Prediction Of Vibration Response Research Articles

Multi-point Vibration Response Prediction Based on Deep Transfer Learning

Multi-point Vibration Response Prediction Based on Deep Transfer Learning

Mitigation of Ice-Induced Vibration of Offshore Platform Based on Gated Recurrent Neural Network

Ice-induced vibration is one of the major risks that face the offshore platform located in cold regions. In this paper, the gated recurrent neural network (GRNN) is utilized to predict and suppress the response of offshore platforms subjected to ice load. First, a simplified model of the offshore platform is derived and validated based on the finite element model (FEM). The time history of the floating ice load is generated using the harmonic superposition method. Gated Recurrent Unit Network (GRU) and the Long-Short-Term Memory Network (LSTM) are composed in MATLAB to predict the behavior of the off-shore platform. Afterward, the linear quadratic regulator (LQR) control algorithm is used to calculate the controlling force for the training of the GRU/LSTM-based prediction controller. Numerical results show that the ice-induced vibration response prediction method based on GRU network design can predict the structural response with satisfying accuracy, and the ice-induced vibration response control method based on the LSTM network and GRU network design can learn the LQR method well and achieve good control effect. Time lag and other problems that the vibration control programs often encountered were solved well.

Nonlinear dynamic analysis of four-station rotary tool holder subjected to harmonic excitation

Four-station rotary tool holder on a lathe is fabricated to achieve transposition operation of turning tools and carry the violent cutting force prior to feed system. Its dynamic characteristic has a potential influence on the structural dynamics and cutting stability of a machine tool. This paper develops a mechanical model for the dynamic characteristic analysis and vibration response prediction. Using the fractal contact theory, the analytical model highlights the rough joint interfacial contact of main components including tool holder body, trapezoidal meshing gear plate and screw shaft. The elastic supports of thrust bearing unit and hollow shaft are also considered. The multi-degree-of-freedom system involving the coupled displacement and piecewise restoring force function is established using lumped mass method. The modal and harmonic excitation tests are performed to investigate the natural property and verify the proposed model. Furthermore, numerical simulation evaluates the effect of external excitation, locking force, fractal parameter, bearing preload and shaft stiffness on dynamic characteristic and stability. The proposed model is promising for the structural optimal design of four-station rotary tool holder.

Fast vibro-acoustic simulation methods of satellite components

PurposeThis paper aims to fast predict vibration responses of specific locations in the satellite subject to acoustic environment. It proposes a set of vibro-acoustic simulation methods of satellite components to represent their conditions in the whole satellite during the ground tests or launching. This study aims to use vibro-acoustic models of satellite components to replace that of hard modeling and time-consuming whole satellite when only local responses are concerned.Design/methodology/approachThis paper adopted experimental and numerical studies, with the latter based on the finite element (FE), statistical energy analysis (SEA) and FE-SEA hybrid theories. The vibro-acoustic model of the whole satellite was built and verified by experimental data. Based on the whole satellite model and experimental results, the fast vibro-acoustic simulation methods of all kinds of typical satellite components were discussed.FindingsThis paper shows that the models about satellite components not only show high consistency but also reduce 61.6% to 99.8% times compared with the whole satellite model. The recommended fast simulation methods for all kinds of typical satellite components were given in comprehensive consideration of the model accuracy, time required and response accessibility.Originality/valueThis paper fulfils an identified need to perform fast vibro-acoustic prediction of the local positions in satellites.

Experimental investigation on the alteration of natural frequency of a flexible pipe adjacent to a bottom plane with the consideration of pipe-plane impact

The obtainment of natural frequencies of near-wall submarine spanning pipelines is the essential basis of the prediction of vibration response and fatigue life. Nevertheless, published literature has not yet taken into account the pipe–wall impact in free attenuation tests and has not offered a method to identify the impact frequency from natural ones. Therefore, the present work experimentally investigates the free attenuation response of a horizontal flexible pipe positioned adjacent to and parallel to a bottom plane with the consideration of pipe–wall collision, aiming to figure out the influences of wall proximity and wall impact on natural frequencies and to provide a measurement method for attenuation tests of such fluid–flexible-structure–solid interaction issues. The experimental results indicate that setting a horizontal initial displacement is easier than setting a vertical initial displacement to get the vertical natural frequencies of a near-wall flexible pipe. The natural frequency of near-wall flexible pipe is a function of the added mass coefficient, decreasing with the reduction of pipe-to-wall distance. Three main alterations of natural frequencies are introduced in the presence of pipe–wall impact. With the imposition of a horizontal initial displacement, the impact and natural frequencies can be distinguished from the wavelet time-frequency contours because of their participations during different time periods.

Performance of Genetic Programming and Multivariate Adaptive Regression Spline Models to Predict Vibration Response of Geocell Reinforced Soil Bed: A Comparative Study

Performance of Genetic Programming and Multivariate Adaptive Regression Spline Models to Predict Vibration Response of Geocell Reinforced Soil Bed: A Comparative Study

A partial similitude method for vibration responses of rotor systems: Numerical and experimental verification

Similitude theory provides the necessary conditions to predict the structural responses of the full-scale prototype through the scaled model, and is widely used in full-scale experiments of large structures. However, the prediction accuracy is insufficient in partial similitude. Aiming at this issue, this paper proposes the frequency adjustment laws to predict vibration responses of full-scale rotor in non-resonant state, since the rotating machinery usually works in non-resonant state. On this basis, a partial similitude method is presented by combining the frequency adjustment laws with the current method. The proposed method provides several scaling laws in the whole range of rotating speed, while only one scaling factor is used to predict the vibration responses in existing methods. The accuracy of the proposed method is verified by the numerical and experimental case studies, where the geometrical distortion is considered. In the numerical case study, the scaling laws of a rotor system are obtained by the proposed method and existing methods. The predicted results of the proposed method are compared with those of the existing methods. It is found the proposed method accurately predicts the displacements and accelerations of prototypes through those of scaled model. Moreover, the proposed method achieves a higher accuracy. The experimental study carries out the testing for the prototype and model test rigs. The experimental results show that the proposed method provides better results in predicting the displacement and acceleration compared with the existing methods. The proposed method allows designers to design a scaled model and to reproduce the vibratory behavior of the full-size prototype, which reduces the difficulty, costs and time of experimental test. Moreover, the proposed partial similitude method has a better performance than the existing methods.

Development of an integrated model for prediction of impact and vibration response of hybrid fiber metal laminates with a viscoelastic layer

The present study proposes an integrated model for prediction of the dynamic behaviors involving vibration and impact on hybrid fiber metal laminates embedded with a viscoelastic layer. Firstly, by combining the Reddy's high-order shear deformation theory and the classical laminate theory, the structural displacement field functions are determined. Then, a predefined criterion, namely the damage criterion based on a key indicator “critical impact velocity”, is proposed to quantitatively estimate whether the composite structure is damaged subjected to impact excitation. In the case that meets this criterion without considering impact damage, the energy method, together with the Duhamel principle and the Simpson numerical integral approach, is utilized to obtain the free and forced vibration solutions. However, in the case that fails to satisfy this criterion, by applying the progressive quasi-static approach, the key impact parameters which include critical the impact contact force and displacement are successfully solved. Some numerical results provided in the literature are utilized to give initial validation of the model. Additionally, the detailed experimental tests are performed on the hybrid plate specimens to further validate the model developed. Using the validated model, the effects of the thickness ratio of the viscoelastic layer to the overall plate and Young's moduli of the viscoelastic layer on the dynamic responses are discussed. The outputs provide important references for this type of composite hybrid structures with improving the anti-vibration and impact resistant capabilities.

Railway crossing vertical vibration response prediction using a data-driven neuro-fuzzy model – Influence of train factors

This paper provides a data-driven model of the vibration response of a railway crossing during vehicle passages. Many of the features of trains passing through instrumented crossing are extracted from measured data. Based on the feature selection process, speed, dynamic axle load and the number of wagons are found proper inputs in the prediction model. Train-crossing interaction response at a crossing due to passing trains is modeled from a data-driven Neuro-Fuzzy soft computing approach. Locally Linear Model Tree (LOLIMOT) is applied to predict the crossing nose acceleration. The model comparison against measurements shows that the ability to predict the extrapolation cases at off-range speeds has satisfactory compatibility. The monitored passing trains are ranked based on the LOLIMOT input space dimension cuts and extrapolation of the model up to higher train speeds. The influence of train factors (i.e. speed, dynamic axle load, number of wagons) on crossing response is demonstrated. Also, based on the analysis results, it is concluded that with a steady increase in train speeds, some trains show a greater amplification in vibration response than others. The results can be applied in data processing in the crossing vibration monitoring and detection of trains with crossing impact sensitive to speed increasing that can lead to proper operation policies to reduce damages and maintenance costs.

Multipoint Vibration Response Prediction under Uncorrelated Multiple Sources Load Based on Elastic‐Net Regularization in Frequency Domain

In order to solve the problems of large number of conditions at inherent frequencies and low prediction accuracy when using multiple multivariate linear regression methods for vibration response prediction alone, an elastic‐net regularization method is proposed. Firstly, a multi‐input and multioutput linear regression model of the multipoint frequency domain vibration response is trained using historical data at each frequency point. Secondly, the trained model under each frequency point is improved by the elastic regularization. Finally, the model is used in a working situation. The predicted vibration response on the experimental dataset of cylindrical shell acoustic vibration showed that the improvement of the multivariate regression vibration response prediction model by elastic regularization can better improve the accuracy and reduce the large number of conditions at some frequencies.

Experimental validation of moving spring-mass-damper model for human-structure interaction in the presence of vertical vibration

The interaction between structures and walking humans is an important factor in vibration serviceability assessment of slender, lightweight, and low-damping structures. When on bridges humans form a human-structure system and interact with the structural vibration. The conventional vertical moving force (MF) model neglects human-structure interaction (HSI) effects. In contrast, a moving spring-mass-damper (MSMD) model is shown to have the potential to incorporate HSI effects leading to more accurate vibration response prediction. The MSMD model parameters have been much studied in biomechanics. However, the literature lacks an experimental calibration of the MSMD model parameters on a vibrating surface for vibration serviceability design and assessment purposes. Consequently, an experimental-numerical methodology is developed to calibrate the MSMD model parameters in the worst-case (resonance) scenario by matching measured and simulated vibration responses. To facilitate simple implementation of HSI effects into engineering practice, results of simulation using a calibrated equivalent moving force (EMF) model are also shown. The walking force on rigid surfaces along with vibration responses of two lively full-scale laboratory footbridges are measured for 23 test subjects by performing a total of 295 trials on the two structures. A parametric study is first performed on the MSMD model using the experimental results. The experimental results of the Monash footbridge are then used as the training dataset to extract optimal MSMD model parameters. The results from the Warwick footbridge are used to validate the model. The validation tests results show a considerable improvement in the vibration response prediction using both models. It was found that when walking in resonance with the bridge, the walker can be modelled to have natural frequency equal to the resonant frequency of the bridge, and that the damping ratio is larger for heavier walkers.

Prediction of floor responses to crowd bouncing loads by response reduction factor and spectrum method

Bouncing is a typical rhythmic crowd activity in entertaining venues, such as concert halls and stadia. When the activity’s frequency is close to the natural frequency of the occupied structure, the corresponding bouncing loads can cause intense structural vibrations resulting in vibration serviceability problems, even structural damage. This study suggests a method for prediction of vibration response due to crowd bouncing by a response reduction factor (RRF) in conjunction with a previously established response spectrum approach pertinent to a single person bouncing. The RRF is defined as a ratio between structural responses with and without taking into account synchronization of body movements of individuals in a bouncing crowd. The variations of RRF with number of persons, structural frequency, bouncing frequency and structural damping ratios have been studied using experimental records of crowd bouncing loads. Based on the findings a practical design curve for RRF has been proposed. Application of the proposed method has been validated on numerical simulations and field measurements of a long-span floor subjected to crowd bouncing loads.

MIMO LS-SVR-Based Multi-Point Vibration Response Prediction in the Frequency Domain

To predict the multi-point vibration response in the frequency domain when the uncorrelated multi-source loads are unknown, a data-driven and multi-input multi-output least squares support vector regression (MIMO LS-SVR)-based method in the frequency domain is proposed. Firstly, the relationship between the measured multi-point vibration response and unmeasured multi-point vibration response is formulated using the transfer function in the frequency domain. Secondly, the data-driven multiple regression analysis problem of multi-point vibration response prediction in the frequency domain is described formally, and its mathematical model is established. With the measured multi-point vibration response as the input and the unmeasured multi-point vibration response as the output, the vibration response history data are assembled as a MIMO training dataset at each frequency. Thirdly, using the MIMO LS-SVR algorithm and MIMO history training dataset, the multi-point vibration response prediction model is built at each frequency point. By comparing the transmissibility matrix method, multiple linear regression model-based method, and MIMO neural network method, the application scope of the proposed method and its advantages are analyzed. The experimental results for acoustic and vibration experiment on a cylindrical shell verified that the MIMO LS-SVR-based method predicts the multi-point vibration response effectively when the loads are unknown, and has higher precision than the transfer function method, multiple linear regression method, MIMO neural network method, and transmissibility matrix method.

Vibration response prediction of coated blisks under multi-point non-contact excitations using mistuning identification data

The mistuning and excitations of the real engineering coated blisk are very complex and it is difficult to predict the vibration response. In this study, a numerical method of response prediction for coated blisks under multi-point non-contact excitations is proposed. The purpose of applying multi-point non-contact excitations to the blades is to get closer to the actual excitations condition of coated blisks. A non-rotating coated academic blisk is used as the research object, the component mode mistuning (CMM) reduced-order technique focusing on blade mistuning is improved to establish the response prediction model of the coated blisk, which includes quantized parameters of the blade substrate mistuning and the mistuning caused by coating. Meanwhile, the effects of the mass, stiffness and damping mistuning of the blisk substrate and the coating on the response are comprehensively considered in the model. In order to preserve the simulation accuracy of the response prediction model, the blade substrate mistuning and the mistuning caused by coating are identified, and the reduced-order model (ROM) is updated by the identification results of mass and stiffness mistuning. The response predictions of the numerical case and actual case of the non-rotating simplified coated academic blisk are carried out respectively. For the numerical case, the results of response prediction are in good agreement with the response calculation results of the high fidelity finite element model (FEM). Compared with the numerical case, the error between the predicted response and the tested response is larger, but this error level is sufficient to meet the requirements of engineering applications. All the results show that the proposed method is effective for predicting the response of the non-rotating coated academic blisks under multi-point excitations.

Modelling and prediction of free vibration response of adhesive bonded corner joint structures

In this paper, free vibration analysis in the adhesive bonded corner joints have been performed using finite element method of ANSYS APDL code. To establish stability and accuracy of the present work, modal responses (natural frequencies and corresponding mode shapes) are evaluated and compared with the existing literature. The influence of various material properties, laminate sequences and aspect ratio on the modal responses of the joint structure have been investigated in details. From the investigation, it is observed that the Glass/epoxy material having a higher aspect ratio show more resistance to vibration. Further, the significance and sensitivity analysis of various factors are evaluated for the natural frequencies of the adhesive joint. The prediction of modal frequencies is performed using ANOVA and ANN method and the most accurate process has been determined.

A nonlinear dynamic vibration model of a defective bearing: the importance of modelling the angle of the leading and trailing edges of a defect

Rolling element bearings eventually become worn and fail by developing surface defects, such as spalls, dents and pits. Previous researchers have tested bearings with defects that have sharp rectangular edges that were used to develop analytical models of a defective bearing. These models have limitations that require smooth surfaces and constant curvature of the bearing components; as well as assuming the defect profile. A method has been created to capture the surface topography of a bearing defect. A numerical model has been developed for a rolling element bearing that uses the measured defect profile and removes the limitations of models by previous researchers that use analytical expressions for contact area and force. The predicted vibration response of a bearing with a defect that has sloped leading and trailing edges on the outer and inner raceway was compared with experimental results. It was found that the new numerical model was able to predict the vibration response of a defective bearing. The defect topographies and the developed model have been made publicly available.

Simulation research of the Pulsating Excitation and Vibration Response of Propeller in Wake Field

The pulsating excitation and vibration response of a highly skewed propeller, running in wake field, was studied by the Fluid-Solid Interaction (FSI) simulation. Coupling calculation of elastic propeller was realized on ANSYS-CFX modules based on the CFD/FEM FSI method, and the rigid results were compared. The results show that, the pulsating thrust of the elastic propeller considering FSI effect has the same low frequency peak as the rigid except the low frequency elastic peak (the first-order natural frequency of propeller), and the low-frequency broadband force amplitude of the elastic propeller is an order of magnitude higher than the rigid. In addition to the correlation between blade frequency and shaft frequency, the propeller also has obvious vibration response at the lower natural frequency. The results are significant to the prediction and control of propeller vibration response.

An overview of dynamic modeling of rolling-element bearings

The marvelous uniqueness of vibration responses of faulty roller bearings can be simply observed through its vibration signature. Therefore, vibration analysis has been claimed as an effective tool not only for primitive detection but also for subsequent analysis. The dynamic behavior of roller bearings has been investigated by systematic modeling of system and its validation under diverse operating conditions. This article presents an overview of imperative marks in the development of dynamic modeling of rolling-element bearing, which especially predicted vibration responses of damaged bearings. This study aims to address dimensional analysis; a new and imperative way to model the dynamic behavior of rolling-element bearings and their real-time performance in a rotor-bearing system. The findings are described with influential advantages over earlier research to pinpoint the intention behind its development. A literature summary is trailed by remarkable findings and future directions for research.

Prediction of Vortex-Induced Vibration Response of Deep Sea Top-Tensioned Riser in Sheared Flow Considering Parametric Excitations

Abstract It is widely accepted that vortex-induced vibration (VIV) is a major concern in the design of deep sea top-tensioned risers, especially when the riser is subjected to axial parametric excitations. An improved time domain prediction model was proposed in this paper. The prediction model was based on classical van der Pol wake oscillator models, and the impacts of the riser in-line vibration and vessel heave motion were considered. The finite element, Newmark-β and Newton‒Raphson methods were adopted to solve the coupled nonlinear partial differential equations. The entire numerical solution process was realised by a self-developed program based on MATLAB. Comparisons between the numerical calculation and the published experimental test were conducted in this paper. The in-line and cross-flow VIV responses of a real size top-tensioned riser in linear sheared flow were analysed. The effects of the vessel heave amplitude and frequency on the riser VIV were also studied. The results show that the vibration displacements of the riser are larger than the case without vessel heave motion. The vibration modes and frequencies of the riser are also changed due to the vessel heave motion

Dynamic modeling and vibration control of a coupled rigid-flexible high-order structural system: A comparative study

A Generalized Differential Quadrature (GDQ) as an accurate numerical technique based on non-uniform grid point distribution, Chebyshev-Gauss-Lobatto (CGL) and Roots of the Legendre Polynomial (RLP) is investigated for active vibration suppression of flexible spacecraft appendages embedded with piezoelectric (PZT) patches. The flexibility of the system is modeled as a sandwich panel with honeycomb core via high-order theories to monitor extra vibrations of the system for high accuracy missions. The coupled governing partial differential equations of the motion and the corresponding boundary conditions were derived through Hamilton's principle. The spacecraft is maneuvered by constant and harmonic torques with different excitation frequency to analyze the vibration sensitivity of the system. The Strain Rate Feedback (SRF) control law is utilized to apply the effects of PZTs action on vibration suppression of flexible appendages. The numerical study of the system characterized by coupled rigid-flexible (high-order) dynamic provides a powerful general tool for analysis of maneuvering spacecraft with smart sandwich appendages and demonstrates the importance of the proposed formulation for the prediction of higher mode vibration response of flexible parts.