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Vibration parameters optimum of 316L steel laser welding under high frequency micro-vibration condition
摘要： High frequency micro vibration combined with laser was applied in the laser welding process parameters were chosen by comparison of weld geometry. In detail, laser power(P) is 2.5kW, welding speed(V) is 1.2m / min, defocusing amount(DA) is -5mm. Three parameters including frequency(F), vibration acceleration(A) and angle(θ) were changed according to the orthogonal test scheme. The microstructure and the tensile properties of the welded joint were compared and analyzed. The morphology of weld tail was analyzed to describe hole stability. It was found that micro-structure and mechanical of joint was significantly influenced by A and F. In the case of vibration resonance, the higher the F, the better the ultimate tensile strength(UTS), and the higher the hardness. When F was 1360 Hz, UTS was 602 MPa. When A was increased from 10 to 60 m/s2, the UTS was improved by 10 MPa. HW and HL were even disappeared in a higher resonance state. Response surface analysis results showed that factors of F and A have significant effects on the width of weld. Width was increased by higher resonance state. It was obtained that optimum process parameters were F=1360 Hz, A= 60 m/s2 and θ = 90°. UTS was 602MPa, hardness was 214.5 Hv, and elongation was 40%. This is mainly due to the grain refinement strengthening.
关键词： Laser welding,Mechanical property,Parameter,Response surface,Vibration
更新于2025-11-28 14:24:20
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In-Fiber Collimator-Based Fabry-Perot Interferometer with Enhanced Vibration Sensitivity
摘要： A simple vibration sensor is proposed and demonstrated based on an optical fiber Fabry-Perot interferometer (FPI) with an in-fiber collimator. The device was fabricated by splicing a quarter-pitch graded index fiber (GIF) with a section of a hollow-core fiber (HCF) interposed between single mode fibers (SMFs). The static displacement sensitivity of the FPI with an in-fiber collimator was 5.17 × 10?4 μm?1, whereas the maximum static displacement sensitivity of the device without collimator was 1.73 × 10?4 μm?1. Moreover, the vibration sensitivity of the FPI with the collimator was 60.22 mV/g at 100 Hz, which was significantly higher than the sensitivity of the FPI without collimator (11.09 mV/g at 100 Hz). The proposed FPI with an in-fiber collimator also exhibited a vibration sensitivity nearly one order of magnitude higher than the device without the collimator at frequencies ranging from 40 to 200 Hz. This low-cost FPI sensor is highly-sensitive, robust and easy to fabricate. It could potentially be used for vibration monitoring in remote and harsh environments.
关键词： fiber vibration sensor,graded index fiber,Fabry-Perot interferometer
更新于2025-11-28 14:23:57
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Effects of three-dimensional vibration on laser cladding of SS316L alloy
摘要： As a widely used approach for surface modi?cation, laser cladding plays a signi?cant role in surface hardening and repairing of metallic parts. However, the defects existing in laser cladding parts, such as cracks, tensile residual stress, and pores, signi?cantly a?ect the performance and the application of the cladding parts. In this study, an SS316L layer was fabricated on a 45 steel substrate using a laser cladding process assisted by three-dimensional vibration. The microstructures and the properties of the coating and the bonding interface with various vibration parameters were analyzed and compared. The microstructures of the cladding layer and the matrix were analyzed by an optical microscope and a scanning electron microscope. The results show that the three-dimensional vibration is able to re?ne the columnar dendrites in the cladding layer. The oscillation accelerates both the liquid ?ow and the thermal transfer of the molten pool, which not only reduces the temperature gradient but also increases the solidi?cation growth rate. Meanwhile, the porosity and the maximum pore size in the cladding layer were signi?cantly reduced by the vibration. The average microhardness of the cladding layer signi?cantly increased assisted by the three-dimensional vibration. Experimental results demonstrate that the e?ects of the three-dimensional vibration are more signi?cant than the single vertical vibration. The proposed approach provides a potential way to improve laser additive manufacturing and remanufacturing.
关键词： laser cladding,microhardness,three-dimensional vibration,microstructure
更新于2025-11-21 11:18:25
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Influence of multiple laser peening on vibration fatigue properties of TC6 titanium alloy
摘要： In this study, typical TC6 titanium alloy was taken to investigate the effects of multiple laser peening (LP) on the vibration fatigue properties and microstructural evolution. The vibration fatigue experiments were conducted, while the vibration fatigue life of the specimens before and after LP was compared and the fracture morphologies were observed by scanning electron microscopy (SEM). In addition, the measurements of residual stress and microhardness were carried out. The microstructures produced by different treatments were also characterized by transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). The experimental results indicated that multiple LP could indeed enhance the vibration fatigue properties of TC6 titanium alloy. Comparing with the investigated specimen without LP, the vibration fatigue life of the specimen subjected to 5 times LP increased by 105.2%. Meanwhile, after 5 times LP, the surface residual stress transformed from tensile stress (+26 MPa) to compressive stress (?485 MPa), and the surface microhardness was 428 HV, which increased by 32.9% compared with the untreated sample. Additionally, high-density of dislocation and deformation twin were also generated after multiple LP. The improvement of vibration fatigue properties was attributed to the rewarding compressive residual stress and the beneficial microstructural evolution induced by multiple LP.
关键词： TC6 titanium alloy,Laser peening,Vibration fatigue properties,Microstructure evolution,Residual stress
更新于2025-11-14 17:04:02
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A Low Frequency Vibration Energy Harvester Using ZnO Nanowires on Elastic Interdigitated Electrodes
摘要： This paper presents a low frequency piezoelectric vibration energy harvester using ZnO nanowires on elastic interdigitated electrodes. The interdigitated electrodes are formed using electroplated Ni and have suspended parts at the edges that are elastic and deformable by applying external force. A spherical Ni ball is used as a proof mass, which transforms a low frequency mechanical vibration into the force applied to deform the elastic electrodes. The ZnO nanowires are grown selectively on the electrodes and can generate a piezoelectric potential when the elastic electrodes are deformed by the proof mass activated by the external mechanical vibration. The proposed operation concept is demonstrated using two different types of energy harvesters, which have simple suspended part and cantilever array structures added to the electrodes, respectively. The output voltage of the fabricated harvesters is measured using a vibration exciter at 6 Hz sinusoidal vibration with an acceleration of 0.5 g. Maximum output power of 12.8 pW and 18.8 pW was generated with a load resistance of 1 MΩ for the harvesters using the simple suspended structure and cantilever array, respectively.
关键词： Spherical Proof Mass,Elastic Interdigitated Electrodes,ZnO Nanowires,Low Frequency Piezoelectric Vibration Energy Harvester
更新于2025-09-23 15:23:52
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[SpringerBriefs in Applied Sciences and Technology] Vibration Analysis of Functionally Graded Piezoelectric Actuators ||
摘要： This book has evolved from the passionate desire of the author in using the modern concepts of piezoelectric materials for the design improvement of sensors and actuators. In this connection, the author took up his doctoral studies whose findings have resulted in this book. The initial focus here is on the basic theory, application, and drawbacks of piezoelectric materials. The types of deformation produced in piezoelectric materials due to different piezoelectric effects are reported briefly. Further, the concept of functionally graded material (FGM) used in the design of piezoelectric materials with graded properties is described. The engineering applications of functionally graded piezoelectric materials (FGPMs) are summarized thereafter. In the latter sections, the modal analysis of FGPM actuators is provided. Two types of actuator geometries are taken into consideration—first is beam, and the second is annular plate. The effects of various parameters on the natural frequencies are given in detail. A detailed account of a new numerical technique called the generalized differential quadrature (GDQ), adopted in this book, is also provided. An extension of this technique for the analysis of FGPM structures becomes an important endeavor. The overall focus is on the vibration analysis of FGPM actuators excited under the shear effect using the GDQ method.
关键词： Shear effect,Piezoelectric materials,Functionally graded materials,Vibration analysis,Actuators,Generalized differential quadrature method
更新于2025-09-23 15:23:52
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An infrared IgG immunoassay based on the use of a nanocomposite consisting of silica coated Fe3O4 superparticles
摘要： A reliable, rapid and ultrasensitive immunoassay is described for determination of immunoglobulin G (IgG). It is making use of biofunctional magnetite (Fe3O4) superparticles coated with SiO2 and serving as an infrared (IR) probe. The unique IR fingerprint signals originating from the transverse and longitudinal phonon modes, respectively, of the asymmetric stretching of the Si–O–Si bridges display a satisfactory resistance to optical interference from the environment. The adoption of Fe3O4 superparticles instead of Fe3O4 nanoparticles as the magnetic core warrants a controllable structure and a strong magnetic response. This facilitates the efficient purification of the probes and the alleviation of the interfacial resistance between the liquid-solid interfaces by using a magnet. The gold-coated substrate was used to immobilize goat-anti-human IgG. The analyte (human IgG) was incubated with the IR probes, and then captured by the substrate immobilized antibody with the assistance of an external magnetic field. The integral area of the IR absorption band between 1250 cm?1 – 900 cm?1 was chosen for quantitative assay. The limit of detection is 95 fM, which is two orders of magnitude better than that without the magnetic field. The assay time was shortened from 2 h to 1 min. High selectivity, specificity, and long-term stability of the immunoassay were achieved. The performance of the assay when analyzing blood samples confirmed the practicability of the method.
关键词： Molecular vibration,IR spectroscopy,Core-shell,Sandwich immunoassay,Self-assembly,Protein,Blood,Superparamagnetism,Magnetic beads
更新于2025-09-23 15:23:52
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Proof-of-principle demonstration of vertical-gravity-gradient measurement using a single-proof-mass double-loop atom interferometer
摘要： We demonstrate a proof-of-principle of direct Earth gravity-gradient measurement with an atom interferometer-based gravity gradiometer using a single proof mass of cold 87Rb atoms. The atomic gradiometer is implemented in the so-called double-loop configuration, hence providing a direct gravity-gradient dependent phase shift insensitive to dc acceleration and constant rotation rate. The atom interferometer (AI) can be either operated as a gravimeter or a gradiometer by simply adding an extra Raman π pulse. We demonstrate gravity-gradient measurements first using a vibration isolation platform and second without seismic isolation using the correlation between the AI signal and the vibration signal measured by an auxiliary classical accelerometer allowing one to bypass the absence of common-mode vibration noise rejection in a double-loop geometry. The simplicity of the experimental setup (a single atomic source and unique detection) and the immunity of the AI to rotation-induced contrast loss make it a possible candidate for onboard gravity-gradient measurements.
关键词： gradiometer,gravity gradient,vibration isolation,atom interferometer,correlation technique
更新于2025-09-23 15:23:52
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Automatic signal quality check and equipment condition surveillance based on trivalent logic diagnosis theory
摘要： In the field of fault diagnosis, inadequate signals measured for equipment condition monitoring may cause incorrect diagnostic results and reduce the accuracy and reliability of the equipment diagnosis system. This paper proposes a method of signal quality check and equipment condition surveillance based on trivalent logic theory, signal histogram analysis and principal component analysis (PCA), in order to automatically evaluate the quality of measured signals to ensure that the signals are real and valid for the condition diagnosis of equipment, and automatically judge the equipment state for condition surveillance. The novelty of this paper are summarized as: (1) Trivalent logic has been expanded appropriately into the trivalent logic diagnosis theory, so that it can be applied to verify the signal quality in the acquisition process for fault diagnosis and equipment condition surveillance; (2) In order to directly and effectively extract features of a signal following any probability density distribution, the histograms of the signal measured for equipment condition diagnosis is used to substitute time domain symptom parameters which have been generally used in equipment diagnosis technology; (3) PCA is used to integrate the histograms to realize signal quality check and equipment condition surveillance on the basis of the trivalent logic diagnosis theory. By the method proposed in this paper, the moment when the signal for equipment condition diagnosis is relatively stable can be found, and the unfavorable signal can be avoided for ensuring the accuracy and reliability of the equipment condition diagnosis. Simulation signals and real signals measured in various conditions from a blower are respectively used to verify the effectiveness of the proposed method.
关键词： Condition monitoring,Fault diagnosis,Measurement errors,Histograms,Vibration measurement
更新于2025-09-23 15:23:52
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Effect of post-annealing on microstructure and piezoelectric properties of ZnO thin film for triangular shaped vibration energy harvester
摘要： In this paper, a triangular shaped piezoelectric vibration energy harvester (TS-PVEH) with zinc oxide (ZnO) thin films as the piezoelectric layer is reported. The effect of post-annealing temperature on the microstructure and piezoelectric performance of ZnO thin film deposited by magnetron sputtering method is investigated firstly. The results show that the optimum post-annealing temperature of 150 °C was the most beneficial to improve the piezoelectric properties of ZnO thin films. Four prototypes of TS-PVEH with different structure parameters are fabricated and optimized. The simulation and experiment results indicate that the height and width of the triangular structure have a significant influence on the vibration mode and the output performance of TS-PVEHs. The optimization results indicate that the third prototype has the best output performance. Its open-circuit voltage and short-circuit current are 290mV and 1.25 μA, respectively, when the vibration acceleration is 5m/s2 and the frequency is 56Hz. Moreover, it has the highest load power density of 0.035μW/cm2 when the load is 0.1MΩ.
关键词： Triangular substrate,ZnO thin film,Structure optimization,Post-annealing temperature,Vibration energy harvester
更新于2025-09-23 15:23:52