exhibit limitations in terms of their properties. Here, a multifunctional active electrode material is reported for an electro‐ionic artificial muscle, employing a triazine framework that incorporates 6,6′‐Dicyano‐2,2′‐bipyridyl (DCB‐TF). The multifunctional DCB‐TF boasts fully conjugated bonds, facilitating fast electron transfer, high porosity for ion accommodation, a substantial surface area of 1800 m2 g−1 for charge storage, numerous active sites for ion interactions, and complete aromatic rings contributing to stability. The application of DCB‐TF to the active electrodes in the electro‐ionic artificial muscles yields remarkable actuation performance, including a substantial bending displacement of 24 mm at 0.5 V and 0.2 Hz, a rapid response time of 2 s, and outstanding durability sustained over 3.4 million continuous cycles. Consequently, these soft actuators have enabled a dragonfly demonstration as a form of kinetic art.

Recovery of angular scattering profiles through a flexible multimode fiber.

Endoscopic angle-resolved light scattering methods have been developed for early cancer detection but they typically require multi-element coherent fiber optic bundles to recover scattering distributions from tissues. Recent work has focused on using a single multimode fiber (MMF) to measure angle resolved scattering but this approach has practical limitations to overcome before clinical translation. Here we address these limitations by proposing an MMF-based endoscope capable of measuring angular scattering patterns suitable for determining structure. Significantly, this approach implements a spectrally resolved detection scheme to reduce speckle and leverages the azimuthal symmetry of the angular scattering patterns to enable measurements that are robust to fiber bending. This results in a unique method that does not require matrix inversion or machine learning to measure a transmitted scattering distribution. The MMF utilized here is 1000 mm in length with a 200 µm core and is demonstrated to recover angular scattering distributions even with bending displacements of up to 30 cm. This advance has a significant impact on the clinical translation of biomedical endoscopic diagnostic techniques that use angular scattering to determine the size of cell nuclei to detect early cancer.

MXene‐Cobalt Hybrid Electrodes for Electroactive Artificial Muscle

We present the synthesis of MXene‐Cobalt hybrid (MX‐Co) utilizing a molten salt approach, targeting the application in artificial muscle technology. Mxenes possess exceptional electronic conductivity and surface chemistry, making them ideal candidates for electrochemical applications. Cobalt, known for its ferromagnetic qualities, is a good match for MXenes and enhances artificial muscles’ mechanical performance. By circumventing hazardous HF acid, we demonstrate a facile and scalable synthesis process for MX‐Co hybrids. Their structural and electrochemical characteristics are revealed through characterization using cutting‐edge spectroscopic and microscopic techniques. When compared to typical PEDOT: PSS electrodes, electrochemical experiments show that MX‐Co electrodes have higher electroactive performance, with enhanced bending deformation under various input conditions. MX‐Co hybrids exhibit a specific capacitance of 77.34 F g–1, 1.6 times higher than PEDOT: PSS, and achieve a substantial enhancement of electrochemical bending displacement, up to 11.72 mm under a low input voltage of 1V, showcasing their potential for soft actuator applications.This article is protected by copyright. All rights reserved.