A validated robust and automatic procedure for vibration analysis of bridge structures using MEMS accelerometers

2020 ◽  
Vol 14 (3) ◽  
pp. 327-354
Author(s):  
Mohammad Omidalizarandi ◽  
Ralf Herrmann ◽  
Boris Kargoll ◽  
Steffen Marx ◽  
Jens-André Paffenholz ◽  
...  
Keyword(s):  
Vibration Analysis ◽  
Damping Ratio ◽  
Fem Analysis ◽  
Cost Effective ◽  
Analysis Procedure ◽  
Modal Parameters ◽  
Bridge Structure ◽  
Modal Damping ◽  
Mems Accelerometers ◽  
Better Than

AbstractToday, short- and long-term structural health monitoring (SHM) of bridge infrastructures and their safe, reliable and cost-effective maintenance has received considerable attention. From a surveying or civil engineer’s point of view, vibration-based SHM can be conducted by inspecting the changes in the global dynamic behaviour of a structure, such as natural frequencies (i. e. eigenfrequencies), mode shapes (i. e. eigenforms) and modal damping, which are known as modal parameters. This research work aims to propose a robust and automatic vibration analysis procedure that is so-called robust time domain modal parameter identification (RT-MPI) technique. It is novel in the sense of automatic and reliable identification of initial eigenfrequencies even closely spaced ones as well as robustly and accurately estimating the modal parameters of a bridge structure using low numbers of cost-effective micro-electro-mechanical systems (MEMS) accelerometers. To estimate amplitude, frequency, phase shift and damping ratio coefficients, an observation model consisting of: (1) a damped harmonic oscillation model, (2) an autoregressive model of coloured measurement noise and (3) a stochastic model in the form of the heavy-tailed family of scaled t-distributions is employed and jointly adjusted by means of a generalised expectation maximisation algorithm. Multiple MEMS as part of a geo-sensor network were mounted at different positions of a bridge structure which is precalculated by means of a finite element model (FEM) analysis. At the end, the estimated eigenfrequencies and eigenforms are compared and validated by the estimated parameters obtained from acceleration measurements of high-end accelerometers of type PCB ICP quartz, velocity measurements from a geophone and the FEM analysis. Additionally, the estimated eigenfrequencies and modal damping are compared with a well-known covariance driven stochastic subspace identification approach, which reveals the superiority of our proposed approach. We performed an experiment in two case studies with simulated data and real applications of a footbridge structure and a synthetic bridge. The results show that MEMS accelerometers are suitable for detecting all occurring eigenfrequencies depending on a sampling frequency specified. Moreover, the vibration analysis procedure demonstrates that amplitudes can be estimated in submillimetre range accuracy, frequencies with an accuracy better than 0.1 Hz and damping ratio coefficients with an accuracy better than 0.1 and 0.2 % for modal and system damping, respectively.

ODS Analysis on the Rack of Batching System Mixer

2013 ◽  
Vol 437 ◽  
pp. 257-260
Author(s):  
Li Zhang ◽  
Guang Yuan Nie
Keyword(s):  
Working Condition ◽  
Damping Ratio ◽  
Side Surface ◽  
Modal Parameters ◽  
Modal Shape ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Before And After ◽  
Structure Vibration ◽  
Batching Machine

By using ODS (Operating Deflection Shapes) technology, the modal parameters of the rack of a batching system mixer under operating condition are identified and the modal shape and modal damping ratio of the rack in a few working frequencies are obtained. The results show that, the batching machine rack on working condition has a significant effect on some frequency and the work principal modes that appear as before and after exercise of two beams above the rack and swaying motion of the brackets of the two side surface. This paper provides a valuable reference for the structure vibration optimization of batching system mixer.

Operational Modal Analysis of Broaching Machine

2012 ◽  
Vol 159 ◽  
pp. 170-175
Author(s):  
Lv Gao Lin ◽  
Shen Shun Ying ◽  
Shu Qiong Chen ◽  
Xiao Tian Lv
Keyword(s):  
Cutting Force ◽  
Natural Frequency ◽  
Fundamental Frequency ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Modal Parameters ◽  
Modal Shape ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Cutting Velocity

Modal parameters for LG51SH broaching machine from operational responses are studied to examine the dynamic properties of mechanical structure. The operational modal is analyzed using PolyMAX method with responsive data of key point in broaching machine, which is excited in practical broaching operation and tested by LMS SCADAIII-105 system. The identified steady state modal, representative modal shape, modal damping ratio and natural frequency in broaching are presented. The test and analysis result shows that there are natural frequency of 38Hz and 192Hz, which are close to multiple of the fundamental frequency of cutting force in broaching, 6Hz, therefore, reasonable cutting velocity should be adopted to void producing fundamental frequency of cutting force in broaching.

Rotor-Blade Coupled Torsional Vibration Analysis Using Modal Parameters Based on FEM Analyses and Experiments

2010 ◽  
Author(s):  
Akira Okabe ◽  
Koki Shiohata ◽  
Takeshi Kudo ◽  
Hideo Yoda ◽  
Shigeo Sakurai ◽  
...  
Keyword(s):  
Torsional Vibration ◽  
Vibration Analysis ◽  
Rotor Blade ◽  
Fem Analysis ◽  
Design Tool ◽  
Modal Parameters ◽  
Disk System ◽  
Fem Method ◽  
Standard Product ◽  
Model Rotor

The quasi-modal technique is used for rotor-blade coupled torsional vibration analysis due to its unique characteristics in providing a visually reduced model. Given the rapid advances in computation technology in recent years, the FEM method is now widely used as a standard product design tool in many industries, because it can reflect a more detailed structure quickly in the design process. In this paper we proposed the use of a commercially available FEM method program (ANSYS®) to calculate quasi-modal parameters of the bladed disk system. This program was applied to the model rotor of two disks with continuously coupled blades. Rotor-blade coupled torsional frequencies of the model rotor based on the FEM based quasi-modal technique were compared with a complete FEM analysis of the model rotor. Both methods gave results in good agreement. We also compared the frequencies measured through rotation testing of the model rotor to calculations. Finally, we presented the procedure for calibrating modal parameters based on the measured blade-disk frequencies. Quasi-modal modeling was judged practicable for feeding back test results to achieve higher accuracy.

A Modeling Method for Vibration Analysis of a Stator Frame of Turbine Generators and Its Application to a Design System: Vibration Analysis and Analysis System

2003 ◽  
Author(s):  
Shigeru Sakamoto ◽  
Tadafumi Kubo
Keyword(s):  
Vibration Analysis ◽  
Damping Ratio ◽  
Modeling Method ◽  
Design System ◽  
Turbine Generator ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Ring Mode ◽  
Structural Parts ◽  
Analysis System

A practical modeling method for predicting vibration characteristics of turbine generator stator frames was developed. The structural parts that compose a stator frame were categorized into three groups: parts that affect ring-mode vibration as mass, parts that affect it as stiffness, and parts that affect it as both. A proper boundary condition, the value of a modal damping ratio, and an accurate representation of exciting forces were examined. The modeling method was then applied to another turbine generator. It was found that the predicted natural frequency agrees with measured one within only a 3% error. Based on the modeling method, a vibration analysis system for design was developed.

Prediction and Avoidance of Chatter in Milling of Thin-Walled Structure

2009 ◽  
Vol 407-408 ◽  
pp. 404-407 ◽  
Author(s):  
Hiroyuki Sasahara ◽  
Yoshihisa Naito
Keyword(s):  
Sound Pressure ◽  
Damping Ratio ◽  
Stability Limit ◽  
Fem Analysis ◽  
Modal Parameters ◽  
Chatter Stability ◽  
3D Cad ◽  
Cutting Experiment ◽  
Thin Walled ◽  
Impulse Force

An objective of this study is to develop a new method for the prediction and the avoidance of chatter vibration in milling operation of thin-walled structure by using 3D-CAD and CAE approach. Also, a new identification method for the modal parameters of a vibration system by analyzing radiated sound pressure from vibrated workpiece accelerated by an impulse force is proposed. Then chatter stability lobes are predicted using those modal parameters. Stiffness and modal shapes of the workpiece were obtained using commercial finite element method (FEM) code, and the model was made by 3D-CAD. The damping ratio, which cannot be determined through FEM analysis, was identified from the relationship between the sound pressure radiated from the workpiece and the impulse force. Chatter stability limit was analyzed with the modal parameters obtained through these procedures, and compared with the cutting experiment on the chatter stability limit. The experimental and predicted stability limits are in good agreement. The proposed procedure will help to set the cutting conditions to avoid the chatter.

scholarly journals Modal Parameter Tracking in a Carbon Fiber-Reinforced Structure over Different Carbon Fiber Angles

2021 ◽  
Vol 9 (11) ◽  
pp. 1214
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Damping Ratio ◽  
Modal Parameters ◽  
Fiber Reinforced ◽  
Tracking Method ◽  
Fiber Angle ◽  
Modal Damping Ratio ◽  
Modal Damping ◽  
Mode Tracking ◽  
Mode Order

The dynamics of carbon fiber-reinforced plastic (CFRP) change according to the carbon fiber angle, and a mode order shift may occur in CFRP specimens. The variation trends in modal parameters differ in each mode; thus, an efficient mode-tracking method is needed to identify the reliable dynamic behavior of the CFRP structure. The mode-tracking method was assumed to be applicable for the same configuration of the tested specimen except for the differences in carbon fiber angle of the CFRP specimen. Simple rectangular specimens were prepared for one isotropic material, SS275, and five anisotropic CFRP specimens with five carbon fiber angles ranging from 0° to 90°. An experimental impact test was conducted to obtain all the modal parameters. The proposed mode-tracking method was applied using three indicators: the modal assurance criterion (MAC) and two modal parameters (resonance frequency and modal damping ratio). The MAC value was valid for the three bending modes at 0°, 30°, and 90°, but not for the two torsional modes. However, the variation in the resonance frequencies was a more efficient indicator with which to track all the modes of interest, except for the second torsional mode. The variation in the modal damping ratio was also a valid indicator for the two torsional modes. Therefore, the proposed three indicators were all required to derive reliable mode tracking for the CFRP specimens considering the mode order shift.

Effect of Bass Bar Tension on Modal Parameters of a Violin's Top Plate

2015 ◽  
Vol 39 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Ewa B. Skrodzka ◽  
Bogumił B.J. Linde ◽  
Antoni Krupa
Keyword(s):  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Normal Value ◽  
Modal Damping

Abstract Experimental modal analysis of a violin with three different tensions of a bass bar has been performed. The bass bar tension is the only intentionally introduced modification of the instrument. The aim of the study was to find differences and similarities between top plate modal parameters determined by a bass bar perfectly fitting the shape of the top plate, the bass bar with a tension usually applied by luthiers (normal), and the tension higher than the normal value. In the modal analysis four signature modes are taken into account. Bass bar tension does not change the sequence of mode shapes. Changes in modal damping are insignificant. An increase in bass bar tension causes an increase in modal frequencies A0 and B(1+) and does not change the frequencies of modes CBR and B(1-).

scholarly journals Heat Exchanger Network Retrofit of an Oleochemical Plant through a Cost and Energy Efficiency Approach

2021 ◽  
Vol 5 (2) ◽  
pp. 17
Author(s):  
Valli Trisha ◽  
Kai Seng Koh ◽  
Lik Yin Ng ◽  
Vui Soon Chok
Keyword(s):  
Energy Consumption ◽  
Heat Exchanger ◽  
Cost Effective ◽  
Capital Cost ◽  
Global Market ◽  
Annual Saving ◽  
Heat Exchanger Network ◽  
First Case ◽  
Payback Time ◽  
Better Than

Limited research of heat integration has been conducted in the oleochemical field. This paper attempts to evaluate the performance of an existing heat exchanger network (HEN) of an oleochemical plant at 600 tonnes per day (TPD) in Malaysia, in which the emphases are placed on the annual saving and reduction in energy consumption. Using commercial HEN numerical software, ASPEN Energy Analyzer v10.0, it was found that the performance of the current HEN in place is excellent, saving over 80% in annual costs and reducing energy consumption by 1,882,711 gigajoule per year (GJ/year). Further analysis of the performance of the HEN was performed to identify the potential optimisation of untapped heating/cooling process streams. Two cases, which are the most cost-effective and energy efficient, were proposed with positive results. However, the second case performed better than the first case, at a lower payback time (0.83 year) and higher annual savings (0.20 million USD/year) with the addition of one heat exchanger at a capital cost of USD 134,620. The first case had a higher payback time (4.64 years), a lower annual saving (0.05 million USD/year) and three additional heaters at a capital cost of USD 193,480. This research has provided a new insight into the oleochemical industry in which retrofitting the HEN can further reduce energy consumption, which in return will reduce the overall production cost of oleochemical commodities. This is particularly crucial in making the product more competitive in its pricing in the global market.

scholarly journals Development and Validation of a Three-Dimensional Printed Multifunctional Trap for Surveillance of Mosquitoes

2021 ◽  
Vol 37 (2) ◽  
pp. 68-75
Author(s):  
Drew David Reinbold-Wasson ◽  
Michael Hay Reiskind
Keyword(s):  
Mosquito Species ◽  
Three Dimensional ◽  
Cost Effective ◽  
Disease Monitoring ◽  
Life History Stage ◽  
Mosquito Trap ◽  
Host Seeking ◽  
Vector Borne ◽  
Development And Validation ◽  
Better Than

ABSTRACT An essential component of vector-borne disease monitoring programs is mosquito surveillance. Surveillance efforts employ various collection traps depending on mosquito species and targeted life-history stage, i.e., eggs, larvae, host-seeking, resting, or gravid adults. Surveillance activities often use commercial traps, sometimes modified to accept specific mosquito species attractants. The advent of widely available and affordable 3D printing technology allows the construction of novel trap designs and components. The study goal was to develop and assess a cost-effective, multipurpose, 6-volt mosquito trap integrating features of both host-seeking and gravid mosquito traps to collect undamaged live specimens: a multifunctional mosquito trap (MMT). We tested the MMT in comparison to commercial traps, targeting gravid Aedes albopictus, host-seeking Ae. albopictus, and total number of host-seeking mosquitos regardless of species. Field evaluations found the MMT performed as well as or better than comparable commercial traps. This project demonstrates an easy to construct, inexpensive, and versatile mosquito trap, potentially useful for surveying multiple mosquito species and other hematophagous insects by varying attractants into the MMT.

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