Experimental and numerical results of dynamics behavior of a nonlinear piezoelectric beam

This article presents a numerical formulation and experimental implementation for the dynamics behavior verification of the nonlinear piezoelectric beam through harmonic excitation. The nonlinear piezoelectric beam dynamic analysis program is developed with MATLAB software. To verify the nonlinear piezoelectric beam dynamic analysis results, the experimental results are used for the vibration analysis of a piezoelectric beam to the harmonic excitation of the base of the beam. Then, the piezoelectric effect on the output voltage, velocity, acceleration values, and the time response are obtained. Afterwards, the effects of the excitation velocity and the position of concentrated mass on the output voltage are verified.     

Swing angle estimation for anti-sway overhead crane control using load cell

Overhead crane movement results in suspended load sway, which may cause dangers and damages. Common anti-sway methods are based on swing angle information. This paper presents a novel method that uses load cell sensors for swing angle estimation. According to our proposed method, a damping signal is generated and added to the speed reference in order to suppress the suspended load sway. Conventional methods of swing angle estimation are based on measurement by camera vision, acceleration, or some other type of sensor. Compared to conventional methods, the proposed method based on load cell is simpler to build and less sensitive to ambient conditions. The effectiveness of the method is verified by computer simulation.     

The combined effect of cryogenic and boronising treatments on the wear behaviour and microstructure of DIN 1.2344 steel

In this study, the effects of cryogenic and boronising treatments on the wear behaviour and microstructure of 1.2344 steel were evaluated. X-ray diffraction analysis and scanning electron microscopy were used to investigate the microstructure, percentage of the retained austenite, and the carbides' morphology. In addition, a micro-hardness test and pin-on-disk wear method were utilised to assess the samples’ wear resistance. The results showed that the use of a cryogenic treatment improved hardness and wear resistance by 25% and 39%, respectively, compared with a quenching - tempering heat treatment. In addition, cryogenic and boronising treatments improved hardness and wear resistance by 228% and 75%, respectively, compared with a quenching - tempering heat treatment. The improvement in the properties of cryogenically treated and boronised-cryogenised samples in comparison with the quenched-tempered ones is due to the transformation of retained austenite to martensite, precipitation of fine carbides, and better carbide distribution. Also, the formation of the Fe₂B phase affected the properties of the boronised-cryogenised samples. Moreover, examining the wear levels revealed that the dominant wear mechanism is adhesive and tribochemical wear.     

Effect of size on the dynamic behaviors of atomic force microscopes

Microsystem Technologies - Accurate mathematical modeling and simulation of cantilever dynamics are crucial to design and fabrication of the atomic force microscope (AFM). Thickness of AFM...     

Simulation of dielectric behavior in RFeO$$_{}$$ orthoferrite ceramics (R = rare earth metals)

Due to their colossal dielectric constant (CDC), \(\hbox {RFeO}_{3}\), orthoferrite ceramics (R = rare earth metal) have recently attracted much attention. In the present research, the dielectric constants of \(\hbox {RFeO}_{3}\) orthoferrite ceramics, whether with or without CDC, have been simulated. The type of synthesis method, the type of R material, temperature, and frequency as the effective parameters on the dielectric behavior are introduced to the model. Another input parameter is the ratio of \(\hbox {Fe}^{+2}/\hbox {Fe}^{+3}\) peak area (in the XPS diagram), which is the most important parameter that affects the CDC behavior. Initially, a colossal database is formed by means of WebPlotDigitizer software and 2930 experimental data, and then the simulation is carried out through gene expression programming. Two case studies are also performed on \(\hbox {PrFeO}_{3}\) and \(\hbox {NdFeO}_{3}\) orthoferrite ceramics to validate the accuracy of the presented model. \(\hbox {PrFeO}_{3}\) exhibits significant CDC behavior whereas the \(\hbox {NdFeO}_{3}\) ceramic samples possess little CDC property, both of which were precisely simulated by the model. Two-dimensional tenth-degree equations resulting from the model predict the dielectric constant variations accurately.     

Illustration of effective parameters on growth of ZnO micro/nano rods, on the borosilicate glass via hydrothermal process

Hexagonal micro/nanorods of ZnO were synthesized via mild hydrothermal growth method under different conditions. The growth of the rods was accomplished in two manners: firstly, on bare borosilicate glass, and secondly, on ZnO seed layer prepared by sol-gel spin coating process. All the obtained surfaces were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The studies demonstrate that, although with the decrease of concentration of precursor solution on bare borosilicate glass, the diameter of the rods decreases, but the orientation will deteriorate and the density of the rods will decrease. On the other hand, hydrothermal growth on the seed layer causes the decrease in the diameter of the rods, while maintaining the orientation along the c-axis; therefore, the presence of seed layer plays an important role in decreasing the diameter of the rods; so that at a constant concentration, compared with the case without seed layer, the diameter of rods decreased 10 times from approximately 500 nm to approximately 50 nm.     

Free vibration analysis of multi-directional functionally graded circular and annular plates

This paper addresses the free vibration of multi-directional functionally graded circular and annular plates using a semianalytical/ numerical method, called state space-based differential quadrature method. Three-dimensional elasticity equations are derived for multi-directional functionally graded plates and a solution is given by the semi-analytical/numerical method. This method gives an analytical solution along the thickness direction, using a state space method and a numerical solution using differential quadrature method. Some numerical examples are presented to show the accuracy and convergence of the method. The most of simulations of the present study have been validated by the existing literature. The non-dimensional frequencies and corresponding displacements mode shapes are obtained. Then the influences of thickness ratio and graded indexes are demonstrated on the non-dimensional natural frequencies.     

A frequency response based structural damage localization method using independent component analysis

Vibration-based structural damage detection has been the focus of attention by many researchers over the last few decades. However, most methods proposed for this purpose utilize extracted modal parameters or some indices constructed on the basis these parameters. Our literature review revealed that few papers have employed frequency response functions (FRFs) for detecting structural damage. In this paper, a technique is presented for damage detection which is based on measured FRFs. Independent component analysis (ICA) has been implemented on the spatiotemporal responses in each frequency in order to reduce the dimension of the data. This is based on the concept that the forced harmonic response of a linear vibrating system can be fully captured utilizing a single ICA mode. A different approach is also presented in which ICA is applied to the frequency domain data. Operational deflection shapes (ODSs) have been decomposed using ICA to localize the damage. The efficiency of both methods is demonstrated through some numerical and experimental case studies.