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This study explores the integration of computer vision with topology optimization for additive manufacturing, with a focus on maximizing eigenfrequency in a design domain. Utilizing custom-developed photogrammetry software, high-resolution images are processed to generate detailed 3D models, which are subsequently converted to STL files with precision. Adaptive meshing in COMSOL 5.3 Multiphysics, controlled through a MATLAB 2023 API, ensures optimal mesh resolution. Prioritizing resource conservation in extraterrestrial environments, the original volume is reduced by 50% while preserving structural integrity. The design domain undergoes rigorous topology optimization in MATLAB, supported by COMSOL's advanced FEM simulation. The optimized design exhibits a 57% performance improvement and a 50% weight reduction, maintaining the desired vibration characteristics, validating the efficacy of the modifications. Moreover, the case with an eccentric mass shows a significant 64% increase in eigenfrequency. [ABSTRACT FROM AUTHOR]

The concept of a 2D cylindrical High Pass Ladder (2D c-HPL) is used in the development of this ultra-high radio frequency (UHRF) volumetric head coil for 7 T tuned at the Larmor frequency of 298 MHz. The architecture of the 2D c-HPL helps to overcome the challenges associated with non-uniform magnetic field distribution. The prototype consists of an individual resonating array of inductance-capacitance (LC) elements and each component is tuned to the precise fo frequency. The tuning of the (i) inductance, (ii) capacitance, (iii) mesh size, and (iv) coupling coefficient play critical roles to attain the desired Larmor frequency. For this proof-of-concept, the prototype of a volumetric head coil consists of a cylindrical array size of 4 × 6, with individual LC components of inductance magnitude, 98 nH and four fixed value capacitors and one tunable capacitor that allowed to achieve the desired precession frequency, fr = 298 MHz. The model was tested for three different fo values of 269, 275, and 286 MHz. The mutual coupling and the eigenfrequencies were compared through bench testing and dispersion equation. The experimental data were in good agreement (<5%) with the theoretical eigenfrequencies from the dispersion relation. The theoretical eigenfrequencies and the experimental eigenfrequencies are in good agreement for eigenmodes (1,2), (1,3), (2,2), (2,3), and (4,3). [ABSTRACT FROM AUTHOR]

This study explores the integration of computer vision with topology optimization for additive manufacturing, with a focus on maximizing eigenfrequency in a design domain. Utilizing custom-developed photogrammetry software, high-resolution images are processed to generate detailed 3D models, which are subsequently converted to STL files with precision. Adaptive meshing in COMSOL 5.3 Multiphysics, controlled through a MATLAB 2023 API, ensures optimal mesh resolution. Prioritizing resource conservation in extraterrestrial environments, the original volume is reduced by 50% while preserving structural integrity. The design domain undergoes rigorous topology optimization in MATLAB, supported by COMSOL’s advanced FEM simulation. The optimized design exhibits a 57% performance improvement and a 50% weight reduction, maintaining the desired vibration characteristics, validating the efficacy of the modifications. Moreover, the case with an eccentric mass shows a significant 64% increase in eigenfrequency.

The purpose of this paper is to construct a methodology which can produce a lightweight panel structure while being satisfied with more than one constraint by using some simple model. In this study, we chose a problem including bending stiffness and the 1st order eigen frequency as constraints and volume minimization as objective function among basic performances which a vehicle requires. So far, we have been trying to solve the problem by using a method consisting of Fully Stressed Design (FSD) and Genetic Algorithm (GA). FSD is an optimization which evaluates only stiffness of a structure based on relationship between thickness and stress, while GA, a broad array method, can have various number of objective functions and constraints. Prior to this study, the authors found a process was effective that stresses on the elements were to be equalized in the 1st step by applying FSD that made an individual superior on static stiffness. In this study, proposed method, which includes a process of equalization on normalized stresses on eigen vibrations, are added to that of static stresses in the 1st step. In the 2nd step, GA is selected. GA conducts operations, such as select, crossing, and mutation repeatedly until this attains a final solution. As for the model, we chose a sandwich panel which is equipped with top and bottom plates and interlayer lattice stiffeners. The reason for this selection is that the sandwich panel is lightweight and superior to stiffness, dumping, and strength. As a result, the obtained model presents a lightweight structure while being satisfied with the requirements of both stiffness and eigen frequency. Moreover, the proposed method attains optimized results earlier than GA without using FSD.

In this work, we focused on investigating the eigen frequency and internal standing wave characteristics of a vertical surface cavity emitting laser operating at a wavelength of 1.55 µm. The design of the cavity involved determining the cavity length, selecting the material for the cavity spacer, and carefully placing the quantum wells within the cavity to achieve maximum overlap with the electric field. In our case, the choice of the dielectric Bragg mirror with SiO2/TiO2 layers helps in achieving high reflectivity and low optical losses. The quantum wells are strategically placed within the cavity to ensure maximum overlap with the electric field. This allows for efficient carrier injection and recombination, leading to laser emission. The specific composition of the quantum wells, In0.54Ga0.46As0.99P0.01 / In0.75Ga0.25As0.55P0.45, indicates the proportions of indium (In), gallium (Ga), arsenic (As), and phosphorus (P) in the material. These compositions are chosen to achieve the desired electronic band structure and emission wavelength. By studying the eigen frequency and internal standing waves in our designed laser cavity, our aim is to understand the resonant modes and behavior of light within the device. This knowledge is crucial for optimizing the laser's performance and improving its efficiency for various applications. [ABSTRACT FROM AUTHOR]

The exploration of structural behavior under the influence of defects is significant for understanding and optimizing the performance of engineering structures. In this study, we delve into the impact of defects on the Eigen frequencies of a flat rectangular plate with all edges simply supported, at an established range of temperatures. By analyzing the Eigen frequencies of the rectangular plate, under diverse conditions such as temperature varying and size defect varying, we seek to provide comprehensive insights on the behavior of such structures in terms of reliability and safety. [ABSTRACT FROM AUTHOR]

The investigation of temperature influence on the Eigen frequencies of structural elements plays a major role in understanding and optimizing the performance of engineering systems. The flat rectangular plates with all edges simply supported are found in numerous applications, ranging from aerospace engineering to civil infrastructure. This study focuses on exploring the dynamic behavior of a flat rectangular plate with all edges simply supported, with or without a longitudinal defect, under varying temperature conditions. As temperature fluctuations can significantly affect material properties and structural responses, a comprehensive analysis of the impact of temperature on Eigen frequencies becomes imperative for the design, reliability, and safety of these structures. In the present paper we aim to provide valuable insights into how temperature variations influence the dynamic response of a flat rectangular plate, with all edges simply supported, with or without a longitudinal defect, thus contributing to the broader knowledge base in structural engineering. [ABSTRACT FROM AUTHOR]

It has not been solved that the fruits and vegetables such as strawberries, cells, blood and a bottle of sake are damaged, broken during transportation. It is the greatest factor in this situation that there is a dangerous vibration frequency range where these are easy to scratch and are prone to death. If there are eigen frequencies within this dangerous frequency range，it is good to be redesigned such that the eigen frequencies within this dangerous frequency range are moved out of the range. But it is difficult to apply the existing topology optimization methods using homogenization method or density method or thickness distribution method. As fundamental research, it is demonstrated the effectiveness of the proposed method based on the strain and kinetic energy density distributions of the targeted eigen modes for a flat plate compared to the conventional topology optimization method using thickness distribution as follows. (1) It is possible to control plural eigen frequencies by deciding interactively how the topology should be changed from the observation of kinetic and strain energy density distributions of the targeted eigen modes in a very short time compared to the conventional topology optimization method. (2) In the case of the proposed method, it is not necessary to get a new topology from the thickness or density distribution after the optimization results. (3) It can be checked the validity of the task set for the conventional topology optimization method by observing the strain and kinetic energy density distributions of the targeted eigen modes which are actively used in the proposed method.

Ultrasonic machining is an advanced machining process which is applied for the machining of tough and fragile materials viz. glass, ceramics, etc. The ultrasonic horn is a most essential component used to transfer the longitudinal mode of vibration to the ultrasonic tool through a transducer. This investigation has considered the design of two different profiles of ultrasonic horns (cylindrical & stepped) using tungsten carbide material in dynamic conditions. Modal analysis is performed to calculate the mode shapes and natural frequencies of both the horn profiles. The dimension of the horns under the frequency of 20 kHz is considered. The analysis is performed using ANSYS 18.1 workbench interface. Harmonic response analysis is executed to compute the stress and deformation behaviour of both the horn profiles. After the stresses are generated, a defect is introduced at the maximum stress point in both the horn design. The defects are generated in three different orientations, viz. along the longitudinal axis, perpendicular axis, and another one is inclined with respect to the oscillation of the horn. The maximum stress is generated in the stepped horn that is 370.55 MPa, where the defect is located at perpendicular to the longitudinal axis with respect to the oscillation of the horn. The current analysis can be considered as the tool to understand the behaviour of the horn in the presence of a defect in ultrasonic machining. [ABSTRACT FROM AUTHOR]

Magnetically levitated (maglev) trains with superconducting technology has been developed rapidly in recent decades due to such promising features as high cruising speed. The second-generation high-temperature superconducting (2G HTS) magnets used on maglev trains are state-of-the-art among different types of magnets, like permanent magnets, electromagnets, or low-temperature superconducting magnets. A series of works have been done by the group on the development of the 2G HTS maglev, including optimal design, manufacturing, and testing of the ground propulsion system and on-board 2G HTS magnet system. In this work, as a continuation of the development progress, the structural dynamics of the on-board 2G HTS magnet system are evaluated. Since the HTS magnets are operated in a cryogenic environment featuring large current inflows, consideration of both the electromagnetic and thermal stresses on the maglev's structural dynamics is necessary. Modal analysis, harmonic response, random vibration, and shock response are conducted, based on standard IEC 61373. Fatigue assessment is also provided. [ABSTRACT FROM AUTHOR]

The two-dimensional problem of the diffraction of an electromagnetic wave by a metal diaphragm of finite thickness in an infinite rectangular waveguide is solved and investigated. Using the method of the integral-series identity, the problem is reduced to an infinite system of linear algebraic equations. Through computational experiments, it was shown that the expansion coefficients of the vectors of the diffracted electromagnetic field from the spectral parameter are of a resonant nature. Based on this, it was concluded that the waveguide region corresponding to the hole in the diaphragm is resonant. Moreover, the resonant frequencies of this region are close to the natural frequencies of the corresponding resonator without holes. [ABSTRACT FROM AUTHOR]

This article investigates piezoelectric materials for harnessing vibrational energy. A nano hollow cylindrical structure based on various piezoelectric materials was designed and utilised to generate the voltage. An accurate and efficient model is developed here, so as to optimized the efficiency of the piezoelectric energy harvester. This work analyses the piezoelectric actuator deflection and involves the Eigen frequency computation. A measurement methodology for investigating the mechanical and electrical behaviour of vibrational harvester's was modelled and analysed by finite element method using COMSOL software. The energy harvesting structure was developed and tested with different piezoelectric materials to attain appreciable voltage through a small deflection. The Simulated results predicts that for the same pressure range, different piezoelectric materials have the different output voltage and Eigen frequencies. The maximum voltage was observed for Barium Titanate (3.0847 V at 250 µm), along with poled Polyvinylidene fluoride. In addition, a comparison was made with different piezoelectric materials ideally suited to intelligent cantilever structure. For optimizing the performance of the piezoelectric energy harvester an accurate and efficient model is required, which was developed in this simulation study. A high voltage value with a small deflection through a cylindrical hollow structure was designed and tested using various piezoelectric materials in this study. [ABSTRACT FROM AUTHOR]

Piezoelectric Micro-Power Generator (PMPG) can produce electrical power as a result of piezoelectric effects. Moreover, producing self-powering devices, especially in small electronic devices with low power requirements such as cardiac pacemakers is one of the objectives of the study. This paper optimizes the quality and damping factors for PMPG by using the Taguchi optimization method instead of a trial and error approach. Eight physical control parameters with three levels, including PMPG layer materials and dimensions are selected in order to study the influence of each parameter of PMPG quality and damping factors. Level eighteen Orthogonal arrays is based on signal-to-noise ratio which is conducted and confirmed by using analysis of variance in determining the PMPG with the best quality and damping factor.18 experiments are conducted with three trials using COMSOL Multiphysics software ver. 5.4 for each one. The PMPG maximum quality factor, the lower damping factor, and the highest efficiency are designed at 1.35 Hz, which is equivalent to 81 beats per min. Both Taguchi and the analysis of variance results conclude that the highest PMPG physical control parameters affect the quality and damping factors at 1.35 Hz from higher to lower order as follows: insulator width of 0.12 mm, 0.2 mm piezoelectric layer width, 20 µm of insulator thickness, 2.5 mm ofproof mass thickness, piezoelectric material of PZT5A, piezoelectric layer thickness of 60 µm, proof mass material of aluminum, and 5 mm proof mass length respectively. COMSOL Multiphysics is used again to study the PMPG with the best parameters, the PMPG resonates at 1.35 Hz, 5.78 Hz, 7.61 Hz, 32.54 Hz, 424.21 Hz, and 448.59 Hz respectively with a different mode of deflections by using Eigen's frequency analysis. The high electric field, the electric energy density, and hence the output power are produced at first resonance frequency at 1.35 Hz in the range of 0.5-2.5 Hz by using frequency response analysis. Transient analysis is conducted at 1.35 Hz, which shows that the PMPG reaches the steady-state after seven seconds of sinusoidal signal excitation with quality factor of 166.67 and damping factor of 0.003. This improves that PMPG works nearly at no damping system and keeps oscillating for a long time before stopping for a single excitation, which opens the door widely in front of fabricating self-powered devices that have been working for a long time, which make them suitable to replace lithium iodide battery in cardiac pacemakers. [ABSTRACT FROM AUTHOR]

The rectangular waveguide is attached to a hole in a wall of rectangular resonator and the corresponding to the hole part of the waveguide boundary is cross-section of the waveguide. The problem of excitation of the resonator by an eigen wave of the waveguide is investigated. The condition on a hole is obtained from the condition defining the wave in the waveguide, outgoing from cross-section. The initial diffraction problem is reduced to some infinite set of linear algebraic equations. Numerical experiment shows that the dependence of expansion coefficients of the field in the resonator on frequency of exciting wave has resonant nature. We propose to use the real values of the resonance frequencies of the running on the hole wave as the initial approximations for eigen frequencies of the resonator with a hole in the wall. [ABSTRACT FROM AUTHOR]

The present study utilizes an analytical method to formulate the three lowest modal frequencies of axially-loaded notched beam through both crack location and load level in a specific format that can be used in existing frequency-based crack-identification methods. The proposed formula provides a basis to shift into two states, one with axial loading and the other without any loading whatsoever. When any two natural frequencies in simply-supported beam with an open crack, subjected to axial load, are measured, crack position and extent can be determined, using a characteristic equation, which is a function of crack location, sectional flexibility, and eigenvalue (natural frequency). Theoretical results show high accuracy for service axial loads. In this range, errors for crack location and extent are less than 12% and 10%, respectively.

This paper presents a numerical analysis of motion dynamics of a two-degree-of-freedom of motion rectilinear oscillatory system with the motion limitations and forced excitation. The analysis of a mechanical-mathematical model with discontinued parameters is based on the numerical integration of differential equations. The forced oscillatory system has been implemented in two automatic armament systems of 12.7mm and 20mm calibers, which have been installed in the light propeller aircraft and transport-combat helicopter. The motion parameters - movement and velocity and forces have been measured on the stand. Motion parameters and force computations were compliant with the analogous values measured on the designed systems. The mechanical-mathematical model of system dynamics can be used for a prediction of the behaviour of a two-degree-of-freedom of the motion system in the stage of parameters adjustment, prior to the design of system elements. The description of the measurement and used equipment is presented as well as a possible way of further work.

Graphene membrane irradiated by weak activating periodic electric field in terahertz range is considered. The corrected formula for the graphene quantum conductivity is found. The obtained formula gives complex conjugate results when radiation polarization direction is clockwise or it is opposite clockwise. The found formula allows us to see that the graphene membrane is an oscillating contour. Its eigen frequency coincides with a singularity point of the conductivity and depends on the electrons concentration. So the graphene membrane could be used as an antenna or a transistor and its eigen frequency could be tuned by doping in a large terahertz-infrared frequency range. The obtained formula allows us also to calculate the graphene membrane quantum inductivity and capacitance. The found dependence on electrons concentration is consistent with experiments. The method of the proof is based on study of the time-dependent density matrix. The exact solution of von Neumann equation for density matrix is found for our case in linear approximation on the external field. On this basis the induced current is studied and then the formula for quantum conductivity as a function of external field frequency and temperature is obtained. The method of the proof suggested in this paper could be used to study other problems. The found formula for quantum conductivity can be used to correct the SPPs Dispersion Relation and for the description of radiation process. It would be useful to take the obtained results into account when constructing devices containing graphene membrane nanoantenna. Such project could make it possible to create wireless communications among nanosystems. This would be promising research area of energy harvesting applications. [ABSTRACT FROM AUTHOR]

The article deal with modal analysis, like natural frequencies and own mode shapes of thin plate. In the first part of article the theory of modal analysis is given. Next part of article is a modal analysis of thin aluminium (Al 99.9) isotropic plate with dimensions 0.10 × 0.10 × 0.002 m. The plate is fixed over the circumference. The solution was carried by numerically in the ANSYS program. In the article the first ten natural frequencies and first ten mode shapes of the plate deflection are presented. [ABSTRACT FROM AUTHOR]

A simplified design procedure for foundations of offshore wind turbines is often useful as it can provide the types and sizes of foundation required to carry out financial viability analysis of a project and can also be used for tender design. This paper presents a simplified way of carrying out the design of monopiles based on necessary data (i.e. the least amount of data), namely site characteristics (wind speed at reference height, wind turbulence intensity, water depth, wave height and wave period), turbine characteristics (rated power, rated wind speed, rotor diameter, cut-in and cut-out speed, mass of the rotor-nacelle-assembly) and ground profile (soil stiffness variation with depth and soil stiffness at one diameter depth). Other data that may be required for final detailed design are also discussed. A flowchart of the design process is also presented for visualisation of the rather complex multi-disciplinary analysis. Where possible, validation of the proposed method is carried out based on field data and references/guidance are also drawn from codes of practice and certification bodies. The calculation procedures that are required can be easily carried out either through a series of spreadsheets or simple hand calculations. An example problem emulating the design of foundations for London Array wind farm is taken to demonstrate the proposed calculation procedure. The data used for the calculations are obtained from publicly available sources and the example shows that the simplified method arrives at a similar foundation to the one actually used in the project. [ABSTRACT FROM AUTHOR]

This is the second of two companion papers which collectively present the effect of rotary inertia on dynamic behavior of rectangular plates. The first part of the two part paper deals with effect of rotary inertia in uniformly thick plates, whereas this part focuses on rotary inertia effect in plates with uniformly varying thickness. A generalized FE code based on FSDT is developed to analyse the free vibration behavior. Plates having different aspect ratio (b/a), taper ratio (δo) and different boundary conditions are analyzed by the nine node isoparametric element. The analysis is performed considering plate thickness ratio varying from h/a = 0.001 to 0.1 i.e. thin as well as sufficiently thick plates. [ABSTRACT FROM AUTHOR]

In this paper, we proposed an improved method for calculating the fringe width of Fraunhofer diffraction. Because the diffraction patterns are equidistant when the diffraction angle is small, the width of fringes can be determined through finding out the spatial frequency of the fringes using Fourier transform. To make the result more precise, the experimental data are compared with the theoretical values having the same range of the image in the frequency domain to get the modified frequency. We applied this method to calculate the diameters of some filaments by measuring their Fraunhofer diffraction fringes. [ABSTRACT FROM AUTHOR]

Recently, in a mechanical structure development focusing on noise and vibration, a numerical analysis like finite element method is the most famous method to expect and improve noise and vibration characteristics of the structure. However, the method is not taken account of uncertainties in structure like part shapes and connecting parts in many cases. It leads to differences between actual these characteristics and results from numerical analysis. And, the quality of the product is probably deteriorated by the uncertainties. Therefore, it is important to suppress the variation of the noise and vibration characteristics by the uncertainties, which is called robust design. In this paper, it is discussed about robust design method to minimize the variation of the eigen frequency by the uncertainties. The robust design method is based on stochastic finite element method and structural optimization. To evaluate the ability of the method, the robust design method is applied to an FE model and a spring mass system, and the method is also tested by the actual structure to confirm the performance.

• Railway sleepers were subjected to 50-times repeated impact loading. • Pre-stressed and LCR sleepers were investigated comparatively before and after impacts. • This is the first study to compare new LCR-6 type sleepers after impact loads. • LCR-6 type sleepers' modal damping values are 274% better. • LCR sleepers' hairline cracks don't cause significant capacity loss. Due to today's high-frequency trainloads and wheel or rail irregularities, the railway system is more exposed to impact loading conditions. In this study, laminated carbon fiber reinforced polyurethane (L-CFRPU) products were used, with a new non-pre-stressed production process, to improve the impact damping characteristics of concrete railway sleepers. New designed LCR-6 type sleepers were compared with standard B70 type pre-stressed concrete sleepers by performing modal analysis before and after a 50 times repeated-330 kN impact loading procedure. This is the first study to compare new LCR-6 type sleepers with prestressed competitors after impact loads. According to the analysis results, FRF magnitude values ​​decrease up to 83% lower in impacted LCR-6 type sleepers compared to impacted B70 type sleepers. After the impact loading procedure, the cracks formed in LCR-6 type sleepers closed and remained below 50-µm width, and according to the simultaneous mechanical test results, these few hairline cracks do not cause a significant mechanical capacity loss, while increasing the damping ratios by 274%. This advantage will be beneficial in extending the service life of sleepers and protecting other railway components from vibration and impact damage. Therefore, while the pre-stressed concrete sleepers have a negative course during their service life, the non-pre-stressed LCR type sleepers show a positive acceleration. [ABSTRACT FROM AUTHOR]