Tip Of Beam Research Articles

Study on Cantilever Beam Tip Response with Various Harmonic Frequencies by Using EDISON Co-rotational Plane Beam-Dynamic Tip Load

In this paper, Euler-Bernoulli beam theories(EB-beam) are used, and Fast Fourier Transformation(FFT) analysis is then employed to extract their natural frequencies using both analytical approach and Co-rotational plane beam(CR-beam) EDISON program. EB-beam is used to analyze a spring-mass system with a single degree of freedom. Sinusoidal force with various frequencies and constant magnitude are applied to tip of each beam. After the oscillatory tip response is observed in EB-beam, it decreases and finally converges to the so-called ‘steady-state.’ The decreasing rate of the tip deflection with respect to time is reduced when the forcing frequency is increased. Although the tip deflection is found to be independent of the excitation frequency, it turns out that time to reach the steady state response is dependent on the forcing frequency.

Two-dimensional concentrated-stress low-frequency piezoelectric vibration energy harvesters

Vibration-based energy harvesters using piezoelectric materials have long made use of the cantilever beam structure. Surmounting the deficiencies in one-dimensional cantilever-based energy harvesters has been a major focus in the literature. In this work, we demonstrate a strategy of using two-dimensional beam shapes to harvest energy from low frequency excitations. A characteristic Zigzag-shaped beam is created to compare against the two proposed two-dimensional beam shapes, all of which occupy a 25.4 × 25.4 mm2 area. In addition to maintaining the low-resonance bending frequency, the proposed beam shapes are designed with the goal of realizing a concentrated stress structure, whereby stress in the beam is concentrated in a single area where a piezoelectric layer may be placed, rather than being distributed throughout the beam. It is shown analytically, numerically, and experimentally that one of the proposed harvesters is able to provide significant increase in power production, when the base acceleration is set equal to 0.1 g, with only a minimal change in the resonant frequency compared to the current state-of-the-art Zigzag shape. This is accomplished by eliminating torsional effects, producing a more pure bending motion that is necessary for high electromechanical coupling. In addition, the proposed harvesters have a large effective beam tip whereby large tip mass may be placed while retaining a low-profile, resulting in a low volume harvester and subsequently large power density.

A parametric investigation on the hysteretic behaviour of CFT column to steel beam connections

The results of a numerical investigation pertaining to the hysteretic behaviour of concrete filled steel tubular (CFT) column to I-beam connections are discussed in detail. Following the verification of the numerical results against the available experimental tests, the nonlinear finite element (FE) analysis was implemented to evaluate the effects of different parameters including the column axial load, beam lateral support, shape and arrangement of stiffeners, stiffness of T-stiffeners, and the number of shear stiffeners. Pursuing this objective, an external CFT column to beam connection, tested previously, was selected as the case-study. The lateral forces on the structure were simulated, albeit approximately, using an incremental cyclic loading reversal applied at the beam tip. The results were compared in terms of hysteretic load-displacement curves, stress distributions in connection, strength, rotation, and energy dissipation capacity. It was shown that external T-stiffeners combined with internal shear stiffeners play an important role in the hysteretic performance of CFT columns to I-beam connections.

SHN490강종의 보-기둥 접합부 형태에 따른 실험적 연구

In this study, an experimental study to evaluate the seismic performance of beam-to-column connection for medium and low-rise building was conducted. Five connections using SHN490 steel were made with test variables such as flange welded or bolted, web welded or bolted. Specimen SHN-W-W is web welded and flange welded type. Specimen SHN-W-B is web welded and flange bolted type. Specimen SHN-B-W is web bolted and flange welded type. Specimen SHN-B-B is web bolted and flange bolted type. Specimen SHN-EP is a connection with the end plate to the beam ends. Cyclic loadings was applied at the tip of beam following KBC2009 load protocol. The load vs rotation curves for different connection are shown and final failure mode shapes are summarized. The connections are classified in terms of stiffness and strength as semi-rigid or rigid connection. Energy dissipation capacities for seismic performance evaluation were compared.

Experimental study of vibrational energy harvesting using Electro-Active paper

This paper presents an estimation of power output produced by an Electro-Active Paper (EAPap) energy harvesting transducer under base vibration. EAPap is very thin cellulose piezoelectric film, which exhibits a direct piezoelectric effect, when subjected to stress. A 50×50 mm2 EAPap patch was bonded on a 100×50×1 mm3 aluminum cantilever structure. Energy harvesting tests were performed on the energy harvesting transducer, without and with a 2 grams proof mass near the tip of the cantilever beam. The voltage, current and power frequency response functions (FRFs) with respect to the base acceleration are identified and presented. The Voltage FRFs show a monotonic trend with increasing the load resistor from 100 kΩ to 1 MΩ, and the current FRFs also demonstrate monotonic dynamic behavior, but the trend is opposite to the voltage FRFs. In contrast to the voltage and current FRFs, the output power FRFs do not show a monotonic trend, exhibiting the maximum value of 150 μW/g2 at 75.1 Hz without the proof mass. The output power increases to 392 μW/g2 at 62.2 Hz when the proof mass is attached. This preliminary study indicates that EAPap is promising for energy harvesting transducers under vibration environment.

Forced Convection Cooling of Low-Power Handheld Devices Using a Vibrating Cantilever Beam

In this study, a convection cooling technique for handheld electronic devices is proposed and investigated. The technique uses bulk airflows generated by a vibrating cantilever beam actuated by a rotating imbalance motor. Analytic coupled physics modeling using an approximate integral method within laminar-flow boundary layers was used to analyze the proposed cooling technique. The cantilever beam and enclosure were designed based on the form factors of a typical handheld device. The bulk airflow cooling performances at various probe locations were investigated experimentally for low and high heating loads and numerically verified. The results indicate that a higher heating load of the heat source results in a larger temperature drop at the same convection rate. Also, for the probe locations away from the heat source and closer to the beam, the resulting temperature drops were relatively small despite a stronger velocity field generated by the beam. This is due first to the heat generated by the vibrating beam itself and second to a circulation of the air heated by the heat source to the rest of the regions in the enclosure. In general, a good agreement between experimental and numerical results was attained, even though a slight difference between two results exists. Overall, significant cooling was achieved by the proposed system. With a beam tip deflection of ±4 mm, nearly an 18-fold increase in the cooling performance was achieved compared to a natural convection case. Furthermore, the cooling performance continues to increase as the tip deflection of the cantilever beam increases. Thus, a cooling system using the bulk airflow generated by a vibrating cantilever beam has much potential as a feasible solution for electronic handheld devices.

Vibration control of a flexible beam driven by a ball-screw stage with adaptive notch filters and a line enhancer

For a low-stiffness beam driven by a ball-screw stage, the lateral vibrations cannot be adequately controlled by a collocated compensator based on rotary-encoder feedback alone. Acceleration signals at the tip of the flexible beam are measured for active vibration control in addition to the collocated compensator. A second-order bandpass filter (a line enhancer) and two notch filters are included in the acceleration-feedback loop to raise modal dampings for the first and the second flexible modes without exciting higher-frequency resonances. A novel adaptation algorithm is devised to tune the center frequencies of the notch filters in real time. It consists of a second-order low-pass filter, a second-order bandpass filter and a phase detector. Improvement of the control system is elaborated progressively with the root-locus and bode-plot analyses, along with a physical interpretation. Extensive testings are conducted on an experimental device to verify the effectiveness of the control method.

Coupling carbon nanotube film microextraction with desorption corona beam ionization for rapid analysis of Sudan dyes (I-IV) and Rhodamine B in chilli oil.

A rapid analysis method by coupling carbon nanotube film (CNTF) microextraction with desorption corona beam ionization (DCBI) was developed for the determination of Sudan dyes (I-IV) and Rhodamine B in chilli oil samples. Typically, CNTF was immersed into the diluted solution of chilli oil for extraction, which was then placed directly under the visible plasma beam tip of the DCBI source for desorption and ionization. Under optimized conditions, five dyes were simultaneously determined using this method. Results showed that the analytes were enriched by the CNTF through the π-π interactions, and the proposed method could significantly improve the sensitivities of these compounds, compared to the direct analysis by DCBI-MS/MS. The method with a linear range of 0.08-12.8 μg g(-1) and good linear relationships (R(2) > 0.93) in a multiple reaction monitoring (MRM) mode was developed. Satisfactory reproducibility was achieved. Relative standard deviations (RSDs) were less than 20.0%. The recoveries ranged from 80.0 to 110.0%, and the limits of detection (LODs) were in the range of 1.4-21 ng g(-1). Finally, the feasibility of the method was further exhibited by the determination of five illegal dyes in chilli powder. These results demonstrate that the proposed method consumes less time and solvent than conventional HPLC-based methods and avoids the contamination of chromatographic column and ion source from non-volatile oil. With the help of a 72-well shaker, multiple samples could be treated simultaneously, which ensures high throughput for the entire pretreatment process. In conclusion, it provides a rapid and high-throughput approach for the determination of such illicit additions in chilli products.

Strain gauges based sensor system for measuring 3-D deflections of flexible beams

A sensor system has been designed for the real time measurement of 3-D deflections of flexible beams (position and orientation of the tip). The sensor system is based on resistive strain gauges placed strategically at different locations of the beam. A linear model based on the classical theory of the deflection of flexible beams has been used to calculate the position and orientation of the beam tip from the strain gauges measurements. Furthermore, it has been necessary to include a nonlinear term in the model to calculate the coordinate x of the beam tip. Experimental results demonstrate the feasibility of the sensor system.

Design of drug-delivery micro-wheel and auto-rolling control by change of gravity center

A micro-dosing system of overall size 5×5×4.2 mm3 for drug delivery is proposed and presented. The drug delivery system mainly consists of a micro-wheel and a micro-drug release mechanism. The motion of the micro-wheel is controlled by its center of gravity via a running disk, which is placed within the hollow micro-wheel and attracted by the actuated micro-solenoids fabricated on the inner wall of micro-wheel in shift. In addition, the micro-wheel is controlled to roll forwards/backwards to the designated location by two sliding mode control strategies: one for long-distance motion (to transport the drug to the vicinity of the spots under disease) and the other for short-distance motion (to decelerate down and stop at the exact drug-release location). On the other hand, the microdrug release mechanism is composed by a cantilever beam and a chamber filled up by medicine. The pyramid tip of the cantilever beam deflected by the applied electrostatic force is designed to penetrate the micro-film which seals the chamber so that the medicine can be released at the specified spot.

A flextensional piezo-composite structure for energy harvesting applications

A piezoelectric energy harvester (PEH) consisting of two cymbal electromechanical transducers and a cantilever beam structure designed and manufactured. The PEH under test is a novel design that aims to keep the transducers permanently under compression forces. Keeping the transducers under compression forces increases the life-time of the piezoelectric ceramics. A parametric study was performed in order to select design variables such as beam length and tip mass subject to constraint that the resonance frequency of the system would not exceed 200Hz. A mathematical model representing the PEH was derived, a finite element (FE) model was built and a parametric study was performed for the optimization of the PEH. The derived mathematical model and the FE model were validated experimentally by the manufactured PEH. DC voltage and power obtained from the PEH were evaluated experimentally for low acceleration levels of 2g (1g=10m/s2). The effect of stacking the piezoelectric disks on energy harvesting performance was also evaluated experimentally. The two type of transducers used are cymbals with single layer (C-PZT1) and two-layer-stacked (C-PZT2) PZT 5H (lead zirconate titanate) disks. Under sinusoidal vibrations of 2g acceleration amplitude, the structure with C-PZT2 transducers (B-PZT2) was able to generate 141.61μW of power at 153Hz across a resistive load (RL) of 40kΩ while the one with C-PZT1 transducers (B-PZT1) generated 104.04μW of power at 166Hz across an RL of 80kΩ.

Efficient Vibration Control with a Semi-Active Vibration Absorber in a Semiconductor Fab

In this paper a new type of semi-active vibration absorber has been developed. The vibration absorber consists of mass block, cantilever beam, magnet lock system, vibration and distance sensors, controller and servo motor. The mass block is fixed on the tip of cantilever beam, and the control process is driven by a servo motor and a transmit gears. Portion of cantilever was cut in form of gear tracks, which can be driven by servo motor through transmit gear to regulate the length of the cantilever beam, and the natural frequency of absorber will also be regulated. After the mass locates in right position (i.e. the natural frequency of absorber is in assigned condition), the magnetic lock will clamp the cantilever beam. The design has the benefit of simplified control system, and extra unknown vibration modes will be averted. A fabrication prototype of the proposed semi-active vibration absorber is constructed and tested to demonstrate the application and modeling of the new cantilever beam damper. By performing the experimental work, the semi-active vibration control system is designed not only for reduce vibration level in resonant condition, but also considered for vibration attenuation in non-resonant conditions.

Numerical investigation of convective heat transfer on a vertical surface due to resonating cantilever beam

In this article a simplified vibrating cantilever beam model is made to simulate the piezoelectric fan. The flow and heat transfer performances induced by the vibrating cantilever beam operating at different flexural modes and opening inlets are studied by numerical simulation. The fluid domain is meshed using a dynamic meshing scheme in order to model the displacement and deformation of the vibrating cantilever beam over time. The results show that the flow patterns generated at different resonance modes change with the deformation of the cantilever beam. The gap between the cantilever beam tip and the heated wall has significant effect on the flow and heat transfer features. By comparison with natural convective heat transfer, heat transfer augmentation ratios by the pseudo-jet induced by vibrating cantilever beam are 1.7–3.1 at the first mode and 1.7–2.7 at the second mode, respectively. For the confined space, the interaction of vortex induced by the vibrating beam and wall jet formed by the pseudo-jet impingement makes the intensity of vortices strong and pushes the vortex core upwards or downwards, contributing for higher heat transfer. Once the gap between the cantilever beam tip and the heated wall is larger than 4 times of vibrating amplitude of the cantilever beam tip (G/A = 4), the effects of opening inlet on pseudo-jet heat transfer are very weak.

Continuum Solid Modeling based FEM Simulation Approach for Single Walled Boron Nitride Nanotube based Biosensing

The present paper investigates the vibrational characteristic of fixed free single walled boron nitride nanotube with attached bacterium or virus on free end to explore their suitability as bacterium or virus detector device or biosensor. The continuum solid modeling based finite element method approach has been used to analyze the various modes and resonant frequency shift caused by bacterium or virus on beam tip. The obtained simulation results have been compared with analytical results based on fixed free beam bending model. To be more precise in present analysis, the vibrational characteristic of four types of single walled boron nitride nanotubes of different lengths of same diameter have been considered. The different types of bacterium or virus at the tip of the fixed free single walled boron nitride nanotubes have been analyzed for their resonant frequency variation based analysis. The obtained simulation results have been found in sensible agreement with the analytical results. The obtained simulation results suggest that detection of the bacterium or virus having mass of 2.90 x 10-23 kg can be effectively performed.

Laser nanoablation of graphite

Experimental data on laser ablation of highly oriented pyrolitic graphite by nanosecond pulsed UV (\(\lambda =193\) nm) and green (\(\lambda =532\) nm) lasers are presented. It was found that below graphite vaporization threshold \(\approx \)1 J/cm\(^{2}\), the nanoablation regime can be realized with material removal rates as low as 10\(^{-3}\) nm/pulse. The difference between physical (vaporization) and physical–chemical (heating + oxidation) ablation regimes is discussed. Special attention is paid to the influence of laser fluence and pulse number on ablation kinetics. Possibility of laser-induced graphite surface nanostructuring has been demonstrated. Combination of tightly focused laser beam and sharp tip of scanning probe microscope was applied to improve material nanoablation.

Thermal actuators featuring large displacements for passive temperature sensing

The thermal actuator presented in this paper consists of two symmetrically V-shaped beam stacks, where each stack consists of six beams in parallel. The stacks are coupled facing each other and slightly shifted along the mirror axis. Both stacks are connected to a lever beam and fixed at four anchor regions to the substrate. Due to the difference in the coefficient of thermal expansion of the material of the beams and the one of the substrate, the tip of the lever moves perpendicular to the mirror axis. The device is fabricated from galvanic deposited nickel on a silicon substrate. Finite element simulations were carried out to optimize the design with respect to the sensitivity and the maximum mechanical stress. The stress needs to be lower than the yield strength of the material. Otherwise, plastic deformations of the beams would lead to irreversible deflections of the beam tip. This limits the overall sensitivity of the design. First results of the device with 400 μm long bent beams show a linear behavior and a sensitivity of 0.5 μm/K and forces of 66 μN/K for a temperature range of ź30 °C up to +40 °C.

Theoretical analysis and simulations of micro-dosing locomotive robot with drug-release mechanism

A micro-dosing system model of overall size 5×5×4.2 mm3 for drug delivery is proposed and presented. The drug delivery system mainly consists of a micro-wheel and a micro-drug release mechanism. The motion of the micro-wheel is controlled by changing the gravity center of a running disk, which is placed within the hollow micro-wheel and attracted by the actuated micro-solenoids fabricated on the inner wall of micro-wheel in shift. In addition, the micro-wheel is controlled to roll forwards/backwards to the designated location by two sliding mode control strategies: one for long-distance motion (to transport the drug to the vicinity of the spots under disease) and the other for short-distance motion (to decelerate down and stop at the exact drug-release location). On the other hand, the micro-drug release mechanism is composed by a cantilever beam and a chamber filled up by medicine. The pyramid tip of the cantilever beam deflected by the applied electrostatic force is designed to penetrate the micro-film which seals the chamber so that the medicine can be released at the specified spot. The so called “pyramid tip” is, in fact, to replace the conventional medical needle. Its profile is like a pyramid to comply with the MEMS (Micro Electro Mechanical System) fabrication process. This “pyramid” is constructed at the free end of a cantilever beam and hence named as a “pyramid tip”.

Analytical solutions to the free vibration of a double-walled carbon nanotube carrying a bacterium at its tip

We calculate the natural frequencies and mode shapes of a cantilevered double-walled carbon nanotube carrying a rigid body—representative of a bacterium or virus—at the tip of the outer nanotube. By idealizing the nanotubes as Bernoulli-Euler beams, we are able to obtain exact expressions for both the mode shapes and characteristic frequency equation. Separate analyses are performed for the special case of a concentrated tip mass and the more complicated situation where the tip body also exhibits inertia and mass center offset from the beam tip.

Energy Enhancement of a Piezoelectric Cantilever Generator with Magnetic Coupling

Vibration energy harvesting has played a major role due to the almost universal presence of mechanical vibrations. It is demonstrated experimentally that a piezoceramic cantilever generator can be substantially enhanced by introducing a magnetic coupling force in this paper. The piezo-electromagnetic generator consists of a 44mm×20mm×0.7mm bimorph piezoelectric ceramic and two Φ8mm×4mm permanent magnets located at the tip of the beam. The greater bending deformation will be caused because of the permanent magnets and applied magnetic field. Then the generated charge is increased because it is proportional to the vibration amplitude of the tip of the beam. Experimental results show that the generated voltage enhances from 3.04V to 4V for the attractive force and changes from 3.04V to 3.78V for the repulsive force when the distance between the magnets is 20mm, increased by 31.6% and 24.3%, respectively. It also shows that the attractive force is better than the repulsive force from the view of enhancing the generation capacity. It proves that the method is effective for improving the output energy of the piezoelectric cantilever.

Experimental and numerical characterization of the structural dynamics of flapping beams

The nonlinear structural dynamics of a slender beam in flapping motion is examined both experimentally and computationally. In the experiments the periodic flapping motion is imposed on the clamped edge of the cantilever beam using a 4-bar crank-and-rocker mechanism. Aluminum beams with nominal dimensions of 150mm×25mm×0.4mm are tested in air over a range of flapping frequencies up to 1.3 times the linear first modal frequency at two different flapping amplitudes, 15° and 30°. The response of the beam is characterized experimentally through bending strain and tip displacement data obtained from foil strain gage and high-speed camera, respectively. It was determined that for the particular combination of beam specimen (dimensions, material properties) and forcing parameters investigated, all experimental responses were periodic. The frequency response curves based upon the experimental bending strain data reveal a secondary superharmonic peak in addition to the primary resonance peak. As the flapping frequency is increased, the response of the beam is observed to change from symmetric (with respect to equilibrium position) periodic vibrations with a period equal to the flapping period to asymmetric periodic vibrations with higher harmonic content featuring local oscillations in the time histories. Experimental tip displacement results show that the beam spends more time during stroke reversals when the flapping frequency is near primary and secondary resonance regions. In addition to experiment, numerical simulations are performed using two-node, isoparametric degenerate-continuum based geometrically nonlinear beam elements. The HHT-α version of the Newmark finite difference scheme is used to discretize the problem in time and a linear viscous damping model is assumed. Overall the numerical simulations agree well with the experiments and capture most of the nonlinear dynamical features of the beam response. It is, however, found that in resonance regions the simulation overpredicts response magnitudes, possibly due to the use of the linear damping model and linear elastic constitutive model. Additional numerical simulations of the beam tip response reveal dynamics which include periodic, asymmetric periodic, quasi-periodic and aperiodic motions.