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Magnetic force microscopy (MFM) is long established as a powerful tool for probing the local stray fields of magnetic nanostructures across a range of temperatures and applied stimuli. A major drawback of the technique, however, is that the detection of stray fields emanating from a sample's surface rely on a uniaxial vertical cantilever oscillation, and thus are only sensitive to vertically oriented stray field components. The last two decades have shown an ever-increasing literature fascination for exotic topological windings where particular attention to in-plane magnetic moment rotation is highly valuable when identifying and understanding such systems. Here, we present a method of detecting in-plane magnetic stray field components, by utilizing a split-electrode excitation piezo that allows the simultaneous excitation of a cantilever at its fundamental flexural and torsional modes. This allows for the joint acquisition of traditional vertical mode images and a lateral MFM where the tip–cantilever system is only sensitive to stray fields acting perpendicular to the torsional axis of the cantilever. [ABSTRACT FROM AUTHOR]

Purpose: To compare the peri-implant bone loss of mandibular complete-arch implant-supported fixed prostheses (FPSs) supported by three and four implants and to correlate with the size of the horizontal and vertical distal cantilever at prosthesis placement (T1) and after 1 year (T2). Materials and Methods: A total of 72 external hexagon (EH) type implants were placed in 20 participants. Of these, 24 supported an FPS with three implants (G3I) and 48 with four implants (G4I). The mandibular implants were named 1, 2, 3, and 4 according to their location in the arch, in a clockwise direction. Digital periapical radiographs were taken at times T1 and T2 for analysis and measurement of peri-implant bone loss. The horizontal and vertical distal cantilevers were measured with a digital caliper and correlated with peri-implant bone loss. Results: The survival rate of implants in G3I was 91.66%, and in G4I it was 97.91%. The mean bone loss in G3I was 0.88 ± 0.89 mm, and in G4I it was 0.58 ± 0.78 mm (P = .225). There was no correlation between distal horizontal cantilevers and bone loss in the studied groups, with G3I being -0.25 (P = .197) and G4I -0.22 (P = .129). Larger vertical cantilevers of implants 1 (P = .018), 3 (P =.015), and 4 (P = .045) correlated with greater bone loss in G4I. Conclusions: The number of implants in an FPS did not influence peri-implant bone loss after 1 year of follow-up. Larger vertical cantilevers influenced greater bone loss in complete-arch implant-supported fixed prostheses supported by four implants. [ABSTRACT FROM AUTHOR]

Colloidal probes are often used in force microscopy when the geometry of the tip–sample interaction should be well controlled. Their calibration requires an understanding of their mechanical response, which is very sensitive to the details of the force sensor consisting of a cantilever and the attached colloid. We present some analytical models to describe the dynamics of the cantilever and its load positioned anywhere along its length. The thermal noise calibration of such probes is then studied from a practical point of view, leading to correction coefficients that can be applied in standard force microscope calibration routines. Experimental measurements of resonance frequencies and thermal noise profiles of raw and loaded cantilevers demonstrate the validity of the approach. [ABSTRACT FROM AUTHOR]

H−T phase diagrams for chromium oxide chloride (CrOCl) are usually obtained using data from the measurements of magnetization and specific heats. Recent works suggest that magnetic anisotropy exists in CrOCl. In this work, we use dynamic cantilever magnetometry, which is sensitive to both magnetization and magnetic anisotropy, to probe phase transitions in CrOCl flakes. Together with magnetization measurements from a Superconducting Quantum Interference Device, four major regions of the CrOCl H−T phase diagram along its c-axis are obtained, which is consistent with the previously reported works. Then, we studied magnetic field induced transitions in CrOCl flakes under four different temperatures. Several transitions in antiferromagnetic state and in incommensurate state, which have not been reported before, were recognized. We believe these transitions probably originate from magnetic anisotropy due to magnetoelastic coupling and lattice reconstruction in CrOCl. Our work provides intriguing experimental results on the intricate magnetic structure of CrOCl, making progress in understanding the rich magnetic states of CrOCl. [ABSTRACT FROM AUTHOR]

Crack localisation is a fundamental step of damage identification. Most of the published research on crack localisation based on natural frequency consists in model updating which requires a great deal of calculation. This paper presents a simple method of crack localisation in composite cantilever beam-type structures. The proposed method consists of classifying the reduction of the first four measured natural frequencies and deducing the damage position from a table. For these purposes, a finite element model is first used to study the direct problem: the vibration behaviour of an intact beam and the changes caused in the damaged state. Then it is shown that the classification of the frequency reduction ratio is different for each damaged zone. Consequently, the beam is discretized into several areas according to the classifications of the first four frequency ratios. Therefore, this discretization is represented in a table to be used in damage localisation. The robustness of the suggested technique is first tested numerically by using the Abaqus/CAE finite element software environment. Then, the applicability of the localisation method is validated experimentally on a cracked glass fibre-reinforced epoxy beam. The results show that the proposed method can successfully localise damage in composite beams. [ABSTRACT FROM AUTHOR]

Low-frequency vibration is the core problem that hinders high-precision equipment's positioning accuracy and control accuracy. However, the response of a nonlinear electrical-mechanical coupling system is nonlinear and quite complicated under the ambient random vibrating environment. This paper presents a vibration suppression method through NARX (Nonlinear autoregressive with external input) neural network and its controller. The experiment platform is designed, and its dynamic model is obtained through system identification. The Neural network direct dynamic inverse control system is established, and the controller is designed. Both the simulation and experimental results show that the NARX identification and the controller can effectively achieve vibration suppression, and the experiment's highest vibration rejection ratio is 90.8%. The vibration suppression technology can be extensively applied to low-frequency vibration systems, such as aerospace equipment and high-precision equipment. [ABSTRACT FROM AUTHOR]

• The strongly nonlinear dynamical system is solved through the homotopy analysis method. • The system exhibits hardening/softening behavior for superharmonic/subharmonic resonance. • The time delay parameters influence the generation and disappearance of subharmonic resonance. The present work discusses the strongly nonlinear dynamical characteristics of the secondary resonance in a cantilever beam system with concentrated mass regulated through displacement and velocity time delay. Through the homotopy analysis method, the potential superharmonic and subharmonic resonance issues are resolved. A detailed analysis is conducted to investigate the influences of the time delay, feedback gain coefficient, excitation amplitude, and damping coefficient on the nonlinear response. The results show that the system exhibits hardening behavior for superharmonic resonance with one or two peaks and softening behavior for subharmonic resonance. In time delay control systems, increasing the damping coefficient occasionally causes an increase in amplitude. Due to the complexity of the system, it is challenging to definitively determine whether displacement or velocity time delay control is more suitable. Only when specific working conditions are given can it be compared which way is better. Prudently choosing the velocity and displacement time delay factors can restrain the amplitude of the system, adjust the response region, jump frequency and the number of solutions. The findings of this paper are thought to be useful in the design of time delay feedback controllers. [ABSTRACT FROM AUTHOR]

A vibration-reducing boring bar with variable damping is proposed as a solution to the issue of poor stability of boring bars during boring machining. This will enhance the stability of boring machining. Firstly, this article places a variable-damping vibration absorber in the cavity at the front end of the boring bar. An excitation coil, a mass block, and a cantilever beam make up the vibration absorber structure. It contributes to damping adjustment by adjusting the excitation coil's energizing voltage, which alters the damping force on the mass block. On this basis, establish a dynamic model and analyze the damping and magnetic field of the variable-damping vibration absorber. Simultaneously building a vibration-damping boring bar system platform based on LabVIEW to monitor and control the vibration status of the boring bar. Finally, the feasibility of the vibration-damping boring bar was verified through performance testing of the vibration absorber and boring experiments. The results showed that the maximum vibration acceleration of the vibration-damping boring bar decreased by about 34.7%. It has been proven that the variable-damping vibration reduction boring bar has a good vibration reduction effect. [ABSTRACT FROM AUTHOR]

ABSTRACT Objective Materials and Methods Results Conclusions Clinical Significance The aim of the present study was to investigate the relation of the implant position to the implant crown and analyze the location and magnitude of bite force.The dimensions of 49 posterior implant‐supported restorations were recorded in terms of: 1. implant diameter, 2. crown length, 3. crown width, 4. crown height, 5. occlusal surface of the restoration. The crown/implant height was measured and the distance between the implant center and the restoration center revealed the size of intra‐coronal cantilevers. The occlusal force analysis determined the point and magnitude of loading. Correlation coefficient r was used for the statistical process and statistical control was carried out with the aid of t‐test with minimum level of significance p < 0.05. ‐ The mean crown‐to‐implant ratio was 0.9 and in short implants (< 10mm) the ratio was 1.28. ‐ Intra‐coronal cantilever extensions ranged from 2.1 mm to 6.35 mm depending on crown size. ‐ Occlusal loading was identified in cantilever areas of the crown. The mean crown‐to‐implant ratio was 0.9 and in short implants (< 10mm) the ratio was 1.28.Intra‐coronal cantilever extensions ranged from 2.1 mm to 6.35 mm depending on crown size.Occlusal loading was identified in cantilever areas of the crown. ‐ Implant center deviates from crown center in 71%–82% of the cases depending on site location. ‐ Implants with non‐ideal position may support a functionally occluding crown. Implant center deviates from crown center in 71%–82% of the cases depending on site location.Implants with non‐ideal position may support a functionally occluding crown.Intra‐coronal cantilevers are a critical factor to avoid clinical complications and should be taken under consideration both in the planning and fabrication phase of implant restorations. [ABSTRACT FROM AUTHOR]

This article delves into a hybrid galloping energy harvester featuring a longitudinally aligned triangular-shaped bluff body. Numerically, it analyzes how the position of a lumped mass influences the average output power of the harvester under concurrent base excitation and galloping. In comparison with traditional hybrid energy harvesters, the impact of three factors—low airflow velocity, small base excitation amplitude, and low frequency—is examined for each case of lumped mass deployment. The findings reveal that optimal mass positioning markedly enhances the harvester's average power output when there are low airflow velocities, small base excitation amplitudes, and low frequencies, constituting a novel contribution to the field. Through numerous numerical simulations, it is determined that the optimal position for deploying the lumped mass is approximately 60–70% along the length of the cantilever beam substrate. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerator (TENG), as a new technique for energy capture, has unique advantages in harvesting high‐entropy energy. In view of the wind‐induced vibration characteristics of power transmission lines, the symmetric elastic bistable triboelectric nanogenerator (EB‐TENG) is introduced in this work. The core component of the EB‐TENG is the elastic bistable cantilever beam structure, which is designed by introducing an elastic perturbation structure to the conventional cantilever beam. This beam results in several sub‐resonance frequencies in addition to the natural frequencies, which broadens the frequency band of the EB‐TENG. In addition, the EB‐TENG adopts a symmetrical cantilever beam to ensure effective harvesting of vibration energy, even in situations of self‐tilting and external tilting vibration. The experimental outcomes confirm that the EB‐TENG can significantly harvest vibration energy in the 7–60 Hz frequency range and delivers the maximum peak power of 2.846 mW, which meets the major vibration frequency range of power transmission lines under the action of breeze. Finally, self‐powered strategy based on EB‐TENG online monitoring devices (such as tower obstruction lights, temperature and humidity sensors, and line high temperature wireless alarms) is constructed. This work helps promote the application of in‐situ self‐powered monitoring based on TENG in smart transmission lines. [ABSTRACT FROM AUTHOR]

The aim of this work is the analysis of passive and semi-active damping methods on the model woven beam with a piezoelectric (PZ) layer. The mathematical model of the PZ layer on cantilever beam is derived. For modeling, real product parameters of PZ layer are used, and through simulation find the optimal values to dampen it. The resistive-inductance passive model, and State-Switch Damping SSD semi-active model are used in this work. The models are processed in the MATLAB Simulink environment and the results of the behavior of the models compared to each other. The program involving passive and semi-active systems, where analyze the behavior of the model for different parameters and the damping capabilities of individual methods are compared. The simulation results show the effectiveness of the semi-active system in comparison with the passive systems, also it shows the passive method is not so effective at low frequency as it in high frequency, and the semi-active method is not optimal for high frequency vibration. [ABSTRACT FROM AUTHOR]

Finite element (FE) simulations of adhesively bonded composite joints were conducted using the cohesive zone model (CZM). To clarify the effect of fracture criteria on the accuracy of the CZM simulation, two types of mixed-mode criteria including the -linear summation model of Modes I and II energy release rates, G I / G IC + G II / G IIC = 1 , and the nonlinear power-law, ( G I / G IC ) n + ( G II / G IIC ) n = 1 , were employed. A CZM formulation using the power-law fracture criterion was developed in this study. The load–displacement curves calculated by the two models were compared with the experimental results obtained from mixed-mode Fernlund–Spelt-type double cantilever beam tests, and the Mode II end-notched flexure (ENF) tests. Calculations using the nonlinear fracture criterion were closer to the experimental results. Consequently, it is concluded that nonlinear fracture modeling is of vital importance for accurate strength analysis of mixed-mode adhesive joints. [ABSTRACT FROM AUTHOR]

A topology optimisation approach that accounts for buckling resistance and manufacturability using fibre-reinforced composites is presented. This approach combines topology optimisation and fibre orientation optimisation to achieve a design with maximum buckling resistance. To ensure the optimal designs can be manufactured using 3D printing, constraints based on the continuity of fibre orientation and fibre path generation are applied. A compressed column, a stubby cantilever and an MBB beam are designed to demonstrate the response of the topology and fibre orientation when accounting for buckling resistance, as well as the compromise due to the inclusion of manufacturing constraints. The results show that the presented approach successfully guarantees manufacturability with a significant increase in buckling resistance. [ABSTRACT FROM AUTHOR]

The classical lateral–torsional instability of a cantilever beam with continuous elastic lateral restraint and a transverse point-load applied at the free end is discussed here through the lens of asymptotic simplifications. One of our main goals is to provide analytical approximations for the critical buckling load, as well as its dependence on various key non-dimensional groups. The first part of this study is concerned with a scenario in which a doubly symmetric beam is constrained to rotate about a fixed axis situated at an arbitrary height above the shear centroidal axis. The second part examines a beam that features a continuous elastic lateral restraint spanning its entire length. Assuming that the stiffness of the constraint, κ (say), is finite, the buckling equations in the second case are described by a system of two coupled fourth-order differential equations in the lateral displacement and the angle of twist. We show that as κ → ∞ , the problem discussed in the first part provides an outer solution for the aforementioned system; the relevant boundary conditions for the next-to-leading-order outer approximation are also derived using matched asymptotics. Our theoretical findings are confirmed by comparisons with direct numerical simulations of the full buckling problem. [ABSTRACT FROM AUTHOR]

The violent vibration of supersonic wings threatens aircraft safety. This paper proposes the strongly nonlinear acoustic metamaterial (NAM) method to mitigate aeroelastic vibration in supersonic wing plates. We employ the cantilever plate to simulate the practical behavior of a wing. An aeroelastic vibration model of the NAM cantilever plate is established based on the mode superposition method and a modified third-order piston theory. The aerodynamic properties are systematically studied using both the timedomain integration and frequency-domain harmonic balance methods. While presenting the flutter and post-flutter behaviors of the NAM wing, we emphasize more on the pre-flutter broadband vibration that is prevalent in aircraft. The results show that the NAM method can reduce the low-frequency and broadband pre-flutter steady vibration by 50%–90%, while the post-flutter vibration is reduced by over 95%, and the critical flutter velocity is also slightly delayed. As clarified, the significant reduction arises from the bandgap, chaotic band, and nonlinear resonances of the NAM plate. The reduction effect is robust across a broad range of parameters, with optimal performance achieved with only 10% attached mass. This work offers a novel approach for reducing aeroelastic vibration in aircraft, and it expands the study of nonlinear acoustic/elastic metamaterials. [ABSTRACT FROM AUTHOR]

This study assesses the geometric distortion of cantilevers fabricated from stainless steel 316L with varying internal structures using Selective Laser Melting (SLM) technology. The cantilevers were printed under identical conditions and subsequently post-processed with Wire Electrical Discharge Machining (WEDM) and heat treatment. The geometric deviations were evaluated using a micrometer and a Coordinate-Measuring Machine (CMM). This research underscores the importance of internal structure selection and post-processing in enhancing the geometric accuracy and mechanical stability of 3D-printed slender structures from stainless steel. By demonstrating that internal geometries can significantly influence the end product's structural performance, the findings provide valuable insights for the design and engineering of Additive Manufactured (AM) components, particularly in applications that involve bending. [ABSTRACT FROM AUTHOR]

For the cantilever beam vibration model with small damping and forced terms, under some special parameter conditions, the corresponding unperturbed system can be described by a planar dynamical system. In this paper, by using the dynamical system method to analyze the unperturbed differential system and find bifurcations from the corresponding phase portraits, the dynamical behavior can be derived. Exact explicit homoclinic and heteroclinic solutions, and periodic solution families can be found. For the periodic perturbation system, the chaotic behavior of system is revealed. Numerical simulations are carried out to illustrate the theoretical results. [ABSTRACT FROM AUTHOR]

Although cantilevered variable nozzle vane (VNV) is already used in engineering practice, few researches about cantilevered variable geometry turbine (VGT) aerodynamic performance can be found in public references. In order to find the difference between conventional and cantilevered VGT performances and provide references for VNV design practice, the aerodynamic performances of three single‐stage VGTs with different VNVs were compared by the three‐dimensional numerical simulation method. The VNVs of VGTs here included conventional, cantilevered, and no clearance VNVs. All three VGTs had spherical endwalls in the nozzle. The influences of nozzle spherical endwalls, vane end clearances, and vane rotation angles on VGT performances were investigated. The computation results show that the nozzle spherical endwalls enhance the radial mass flow immigration in the nozzle front part and increase the turbine mass flow rate by 0.79%. Some nozzle vane end clearance leakage flows near the vane trailing edge with higher axial speed can improve the mass flow rate further. Compared with the no clearance VGT, the conventional VGT efficiency is lower by 0.0082, and the cantilevered VGT efficiency is lower by 0.0293. When the VNV rotation angle increases by 1°, the VGT mass flow rate decreases by approximately 0.36 kg/s, and the expansion ratio improves by around 0.05. The cantilevered VGT had enormous VNV hub leakage loss, and its efficiency was lower than the conventional VGT by at least 0.01 within the range of VNV rotation angles. The cantilevered VNV hub creates more loss when VGT works at lower expansion ratio conditions. [ABSTRACT FROM AUTHOR]

AbstractThis study shed light on the simultaneous effects of bistability and electrical resistor on the equivalent damping of a piezoelectric cantilever beam energy harvester. Damping coefficient has a direct effect on the frequency bandwidth of an oscillating system. This paper, extends the experimental-analytical balanced energy (BE) method to obtain the damping change due to bistability of a piezoelectric energy harvester. By using extended Hamilton principle and Euler-Lagrange formulation with nonlinear magnetic field relations, the governing equations of the system are derived. Then the equivalent BE viscous damping model was adopted and the equivalent damping term is achieved. In BE method, the test signals are registered into the proposed BE algorithm, then the equivalent viscous damping coefficient of the system will be obtained. In the end, the effects of bistability and electrical resistor of the power circuit of piezoelectric patch is discussed. According to the results, by increasing the bistability of the system, the equivalent damping of the system will also increase. Besides by escalation the value of electrical load in piezoelectric power circuit, the value of the equivalent damping coefficient reaches a maximum value. This behavior is originated from the extracted power of the system. [ABSTRACT FROM AUTHOR]

To measure the interfacial fracture toughness of ceramic/metal interfaces such as thermal spray coatings, a novel modified cantilever beam bending method is proposed. Finite element simulations are used to determine the energy release rate and phase angle for an interfacial crack in a bi-layered cantilever for varying modulus, thickness and beam aspect ratios. A high-throughput experimental procedure for the new test geometry is presented to extract a large number of measurements of interface fracture energy from the same sample, using digital image correlation. Interfacial fracture energies G C , determined using this method are compared for thermal spray coatings of Alumina and YSZ on steel substrates. G C of these coating-substrate combinations follow the same trend as measured from four-point bending or modified clamped beam bend techniques. Advantages and limitations of the technique in comparison to other methods in practice are discussed. [ABSTRACT FROM AUTHOR]

Operational Modal Analysis (OMA) refers to the modal analysis with only output vibration signals of a structure in its operating state. Classic OMA has developed multiple recognition methods in both the time and frequency domains, where when the random excitation is unknown, the excitation chromaticity is usually treated as white color, which can often cause errors and affect the accuracy of identifying frequencies or damping ratios. In this article, the chromaticity recognition function is defined and a method Chromaticity Recognition Technology (CRT) for identifying noise chromaticity based on system response is proposed. Then, a simulation example is presented. The noise chromaticity is identified for the response of the system under four types of colored noise excitation, and the results of the identification of operational mode parameters with and without CRT are compared. Furthermore, the sensitivity of traditional OMA to different colored noise has been investigated. An experiment with a cantilever under base excitation of pink noise has been undertaken and the results demonstrate the feasibility of the proposed CRT in this paper. [ABSTRACT FROM AUTHOR]

AbstractThe distribution of discrete piezoelectric patches critically influences the vibration control performance of beams. However, few studies have comprehensively addressed this issue for piezoelectric beams under different boundary conditions, especially when both traditional and optimal control strategies are considered. This paper investigates the optimal placement of piezoelectric actuator/sensor pairs for beams with cantilever, simply supported, and clamped boundary conditions, using a genetic algorithm (GA) based on the principle of minimum retained energy. The performance of active vibration control laws, including classical methods such as direct proportional feedback, constant gain negative velocity feedback, and model-based linear quadratic regulator (LQR) control, is thoroughly investigated. [ABSTRACT FROM AUTHOR]

Quantum sensors find applications ranging from material science to biophysics. Nitrogen‐vacancy (NV) center in diamond has been successfully implemented for measuring various types of signals. Optical NV center readout, routinely used in confocal microscopes, allows achieving high spatial resolution down to the diffraction limit. This work describes in detail the combined confocal‐atomic‐force microscope (confocal‐AFM), which takes advantage of sharp AFM cantilevers, and shows its possible applications for nanoscale resolution. It demonstrates the sub‐diffractional localization of NV centers with platinum‐coated cantilevers and the ability to separately address optically unresolved sensors using cantilevers with ferromagnetic coating. The presented setup exhibits a lateral resolution of 13 nm, providing a tool for nanoscale quantum sensing. [ABSTRACT FROM AUTHOR]

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The free oscillations of a functionally graded (FG) porous vertical cantilever beam in the frame work of Euler–Bernoulli beam theory is investigated. The beam is subjected to the gravity-load and the properties of the FG material such as the modulus of elasticity and the density are supposed to change through the thickness of the beam according to power-law relations. The equation of motion is derived using Newton's second law. The Numerical Chebyshev collocation method is utilized to determine the transverse frequencies of the FG porous hanging and standing cantilever Euler–Bernoulli beams. A parametric study is conducted to determine the effects of various factors such as the transverse functionally graded index, the porosity factor, and the elastic and the mass density ratios on the natural frequencies and the mode shapes of the FG porous vertical hanging and standing cantilever thin beams under their self-weight. The accuracy of the proposed numerical method is evaluated through comparisons of the frequencies obtained from the present approach with those available in previous literature. In general, it was observed that the elastic ratio has a softening impact on the frequencies except for the fundamental frequency which remains constant as the elastic ratio increases. Moreover, the porosity parameter and the power-law index may have a softening or hardening impact on the frequencies, and the behavior of these frequencies depends on the values of the elastic and the mass density ratios. [ABSTRACT FROM AUTHOR]

By using a computational model based on the immersed-boundary framework, a new mode of symmetry breaking is discovered in a fluid–structure interaction problem featuring an array of cantilever plates in a cross flow whose strength and direction varies sinusoidally with time. Specifically, within the physical parameters considered in this study, the motion of a single plate remains symmetric, whereas a system containing multiple plates can move asymmetrically so that the symmetry-breaking instability comes from fluid-dynamic interactions among individual plates. Further examination suggests that vortices shed from the free ends of the plates play an important role. Indeed, symmetry breaking occurs only when these vortices are sufficiently strong and when the distance between plates lies within certain range. If the distance is too small, a vortex shed from one plate can only stay in the gap between this plate and its neighboring plate for a short time so that it does not have the chance to interact extensively with the neighbor. On the other hand, if the distance is too large it is also difficult for this vortex to interact with the neighbor since it has to travel a long distance to reach there while the background flow keeps changing its direction. In either case, the system does not display asymmetric behavior. [ABSTRACT FROM AUTHOR]

Over the past decade, various researchers have shown the practicality of extracting electrical energy from vibrating structures. The primary objective of this research was to optimize the parameters of a basic cantilever harvester to maximize the energy production of electricity from surrounding mechanical energy. A distributed parameter model and its modal solution were utilized to determine the design variables via a parametric investigation. It is important to ensure sufficient power generation when there is a wide range of frequencies being excited, without any specific frequency being emphasized. The cost function for the optimization problem was defined as the average power within a specific frequency range, considering geometric and physical restrictions. It was discovered that different parameters' values can be utilized to generate varying maximum power levels for different frequency ranges. Furthermore, a comparative analysis was performed between the finite element method (FEM) using ANSYS and the current harvesting model. The comparison demonstrated a high level of concordance, enabling the utilization of the finite element method (FEM) for subsequent investigation. [ABSTRACT FROM AUTHOR]

Board furniture's performance and scientific design are making it popular. Research on simplifying furniture joints reduces design cycles and costs and improves structural safety. In this article, using a cantilever beam to calculate deflection theoretically simplifies the L-shaped component model and yields a joint elastic modulus formula. Finite element analysis (FEA) confirms the effectiveness of this simplified model by comparing its results with experimental data. In simplified components, the joint elastic modulus increases with length (l2) and stabilizes at l2/b ≥ 6 (b is the board's thickness). The variation pattern of the joint elastic modulus equals that of the stiffness, proving its usefulness in assessing component deformation resistance. Furthermore, the component strength and stiffness are also affected by the screw spacing and connector type. In particular, the connectors type affects bamboo-oriented strand board (BOSB) component performance more than wood-oriented strand board (WOSB). Compared to WOSB, BOSB components have superior strength and stiffness and are more stable. The recommended screw spacing for L-shaped components is 48 mm. BOSB components fixed with two-in-one and metal nuts utilizing threads embedded in the board have better strength and stiffness, while for WOSB components, nylon nuts, and wooden dowel pins are more appropriate for securing. [ABSTRACT FROM AUTHOR]

The structural stability of clamped-free beam-columns resting on a two-parameter foundation under a nonconservative force is investigated. The higher-order beam theory is developed by considering the warping of the cross-section, rotary inertia, and axial force's direction. The characteristic equation of dynamic stability of rectangular/circular cantilevers on a Winkler-Pasternak foundation is obtained for a generalized follower force. Critical loads for divergence instability and flutter instability are evaluated. The influences of foundation stiffness, cross-sectional warping shape, the tangency coefficient on the critical loads are analyzed. The load-frequency interaction-curves are given for different directions of the follower force. The normal/shear stiffness of foundation on divergence and flutter loads has different effects. The normal stiffness increases the first divergence load but decreases the flutter load, reducing to the Herrmann–Smith paradox for Euler columns. The rise of shear stiffness enlarges the first divergence load and lowers the flutter loads. The effects are more sensitive for short beam-columns. Different warping shapes slightly affect the critical loads and the natural frequencies. The exponential warping shape gives the smallest critical divergence loads and the fundamental frequencies. The results of Haringx hypothesis are larger than those of Engesser hypothesis. For shorter columns, the classical results are overestimated and the higher-order beam theory is necessary. [ABSTRACT FROM AUTHOR]

In this letter, we present interfacial fracture toughness data for a polymer-metal interface where tests were conducted at various test temperatures T and loading rates δ ˙ . An adhesively bonded asymmetric double cantilever beam (ADCB) specimen was utilized to measure toughness. ADCB specimens were created by bonding a thinner, upper adherend to a thicker, lower adherend (both 6061 T6 aluminum) using a thin layer of epoxy adhesive, such that the crack propagated along the interface between the thinner adherend and the epoxy layer. The specimens were tested at T from 25 to 65 °C and δ ˙ from 0.002 to 0.2 mm/s. The measured interfacial toughness Γ increased as both T and δ ˙ increased. For an ADCB specimen loaded at a constant δ ˙ , the energy release rate G increases as the crack length a increases. For this reason, we defined rate effects in terms of the rate of change in the energy release rate G ˙ . Although not rigorously correct, a formal application of time–temperature superposition (TTS) analysis to the Γ data provided useful insights on the observed dependencies. In the TTS-shifted data, Γ decreased and then increased for monotonically increasing G ˙ . Thus, the TTS analysis suggests that there is a minimum value of Γ. This minimum value could be used to define a lower bound in Γ when designing critical engineering applications that are subjected to T and δ ˙ excursions. [ABSTRACT FROM AUTHOR]

Self-shading building form has a significant influence on indoor solar gains and energy performance. This paper presented a methodology for quantifying self-shading building forms, which categorized them into three types: inclined, cantilevered, and hybrid (inclined and cantilevered). The prediction model for the quantitative indexes and solar heat gains through windows was established through regression analysis, while the influence of proposed self-shading building forms on energy performance in different climatic regions of China was evaluated and compared. Results suggest that energy-saving potential of the cantilevered type is the highest, followed by the hybrid type. Compared to the south orientation, energy-saving potentials for east and west orientations are more pronounced. As building location changes from south to north, energy-saving potential is increasingly influenced by orientation. The proposed self-shading building forms have a maximum energy-saving potential of 14%, 23%, and 22% for Jinan, Shanghai, and Guangzhou respectively. Finally, corresponding design strategies were suggested to provide guidance and assistance for designers. [ABSTRACT FROM AUTHOR]

Unstable block collapse is an important factor affecting the safety of tunnel construction process. Based on the collapse accident of a block in Qingdao, the failure mechanism of a large-span tunnel with unstable blocks and the control effect of the length, prestress and spacing of pre-stressed rock bolts on the surrounding rock are studied through the model test and combination of numerical calculation, the on-site support optimization scheme is proposed. It is found that the surrounding rock on both sides of the vertical joint has a slight dislocation first, and then the joint opens, and the rock on both sides roughly forms a relative cantilever structure. Pre-stressed rock bolt has the function of limiting block slip and providing radial binding force, and pre-stressed rock bolt restricts the opening of joints and enhances the bearing capacity of surrounding rock. The bolt length is the key factor affecting the bolt support effect, followed by prestress force, and finally the bolt spacing. [ABSTRACT FROM AUTHOR]

Copyright of Kieferorthopädie: die Zeitschrift für die Praxis is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An attached cantilever scaffold, which mainly consists of a cantilever horizontal steel beam and a diagonal bar, is a new type of cantilever scaffold. The upper end of the diagonal bar is attached to an upper floor slab by a hinge, while the lower end is connected to a cantilever beam. Therefore, the position of the lower suspension point has a significant impact on the overall mechanical performance. However, current research on this topic is limited. Thus, in this study, we aim to optimize the mechanical behavior by changing the lower suspension point position. An optimization methodology based on the genetic algorithm is proposed. This methodology has been demonstrated to be efficient and accurate enough to determine the optimal lower suspension point position of a diagonal bar. The effects of different beam cross-sections, diagonal bar diameters, and upper suspension point positions are further investigated. The bearing capacity is shown to improve by more than 100% and 30% for hinged and rigidly connected cantilever beams when the proposed optimization methodology is adopted. The analysis in this study can serve as a reference for the optimal design of an attached cantilever scaffold and can provide a theoretical basis for developing related design software. [ABSTRACT FROM AUTHOR]

Once constructed, the Baku White City pedestrian bridge will be a landmark for the newly developed White City district in the east of the Capital. Designed by UNStudio, the bridge crosses the highway of 8th November Avenue and connects the newly build city to the seaside, forming a wide promenade. Due to the pending construction of the mall as future bridge support, the bridge had to be redesigned. A cantilevering viewing platform will highlight the bridge's ending. This paper covers the structural design of the architecturally shaped cable stayed bridge, supported through a 46 m high A‐shaped, slightly curved pylon. Based on 3‐D modelling in Rhino® and Grasshopper®, the FE‐software SOFISTIK® is used both for cable force finding and bridge design. The structural system, steel structure's specific detail for cable connection and its design approach have been documented. [ABSTRACT FROM AUTHOR]

Cantilevers are elements typically used in the design of various structures such as factory halls or cantilever cranes. Traditionally, such elements are made of standard profiles or, in the case of large loads, by welding from standard sheets. Often, due to stationary conditions of exploitation, no attention is paid to mass reduction. Increasingly stringent requirements on reducing costs, but also on reducing environmental impact through reducing energy consumption necessary for the production, processing, and transport of materials, facilitate the application of optimization to obtain a construction solution with minimal mass. However, doing so requires advanced high-cost computer tools and increases the required competencies of designers. In this paper, a series of optimizations have been carried out for typical reach and load values of cantilevers aiming to create a database that will facilitate algorithms for selecting cross-sectional dimensions suitable for production using either additive technologies or traditional methods. [ABSTRACT FROM AUTHOR]

This Letter presents an active control method for the vibration of piezoelectric structures. First, a controller based on nonlinear extended state observer is designed to improve the disturbance rejection capability of the vibration structure. Additionally, an improved nonlinear active disturbance rejection control (IMNADRC) method is combined with Smith predictor for time delay compensation, resulting in Smith predictor-based IMNADRC. Finally, numerical simulations and experiments are carried out for active vibration suppression of piezoelectric beam under fixed harmonic excitation and variable harmonic excitation, respectively. The results show that the proposed method has good control effect on structural vibration suppression and is highly adaptable to various external excitations. [ABSTRACT FROM AUTHOR]

Taking the nonlocal effect into account, the vibration governing differential equation and boundary conditions of a magnetostrictive composite cantilever resonator were established based on the Euler magnetoelastic beam theory. The frequency equation and vibration mode function of the composite cantilever were obtained by means of the separation of variables method and the analytic solution of ordinary differential equations. The lateral deflection, vibration governing equations, and boundary conditions were nondimensionalized. Furthermore, the natural frequency and modal function of the composite beam were quantitatively analyzed with different nonlocal parameters and transverse geometry dimensions using numerical examples. Compared with the results without considering the nonlocal effect, the influence of the nonlocal effect on the vibration characteristics was analyzed. The numerical results show that the frequency shift and frequency band narrowing of the magnetostrictive cantilever resonator are induced by nonlocal effects. In particular, the high-frequency vibration characteristics, such as vibration amplitude and modal node of the composite beam, are significantly affected. These analysis results can provide a reference for the functional design and optimization of magnetostrictive resonators. [ABSTRACT FROM AUTHOR]

In this study, an improved discontinuous deformation analysis method with sub-block strategy is introduced to numerically simulate mixed-mode fractures. This approach partitions the material domain into continuum and potential discontinuum regions, applying specialized modeling techniques to each. In the continuum region, penalty-like bonding springs are employed to glue the sub-blocks together to capture the elastic behavior of the material. In the potential discontinuum region, the cohesive springs with the stiffness based on the cohesive zone model are implemented between sub-blocks to reproduce the process of crack nucleation and propagation. The primary advantage of this method is its capability to effectively model the transition of quasi-brittle solids from a continuous to a discontinuous stage through the degradation of cohesive springs. This accurately represents material failure while maintaining stability and consistency along uncracked interfaces. Another significant benefit is the method's efficiency, as it avoids complex contact operations along sub-block interfaces before the cohesive spring between them fails. Validation through various benchmark numerical examples, such as cantilever beam-bending and diverse fracture simulations, demonstrates the method's accuracy and robustness by comparing the results with analytical solutions. These comparisons show that the proposed method effectively captures the interplay between tensile and shear traction components in the mixed-mode crack propagation process. [ABSTRACT FROM AUTHOR]

Highlights To efficiently design the stiffness of the laminated composite blade‐like structure, an analytical method to assess deformation of variable cross‐section laminated beam under cantilever bending load was developed, in which a local ply density matrix method was introduced to characterize the ply‐up in arbitrary cross‐section after ply drop‐off process and infinitesimal element segment method was used to convert complex variable cross‐section specimen into local equal cross‐section beam structure. The model was validated by the cantilever beam experiment with relative predicted error of stiffness of 5.7%. Inner and outer ply drop‐off models were analyzed using the proposed analytical method. The results show that: (1) stiffness of the outer ply drop‐off model is the highest, at 13.07 N/mm, while that of the inner ply drop‐off model 2 is the lowest, about 17.8% lower than the outer ply drop‐off model; (2) maximum relative deformation difference between the inner ply drop‐off model 2 and outer ply drop‐off model is 21.7% at the free side of the cantilever beam. It indicates that anti‐deformation ability of the variable cross‐section laminated structure can be efficiently designed by the proposed analytical method, especially for the section close to the free side. Developed a bending stiffness prediction method for composite beam. Variable cross‐section feature of the composite laminate was considered. Local ply density matrix method was introduced to characterize ply drop‐off. Proposed method was validated by cantilever beam bending experiment. Inner and outer ply drop‐off models were compared by the proposed method. [ABSTRACT FROM AUTHOR]

To address the serious acoustic performance deterioration induced by air leakage in the low-frequency range and the asynchronous vibration in electroacoustic transduction structures near the resonant frequency, a novel sealing strategy is proposed that targets one of the most widely reported piezoelectric MEMS speaker designs. This design consists of multiple cantilever beams, in which the air gaps between cantilevers are automatically and selectively filled with liquid polydimethylsiloxane (PDMS) via the capillary effect, followed by curing. In the proof-of-concept demonstration, the sound pressure level (SPL) within the frequency range lower than 100 Hz markedly increased after sealing in an experiment using an IEC ear simulator. Specifically, the SPL is increased by 4.9 dB at 20 Hz for a 40 Vpp driving voltage. Moreover, the deteriorated SPL response near the resonant frequencies of the cantilever beams (18 kHz–19 kHz) caused by their asynchronous vibration induced by the fabrication process nonuniformity also significantly improved, which successfully increased the SPL to approximately 17.5 dB. Moreover, sealed devices feature nearly the same SPL response as the initial counterpart in the frequency band from 100 Hz to 16 kHz and a total harmonic distortion (THD) of 0.728% at 1 kHz for a 40 Vpp driving voltage. Compared with existing sealing methods, the current approach offers easy operation, low damage risk, excellent repeatability/reliability and excellent robustness advantages and provides a promising technical solution for MEMS acoustic devices. [ABSTRACT FROM AUTHOR]

To solve the supporting problem of high-stress red shale roadway in Kaiyang phosphate mining area, the mechanical properties and microstructure of red shale are studied. The results show that the compressive strength of the red shale is related to the bedding angle, and the strength of the 0° samples is the highest, and the strength of the 60° and 30° samples decreases gradually. With comprehensive consideration, the composite supporting method of cantilever piles and grid arch is adopted. Combining the numerical simulation and theoretical calculation, the parameters of cantilever pile with interval distance of 5 m and rock-socketed depth of 500 m are more reasonable. The monitoring results show that the roof subsidence was controlled within 250 mm, and the floor heave was within 100 mm, which could effectively control the severe deformation of the roadway and also is of great significance to the safe mining of phosphate resources. [ABSTRACT FROM AUTHOR]

The critical lateral buckling load of cantilever beams with IPE cross-section was calculated using analytical closed-form equations and numerical finite element analyses within the scope of the research. The equations suggested in the specifications for simply supported beams were used to calculate the buckling load of cantilever beams. The rationality of the values calculated due to this is not fully known. In the research, a single loading was made to the shear center at the free end of the cantilever beam. Cantilever length and section height were kept variable. As a result, it has been determined that there are partial differences in the analysis result obtained from the elastic stability theory and finite element method. Accordingly, the results obtained from ANSYS and SAP2000 analyses confirm each other. On the other hand, the results obtained using the formulation of Timoshenko and Gere, the calculation results made according to the AISC and DCCPSS regulations, and the results obtained from the LTBeam program confirm each other. However, it differs from the FEA analysis due to the cantilever beam length’s shortening and the section height increase. Thus, to obtain accurate and reliable results in the buckling load calculation of cantilever beams, the equations used in analytical calculations were optimized according to finite element analysis (FEA) results. As a result of the study conducted according to the error criteria, it was determined that the updated equation results gave similar results to the FEA results. [ABSTRACT FROM AUTHOR]

This work aims to develop an experimental investigation into the effectiveness of the sliding-mode approach for hybrid vibration-based energy harvesting. A proposed sliding-mode triboelectric-electromagnetic-piezoelectric energy harvesting model involves a cantilever beam with a tip mass exposed to magnetic and frictional forces. The experimental findings indicate that the system can achieve its peak inter-well oscillation output within a low-frequency range of 4Hz–6Hz. Friction has a lesser impact on the open-circuit voltage output at an excitation acceleration of 1.5g compared with 1g. The distribution of tri-stability changes with the presence of friction. This model provides a deeper understanding of the influence of the dry friction coefficient (0.2–0.5) on the interactive behaviors of different generator units. [ABSTRACT FROM AUTHOR]

This work explores the response of a cantilever plate attached to a cylinder in a wind tunnel under an impact excitation. A detailed computer-aided design (CAD) model and the finite element analysis (FEA) modal simulation of the experimental setup are introduced. Two experimental techniques are thoroughly discussed: an accelerometer-based experimental modal analysis (EMA) method, and a non-contact, full-field, high-speed digital image correlation (DIC)-based operational deflection shape (ODS) analysis method. The experimental and FEA results of the first seven natural frequencies, mode shapes, and ODSs of the cantilever plate are presented and compared. The percent differences between the EMA and FEA natural frequency results are less than 4.8%, and the modal assurance criterion (MAC) values between the EMA and FEA mode shapes are at least 0.845. The percent differences between the ODS analysis and FEA natural frequency results are less than 3.4%, while the MAC values between the ODS analysis ODSs and FEA mode shapes are at least 0.728. The percent differences between the EMA and ODS analysis natural frequency results are less than 3.5%, and the MAC values between the EMA mode shapes and ODS analysis ODSs are at least 0.505. There are two sets of two different mode shapes and ODSs with relatively high correlation. One set is a set of two closely spaced modes and ODSs approximately 20 Hz apart with obvious similarities in shape. The other set is a set of two modes and ODSs approximately 100 Hz apart that share less obvious similarities in shape. [ABSTRACT FROM AUTHOR]

Accurately measuring the coefficient of friction (COF) is the fundamental prerequisite of superlubricity research. This study aimed to reduce the COF measurement resolution Δμ of atomic force microscopy (AFM). Based on the theoretical model, a distinctive strategy was adopted to reduce Δμ by optimizing the cantilever's cross-section of the AFM probe, inspired by civil engineering. Δμ can be reduced by decreasing the width of the horizontal side wR and the wall thickness t and increasing the width of the vertical side wH. Moreover, the I-shape demonstrates the highest reduction in Δμ, followed by the U-shape. Considering the processability, the AFM probe with the U-shaped cross-sectional cantilever was investigated further, and the dimensions are 35 µm wR, 3.5 µm wH, 0.5 µm t, 50 µm l (cantilever length), and 23 µm htip (tip height). The finite element analysis results confirm its reliability. After being fabricated and calibrated, the AFM probe achieves the minimal Δμ of 1.9×10−6 under the maximum normal force so far. Additionally, the friction detection capability of the fabricated AFM probe improves by 78 times compared to the commercial tipless-force modulation mode (TL-FM) AFM probe with the conventional solid rectangular cross-sectional cantilever. This study provides a powerful tool for measuring 10−6 COF. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)