Vibration Environment Test Research Articles

Dynamic identification methods and artificial intelligence algorithms for damage detection of masonry infills

The failure of non-structural components after an earthquake is among the most expensive earthquake-incurred damage, and may also have life-threatening consequences, especially in public buildings with very crowded facilities, because exposition is high and the risk increases accordingly. The assessment of existing non-structural components is particularly complex because in-depth in situ investigation is necessary to detect the presence of deficiencies or damage. This problem concerns interior and exterior partitions made of various materials (e.g., glass and masonry), as well as equipment and facilities in construction (building, industry, and infrastructure). Defining the boundary conditions of these components is of paramount importance. Indeed, external restraints (i) affect dynamic properties and, thus, the action experienced during an earthquake, and (ii) influence the capacity to detach the component before failure from the bearing structure (e.g., an infill wall connected to the main structural frame, or equipment connected to secondary structural members such as floors). The authors, therefore, conducted environmental vibration tests of an infill wall and refined a finite element model to simulate typical damage scenarios to be implemented on the wall. Selected damage scenarios were then artificially realized on the existing infill and further ambient vibration tests were performed to measure the accelerations for each of them. Finally, the authors used these accelerations to detect the damage by means of established OMA, as well as innovative machine learning techniques. The results showed that convolutional variational autoencoders (CVAE), coupled with a one-class support vector machine (OC-SVM), identified the anomaly even when the OMA exhibited limited effectiveness. Moreover, the machine learning procedure minimizes human interaction during the damage detection process.

FE Model Updating of Continuous Beam Bridge Based on Response Surface Method

In this paper, A high-order response surface method is proposed for finite element model updating of continuous beam bridges. Firstly, based on visual inspection and environmental vibration testing, the peak picking (PP) method and random subspace identification (SSI) method are used to identify the dynamic characteristic parameters of the structure. Then, the finite element model of the continuous beam bridge is updated based on the third-order response surface method. It can be concluded that the results of the updated finite element model are in good agreement with the test results, and the maximum error between the calculated and measured frequency is less than 3%, with MAC values greater than 85%. Moreover, the updated finite element model can reflect the current situation of real bridges and serve as the basis for bridge health monitoring, damage detection, and safety assessment.

Estimation of the fundamental period of vibration of the dental clinics and the dental classroom of the Catholic University of Cuenca using environmental vibration recordings

In the Faculty of Dentistry of the Catholic University of Cuenca, located in the city of Cuenca, province of Azuay. The lecture hall and the clinics of the faculty are built. These structures were built during 2018 and 2019. Due to the seismic events occurred in recent years, monitoring was carried out to obtain the characterization of the dynamic behaviour. The two structures are formed by a structural system based on structural steel frames (beam-column), the structure for laboratory use has metal columns filled with concrete, while the structure for classroom use has metal columns without concrete filling. The main objective was to obtain the vibration periods experimentally from the recording of environmental vibrations and also to obtain them analytically with mathematical models elaborated in structural analysis programs and environmental vibration tests were performed. The results show that building 1, composed by the dentistry clinic, obtained a vibration period of 0.41 s in X and 0.33 s in Y (Analytical Model); and, in the environmental vibration test it showed a period of 0.46 s in X and, 0.30 in Y. Building 2, composed of the dental faculty classroom, obtained periods of 0.53 s in X and 0.29 s in Y (Analytical Model). While in the environmental vibration studies they gave values of 0.52 s in X and 0.26 in Y.

Review on the Prediction and Control of Structural Vibration and Noise in Buildings Caused by Rail Transit

As rail transportation continues to advance, it provides significant convenience to the public. However, the environmental vibration and noise generated during its operation have become major concerns for residents living near rail lines. In response to these concerns, the “Law on the Prevention and Control of Noise Pollution” was promulgated in China, bringing attention to this issue within the rail transportation sector. This review summarizes the regular features observed in environmental vibration and secondary structural noise tests on different sections, including embankment sections, bridge sections, underground railroads and vehicle sections. Furthermore, it introduces several physical models utilized in the study of environmental vibration and secondary structural noise, focusing on three key aspects: excitation sources, propagation paths and the modelling of building structures. This paper also explores the introduction of data-driven models related to big data and artificial intelligence to enhance the accuracy and efficiency of research in this field and provides an overview of commonly used measures to control train-induced environmental vibrations and secondary noise in buildings. These measures are discussed in terms of excitation sources, propagation paths, and receivers, offering insights into effective strategies for mitigating the impact of rail transportation on nearby residents. Finally, this study highlights the primary findings and offers pertinent recommendations. These recommendations include considerations regarding both laboratory and on-site testing procedures, challenges associated with the deployment of data-driven models and key parameters for designing and utilizing low-stiffness fasteners.

Application of Sonic Tests and Modal Identification in the Characterization of Masonry Walls

This work contemplates the application of non-destructive techniques, sonic and environmental vibration tests, on a set of soil-cement compressed earth blocks reinforced masonry walls, which were built in laboratory, under the project SHS-Multirisk. The present work constitutes a comparative study that aimed at verifying the reliability of the sonic test method in masonry characterization and in testing a methodology of combined tests for structural assessment. For that purpose, a numerical model of the walls was developed and calibrated with the mechanical properties that were calculated from the sonic tests data. The results of the simulation of the numerical model were compared with the results of the environmental vibration tests, which enabled to reach a correlation between the frequencies, as well as enabling the indirect sonic tests, which were performed in the vertical direction, to result in an accurate prediction of the Young modulus to be used in the numerical models.

A three-stage criterion to reveal the bolt self-loosening mechanism under random vibration by strain detection

To study the self-loosening mechanism of fastening bolts, the triaxial random vibration environment test for a print circuit board is carried out with the triaxial vibrostand, and the simulation of the self-loosening process of bolts under the same vibration environment is made by the finite element method analysis, which obtains the curves of root mean square value of strain of monitored points varying with tightening torques. The strain curves obtained from the simulation have good consistency with both the test results and the fitted curves of the mode frequency differences, which effectively reveals the self-loosening mechanism of fastening bolts. Further the curves of the root mean square of strains respectively under the triaxial and uniaxial random vibrations are compared, and the difference between the curves reflecting their bolt self-loosening extents is found. Thus, a new method for determining the bolt self-loosening in the triaxial random vibration test by the root mean square of strains is proposed.

Experimental and numerical investigations of the dynamic responses of low and medium speed maglev train-track-bridge coupled system

In recent years, low and medium speed maglev (LMSM) transportation system has been greatly promoted in China to meet different social demands. Accordingly, a LMSM train using levitation frames with mid-set air springs has been developed, and it is necessary to investigate the dynamic characteristics of its train-track-bridge coupled system. First, environmental vibration tests were conducted on the bridge to study its self-vibration characteristics. Then, field tests were carried out on this coupled system within the 60 km/h speed range. Subsequently, a three-dimensional rigid-flexible coupled dynamics model of the system was developed to evaluate its dynamic behavior at higher speeds. Results show that the first-order vertical and lateral bending frequencies of the bridge are 7.32 Hz and 6.00 Hz, respectively; train speed has little effect on the vertical dynamic displacement of the track-bridge system, yet has a significant impact on the acceleration responses of the coupled system; key dynamic indicators of the bridge meet the relevant requirements; the vertical ride quality of car body is not so good as that in the lateral direction, but on the whole the train has “Good” ride quality. These results can provide a useful reference for the optimal design of LMSM transportation systems.

Simulación numérica del comportamiento sísmico de muros de concreto reforzado

El sistema constructivo de muros delgados de concreto reforzado (MDCR) es uno de los más utilizados actualmente en países como Bolivia, Perú, Venezuela, Ecuador, y Colombia. Estas edificaciones se han diseñado con la normatividad de estos países, la cual, en la mayoría de los casos no tiene prescripciones específicas adecuadas para este tipo de construcción, puesto que sus lineamientos para diseño de concreto reforzado se basan en las versiones previas del ACI-318, definidas para el sistema tradicional de muros de concreto reforzado, que dispone de muros con espesores mayores que facilitan el detallado del refuerzo, el confinamiento del concreto y permiten controlar la inestabilidad fuera del plano. Diversas investigaciones y los eventos sísmicos de Chile en 2010 y Nueva Zelanda en 2011 sugieren que el sistema de MDCR podría presentar un desempeño limitado ante un evento sísmico, por lo tanto, se requiere caracterizar mejor su comportamiento estructural. Con la finalidad de evaluar el desempeño de estas edificaciones, se propone el uso de un software comercial, ampliamente usado en las oficinas de cálculo, para la modelización de MDCR y de los edificios de este sistema constructivo, considerando su comportamiento no lineal. Se usará la formulación de elementos en capas (Shell layered) del programa ETABS. Los modelos de muros son ajustados mediante la respuesta experimental de ensayos de muros representativos de este sistema estructural, tomados de referencias bibliográficas reconocidas. El modelo de las edificaciones se ajustará mediante la identificación de las propiedades dinámicas reales obtenidas de la instrumentación de un edificio típico, mediante una prueba de vibración ambiental. Los resultados de la simulación numérica permitieron evaluar el comportamiento de estas construcciones y confirman que este tipo de software es una herramienta válida, relativamente simple y de bajo consumo computacional para obtener una respuesta más acertada del desempeño de este sistema constructivo.

Fem Model Calibration of Experimental Environmental Vibration Tests on Two Churches Hit by L’Aquila Earthquake

ABSTRACT The paper deals with the seismic investigation of two masonry churches, namely Visitazione and San Giuliano, which are located in Poggio Picenze, a small town about 10 km far from L’Aquila. The seismic response assessment of the churches, which were damaged by the severe seismic event occurred in Italy on 2009 April 6th, has been performed by means of experimental dynamic tests and numerical analyses. Firstly, an experimental campaign based on Ambient Vibration Tests (AVTs), which are non-destructive tests especially applied to historical and monumental buildings for evaluating their modal response, has been carried out on the selected constructions in the framework of a cooperation activity between the Ss. Cyril and Methodius University of Skopje and the University of Naples “Federico II”. Such an experimental activity has allowed to obtain the dynamic properties of the examined structures, namely natural frequencies, vibration mode shapes and damping coefficients. The experimental results have been subsequently used to implement a numerical FEM model of the churches in the ABAQUS non-linear analysis software environment. Dynamic linear FEM analyses have been conducted in order to calibrate the experimental results in order to simulate as well as possible the real structural behaviour of inspected churches. Finally, the performed analyses have been of a fundamental importance for both detecting damages into the constructions and programming effective retrofitting interventions.

Adaptive vibration control on electrohydraulic shaking table system with an expanded frequency range: Theory analysis and experimental study

Abstract Active vibration control using electrohydraulic shaking table (EHST) system is widely applied in civil engineering, automotive industry, environmental vibration testing and other situations where large actuating forces are needed. However, the electrohydraulic actuators (actuating systems) often suffer from drawbacks of limited frequency bandwidth, varying system parameters and so forth. In view of the limits mentioned above, this study hopes to seek out proper solutions to minimize the influence from those drawbacks. We first design a full state feedback-feedforward servo controller, which is able to extend the frequency bandwidth of EHST system, by constructing the analytical models of the servo valve and hydraulic cylinder. Numerical simulations show that the proposed servo controller is able to compensate for the attenuation-band of hydraulic cylinder and thus improve the upper frequency limit of the whole system to a degree that is higher than the natural frequency of servo valve. Afterwards, we propose a frequency domain adaptive power level control (APLC) algorithm for solving the problem of parametric variations of EHST system in application of power level control (i.e., simulate vibration based on certain power spectrum). Numerical simulations show that although APLC algorithm is not able to get exactly same spectrum and waveform at every independent trial, the power level of every trail will finally converge to the target power spectrum. Finally, an experimental validation was conducted based on an EHST system with 3 ton maximum force and 1.2 m × 1.2 m horizontal table. The results show that the proposed algorithms have greatly improved the effective bandwidth and the power level of the controlled system response can finally match the target power spectrum within an accuracy of ±3 dB.

Environmental Vibration Testing of Space Payloads

Engineers ensure payloads such as satellites will not malfunction with extensive, but carefully limited, vibration testing

Research on D Subminiature Connector Plugging Method on Spacecraft

This paper reviews the applications of D Subminiature connectors in assembly and integration process of spacecraft. The locking force control is a key factor through analysis of D-Sub connectors plugging method, To meet the general locking force control of male screw of D-Sub connectors in assembly and integration process of spacecraft, the vibration environment test of cable bracket with D-Sub connectors is designed to set the torque value of male screws of D-Sub connectors, and two kinds of torque wrenches are designed.

Health monitoring device design and application for large synchronously excited multi-shaker vibration test facility

There are different kinds of equipments distributed in different locations for a large complicated multi-shaker vibration test facility, so it is challenging to monitor the real state of test facility thoroughly during its operation. Long-term operation of this test facility will lead to the degradation of reliability and malfunction, and sometimes the emergency stop of the whole test system that threatens the safety of the spacecraft seriously. This paper presents in detail the design and application of a set of health monitoring device for a large multi-shaker vibration test facility which is capable of monitoring the operation state in real time and predicting the potential malfunction of the whole test facility to ensure the reliability of this large test system and safety of the spacecraft during its environmental vibration test.

An Innovative Diagnostic Film for Structural Health Monitoring of Metallic and Composite Structures.

A novel lightweight diagnostic film with sensors/actuators and a multiple-path wiring option using inkjet printing was developed. The diagnostic film allows for systematic, accurate, and repeatable sensor placement. Furthermore, the film is highly flexible and adaptable for placement on complex configurations. The film can be attached to the surface of the structure through a uniform secondary boundary procedure or embedded within the composite layup during curing. The surface-mounted film can simply be peeled off for repair or replacement without scratching or damaging the part. The film offers significant weight reduction compared to other available technologies. A set of extreme temperature, altitude, and vibration environment test profiles were carried out following the Radio Technical Commission for Aeronautics (RTCA) DO-160 document to assess the durability and performance of the diagnostic film for onboard application. The diagnostic film was shown to be durable and reliable in withstanding the variable operational and harsh environmental conditions of tests representing the conditions of regional aircraft.

Control algorithm update for multi-input multi-output random environment test

Abstract When conducting multi-input multi-output (MIMO) random vibration environment test, response spectral lines of under test article may exceed their tolerances and some of them can hardly be controlled by control algorithms. The cause of this phenomenon is the high level noises in the input forces, which are induced by the inverse of the ill-conditioned frequency response function matrices. These spectral lines may even trigger the instability of control algorithms and eventually result in an accidental test shutoff. The classical control algorithm for MIMO random vibration environment test contributed by Smallwood is analyzed theoretically and experimentally in the paper to reveal its weakness on dealing with this kind of error. An updated algorithm is proposed on the basis of inverse theory to overcome the difficulty of controlling these stubborn spectral lines. The main idea of the work is to reduce the level of noise components in input forces by regularizing singular values of ill-conditioned frequency response function matrices. An adjusting rule is set up according to the auto-power spectra tolerances. A simulation and an experiment are supplied in the paper to verify the effectiveness of the updated algorithm, the results are satisfactory.

Airborne Transducer Integrity under Operational Environment for Structural Health Monitoring.

This paper investigates the robustness of permanently mounted transducers used in airborne structural health monitoring systems, when exposed to the operational environment. Typical airliners operate in a range of conditions, hence, structural health monitoring (SHM) transducer robustness and integrity must be demonstrated for these environments. A set of extreme temperature, altitude and vibration environment test profiles are developed using the existing Radio Technical Commission for Aeronautics (RTCA)/DO-160 test methods. Commercially available transducers and manufactured versions bonded to carbon fibre reinforced polymer (CFRP) composite materials are tested. It was found that the DuraAct transducer is robust to environmental conditions tested, while the other transducer types degrade under the same conditions.

Dynamic Model Updating of Satellite Structure Using Vibration Test Data

This paper presents the model updating technique for satellite structure by using the vibration environment test data. In the paper, several key technique issues related to the model updating of satellite structure, such as selection of updating parameters, model reduction, damping identification, etc, have been discussed. As an example, the model updating for a satellite central cylinder structure using the shaker vibration environment test results is described. It is proved that the techniques presented are effective for engineering applications.

Optimal Force Inputs for Environmental Vibration Testing of Full Scale Slender Aerospace Vehicles

A hypothesis is presented in this paper for evaluating the root mean square (RMS) errors in acceleration for determining the optimal locations of the exciters during the vibration testing of slender flexible structures, e.g., missiles, rockets, and space vehicles. Simulation studies are carried out on a realistic slender nonuniform beam in a free–free conditions to characterize the error estimations in the desired and achieved acceleration spectra at different locations of the structure. The optimal locations of the exciters are obtained using a real-coded genetic algorithm (RCGA) with minimal required force levels and the corresponding RMS error estimates. It has been observed that RMS force levels are a minimum when the exciter and control sensor locations are noncollocated. This study also provides a methodology in deriving the optimum force levels required for the environmental vibration testing of the full vehicle structure. The RMS error levels are found to be a minimum at the control sensor locations.

Dynamic Load Test and Data Analysis of Tiansheng Bridge

This test took dynamic strain detection method depending on time history curve of the dynamic deflection or the dynamic strain analysis of moving load in the control section to obtain impact factor. Using the method of environmental random vibration testing tested vibration response signals of L / 4 section of bridge test span , the cross section and 3 L / 4 section to identify the dynamic characteristics parameters of the overall vibration of Bridge, so that to determine current situation of application , assess the carrying capacity of bridge and test design load bearing capacity. According to the results of load test,the bearing capacity of Tiansheng bridge meets the requirements of "road - grade I" load level.

The Present Situation and Progress of Vibration Environment Test Technology

This paper reviews the research status of vibration environment test equipment and technology. The development of modern vibration measuring sensors, types, processing technology, structure principle and the main performance index of the sensor is made by brief introduction and analysis, the problems existing in the vibration environment test is pointed out, at the same time for their application in the field of modern industry be also made by corresponding introduction.