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The finite element analysis of CFV12000 motorized spindle is carried out in the ANSYS Workbench 16.0. And the free mode experiment is carried out for the actual structure. The finite element model is modified according to the experimental results, so that the model can accurately reflect the actual situation of the motorized spindle. Then the harmonic response of the modified finite element model is analyzed to predict the dynamic characteristics in the actual machining process of the spindle. Finally, the structure of the spindle is optimized to improve its dynamic performance. The rationality of the structure design of the electric spindle is proved, which lays the foundation for the optimization of the structure of the electric spindle and the improvement of its dynamic characteristics. [ABSTRACT FROM AUTHOR]

The oil pipeline is a critical component that influences the vibration and noise levels of the hydraulic system. Inadequate design may result in resonance or leakage issues, rendering it susceptible to external vibration excitation. To enhance the reliability of the hydraulic pipeline, simulations and analyses were conducted on its modal, harmonic response, and fatigue characteristics. Based on the results of harmonic response analysis and strength analysis, an effective reinforcement scheme was proposed and validated. By inputting the acceleration load to the pipeline system for frequency response analysis, the influence of different excitation forces on the pipeline stress can be determined. The findings indicate that pipeline vibration primarily occurs in the outlet pipe of the transmission, with significant stress and vibration displacement observed at the thermostat valve support. Following structural improvements, there was a notable reduction in stress levels at the transmission outlet pipe, along with a shift in maximum stress position due to additional support. This enhancement has improved both structural stiffness of the outlet pipe and overall stability of the pipeline system. [ABSTRACT FROM AUTHOR]

This study presents a numerical investigation of the dynamic behavior of graphene platelet (GPL)-reinforced ethylene tetrafluoroethylene (ETFE) tensile membrane structures subjected to harmonic excitation. Modal and harmonic response analyses were performed to assess both the natural frequencies and the dynamic responses of the ETFE membrane. GPLs were employed as the reinforcements to enhance the mechanical properties of the membrane materials, whose Young's modulus was predicted through the effective medium theory (EMT). Parametric studies were conducted to examine the impact of pre-strain and the attributes of the GPL reinforcements, including weight fraction and aspect ratio, on the natural frequencies and amplitude–frequency response curves of the membrane structure. The first natural frequency substantially increased from 5.46 Hz without initial strain to 31.0 Hz with the application of 0.1% initial strain, resulting in a frequency shift that moved the natural frequency out of the range of typical wind-induced pulsations. Embedding GPL fillers into ETFE membrane was another potential solution to enhance the dynamic stability of the membrane structure, with a 1% addition of GPLs resulting in a 48.6% increase in the natural frequency and a 45.1% reduction in resonance amplitude. GPLs with larger aspect ratios provided better reinforcement, offering a means to fine-tune the membrane's dynamic response. These results underscore that by strategically adjusting both pre-strain levels and GPL characteristics, the membrane's dynamic behavior can be optimized, offering a promising approach for improving the stability of structures subjected to wind-induced loads. [ABSTRACT FROM AUTHOR]

In order to study the structural performance of the new bend-twist coupling blade, NREL 5 MW blade was taken as the prototype, and the geometric model of the blade was established by using NX Open Grip parameterization language. The composite lamination design was carried out in accordance with the real processing technology, and the aerodynamic force of the blade was obtained by the computational fluid dynamics (CFD) method. The bend-twist coupling characteristics, harmonic response and strength of conventional and bending-torsional coupling blades were analyzed respectively. The results show that the blade tip displacement increases with the increase of the web deflection. For the same angle, the blade tip displacement of γ > 0 blades was smaller than that γ < 0 blades. The bend-twist coupling effect is the most obvious when γ = 10° and 15°. Compared with the conventional blade, the second-order displacement responses of bend-twist coupling blades are significantly reduced. The γ = 15° blade can reduce the stress on the surface and has a good load reduction performance.

Hydraulic turbines have become indispensable for harnessing renewable energy sources, particularly in-pipe hydraulic turbine technology, which leverages excess energy within pipeline systems like drinking water distribution pipes to produce electrical power. Among these turbines, the propeller-type axial turbine with circular blades stands out for its efficiency. However, there is a notable lack of literature on fluid dynamics and structural behavior under various operational conditions. This study introduces a comprehensive methodology to numerically investigate the hydraulic and structural responses of turbines designed for in-pipe installation. The methodology encompasses the design of circular blades, followed by parametric studies on fluid dynamics and structural analysis. The circular blade's performance was evaluated across different materials, incorporating static, modal, and harmonic response analyses. Results showed that the circular blade achieved a peak hydraulic efficiency of 75.5% at a flow rate of 10 l/s, generating 1.86 m of head pressure drop and 138 W of mechanical power. Structurally, it demonstrated a safety factor exceeding 1 across the entire hydraulic range without encountering resonance or fatigue issues. This research and its methodology significantly contribute to advancing the understanding of designing and assessing the fluid dynamic behavior and structural integrity of circular blades in axial propeller-type turbines for in-pipe installations, serving as a valuable resource for future studies in similar domains. [ABSTRACT FROM AUTHOR]

This article is devoted to the problem of signal decomposition into periodic and aperiodic components. According to the proposed approach, there is no need to evaluate the aperiodic component as a difference between the total signal of its periodic components. This research aims to create a general analytical approach that combines the Fourier and Maclaurin series methodologies into a single comprehensive series. As a result, analytical expressions for determining deposition coefficients were established for an aperiodic signal with a monoharmonic overlay. Recurrence relations were established to determine the coefficients of this series. These relations allow direct integrations of the obtained values of integrals to be avoided. The evaluated numerical values of the coefficients are also presented graphically and tabulated. It was proven that the values of these coefficients are universal numbers since they do not depend on the period/frequency of oscillations. The reliability of the proposed approach was confirmed by the fact that the evaluated coefficients are equal to the Fourier series coefficients in the case of a periodic signal. Also, for an aperiodic signal, these coefficients were reduced to the coefficients of the Maclaurin series. The usability of the proposed generalized analytical approach for signal decomposition is for control and monitoring systems of processes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mechanical Strength / Jixie Qiangdu is the property of Zhengzhou Research Institute of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Gamma oscillations, thought to arise from the activity of ɣ‐aminobutyric acid (GABA)ergic interneurons, have potential as a biomarker for schizophrenia. Gamma‐band auditory steady‐state responses (ASSRs) are notably reduced in both chronic and early‐stage schizophrenia patients. Furthermore, alterations in gamma‐band ASSRs have been demonstrated in animal models through translational research. However, the 40‐Hz harmonic responses of the 20‐Hz ASSR are not as well‐characterized, despite the possibility that these harmonic oscillatory responses may reflect resonant activity in neural circuits. In this study, we investigated the 40‐Hz harmonic response to the 20‐Hz ASSR in the early stages of schizophrenia. The study recruited 49 participants, including 15 individuals at ultra‐high‐risk (UHR) for psychosis, 13 patients with first‐episode schizophrenia (FES), and 21 healthy controls (HCs). The 40‐Hz harmonic responses of the 20‐Hz ASSR were evident in all groups. Interestingly, while previous report observed reduced 40‐Hz ASSRs, the 40‐Hz harmonic responses of the 20‐Hz ASSR were not reduced in the UHR or FES groups. These findings suggest that the gamma‐band ASSR and its harmonic responses may represent distinct aspects of pathophysiology in the early stages of schizophrenia.

This study presents a numerical investigation of the dynamic behavior of graphene platelet (GPL)-reinforced ethylene tetrafluoroethylene (ETFE) tensile membrane structures subjected to harmonic excitation. Modal and harmonic response analyses were performed to assess both the natural frequencies and the dynamic responses of the ETFE membrane. GPLs were employed as the reinforcements to enhance the mechanical properties of the membrane materials, whose Young’s modulus was predicted through the effective medium theory (EMT). Parametric studies were conducted to examine the impact of pre-strain and the attributes of the GPL reinforcements, including weight fraction and aspect ratio, on the natural frequencies and amplitude–frequency response curves of the membrane structure. The first natural frequency substantially increased from 5.46 Hz without initial strain to 31.0 Hz with the application of 0.1% initial strain, resulting in a frequency shift that moved the natural frequency out of the range of typical wind-induced pulsations. Embedding GPL fillers into ETFE membrane was another potential solution to enhance the dynamic stability of the membrane structure, with a 1% addition of GPLs resulting in a 48.6% increase in the natural frequency and a 45.1% reduction in resonance amplitude. GPLs with larger aspect ratios provided better reinforcement, offering a means to fine-tune the membrane’s dynamic response. These results underscore that by strategically adjusting both pre-strain levels and GPL characteristics, the membrane’s dynamic behavior can be optimized, offering a promising approach for improving the stability of structures subjected to wind-induced loads.

Gamma oscillations, thought to arise from the activity of ɣ‐aminobutyric acid (GABA)ergic interneurons, have potential as a biomarker for schizophrenia. Gamma‐band auditory steady‐state responses (ASSRs) are notably reduced in both chronic and early‐stage schizophrenia patients. Furthermore, alterations in gamma‐band ASSRs have been demonstrated in animal models through translational research. However, the 40‐Hz harmonic responses of the 20‐Hz ASSR are not as well‐characterized, despite the possibility that these harmonic oscillatory responses may reflect resonant activity in neural circuits. In this study, we investigated the 40‐Hz harmonic response to the 20‐Hz ASSR in the early stages of schizophrenia. The study recruited 49 participants, including 15 individuals at ultra‐high‐risk (UHR) for psychosis, 13 patients with first‐episode schizophrenia (FES), and 21 healthy controls (HCs). The 40‐Hz harmonic responses of the 20‐Hz ASSR were evident in all groups. Interestingly, while previous report observed reduced 40‐Hz ASSRs, the 40‐Hz harmonic responses of the 20‐Hz ASSR were not reduced in the UHR or FES groups. These findings suggest that the gamma‐band ASSR and its harmonic responses may represent distinct aspects of pathophysiology in the early stages of schizophrenia. [ABSTRACT FROM AUTHOR]

The interest in wind-assisted ship propulsions (WASPs) is increasing to improve fuel efficiency and to reduce greenhouse gas emissions in ships. A rotor sail, one of the typical WASPs, can provide auxiliary propulsive force by rotating a cylinder-shaped structure based on the Magnus effect. However, due to its huge rotating structure, a meticulous evaluation of the influence on the ship structure and dynamical stability of the rotating structure should be conducted in the design stage. In this respect, an analysis of the rotating structure for a 30 m height and 3 m diameter rotor sail was conducted in this study. First, a 4DOF (four-degree-of-freedom) model was derived to simplify the dynamics of the rotor sail. Using the 4DOF model, natural frequencies for four low-order modes of the rotor sail were calculated, and frequency responses at support points were predicted. Next, a comparison and validation with the finite element model of the rotor sail were carried out. For the 1st and 2nd natural frequencies, a difference of approximately 0.3 Hz was observed between the 4DOF model and the finite element model, confirming the effectiveness of the 4DOF model for low-order modes. In analysis with changes in the bearing supporting stiffnesses, it was verified that lower support bearings have a significant impact on rotor dynamics compared to upper support bearings. Vibration response at the upper support was also confirmed through frequency response analysis caused by imbalance at Thom disk and mid-plate. Additionally, when estimating the eccentricity of the Thom disk as imbalance, a limit of eccentricity error could be set as 24 mm. The presented modeling procedures and analysis results can be references during early design stage of a novel rotor sail structure. [ABSTRACT FROM AUTHOR]

Relevance of the research. Numerical studies of structural frequency response of a large-span building with cylindrical-and-slab roof as a large mechanical system were carried out. Finite element model No. 1 “Superstructure-Fixed-end” . The purpose of the study was to develop the methodology for modal analysis of a large-span building structure with a cylindrical-and-slab roof as a mechanical system with a large number of degrees of freedom . Methods. Numerical analysis of the building dynamics was carried out with the use of the САЕ (Computer-aided engineering) software package Femap NX NASTRAN, which implements the finite element method. Results. The “dangerous” resonant frequencies and forms of harmonic oscillations of the structure were revealed, and the sensitivity of the buildings’ reactions to various structural changes was analyzed. Frequency analysis of harmonic response of the building allowed to obtain dependences of amplitude values of nodal displacements (accelerations) and stresses in finite elements from the frequency of the inducing external force. In the next article, it is proposed to conduct a dynamic analysis of a large-span building with a cylindrical-and-slab roof for seismic effects.

Harmonic oscillations of piezoceramic functional-gradient sectioned hollow cylinders are studied, taking into account energy dissipation. A cylinder of finite length is considered. Cylinder consists of an even number of sections polarized in the circular direction, which are connected to each other by similar sides. The material is considered to be functionally heterogeneous in the direction of the previous polarization. The cylinder is loaded by the potential difference applied to the flat faces of the sections. The calculation is performed by the finite element method. Damping matrices forming and determining of coefficients corresponding to methods of introducing frequency-independent damping and Rayleigh damping is described. Electric losses are taken into account by entering the dielectric loss tangent or dielectric loss tangent matrix. The result of calculations is compared with the result obtained with the help of complex elastic and dielectric moduli. Amplitudefrequency characteristics are constructed for movements, charge on the electrodes, electrical admittance and its logarithm, taking into account damping. Energy dissipation consideration is related to the experimental data due to the mechanical quality factor of the piezo element. The frequencies of electrical resonances, anti-resonances and corresponding electromechanical coupling coefficients for functionally inhomogeneous and homogeneous cylinders are determined. For the functional-gradient piezoelectric element of the considered configuration, the maximum CEMC occurs at the frequency of the second electrical resonance. At this frequency, the dynamic stress-strain state of the cylinder is investigated. Forms of oscillations and distribution of stress amplitude values are constructed. The largest normal stresses according to the Coulomb-Mohr strength theory are determined and compared with the von Mises strength theory. FEA allows three-dimensional calculation of harmonic oscillations of functional-gradient piezo elements of complicated geometry. The determined frequencies of electrical resonance and anti-resonance and the corresponding CEMC make it possible to choose the most effective operating mode of the piezo element. The FEM mathematical apparatus makes it possible to quickly and qualitatively evaluate the strength, determine the charge on the electrodes, the current in the circuit, build the amplitude-frequency characteristics of admittance and impedance, and evaluate the efficiency of energy conversion. [ABSTRACT FROM AUTHOR]

To show dynamic properties of a motorized spindle at high speed, C01 type motorized spindle bearing-rotor system is used as a study object, and the dynamic model of the bearing-rotor system is established. The method to analyze vibration characteristics of motorized spindles by power flow is proposed, and it is found that the vibration energy is not necessarily considerable at the position where the vibration displacement response is significant. Finally, the system vibration energy distribution under different bearing stiffness is analyzed. The power flow method can analyze the dynamic characteristics of the bearing-rotor system in terms of energy distribution. [ABSTRACT FROM AUTHOR]

Tubes, actuators, and aeroplane landing gears are instances of tubular elements with deep holes and thin-wall constructions; such components are the backbone of the aerospace industry. Precision machining of interior holes of cylindrical objects with narrow bores and significant depth to diameter ratios (> 7–8) is more difficult, which highlights the need of grinding such deep holes. In this study, an enhanced construction of the deep hole internal grinding machine is developed and the structural behavior with two different materials cast iron and artificial granite material studied. The internal grinding shaft tool structure is a critical component of this grinding machine, and it is one of the most important variables affecting surface grinding quality due to the structure's length and intricacy, as well as its restrictive outside dimensions. While carrying out the study of machine structure, shaft is also exclusively analyzed with an optimized design. Being the most crucial part of the machine, shaft design was verified through the comparative study of theoretical, simulation analyses, and experimental work. [ABSTRACT FROM AUTHOR]

This study focuses on the analysis of a linear hydrostatic bearing using harmonic frequency response and harmonic response simulations. The aim is to evaluate the feasibility of replacing the existing alloy steel material with a metal matrix composite (MMC) in terms of its performance and dynamic characteristics for both the base and carriage parts. The simulation results indicate that the MMC material exhibits higher resonant frequencies and improved damping capabilities compared to the structural steel material. The higher resonant frequencies observed in the MMC material are attributed to its stiffness and structural properties. These properties contribute to increased natural frequencies and improved vibration damping characteristics. This suggests that incorporating the MMC material in the bearing design could enhance motion control, improving the ability to precisely control and manipulate the movement of components or systems. In the context of ultraprecision machining applications, incorporating the MMC material in the hydrostatic bearing design can also lead to a more accurate and controlled motion, resulting in improved precision and finer machining outcomes. The displacement analysis confirms that both materials meet the specifications provided by the manufacturer, supporting the viability of using MMC as an alternative. However, further experimental validation and considerations of material feasibility, manufacturing factors, and cost-effectiveness are necessary before implementing the MMC material in practical applications. Overall, this research highlights the potential benefits of MMC in the design of linear hydrostatic bearings, paving the way for enhanced performance in ultraprecision machining processes. [ABSTRACT FROM AUTHOR]

An experimental and numerical study on the mechanical and damping properties of styrene-butadiene rubber (SBR) composites with graphene nanoparticles (GNP) and carbon black (CB) is presented in this paper. The composites were tested for mechanical properties such as hardness and tensile strength. It is observed that the composites with GNP & CB fillers have higher stiffness and percentage elongation for failure. A scale model of the chassis was subjected to forced vibration to find the damping properties of each of the prepared composites. The experimental results were used to create a numerical model in ANSYS software using Yeoh's hyper-elastic model to generate a hyper-elastic material to simulate the composite property and to perform harmonic response analysis in ANSYS. The results from experiments and theoretical findings exhibited good agreement.

The interest in wind-assisted ship propulsions (WASPs) is increasing to improve fuel efficiency and to reduce greenhouse gas emissions in ships. A rotor sail, one of the typical WASPs, can provide auxiliary propulsive force by rotating a cylinder-shaped structure based on the Magnus effect. However, due to its huge rotating structure, a meticulous evaluation of the influence on the ship structure and dynamical stability of the rotating structure should be conducted in the design stage. In this respect, an analysis of the rotating structure for a 30 m height and 3 m diameter rotor sail was conducted in this study. First, a 4DOF (four-degree-of-freedom) model was derived to simplify the dynamics of the rotor sail. Using the 4DOF model, natural frequencies for four low-order modes of the rotor sail were calculated, and frequency responses at support points were predicted. Next, a comparison and validation with the finite element model of the rotor sail were carried out. For the 1st and 2nd natural frequencies, a difference of approximately 0.3 Hz was observed between the 4DOF model and the finite element model, confirming the effectiveness of the 4DOF model for low-order modes. In analysis with changes in the bearing supporting stiffnesses, it was verified that lower support bearings have a significant impact on rotor dynamics compared to upper support bearings. Vibration response at the upper support was also confirmed through frequency response analysis caused by imbalance at Thom disk and mid-plate. Additionally, when estimating the eccentricity of the Thom disk as imbalance, a limit of eccentricity error could be set as 24 mm. The presented modeling procedures and analysis results can be references during early design stage of a novel rotor sail structure.

Abstract The importance of appropriate offshore wind turbine (OWT) monopile structural modelling technique cannot be overstated in the successful design and installation of a new generation of larger and heavier structures to deliver the increasing capacity demand. The lack of clear design guidance and acceptable structural modelling techniques across the industry results in a range of conservative but expensive design and installation techniques. Most of the OWT monopile modelling efforts lie in the substructure (foundation) and interaction with the supporting soil which is highly nonlinear along the length of the embedment depth of the monopile structure. Typically, monopile offshore wind turbine structural modelling can be completed using, amongst others, one of the following techniques: 3D finite element modelling with mass soil foundation, API p‐y curve soil springs, JeanJean soil springs, and the newly developed PISA modelling approach. The study presented in this paper considers the application of the 3D finite element modelling with mass soil, API p‐y soil springs, and the JeanJean soil springs technique. By comparing the structural response, the 3D finite element modelling with mass soil results in an improved natural frequency and harmonic response. Furthermore, a reduced displacement was observed in the 3D finite element model with mass soil which will ultimately result in a corresponding improvement in the structure's useful operational design life. The application of the API p‐y soil springs, JeanJean soil springs, and other modelling techniques requires extensive calibration to ensure the correct structural response and behaviour are achieved. This becomes a key factor as the boundaries of the size of the structure and turbine capacity are pushed even further for the new concept generation offshore wind turbines, which are required to deliver a higher capacity of 12 to 15 MW with the aim of achieving 20 MW, whilst achieving an efficient cost‐effective engineering design and installation process.

In this study, the dynamic structural and mechanical properties of the polymer composite with natural fiber reinforcement have been investigated experimentally and numerically. First of all, three different types, one-, three- and five-layered jute-epoxy and hemp-epoxy laminated composite, have been manufactured using the hand lay-up method. The tensile strength, bending strength and shear strength of the fabricated composite material have been investigated experimentally using Universal Testing Machine. The density is measured using a density measurement kit using Archimedes principle. Further, frequency and damping factors are also investigated using a vibration test setup. Later on, the numerical model is developed in finite element-based software ANSYS. Different natural frequency modes and corresponding damping factors have been investigated numerically. The mechanical and structural characteristics obtained experimentally and numerically are analyzed and discussed in detail. From the investigation, it is found that the hemp-epoxy composite has a greater strength and stiffness compared to the jute-epoxy composite, irrespective of the number of fiber layers used. Further, it is also found that with the increase in fiber layers or fiber percentage in the composite, the strength and stiffness of the fabricated composite increase significantly.

This paper focuses on the magneto-aero-elastic nonlinear resonances, bifurcations and chaos for superharmonic and subharmonic responses of conductive circular plates spinning in air and magnetic fields. The electromagnetic forces acting on in-plane are presented by using electromagnetic field theory, and a rotational dissipative damping aerodynamic model is employed to characterize the aerodynamic forces acting on the plates. Considering the effects of the geometric nonlinearity and centrifugal tensioning, the magneto-aero-elastic governing equations of spinning conductive circular plates are derived by the Hamiltonian principle. Based on the mode shapes with Bessel functions, the transverse nonlinear vibration differential equations of spinning plates with clamped-edge are derived by the Galerkin method. Amplitude-frequency equations for subharmonic and superharmonic responses are obtained by using the approach of multiple scales, respectively. Numerical calculations indicate the influences of important parameters (e.g. magnetic field intensity, excitation amplitude and rotational speed) on amplitude frequency characteristics. Moreover, it is demonstrated by the numerical results that system responses are sensitive to the variation of these important parameters, where the complex intermittency, period-doubling and chaotic dynamical behaviors exist. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Functionally Graded Materials (FGM) are extensively employed for hip plant component material due to their certain properties in a specific design to achieve the requirements of the hip-joint system. Nevertheless, if there are similar properties, it doesn’t necessarily indicate that the knee plant is efficiently and effectively working. Therefore, it is important to develop an ideal design of functionally graded material femoral components that can be used for a long period. A new ideal design of femoral prosthesis can be introduced using functionally graded fiber polymer (FGFP) which will reduce the stress shielding and the corresponding stresses present over the interface. Herein, modal analysis of the complete hip plant part is carried out, which is the main factor and to date, very few research studies have been found on it. Moreover, this enhances the life of hip replacement, and the modal, harmonic, and fatigue analysis determines the pre-loading failure phenomena due to the vibrational response of the hip. This study deals with the cementless hip plant applying the finite element analysis (FEA) model in which geometry is studied, and the femoral bone model is based in a 3D scan.

Vibration is a common and urgent technical issue in the steel industry. The world's first multi-mode continuous-casting and rolling plant of Shou Gang Jing Tang Iron and Steel Co., Ltd. (Tangshan, China), has a finishing mill, F3, that experiences frequent, strong vibrations during the process of rolling thin-gauge (<1.5 mm) strip steel, which have seriously hindered the production of high-quality thin strip steel products. The changes in the strips' surface quality are among the factors that induce rolling mill vibrations. In this study, considering the nonlinear surface quality of strip steel, a finite element model of the F3 mill was established, and the harmonic response method was used to obtain a rolling mill vertical system in the ANSYS environment. This study assesses the sensitive amplitude versus frequency characteristics curve of a torsional coupling system, the influence of strip thickness and strip hardness fluctuations on the vibration of the primary drive system, and the dynamic amplitude versus frequency characteristics of the three directions on the top of a torii. Finally, the field experiment verifies the correctness of the analytical results, which provides theoretical guidance for suppressing rolling mill vibrations and has a certain application value. [ABSTRACT FROM AUTHOR]

This study measures the impact of the cut-out shape on the fundamental frequency and the harmonic response of thin composite circular plates under fixed boundary conditions. For this purpose, the Finite Element Method has been employed using the SHELL181 element of ANSYS Workbench 18.2 software. Nine different circular plates having central equilateral triangle, square, regular pentagon, regular hexagon, regular heptagon, regular octagon, regular nonagon, regular decagon, and circular cut-outs have been designed to understand the changes in the vibrational behavior of a structure as the cut-out geometry approximates to circular. Additionally, a solid circular plate has been modelled for comparison purposes. To investigate the effect of the cut-out shape more deeply, all structures have been designed as cross-ply and angle-ply composites. The free vibration analysis has been performed to obtain the fundamental frequency of each structure. The harmonic response analysis problem has been solved by employing the Mode Superposition Method and considering a constant damping ratio. The results of the study have been interpreted by considering the displacement response, stress, and phase shifts at a certain frequency range. The results indicate that the shape of the cut-out considerably affects the fundamental frequency and harmonic response of the circular structure regardless of its fiber orientation. [ABSTRACT FROM AUTHOR]

First, the flexibility matrix of the rolling mill interfaces is extracted with Jetmundsen substructure synthesis method, and the power flow mode of the interfaces is obtained and discussed when the property of components of the interface changes with the analytical method. Second, finite element analysis (FEA) method is applied to analyse the power flow harmonic response in each interface of the rolling mill components and their power flow conductivities. The relation among the stiffness, the length of rodless cavity of the Hydraulic Gauge Control cylinder of the mill and the conductivity is discussed. Then, the power flow experimental result shows that the Hydraulic Gauge Control cylinder vibrates violently when the length of rodless cavity of the cylinder approaches 50 and 100 mm. Finally, the result comparison among analytical, FEA and experimental method is introduced. [ABSTRACT FROM AUTHOR]

The importance of appropriate offshore wind turbine (OWT) monopile structural modelling technique cannot be overstated in the successful design and installation of a new generation of larger and heavier structures to deliver the increasing capacity demand. The lack of clear design guidance and acceptable structural modelling techniques across the industry results in a range of conservative but expensive design and installation techniques. Most of the OWT monopile modelling efforts lie in the substructure (foundation) and interaction with the supporting soil which is highly nonlinear along the length of the embedment depth of the monopile structure. Typically, monopile offshore wind turbine structural modelling can be completed using, amongst others, one of the following techniques: 3D finite element modelling with mass soil foundation, API p‐y curve soil springs, JeanJean soil springs, and the newly developed PISA modelling approach. The study presented in this paper considers the application of the 3D finite element modelling with mass soil, API p‐y soil springs, and the JeanJean soil springs technique. By comparing the structural response, the 3D finite element modelling with mass soil results in an improved natural frequency and harmonic response. Furthermore, a reduced displacement was observed in the 3D finite element model with mass soil which will ultimately result in a corresponding improvement in the structure's useful operational design life. The application of the API p‐y soil springs, JeanJean soil springs, and other modelling techniques requires extensive calibration to ensure the correct structural response and behaviour are achieved. This becomes a key factor as the boundaries of the size of the structure and turbine capacity are pushed even further for the new concept generation offshore wind turbines, which are required to deliver a higher capacity of 12 to 15 MW with the aim of achieving 20 MW, whilst achieving an efficient cost‐effective engineering design and installation process. [ABSTRACT FROM AUTHOR]

The RNG k-ε model turbulence model is used to carry out a CFD numerical simulation of the dual-flow channel pumping station. Through the model test, the accuracy of the numerical simulation of the dual-flow channel pump device is verified. Using the harmonic response analysis method, the water pressure fluctuating load calculated under different startup conditions under the design water level is applied to the pumping station. In this way, the dynamic response law of the pump station structure under the action of water pressure pulsation is studied. The calculation results show that the values of pressure pulsation in the drainage condition and the water diversion condition are relatively close, and the main difference is the difference in the water levels of the inlet and outlet water. Under different working conditions, the amplitude of the pumping station building basically shows the characteristics that the vertical amplitude is greater than the horizontal amplitude. The maximum dynamic displacement under drainage condition is greater than that under the diversion condition, and the maximum dynamic displacement appears at the control gate. Under the three working conditions, the maximum dynamic stress of each characteristic part of the pumping station building is low. The maximum total dynamic stress under the drainage condition is greater than that under the diversion condition. [ABSTRACT FROM AUTHOR]

The use of smart and advanced composite materials instead of conventional metals is foreseen in material sciences due to the development of novel manufacturing techniques. In this regard, a novel type of composite materials "functionally graded materials (FGM)" has attained great attention owing to their intrinsic mechanical characteristics. FGM have been the focus for researchers for analytical formulation, static structural (large deformation, material nonlinearity) analysis as well as for dynamic analysis on simple beams and on structure having non-uniform tapered rectangular profile considering different boundary conditions. No focus is made to thin structure having non-uniform circular cross-sections. This study aims to deal with analyzing the "dynamic behavior of thin circular non-uniform truncated conical section" which is mostly used for manufacturing of fishing rod. This works primarily compares the static, modal, and harmonic analysis under the application of loads of 50 N acting on fishing rod made up of conventional steel, composite (carbon fiber) steel, and functionally graded material (FGM) with the help of ANSYS®. Firstly, static analysis performed to analyze the structural behavior under the application of static loadings. After that modal analysis performed and first five modes selected for Steel; from 0 to 600 Hz, for Carbon Fiber; from 0 to 850 Hz and for FGM; from 0 to 900 Hz for harmonic analysis. Maximum defection at resonance for steel is 7.94 mm, for composite is 74.4 mm, and for FGM is just 0.032 mm. The comparison of these results clearly depicts that FGM is having excellent vibration suppression performance as compared to other two materials under consideration. This confirms that thin structure (non-uniform circular profile) made of FGM can be used efficiently for the intended applications in future. [ABSTRACT FROM AUTHOR]

Stiffened plates are employed in various engineering structures including aerospace, civil, naval, etc. These structures may be subjected to harmonic loads. Therefore, it is essential to understand the harmonic response of a cracked stiffened structure. This study presents the effects of the crack location on the free vibration and harmonic response of the stiffened plates. For this purpose, horizontal and vertical cracks are modelled throughout the fixed from two-side structure. The analyses are performed via the Finite Element Method and the Mode Superposition technique. The natural frequencies and the displacement responses of the cracked and healthy structures are obtained and interpreted. It is concluded that a horizontal crack can decrease the third natural frequency by 60% as it is located in the center of the stiffened plate that is fixed from its nonstiffened edges. Thus, the displacement response of the stiffened structures is increased by 18% in the presence of the side horizontal or vertical cracks, which are located at the free ends of the stiffened structures no matter which boundary condition is considered. [ABSTRACT FROM AUTHOR]

Functionally Graded Materials (FGM) are extensively employed for hip plant component material due to their certain properties in a specific design to achieve the requirements of the hip-joint system. Nevertheless, if there are similar properties, it doesn't necessarily indicate that the knee plant is efficiently and effectively working. Therefore, it is important to develop an ideal design of functionally graded material femoral components that can be used for a long period. A new ideal design of femoral prosthesis can be introduced using functionally graded fiber polymer (FGFP) which will reduce the stress shielding and the corresponding stresses present over the interface. Herein, modal analysis of the complete hip plant part is carried out, which is the main factor and to date, very few research studies have been found on it. Moreover, this enhances the life of hip replacement, and the modal, harmonic, and fatigue analysis determines the pre-loading failure phenomena due to the vibrational response of the hip. This study deals with the cementless hip plant applying the finite element analysis (FEA) model in which geometry is studied, and the femoral bone model is based in a 3D scan. [ABSTRACT FROM AUTHOR]

In order to solve the problem of resonance and sound in the running process of water lubricated rubber stern bearing， the dynamic response analysis of stern bearing is carried out based on ANSYS finite element analysis platform. Firstly， the low order natural frequencies and modes of stern bearing are obtained by modal analysis. Secondly， the response rule of the stern bearing with the frequency change is obtained by using the harmonic response analysis， so the natural frequencies which affect the dynamic characteristics of the stern bearing are determined. Finally， the sensitivity analysis of the structural parameters is carried out， and the influence factors of the vibration characteristics are sorted， the basis for reducing the experimental cost and the dynamic design of stern bearing is provided.

As part of an ongoing study into hydropower runner failure, a submerged, vibrating blade is investigated both experimentally and numerically. The numerical simulations performed are fully coupled acoustic-structural simulations in ANSYS Mechanical. In order to speed up the simulations, a model order reduction technique based on Krylov subspaces is implemented. This paper presents a comparison between the full ANSYS harmonic response and the reduced order model, and shows excellent agreement. The speedup factor obtained by using the reduced order model is shown to be between one and two orders of magnitude. The number of dimensions in the reduced subspace needed for accurate results is investigated, and confirms what is found in other studies on similar model order reduction applications. In addition, experimental results are available for validation, and show good match when not too far from the resonance peak.

This paper is focusing on diagnosis for longitudinal and radial vibrations of turbomachinery coupled with induction motors. In this context, extensive field vibration measurements are conducted and analysed to identify the source of predominant vibrations on rotor bearing system in a chosen centrifugal compressor in the radial and longitudinal directions. As a first step, the measured overall vibration levels at multiple locations on bearing surface are compared with the existing ISO standard limits. These measurements showed severe longitudinal vibration values and failure of thrust collar assembly which were not considered in turbomachinery (API) design standards. The second step in diagnosis for vibration spectrum measurements are conducted both in longitudinal and radial directions during transient and steady state operations to find the vibration source and thrust collar assembly failure mechanism. This study on vibration diagnosis and analysis on turbomachinery is useful in correcting the severe longitudinal vibrations and damage control measures and corrections associated with static eccentric airgaps through motor air gap diagram. [ABSTRACT FROM AUTHOR]

In view of the problem that the resonance phenomenon occurs in the process of parallel machine, which leads to the deformation of the mechanism and affects the machining precision. The 6-bar parallel machine is taken as the research object, and topology optimization method is used to optimize the bed of the parallel machine. Firstly, the optimized parts of the bed are determined as the column, the cross frame and fixed platform, which are optimized by topology optimization module in HyperWorks. The column and cross frame are optimized by adding some reinforcement. The size of the stiffeners of the column is further optimized. Modal analysis and harmonious response analysis are used to verify the whole machine. Comparing the model before and after optimization, it is found that the total mass of the optimized model is reduced by 17.8%, and the first three order resonance frequencies increases by 19.56%, 20.62% and 0.091%, respectively. The resonance peak decreases by 49.454%, 29.036% and 0.0078% in X, Y and Z directions. The analysis of the results show that the optimized parallel machine avoids the occurrence of resonance during processing, and the machining accuracy has been significantly improved. [ABSTRACT FROM AUTHOR]

In this paper, the propagation of bounded uncertainties in the dynamic response of a misaligned rotor is investigated using a Legendre collocation based non-intrusive analysis method. A finite element rotor model is used and the parallel and angular misalignments are modelled by additions of stiffness and force terms to the system. A simplex meta-model for the harmonic solutions of the vibration problem is constructed to take into account the uncertainties. The influences of uncertainties in the fault parameters are analysed and the calculation performance of the interval method is validated. Different propagation mechanisms of the uncertainties are observed in the interval responses and discussed in case studies. The results of this study will promote the understandings of the nonlinear vibrations in misaligned rotor systems with interval variables. [ABSTRACT FROM AUTHOR]

Harmonic radar transponders are passive RF tags that produce a harmonic response when illuminated with an RF signal. With a Schottky diode as the main component, the tag current is usually modelled as an exponential function of antenna voltage, resulting in an approximate polynomial function for small signals. The authors introduce the Lambert function that accounts for the resistive load and leads to a two-region tag model: a power series representation for small signals and an asymptotic linear large-signal model. Furthermore, they provide the relationship between the modulated bandpass signals at the input and output of the tag in the two regions by expressing the tag signals with complex envelopes. The derived expressions offer deeper insight of the transponder's impact on the operation of harmonic radar systems. [ABSTRACT FROM AUTHOR]

Due to the long-term problem of electricity and potable water in most developing and undeveloped countries, predominantly rural areas, a novelty of the pendulum water pump, which uses a vertically excited parametric pendulum with variable-length using a sinusoidal excitation as a vibrating machine, is presented. With this, more oscillations can be achieved, reducing human effort further and having high output than the existing pendulum water pump with the conventional pendulum. The pendulum, lever, and piston assembly are modeled by a separate dynamical system and then joined into the many degrees-of-freedom dynamical systems. The present work includes friction while studying the system dynamics and then simulated to verify the system’s harmonic response. The study showed the effect of the pendulum length variability on the whole system’s performance. The vertically excited parametric pendulum with variable length in the system is established, giving faster and longer oscillations than the pendulum with constant length. Hence, more and richer dynamics are achieved. A quasi-periodicity behavior is noticed in the system even after 50 s of simulation time; this can be compensated when a regular external forcing is applied. Furthermore, the lever and piston oscillations show a transient behavior before it finally reaches a stable behavior.

Abstract Nanocomposites are preferred over conventional materials because of their superior mechanical properties. Studies need to be carried out, especially on the dynamic response of the composite material. The objective of the present work is to study the dynamic response of Carbon-Nanotube-Reinforced-Polymer (CNRP) material by developing a 3D multiscale finite-element model of the Representative Volume Element (RVE) of the composite material to determine its dynamic properties, in terms of its natural frequencies and damping properties. A computational model consisting of a Single-Walled Carbon Nanotube (SWCN), an interface region and the polymer matrix is constructed for this purpose. The SWCN is modeled as a space frame structure by using the Morse potential and as a thin shell model based on Donnell's Shell Theory. The polymer matrix is modeled with the Mooney-Rivlin strain energy to calculate its non-linear response and the interface region is modeled via van der Waals links based on the Lennard-Jones Potential. The natural frequencies of CNRP are compared with the natural frequencies of the polymer matrix. A relation between damping ratio and natural frequencies is then obtained. Finally, the analysis of harmonic response is conducted to characterize the effects of the SWCN reinforcement in the polymer material. [ABSTRACT FROM AUTHOR]

In order to improve the impact mechanism of the impacting and breaking rock roadheader dynamic characteristics under the cycle impact load,the first six natural frequency and mode shape as well as the displacement-frequency curves were obtained by using stress wave synthesis theory and finite element method in the paper,the modal and harmonic response of the mechanism were analyzed,the main deformation portion and main vibration direction and three axial weakest points of the mechanism were confirmed,structure size optimization of the rocker arm were adopted with multiple objective genetic algorithm,The maximum displacement response of the mechanism was reduced,and the dynamic characteristics of the mechanism were improved,which provides a method and basis for researching and improving the dynamic performance of the mechanism.

The cycloid gear and the crankshaft are important parts of a RV reducer,and the bending deformation at Rome dots of the component is one of the main failure forms of the RV reducer. Therefore,taking the RV- 250 reducer as the research object,and the RV- 250 reducer model without interference is built.Based on the characteristic of periodic input,uing the finite element method,the harmonic response analysis of RV reducer is completed and the amplitude frequency response curve of the eccentric shaft and the cycloid gear of the key components are obtained,as well as the index of dynamics such as natural frequency and the response amplitude. Results show that it will lead to the cycloid gear bending vibration and axial deformation when the vibration force of eccentric shaft is around 360 Hz,a theoretical basis for the optimal design of the cycloid gear and the crankshaft is provided.

Abstract The dynamic behavior of counter flow heat exchangers is studied using the harmonic response. To solve the set of partial differential equations the complex notation is used so that these equations become ordinary differential equations. In an appendix it is shown that assuming a uniform temperature in a cross section of the separating wall is correct for the example used as comparison. Experimental results dealing with a double pipe heat exchanger are compared with results obtained by assuming the correlations to be used for the convection heat transfer coefficients. The comparison is satisfactory when the excitation is applied to the inner tube fluid. It is less accurate when the excitation is applied to fluid flowing in the annulus. Finally it is shown that the residence time of the fluids is linked to a peak in the response curves. [ABSTRACT FROM AUTHOR]

Abstract Optimum design and failure prevention against diverse degradation mechanisms of reactor vessel internals(RVIs) are one of safety concerns in nuclear industries. The present study is to investigate effectiveness of current evaluation procedure of the RVIs under pump pulsating conditions as a part of comprehensive vibration assessment program. At first, pressure propagation analyses were performed subjected to typical steady-state and transient conditions to generate pulsating pressure distributions. Subsequently, modal analyses were conducted to examine effect of coolant modeling on dynamic characteristics. Harmonic response analyses were also carried out to examine effect of integrated assembly and numerical analyses data were compared each other and with limited measured data. As a result, it was proven that the integrated assembly with the coolant modeling could predict further realistic behaviors of RVIs instead of the current sub-component models adopting equivalent added-mass assumption. [ABSTRACT FROM AUTHOR]

Yuan, L., 2018. Harmonic response of power coupling mechanism of coastal ship. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 86–92. Coconut Creek (Florida), ISSN 0749-020 8. A non-interference simulation model of the coupling mechanism of a heavy-duty hybrid vehicle is established. Based on the characteristics of periodic input, the dynamic response of the power coupling mechanism under the rated torque is analyzed by finite element method, and the key components are obtained. The results show that the excitation force of the planet carrier at about 2000 Hz will cause the planetary wheel to bend and axial deformation, as the planetary gear and the planetary carrier optimization design provides a theoretical basis. [ABSTRACT FROM AUTHOR]

Since the particle damping is highly developed and widely used to suppress the structure vibration and a more efficient and accurate technique for predicting the harmonic responses of particle-damping structure is in need, this paper presents a novel technique to predict the harmonic response of particle-damping structure based on iterative solution method and ANSYS ® secondary development technology. In order to establish the iteration solution method for predicting the harmonic response of particle-damping structure, iteration scheme of particle-damping structure (system) is derived from the mechanical dynamic formulae and particle damping formulae. For single or multiple degree of freedom system, basic solutions of each iteration cycle are solved by mathematical model, while the solutions of continuous systems are solved by ANSYS ® in this paper. To conduct harmonic analysis of highly nonlinear particle-damping system in ANSYS ® , iterative solution method (i.e. iteration scheme) is coded into program by ANSYS ® Parametric Design Language (APDL). Based on the code, module of particle damping is developed and interfaces are created in ANSYS ® using User Interface Design Language (UIDL). To verify the accuracy of the novel technique, two research cases are detailed introduced and frequency response functions (FRFs) of acceleration are obtained by simulations and experiments. It's worthwhile to note that simulation results have excellent consistency with the experiment results. In addition, the simulations conducted by ANSYS ® using iteration solution method developed in this paper is more efficient and consumes less computer resources than previous methods. Consequently, both accuracy and higher efficiency of the novel technique are guaranteed. [ABSTRACT FROM AUTHOR]

Analysis of the highest temperature in the machining processes, namely the flash temperature, helps to understand the physics of the process, to improve cutting tool geometry, and to achieve high performance machining. In the present work, the interaction between cutting grain and workpiece material in grinding process is analyzed. Single diamonds are considered for machining, which operates in comparison to other measurements in the range of grinding speed. The highest temperature in the grain-material interaction and cutting forces are measured. In order to measure the flash temperature, an innovative method to measure and analyze the temperature through the diamond grain in the cutting zone by a two-color pyrometer is proposed. Furthermore, cutting forces are measured simultaneously. In order to measure the temperature in the cutting zone, an accurate connection between diamond and pyrometer fiber is required. Thus, the diamond tool holders are manufactured by electrical discharge machining (EDM) milling in deionized water. A 0.5-mm-diameter hole is drilled in each holder to connect the diamond precisely to the pyrometer fiber. Machining processes are performed with 30 μm depth of cut, cutting length of 20 mm, and cutting speed of 65 m/s on Ti6Al4V. The cutting tool is fixed, and the shape of the rotating workpiece is optimized. The diamond holder with the specific shape is designed and manufactured. Quasi-static, dynamic, modal, and harmonic response analyses are performed in order to reduce vibrations and chattering. The measured flash temperature is 1380 °C and cutting normal, tangential, and axial forces are measured. [ABSTRACT FROM AUTHOR]

This paper presents a new spectral element based on the dynamic stiffness matrix of a prestressed cylindrical shell. The dynamic stiffness matrix is built using first-order shear deformation theory, and natural frequencies are processed easily. Vibration analyses are performed with numerical examples to determine the performance of this approach and the effect of prestressing on frequency response functions. This element has many advantages over the finite element method in terms of accuracy, model size and computing time. [ABSTRACT FROM AUTHOR]