Effect Of Displacement Amplitude Research Articles

Effects of displacement amplitude and normal force on fretting wear behavior of zirconium alloy tube in simulated primary water of PWR

Grid-to-rod (GTR) fretting wear was identified as the primary cause of fuel assembly failure. A high temperature pressurized water fretting wear system was designed and fabricated to study the fretting wear behavior between the actual cladding tube and grid dimple. Test parameter combinations of displacement amplitude (±10 ∼ ±50 μm) and normal force (10 ∼ 40 N) were selected by previous fretting map. The findings of the study revealed that the extent of fretting damage on Zr alloy tubes, under the gross slip regime (GSR), was primarily influenced by the displacement amplitude rather than the normal force. It was also noted that the mixed fretting regime could potentially be more hazardous than GSR due to the initiation and propagation of fatigue cracks. In addition, a fretting damage prediction model was successfully developed based on the previous fretting map.

Design and performance evaluation of piezoelectric tube stack energy harvesters in railway systems

Capturing vibration energy of track structures using piezoelectric energy harvesters has attracted increasing attention for powering wireless sensor networks along railway line. To better use the vertical space below steel rail, a kind of piezoelectric tube stack energy harvesters is proposed in this paper, which can be placed at the bottom of the steel rail to harvest the vibration energy of the vertical displacement induced by the moving train. The harvester consists of a displacement transmission rod, a compression spring, a force transmission metal tube, a piezoelectric tube stack, a whole metal shell, screw bolts, and a wire hole. The advantage of this design is to fully combine the heights of the compression spring, the force transmission metal tube and the piezoelectric tube stack, which helps reduce the vertical height of the device and enables its wide application to a variety of tracks, including, ballast track, ballastless track, and steel-spring floating slab track. Energy harvesting performance of the developed piezoelectric tube stack energy harvester is investigated experimentally, which is consistent with the theoretical results of the simplified model of such a harvester reported. Effects of displacement amplitude, displacement frequency, spring stiffness, resistance, and key parameters of piezoelectric tube stack on the energy harvesting performance of the harvester are also discussed. The present study provides a new design concept for developing piezoelectric energy harvesters used in railway systems with the smaller vertical space below steel rail.

Higher-order photon antibunching of phase-variable squeezed coherent state

<sec>Squeezed state has important applications in quantum communication, quantum computing, and precision measurement. It has been used to improve the sensitivity and measurement accuracy of gravitational wave detectors. Currently, squeezed state can be prepared by optical parametric oscillators, four-wave mixing, and atom–optomechanical coupling. As a typical non-classical light, the photon statistics of squeezed state usually shows obvious bunching effect, but it can also present photon antibunching effect through interference or photon subtraction operation. More importantly, squeezed coherent state is prepared by performing displacement operation on the squeezed state. In the case of certain displacement and squeezing operations, squeezed coherent state with obvious antibunching effect can be produced. The squeezed coherent state with photon antibunching effect can be employed to achieve super-resolution imaging beyond the diffraction limit, and the state exhibits good particle features which can suppress the multiphoton emission. Then it has become a focus for studying the antibunching effect and quantum statistical properties of squeezed coherent state at a single-photon level.</sec><sec>The photon antibunching effect can be characterized by the second-order photon correlation <i>g</i><sup>(2)</sup>(τ), which is introduced by Glauber to determine the non-classical properties of the light field. Namely, the second-order photon correlation <i>g</i><sup>(2)</sup> can be used as a metric to distinguish different lights. Hanbury Brown-Twiss (HBT) scheme is used to measure the second-order photon correlation experimentally. However, the second-order photon correlation <i>g</i><sup>(2)</sup> can reflect only the variance of the photon-number statistical distribution. In order to obtain more information about the photon statistical distribution and non-classical features, it is necessary to measure higher-order photon correlations. Then the higher-order photon correlations for different light fields are studied by extending the traditional HBT scheme and combining with multiplex single-photon detection technology. This method can be applied to ghost imaging, characterization of single-photon detectors, research of exciton dynamics, and analysis of NV center fluorescence emission. However, the research on photon statistics of the squeezed state focuses mainly on the second-order photon correlation and the effect of displacement amplitude on the statistical properties. The effect of squeezed phase on photon antibunching and higher-order photon correlation of squeezed coherent states, with background noise and detection efficiency taken into consideration, have not been investigated.</sec><sec>In this paper, we study high-order photon correlations and antibunching effect of phase-variable squeezed coherent state based on an extended HBT scheme. The photon statistics of the squeezed coherent state manifests prominent antibunching effect by adjusting the squeezing parameter r, displacement amplitude <i>α</i> and squeezing phase <i>θ</i>. The antibunching effect of the state can be obtained in a wide range of <i>α</i>-<i>r</i> parameter space when squeezing phase <i>θ</i>∈[0,π/2]. In an ideal case, the minimum antibunching values of the squeezed coherent state are <i>g</i><sup>(2)</sup> = 4.006 × 10<sup>–4</sup>, <i>g</i><sup>(3)</sup> = 1.3594 × 10<sup>–4</sup> and <i>g</i><sup>(4)</sup> = 6.6352 × 10<sup>–5</sup>. When the detection efficiency <i>η</i> = 0.1 and background noise <i>γ</i> = 10<sup>–6</sup>, the strong antibunching effect can still be observed, specifically, <i>g</i><sup>(2)</sup> = 0.1740, <i>g</i><sup>(3)</sup> = 0.0432, <i>g</i><sup>(4)</sup> = 0.0149. The results indicate that the antibunching effect of higher-order photon correlation has strong robustness against the experimental environment. In addition, the antibunching effect of the phase-variable squeezed coherent state is studied as a function of the measured mean photon number <<i>n</i>> and the squeezing degree S. When the measured mean photon number is much less than 1 and the squeezing parameter is less than 10<sup>–4</sup>, a prominent photon anti-bunching effect of <i>g</i><sup>(<i>n</i>)</sup> <inline-formula><tex-math id="Z-20220921173504">\begin{document}$\ll $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220574_Z-20220921173504.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220574_Z-20220921173504.png"/></alternatives></inline-formula> 0.5 can still be obtained. The results show that the control of the squeezing phase <i>θ</i> can be used to prepare the squeezed coherent state with obvious antibunching effect, which has potentially important applications in quantum metrology and secure communication.</sec>

The Effect of Displacement Amplitude on Fretting Wear Behavior and Damage Mechanism of Alloy 690 in Different Gaseous Atmospheres.

The effect of displacement amplitude on fretting wear behavior and damage mechanisms of alloy 690 in air and nitrogen atmospheres was investigated in detail. The results showed that in air, the friction coefficient gradually increased with the increase in displacement amplitude which conformed to the universal law. In nitrogen, however, it had the highest point at the displacement amplitude of 60 μm due to very strong adhesion. Whether in air or nitrogen, the wear volume gradually increased with the increase in displacement amplitude. The wear volume in air was larger than that in nitrogen except at 30 μm. At 30 μm, the wear volume in air was slightly smaller. With an increase in displacement amplitude, a transformation of fretting running status between partial slip, mixed stick-slip, and final gross slip occurred along with the change of Ft-D curves from linear, to elliptic, to, finally, parallelogrammical. Correspondingly, the fretting regime changed from a partial slip regime to a mixed regime to a gross slip regime. With the increase in displacement amplitude, the transition from partial slip to gross slip in nitrogen was delayed as compared with in air due to the strong adhesion actuated by low oxygen content in a reducing environment. Whether in air or nitrogen, the competitive relation between fretting-induced fatigue and fretting-induced wear was prominent. The cracking velocity was more rapid than the wear. Fretting-induced fatigue dominated at 30 μm in air but at 30–60 μm in nitrogen. Fretting-induced wear won the competition at 45–90 μm in air but at 75–90 μm in nitrogen.

Investigation on fretting wear of Al-Li alloy

PurposeThis paper aims to investigate the fretting wear mechanism of an Al-Li alloy at room temperature, the tangential fretting wear tests were carried out.Design/methodology/approachThe effects of displacement amplitude and fretting frequency on the tangential fretting wear characteristics were mainly investigated. The experimental data obtained are analyzed and compared.FindingsThe results indicated that the fretting friction coefficient increased with the increase of displacement amplitude. As the displacement amplitude increased, the wear scar morphology changed significantly, mainly in terms of delamination debris and furrow scratches. The wear mechanism changed from initial mild wear to more severe oxidative wear, adhesive wear and abrasive wear.Originality/valueThis paper extends the knowledge into mechanical tight connections. The conclusions can provide theoretical guidance for the fretting of mechanical tight connections in the field of automotive lightweight and aerospace.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2019-0490/

An enhanced constitutive model for the nonlinear mechanical behavior of the elastic-porous metal rubber

This work aims to develop an enhanced constitutive model to efficiently capture the nonlinear mechanical properties of the elastic-porous metal rubber such as hysteresis characteristics and variable stiffness behavior. As a key fabrication variable, the normal distribution of the three-dimensional interlocked angle is introduced to describe the orientation arrangement of the metal wires and to develop an equivalent stiffness model of the elastic-porous metal rubber. Integrating with the evolution of the typical hysteresis loops, different function-fitting methods are used to describe the mechanical behavior under loading and unloading paths. In particular, the effect of displacement amplitude on the mechanical properties in the unloading process is addressed. From the results, it is observed that the hysteresis loop curves predicted by the enhanced constitutive model show a great agreement with the experimental results. The enhanced constitutive model has better prediction accuracy as compared to the other constitutive models (such as the micro-spring model and the porous material model). In addition, the anisotropic behavior and the dynamic property associated with stiffness and energy dissipation of elastic-porous metal rubber are analyzed and discussed.

FRICTION AND WEAR BEHAVIORS OF Ti6Al4V ALLOY TREATED BY PLASMA Ni ALLOYING

The Ni modified layer was prepared on surface of the Ti6Al4V substrate by plasma surface alloying technique (PSAT). The cross-section micro structure, phase structure and microhardness of Ni modified layer were studied. The friction and wear behavior of the Ni modified layer and the Ti6Al4V substrate were analysed. The effects of displacement amplitude, frequency and fretting time on friction coefficient of the Ni modified layer were investigated. The results indicated that the wear rate was lower compared with that of the Ti6Al4V substrate. Friction coefficient of the Ni modified layer increased with the increase of frequency. But it was insensitive to the change of wear time and the displacement amplitude. The wear mechanism of the Ti6Al4V was adhesion and abrasion wear mechanism while the Ni modified layer showed slightly abrasion wear.

Effect of displacement amplitude on fretting wear of 304 stainless steel in air and sea water

AbstractThe fretting wear behaviours of 304 stainless steel at different displacement amplitudes were investigated by using a SRV‐IV fretting tester in air and sea water, respectively. In air, the friction coefficient as well as the fretting damage of 304 stainless steel increased with the increase of displacement amplitude, and the fretting regime changed from partial slip regime to gross slip regime. Correspondingly, the wear mechanisms transformed from local fatigue and slight oxidation to the combination damages of adhesion wear, abrasive wear, and oxidation. Compared with the dry friction conditions, sea water had a strong effect on fretting behaviour of 304 stainless steel. Adhesion wear was effectively suppressed due to the cooling and lubrication effect of sea water. Therefore, friction coefficient and wear depth decreased significantly. And the damages of 304 stainless steel in sea water were mainly caused by abrasive wear, slight adhesion wear, and corrosion wear.

Numerical study of heat transfer in parallel-plate heat exchangers in thermoacoustic engine

For designing thermoacoustic devices, heat transfer problem of heat exchangers is a key point and is not solved completely yet. In the present study, both computational fluid dynamics (CFD) simulations and numerical analysis based on linear thermoacoustic theory are performed, and heat transfer characteristics, heat fluxes, and Nusselt numbers are investigated from both numerical results. Especially, through parametric studies by linear analysis, the effect of displacement amplitude and thermal penetration depth on heat transfer is discussed. In this simulation, a regenerator is located between hot and cold heat exchangers, and the effect of each channel size is also investigated. Furthermore, simulated results are compared with the conventional heat transfer models for oscillatory flow, and the verifications of those models or simulations are executed. On the other hand, by comparing the CFD results with linear analysis, non-linearity of heat transfer included in thermoacoustic phenomena is also discusse...

Experimental study of SS316L cantilevered cylindrical shells under cyclic bending load

In this research, softening and ratcheting behaviors of SS316L cantilevered cylindrical shells under cyclic bending load were investigated. Experimental tests were carried out by a Servo-Hydraulic INSTRON 8802 machine. Force-control and displacement-control loadings were applied and the effects of displacement amplitude, mean force, loading history and cutout position were examined. Under displacement-control loading, softening behavior was observed due to growth of ovalization and it was shown that as the displacement amplitude increases, softening rate and density of plastic energy increase. Accumulation of the plastic strain or ratcheting phenomenon occurred under force-control loading with nonzero mean force. Increase of the mean force accompanied with an increase in the accumulation of the plastic deformation and its rate. In loading history, it was seen that prior load with higher force amplitude retards the ratcheting behavior and plastic deformation of subsequent load with smaller force amplitude. In addition, due to sensitivity of cutout to the bending moment, as the position of the cutout changes from the middle of shell towards the cantilevered end, the accumulation of the plastic deformation increases.

Effects of displacement amplitude on fretting wear behaviors and mechanism of Inconel 600 alloy

The fretting test on Inconel 600 alloy at different displacement amplitudes was conducted at room temperature in air with a relative humidity of 30–40% using an SRV IV fretting test rig. The effects of displacement amplitude on the ratio of tangential force to normal load and wear volume were analyzed. The worn surfaces and cross-sectional morphologies were subsequently investigated using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The results indicated that the displacement amplitude had a strong effect on fretting wear behaviors and wear mechanism. With the increase of fretting amplitude, the ratio of tangential force to normal load and wear volume increased, and the fretting mode gradually transformed from mainly adhesion to fully slide. Correspondingly, the wear mechanism transformed from local adhesive damage to the combination damage of oxidation and delamination wear. Microcracks in the wear scar strongly depended on fretting mode. There was no microcrack in the adhesion zone, however microcracks were usually found in the slide zone and the junction zone of slide and adhesion. As a result of plowing effect on the edge of the wear scar, the shape of the worn scar changed from round to ellipsoidal and the formation of delamination cracks in the subsurface. Fretting created a gradient strain in the subsurface of worn scar, and resulted in the formation of nanocrystalline in tribological transformed structure layer under the worn scar.

A Numerical and Experimental Investigation of Fretting Wear and a New Procedure for Fretting Wear Maps

In this investigation, the fretting wear phenomenon was investigated experimentally and analytically. For the analytical investigation, a combined finite discrete element model (FDEM) was developed to study the effects of displacement amplitude and normal force on fretting wear. The FDEM was used to investigate the wear of a fretting Hertzian line contact calculated using the Archard and dissipated energy wear theories. Although the FDEM results from each theory were in agreement, the dissipated energy approach more accurately predicted the wear volumes obtained from experimental measurements. A fretting wear test rig (FWTR) was used to verify and corroborate the results and conclusions of the numerical investigation. The results indicated that the dissipated energy equation better describes wear in fretting contacts than the Archard equation. An energy dissipation rate map was developed from the experimental results, showing the effect of normal force and displacement amplitude on frictional energy loss. The energy dissipation rate map was used to create a steady-state fretting wear map.

Effect of displacement amplitude on fretting fatigue behavior of hoisting rope wires in low cycle fatigue

Abstract The effect of displacement amplitude on fretting fatigue behavior of steel wires in low cycle fatigue at two cyclic strain levels was investigated. Evolutions of normalized tangential force and morphologies of contact scars were investigated to examine the wear mechanisms. Fretting regime and fretting fatigue life were explored. Acoustic emission technique was utilized to reveal wire failure mechanisms. The results show that an increase of displacement amplitude increases normalized tangential force but decreases the fretting fatigue life. Fretting contact conditions are all mixed fretting regimes. Fretting damage and crack nucleation and propagation accelerate with increasing displacement amplitude.

1850 ボイドを含むBGAはんだ接合部のき裂進展経路に及ぼす変位振幅の影響(J09-2 はんだ接続部の強度信頼性評価,J09 電子情報機器,電子デバイスの熱制御と強度・信頼性評価)

1850 ボイドを含むBGAはんだ接合部のき裂進展経路に及ぼす変位振幅の影響(J09-2 はんだ接続部の強度信頼性評価,J09 電子情報機器,電子デバイスの熱制御と強度・信頼性評価)

Influence of fretting regimes on the tribocorrosion behaviour of Ti6Al4V in 0.9 wt.% sodium chloride solution

The effect of displacement amplitude, normal force and tribometer stiffness on the tribocorrosion response of a Ti6Al4V alloy in contact with a smooth alumina ball was investigated using a fretting corrosion rig equipped with an electrochemical cell. The roughness of the alloy plates was 0.6 μm, typical for the surface of hip joint stems. All experiments were carried out in 0.9 wt.% NaCl under anodic polarisation at a potential of 0.5 V versus the silver–silver chloride reference electrode, corresponding to the passive potential region. Anodic current, load, friction force and displacement amplitude were monitored in real time. Wear volume and surface morphology were evaluated at the end of fretting experiments. Results show that the prevailing fretting regime critically affects the overall system behaviour. Only fretting regimes involving slip led to measurable wear and to an enhancement of the anodic current. Previously developed tribocorrosion models for passivating metals were found to well describe the effect of normal force and displacement amplitude on the anodic current.

Effect of shot peening on the fretting wear of Ti–6Al–4V

In this paper, we report on the fretting wear behaviour of polished and shot peened Ti–6Al–4V specimens. For fretting experiments, due to micro-displacements at the interface between two contacting surfaces, two types of damage can be observed: crack initiation and debris formation. Shot peening, which is already well known for improving fatigue resistance of titanium alloys, is shown to have a beneficial effect on the crack initiation and propagation under fretting wear loading, as cracks observed on specimens after cylinder-on-flat fretting tests are shorter in shot peened specimens than in polished ones. It is also demonstrated that shot peening decreases the friction coefficient only at the beginning of the test, as long as the asperities induced by shot peening are not worn-off. The effects of displacement amplitude, normal force and test duration on the wear volume have been investigated: in all cases, shot peening has no significant impact on the wear process. The same amount of debris are formed and ejected for both polished and shot peened specimens. Moreover, it is found that, for both types of specimens, the linear relation, developed for steels and hard coatings, between wear volume and cumulated dissipated energy is not valid in the present case as different wear volumes are measured for the same cumulated dissipated energy, depending on the experimental conditions (normal force, displacement amplitude). Using the test duration as the variable parameter, energy wear coefficients are calculated for different experimental conditions.

Effect of displacement amplitude in oil-lubricated fretting

Fretting behaviour have been investigated in oil lubrication, covering a large range of amplitude from 2 to 400 μm. Two types of oil and contact pair on fretting behaviour were studied. A significant reduction in the coefficient of friction occurred above critical displacement amplitude. Analysis of fretting condition in combination with fretting mark examinations reveal that, at an early stage, fretting behaviour depended upon oil boundary lubrication, and was later closely associated with the degree of oxygen access and penetration of oil into the interface. Compared to dry conditions, a great difference in fretting regime behaviour and contact wear was observed.

Testing and steady state modeling of a linear MR damper under sinusoidal loading

A linear magnetorheological (MR) damper, supplied by Lord Corporation, was tested and modeled. Under dynamic conditions, the effects of displacement amplitude, frequency, and magnetic fields on the mechanical properties of MR damper, such as damping force, equivalent-damping capability, were experimentally studied with an INSTRON test machine. A viscoelastic-plastic model is proposed to model the MR behavior. It is shown that the damper response can be satisfactorily predicted with this model.