Edge Deformation Research Articles

Semiclassical Scattering by Edge Imperfections in Topological Insulators Under Magnetic Field

We study the scattering of edge states of 2D topological insulator in the uniform external magnetic field due to edge imperfections, common in realistic 2D topological insulator samples. The external magnetic field breaks time-reversal symmetry, opening the possibility of the scattering of otherwise topologically protected fermionic edge states. The scattering happens to be always an over-barrier event, irrespective of the shape of the edge deformation and magnitude of the magnetic field. We use the advanced Pokrovsky–Khalatnikov semiclassical approach, which allows us to obtain analytically both the main exponential and pre- exponential factors of the scattering amplitude for wide classes of analytic deformation profiles.

Flapping-wing energy harvesting experiences with modified time variations at high re-number

AbstractWind-energy converters with rotating blades are most common for energy harvesting. In special cases a system of flapping wings may be of interest where the wings are oscillating in combined pitching and flapping (plunging) modes respectively. Then the ratio of pitching and plunging amplitudes is of main concern: If the amplitude of the pitching motion exceeds the amplitude of the induced angle of the plunging motion, energy transfer from the oncoming flow is present. To accomplish maximum energy transfers and maximum efficiencies a considerable number of parameters have to be varied. Most of the published investigations assume harmonic time variations of both pitching and plunging motion. In the present paper the time variation will be modified such that the stroke reversal times are favorably be influenced, i.e., the fraction of the period where the airfoil changes the angle of attack from its maximum to its minimum or vice versa. In the present paper this variation is represented by an analytical function. Further, the phase between pitch and plunge motion and the time dependent deformation of the airfoil-leading edge will be investigated. It will be shown that the different variations and modifications will lead to considerable increases of power transfer and efficiency.

Nature of host–guest interaction of cyclic alcohols in β-Cyclodextrin: A molecular view of its structural features

Host- guest complexes are commonly found in several disciplines such as biochemistry, cosmetics, food, pharmaceuticals, and the environment. Studying the relationships between host and guest is essential in this context to understand their physicochemical behavior. This study aimed to examine the intermolecular interactions of cyclic alcohols within β-cyclodextrin (β-CD). The experimental spectroscopic results demonstrated the formation of the studied complexes. In this work, two orientations were used: orientation A (hydroxyl group toward the primary hydroxyl of β-CD) and orientation B (hydroxyl group toward the secondary hydroxyl of β-CD). The results indicate that regardless of the orientation used, the profile energy is thermodynamically favorable. However, there are differences in terms of greater or less stability in terms of the thermodynamic parameters studied. Physicochemical properties demonstrate that the host–guest complex forms spontaneously, and exothermic mode. The interaction between cyclic alcohols and β-CD in orientation A promotes a more pronounced deformation of the secondary edge of β-CD. Moreover, the arrangement of moleculesdemonstrates that intramolecular hydrogen bonds are less stable between the glycosidic units of β-CD. This arrangement may help or hinder the development of intermolecular hydrogen bonds.

Predicting recoater interference in laser powder bed fusion process by considering both global thermal deformation and local edge deformation using the modified inherent strain method

Preventing recoater interference and crash is essential in the laser powder bed fusion (L-PBF) process for printing parts with overhangs, as these issues compromise product quality by increasing surface roughness, reducing dimensional accuracy, and introducing defects into the parts. This work proposes an integrated simulation and experimental framework to predict initial recoater interference for a given part designed for L-PBF fabrication. In this framework, the criterion for recoater interference is defined to occur at an overhang edge when its deformation in the build direction exceeds the thickness of a newly spread powder layer after recoating. The build-directional deformation at an overhang edge is postulated to be the sum of two contributions: global thermal deformation and local edge deformation. The global thermal deformation, generated by the relaxation of thermal stresses induced by rapid laser melting and solidification over the entire part, is predicted using the modified inherent strain (MIS) method. A key novelty of this work lies in employing location-dependent inherent strains (ISs) in the MIS method for overhangs, which shows a 65 % improvement in the prediction accuracy of the global thermal deformation compared to using constant ISs. The local edge deformation, associated with the melt pool dynamics and induced near the edge, is estimated by reconciling the MIS simulated and experimentally measured deformation on several overhang wedges. The validity of the proposed framework for predicting recoater interference is confirmed by experiments on different part geometries with overhangs.

Lower extremity woven and nonwoven venous stent morphology and luminal changes

ObjectiveVenous stents are a common treatment modality for obstructive venous disease. Venous stents differentiate themselves by either a woven or braided structure, open or closed cell arrangement or based on material composition (elgiloy vs nitinol). Changes in the morphology of venous stents over time may contribute to restenosis or thrombosis. Woven elgiloy stents are prone to proximal and distal edge deformation compared with dedicated venous stents, which offer increased radial force at stent edges. The objective of this study is to describe luminal morphological changes among various venous stents and between woven to nonwoven venous stent configuration, over time. MethodsA retrospective review at a single institution between January 2014 and June 2021 identified patients treated with venous stents. Patients with iliac and/or femoral venous stents with intraoperative intravascular ultrasound and a postoperative computed tomography scan were included in the study. Cross-sectional diameters measurements were taken at proximal, middle, and distal portions of each stent from intravascular ultrasound examination at the time of initial stenting and compared with the cross-sectional diameter measurements taken from computed tomography imaging at follow-up. A paired t test was used to compare the luminal change with a D'Agostino-Pearson test used for normality. ResultsFifty-four stents distributed among 38 patients were identified. The mean time to follow-up was 17.5 months. Stents were placed in the common iliac vein (n = 37, 68.5%), external iliac vein (n = 14, 25.9%), and common femoral vein (n = 3, 5.6%). Implanted stents included the Boston Scientific Wallstent (n = 23, 42.6%), Bard Venovo (n = 3, 5.6%), Boston Scientific Vici (n = 23, 42.6%), and Medtronic Abre (n = 5, 9.3%). The mean luminal loss was measured at 2.12 mm proximally (95% confidence interval [CI], 1.64-2.60; P<.001), 1.29 mm at the mid-stent (95% CI, 0.83-1.74, P<.001), and 1.56 mm distally (95% CI, 0.99-2.12; P<.001). There was no significant difference in luminal changes between woven and nonwoven stents at proximal (P = .374), middle (P = .179), and distal (P = .609) stent measurements. ConclusionsThis study reports morphological changes within venous stents and between woven and nonwoven venous stents. Our findings demonstrate that the edge-stent luminal decrease traditionally attributed to woven configurations also occurs with the newer nonwoven stents. Additional factors such as anatomical location, pelvic curvature, and other external forces may be accountable for this change rather than geometrical configuration of the stent.

Deformations of cuspidal edges in a 3-dimensional space form

Deformations of cuspidal edges in a 3-dimensional space form

Honeycomb structure filling morphing wing trailing edge: Design strategy, deformation feedback, and active control

Abstract Pursuing highly efficient aerodynamic efficiency in aircraft has driven the development of morphing wing technology. However, there are still limitations to morphing wing technology, including adaptation of load and deformation, and deformation monitoring and control. This work introduces an intelligent trailing edge structure that balances deformation and load-bearing and achieves deformation monitoring and active control. Firstly, we employ a honeycomb structure for non-uniform filling of the trailing edge. The filling method is obtained through inverse design using a genetic algorithm based on neural networks, allowing the device to undergo continuous deformation while meeting load-bearing requirements. The bending deformation of the wing is achieved using shape memory alloy (SMA) wire. Additionally, we design and fabricate a metal-based multichannel flexible sensor, and based on beam bending theory, we establish the strain–displacement relationship. These sensors are affixed to the trailing edge surface, enabling real-time monitoring and active control of trailing edge deformation. Building an experimental platform to test this system, the results show that the sensors can accurately give feedback on the degree of wing deformation, and the error of active deformation control technology is less than 4%. This provides a new method for the deformation feedback control closed-loop system of intelligent variant wings.

Experimental assessment of a morphing trailing edge device for wind turbine blade performance improvement

Nowadays, wind energy plays a central role in the renewable energy production, and the optimization of wind turbine performance is the focus of current research studies. In this context, morphing trailing edge system could be a promising solution to enhance wind turbine blades' aerodynamic performance. In this paper, an innovative morphing trailing edge system was designed, developed, and tested to improve the performance of a wind turbine blade airfoil. The trailing edge deformation is electrically operated through piezoelectric actuators and a compliant surface. Wind tunnel tests were performed for the sake of system validation at Reynolds number equal to 1.75×105 and 3.5×105 and an angle of attack ranging from −8° to 8°. The results put in evidence the effectiveness of the proposed morphing trailing edge system to enhance the aerodynamic performance. The trailing edge deformation allows to increase or decrease the lift coefficient. The mean percentage difference of lift coefficient was found equal to −83.6% and 68.4% for an upward and downward deflection, respectively. Meanwhile, the drag coefficient does not have a significant variation. Consequently, the aerodynamic efficiency will be increased or decreased keeping the angle of attack unchanged. The mean percentage difference of efficiency was found equal to −83.2% and 77.5% for an upward and downward deflection, respectively. In this way, it would be possible to optimize wind turbine blades' efficiency and production under different operating conditions.

Influences of island size on the forming quality, microstructure, and tensile properties of laser powder bed fusion Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy

Island scanning can reduce the residual stress in the process of laser powder bed fusion (LPBF), however, the role of island size has rarely been systematically investigated. Herein, the influences of island size on the forming quality, microstructure, and tensile properties of LPBF-processed Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy were experimentally investigated coupled with a finite element simulation. Moreover, the alloy composition and microstructure around pores were investigated in the overlapped zone of island scanning. It was found that the laser jumps and the deformation of island edges formed the gully morphologies in the overlapped zone, which resulted in poor forming quality. Meanwhile, the overlapped zone generated several peak temperatures in a short time, leading to the increase of α′ phase transformations and basketweave α′ phases. The fracture behavior of the alloy was affected by the presence of oxides and non-uniform microstructures around pores. The samples with small island sizes had a complex microstructure, poor forming quality, high tensile strength, and low elongation, respectively. Therefore, the ultimate tensile strength and elongation of the sample with an island size of 2 mm were 1310 MPa and 5.6 %, and the corresponding values for the sample with 7 mm were 1193 MPa and 10.4 %, respectively. The findings of this work can shed some light on the relationship between the mechanical properties of LPBF-fabricated alloys and island size.

Study on Fluid–Structure Interaction of a Camber Morphing Wing

The influence of trailing edge deformation on the aerodynamic characteristics of camber morphing wings is an important topic in the aviation field. In this paper, a new memory alloy actuator is proposed to realize trailing edge deformation, and computational fluid dynamics (CFD) and wind tunnel experiments are used to study the influence of trailing edge deformation on the aerodynamic characteristics of the camber morphing wings. The experiments was carried out in a transonic wind tunnel with Mach numbers ranging from 0.4 to 0.8 and angles of attack ranging from 0° to 6°. The external flow fields and aerodynamic force coefficients with and without deformation were calculated using the CFD method. A loose coupled method based on data exchange was used to achieve a fluid–structure interaction (FSI) analysis. The research results indicate that when the trailing edge is deflected downwards, the phenomenon of shock wave forward movement reduces the negative pressure area on the upper wing surface, increases the pressure on the lower wing surface, and ultimately increases the total lift. This work provides a new approach for the implementation of trailing edge deformation and a powerful data reference for the design of camber morphing wings.

Enhance Hydrogen Evolution Reaction Performance via Double-Stacked Edges of Black Phosphorene.

Based on the density functional theory (DFT) calculations, we explored the structures and HER catalytic properties of reconstructed and double-stacked black phosphorene (BP) edges. Ten bilayer BP edges were constructed by the double stacking of three typical monolayer edges, i.e., zigzag (ZZ) edge, armchair (AC) edge, skewed diagonal (SD) edge, and their reconstructed derivatives with their layer's configurations, edge deformations and thermodynamic stabilities were discussed. Based on these edges, five chemical sites on four bilayer BP edges were selected to be promising candidates for a HER catalyst, which present higher HER activities than that of Pt(111). Besides, among these four edges, two edges have even lower energetic barriers for the Tafel reaction. Compared with the monolayer edges, these selected bilayer BP edges confirm the remarkable enhancement of the HER catalytic properties, which can be attributed to their unique edge structures and the enhanced electronic densities after the hydrogen adsorptions. Finally, the thermostability of these edges at room temperature has also been proved by the DFT-MD simulations. This theoretic study deepens our fundamental understanding of the double-stacked edge structures of the BP and provides a new way for the rational design of highly efficient and noble-metal-free HER catalysts.

Enhancing ion mobility spectrometry performance through a programmable ion swarm shaping method based on Bradbury-Nielsen gates

The ion gate is a critical element in drift tube ion mobility spectrometry (IMS) as it directly influences the resolving power and sensitivity of the system. However, the conventional Bradbury-Nielsen gate (BNG) often leads to deformation of the ion swarm shape, resulting in reduced resolving power and significant discrimination effects. To address these limitations, we propose a novel method that incorporates a cutting phase following the gate opening. This approach effectively reduces trailing edge deformation, resulting in a maximum resolving power of over 100 and increased signal intensity. Additionally, this method maintains high resolving power even during longer gate opening times. Remarkably, this method not only significantly reduces the mobility discrimination effect but also enables the achievement of reverse discrimination by adjusting the duration of the cutting phase. Consequently, it demonstrates the potential to selectively amplify the peak height of target ions. Our method offers straightforward implementation across all IMS systems utilizing the BNG, thereby significantly improving system performance.

Crashworthiness and dimensional stability analysis of zero Poisson's ratio Fish Cells lattice structures

The present article introduces Zero Poisson's Ratio (ZPR) Fish Cells metamaterial and investigates the effects of Poisson's ratio on the crashworthiness of Positive (PPR), Negative (NPR), and Zero Poisson's ratio lattice structures. High-fidelity Finite Element (FE) models of the proposed sandwich structures are built, based on identical domains for unit cells. Impact performances of lattice structures are addressed for low (2 m/s) and high (5 m/s) impact velocities in three orthogonal directions. The parameters investigated for crashworthiness include impactor's penetration depth, von Mises stress distribution, edges deformation and dimensional stability. Numerical results demonstrate that, unlike PPR and NPR models, the Fish Cells ZPR model possesses greater lateral stability and structural integrity with minimal edge deformations in all three directions. This leads to reduced lateral impact transfer to adjacent components and localised damaged zones, increasing the life span of structural components while reducing maintenance and repair downtime. Experimental analyses are conducted on the Fish Cells metamaterial through a drop tower test for demonstrating agreement with simulations and validation of the proposed modelling approach.

Numerical Analysis of Edge Deformation and Force via Continuous Function Curves in Vertical Rolling Process

Numerical Analysis of Edge Deformation and Force via Continuous Function Curves in Vertical Rolling Process

A Thermomechanical Model for Time-Varying Deformations of Spigot Interference Connection under Shrink-Fitting Assembly

The interference fit connection structure is widely employed in various industries. Different from the conventional connection structure, the aero-engine rotor connection has a spigot-bolt structure. The quality of the shrink-fitting assembly process directly affects the final assembly performance of the rotor. The complexity of the connection structure and the time-varying thermal deformation bring great challenges in analyzing the formation patterns of connection performance. However, existing methods of interference connection analysis are mainly used in the wide range of interference connection structures, which makes them difficult to apply in low height interference connection for aero-engine rotors. This paper introduces a thermomechanical interference fit pressure model. First, a theoretical model for interference fit pressure considering temperature-variable loads is established to obtain the time-varying pressure during the assembly process. Second, a finite element model is established to explore the influence of interference and temperature loads on the spigot pressure and the mounting edge deformation. Finally, the experiments validate the accuracy of both the theoretical model and the finite element analysis. The results indicate that during the shrink-fitting assembly process, the interference fit pressure exhibits a nonlinear evolution trend, and the warping deformation of the mounting edge is a result of the combined influence of temperature and interference fit pressure. The law found in this paper has an application prospect in the process parameter setting of shrink-fitting assembly for special structures.

Bending performance of Y-shaped joints of subway station built by enlarging two parallel shield tunnels

Based on the characteristics of the Y-shaped joint of a subway station built by enlarging two parallel shield tunnels, a bending mechanical model of the segmental joint was proposed. The model was used to characterize the cracking and crushing of concrete, the yielding of the bolt, and the damage of the segmental joint. Theoretical equations were derived for the bending stiffness of the joint under various forms of joint opening. Bending experiments were conducted on full-scale models of the joints under different structural configurations. The results demonstrated that the nonlinear properties of the joint structure were evident under loading and that the bending stiffness of the joint initially increased and then decreased. The computed values were in good agreement with the experimental results for the pre-embedded connector joint when lc was 0.5 times the height of the compression zone, where lc was the effect depth of the compressive deformation of the outer edge of the concrete. The axial force had a great influence on the bending stiffness. The mechanical performance of the joint was influenced not only by the change in the stress–strain curve of the concrete from the rising stage to the descending stage but also by the structural morphology of the rotational angle of the joint.

Evaluating trunnionosis in modular anatomic shoulder arthroplasties: a retrieval study.

Shoulder arthroplasty procedures are widely indicated, and the number of shoulder arthroplasty procedures has drastically increased over the years. Rapid expansion of the utilization of reverse total shoulder arthroplasty has outpaced the more modest growth of anatomic total shoulder arthroplasty (aTSA) while shoulder hemiarthroplasty (HA) has trended down. Recently, shoulder prostheses have transitioned to increasingly modular systems offering more individualized options with the potential for decreased pain and increased range of motion. However, increased primary procedures has resulted in increased revision surgeries, with one potential cause being fretting and corrosion damage within these modular systems. Following institutional review board approval, 130 retrieved aTSA and 135 HA explants were identified through database query. Humeral stem and head components were included in all 265 explants, whereas 108 included polyethylene glenoid liner components. All explanted components were macroscopically evaluated for standard damage modes, and taper junctions were microscopically examined for fretting/corrosion using a modified Goldberg-Cusick classification system that was 4-quadrant graded for both the male and female component. Medical records were reviewed for patient demographics and surgical information. In this series, 158 of explants were from female patients (male=107), and 162 explants were from the right shoulder. Average age at implantation was 61 years (range: 24-83), average age at explanation was 66 years (range, 32-90), and average duration of implantation was 61.4 months (range, 0.5-240). Scratching, edge deformation, and burnishing were the most commonly observed standard damage modes. Of the 265 explants, 146 had a male stem component vs. 118 with a female stem component. Average summed fretting grades on male and female stem components were 8.3 and 5.9, respectively (P<.001). Average summed corrosion grades for male and female stem components were 8.2 and 6.2, respectively (P<.001). Wider male tapers (>11 mm) showed significantly less fretting and corrosion (P<.001). Lastly, mismatched metal compositions between the head and stem components showed greater fretting and corrosion damage (P=.002). In this series of 265 aTSA and HA explants, there was substantial damage present on the explanted components. All components demonstrated macroscopic damage. In this retrieval study, small-tapered male stems with small, thin female heads and mismatched metal composition between components were risk factors for increased implant wear. As shoulder arthroplasty volume increases, optimizing design is paramount for long-term success. Additional work could determine the clinical significance of these findings.

Effect of spanwise distributed camber morphing on dynamic stall characteristics of a finite-span wing

This paper investigates the influence of the spanwise-distributed trailing edge camber morphing on the dynamic stall characteristics of a finite-span wing at Re = 2 × 105. The mathematical model of the spanwise-distributed trailing-edge camber morphing is established based on Chebyshev polynomials, and the deformed wing surface is modeled by a spline surface according to rib's morphing in the chordwise direction. The computational fluid dynamics method is adopted to obtain flow-field results and aerodynamic forces. The shear-stress transportv-γ model is introduced and the overset mesh technique is adopted. The numerical results show that the spanwise distributed trailing edge morphing obviously changes the aerodynamic and energy transfer characteristics of the dynamic stall. Especially when the phase difference between the trailing edge motion and the wing pitch is −π/2, the interaction between the three-dimensional leading-edge vortex and trailing-edge vortex is strengthened, and the work done by the aerodynamic force turns negative. This indicates that the trailing edge deformation has the potential to suppress the oscillation amplitude of stall flutter. We also found that as the trailing-edge camber morphing varies more complex along the spanwise, and the suppression effect decreases accordingly.

Design and validation of a variable camber wing structure

Variable camber wing technology is one of the important development trends of green aviation at present. Through smooth, seamless, continuous and adaptive change of wing camber, the aerodynamic performance is improved in achieving increase in lift and reduction in resistance and noise. Based on the aerodynamic validation model CAE-AVM, Chinese Aeronautical Establishment (CAE) has carried out the design and validation of a variable camber wing, proposed an aerodynamic deformation matrix for the leading and trailing edges of aircraft wings in take-off, landing and cruise conditions. Various structures and driving schemes are compared, and several key technology problems of leading and trailing edge deformation are solved. A full-size leading edge wind tunnel test piece with a span of 2.7 m and a trailing edge ground function test piece are developed. The deformation and shape maintenance capabilities of the leading edge is verified under real wind load conditions, and the load bearing and deformation capabilities of the trailing edge is verified under simulated follow-on load. The results indicate that the leading and trailing edges of the variable camber wing can achieve the required deformation angle and have a certain load-bearing capacity. Our study can provide some insights into the application of variable camber wing technology for civil aircraft.

An Eigenanalysis of Angle-Based Deformation Energies

Angle-based energies appear in numerous physics-based simulation models, including thin-shell bending and isotropic elastic strands. We present a generic analysis of these energies that allows us to analytically filter the negative eigenvalues of the second derivative (Hessian), which is critical for stable, implicit time integration. While these energies are usually formulated in terms of angles and positions, we propose an abstract edge stencil that succinctly parameterizes the edge deformation, and allows us to derive generic, closed-form analytical expressions for the energy eigensystems. The resultant eigenvectors have straightforward geometric interpretations. We demonstrate that our method is readily applicable to a variety of 2D and 3D angle-based elastic energies, including both cloth and strands, and is up to 7× faster than numerical eigendecomposition.