scholarly journals Experimental Modal Analysis of a Linear Reciprocating Tribometer for Maximum Reciprocating Frequency

2021 ◽  
Author(s):  
Harish Thetanikkal Viswanathan ◽  
◽  
Prem Kumar John ◽  
Rajeev Vamadevan Rajalekshmi ◽  
◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Modal Analysis ◽  
Frictional Force ◽  
Friction And Wear ◽  
Impact Testing ◽  
Measuring System ◽  
Modal Parameters ◽  
Maximum Frequency ◽  
Stroke Length ◽  
Modal Frequency

This work demonstrates estimation of critical reciprocating frequency of a fabricated linear pin-on-reciprocating plate tribometer by modal analysis. Experimental investigation by impact testing and numerical analysis using ANSYS Work bench 14 were performed to extract the modal parameters of individual subsystems. The authors could not find reported literature on of estimation of critical reciprocating frequency of pin-on-reciprocating plate tribometer. Authors developed a pin-onreciprocating plate tribometer that can simulate friction and wear under reciprocating sliding conditions for stroke lengths up to 150 mm. The developed pinon- reciprocating plate tribometer had a loading sub system, transmission subsystem and measurement subsystem. From experimental and numerical estimation of modal parameters, transmission subsystem found to had the lowest modal frequency of 18 Hz. Maximum frequency of reciprocation then fixed at 30% of the lowest modal frequency of 18 Hz that is 5 Hz. Confirmatory friction tests were then conducted on the tribometer and found that identification of maximum frictional force was difficult when the reciprocating frequency of plate of tribometer exceeded 4 Hz due to vibrations in measuring system and agreed with the reported literature. This work addresses the need of methodology for establishing critical reciprocating frequency of tribometer. This paper elaborates the modal analysis of a fabricated linear reciprocating tribometer. Resonance of subsystems in reciprocating tribometer affects experimental estimate of coefficient of friction (CoF). Subsystems have their own individual modal frequencies. Hence, modal analysis of all subsystems becomes obligatory. Tribometer developed for this study can simulate reciprocating friction and wear for stroke lengths up to 150 mm. Experimental and numerical analysis utilized to identify modal frequency of individual subsystems. Tests identified that transmission subsystem had the lowest modal frequency of 18 Hz. Maximum frequency of reciprocation then fixed at 4Hz. This is 25% of the lowest modal frequency of 18 Hz as delineated in literature. Confirmatory friction tests then conducted on the tribometer. Resolving maximum frictional force along the stroke length was impossible over 4 Hz of reciprocating frequency. This is 25% of the lowest modal frequency of structure and agreed with the reported literature. Authors sincerely hope the methodology used in this paper will guide fellow researchers for modal analysis of reciprocating tribometer.

scholarly journals Influence of Crack on Modal Parameters of Cantilever Beam Using Experimental Modal Analysis

2018 ◽  
Vol 1 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Siva Sankara Babu Chinka ◽  
Balakrishna Adavi ◽  
Srinivasa Rao Putti
Keyword(s):  
Numerical Analysis ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Cantilever Beam ◽  
Damping Ratio ◽  
Crack Depth ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Crack Location

In this paper, the dynamic behavior of a cantilever beam without and with crack is observed. An elastic Aluminum cantilever beams having surface crack at various crack positions are considered to analyze dynamically. Crack depth, crack length and crack location are the foremost parameters for describing the health condition of beam in terms of modal parameters such as natural frequency, mode shape and damping ratio. It is crucial to study the influence of crack depth and crack location on modal parameters of the beam for the decent performance and its safety. Crack or damage of structure causes a reduction in stiffness, an intrinsic reduction in resonant frequencies, variation of damping ratios and mode shapes. The broad examination of cantilever beam without crack and with crack has been done using Numerical analysis (Ansys18.0) and experimental modal analysis. To observe the exact higher modes of beam, discretize the beam into small elements. An experimental set up was established for cantilever beam having crack and it was excited by an impact hammer and finally the response was obtained using PCB accelerometer with the help sound and vibration toolkit of NI Lab-view. After obtaining the Frequency response functions (FRFs), the natural frequencies of beam are estimated using peak search method. The effectiveness of experimental modal analysis in terms of natural frequency is validated with numerical analysis results. This paper contains the study of free vibration analysis under the influence of crack at different points along the length of the beam.

Modal Parameter Validation in Coupled Vibro-Acoustical System

2011 ◽  
Vol 301-303 ◽  
pp. 629-634
Author(s):  
Yi Feng Xu ◽  
Jun Wang
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Reciprocity Theorem ◽  
Modal Parameters ◽  
Modal Parameter ◽  
Modal Frequency ◽  
Simulation Results ◽  
Modal Truncation ◽  
Acoustic Boundary Element ◽  
Element Algorithm

The aim of this paper is to validate the modal parameters used in coupled structural finite element and acoustic boundary element algorithm to analysis the structure subjected to diffuse acoustic field. The theoretical deduction of non-symmetric coupled vibro-acoustical modal analysis was introduced firstly. In order to verify the modal truncation frequency how to affect the simulation results, based on the reciprocity theorem used in coupled FE-BE model, three different truncation frequency conditions were performed. The contrastive results show that twice the upper calculation frequency as the truncated modal frequency can make the simulation effectively and efficiently.

Experimental Modal Analysis of Compressor Vibration Isolating System Based on LMS Test.Lab

2011 ◽  
Vol 121-126 ◽  
pp. 3283-3288
Author(s):  
Li Zhang ◽  
Hao Chen ◽  
Yan Jue Gong ◽  
Jing Wang
Keyword(s):  
Resonance Frequency ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Single Layer ◽  
Experimental Modal Analysis ◽  
Impact Testing ◽  
Modal Parameters ◽  
Isolation System ◽  
Refrigeration Unit ◽  
Comparison Results

In order to reduce vibration and noise of the compressor used in small and medium-sized refrigeration unit, this paper designs different vibration isolating systems and carries out experimental modal analysis based on LMS Test. Lab Impact Testing software. The comparison results of modal parameters of four different vibration isolating systems show that the natural frequency of single-layer vibration isolating system is higher than that of non-isolation system and effectively avoids the second order resonance frequency. Furthermore the natural frequency of double-layer vibration isolating system has reduced due to the additional middle-mass. And the system's natural frequency decreases obviously with the increase of middle-mass which is far from resonance frequency and significantly improve the effect of vibration isolating system.

Analysis and Design of a Gantry Support Frame

2012 ◽  
Vol 271-272 ◽  
pp. 762-766
Author(s):  
Ling He ◽  
Gao Qi Zhang ◽  
Heng Yu Wu ◽  
Ya Li Lei ◽  
Zhi Gang Wang
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Simulation Analysis ◽  
Dynamic Performance ◽  
Impact Testing ◽  
Modal Frequency ◽  
Analysis And Design ◽  
Finite Element Software ◽  
Support Frame ◽  
Testing Module

This paper increases product modal frequency and improves machine dynamic performance while ensuring product static accuracy in method of design, simulation analysis, and testing verification for the purpose of improvement of PCB boring machine gantry support frame integrated modal based on Abaqus finite element software platform as well as Impact Testing module and Modal Analysis module of Test.lab

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-).

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

scholarly journals Comparison of Mode Shapes of Carbon-Fiber-Reinforced Plastic Material Considering Carbon Fiber Direction

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 311
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Modal Analysis ◽  
Dynamic Behavior ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic

Previous studies have demonstrated the sensitivity of the dynamic behavior of carbon-fiber-reinforced plastic (CFRP) material over the carbon fiber direction by performing uniaxial excitation tests on a simple specimen. However, the variations in modal parameters (damping coefficient and resonance frequency) over the direction of carbon fiber have been partially explained in previous studies because all modal parameters have only been calculated using the representative summed frequency response function without modal analysis. In this study, the dynamic behavior of CFRP specimens was identified from experimental modal analysis and compared five CFRP specimens (carbon fiber direction: 0°, 30°, 45°, 60°, and 90°) and an isotropic SCS13A specimen using the modal assurance criterion. The first four modes were derived from the SCS13A specimen; they were used as reference modes after verifying with the analysis results from a finite element model. Most of the four mode shapes were found in all CFRP specimens, and the similarity increased when the carbon fiber direction was more than 45°. The anisotropic nature was dominant in three cases of carbon fiber, from 0° to 45°, and the most sensitive case was found in Specimen #3.

scholarly journals Identification of modal parameters of machine tools during cutting by operational modal analysis

Procedia CIRP ◽  
2018 ◽  
Vol 77 ◽  
pp. 473-476 ◽  
Author(s):  
Jan Berthold ◽  
Martin Kolouch ◽  
Volker Wittstock ◽  
Matthias Putz
Keyword(s):  
Modal Analysis ◽  
Machine Tools ◽  
Operational Modal Analysis ◽  
Modal Parameters

Evaluation of the effect of operational modal analysis algorithms on identified modal parameters of railway bridges

2021 ◽  
Author(s):  
Mohammadreza Salehi ◽  
Kultigin Demirlioglu ◽  
Emrah Erduran
Keyword(s):  
Modal Analysis ◽  
Health Monitoring ◽  
Iron Ore ◽  
Operational Modal Analysis ◽  
Modal Parameters ◽  
Vibration Source ◽  
Light Weight ◽  
Railway Bridges ◽  
Different Types ◽  
Vibration Responses

<p>The accuracy of modal parameters identified by Operational Modal Analysis (OMA) algorithms is of vital importance in vibration-based health monitoring. This paper reports the effects of using different OMA algorithms on identified modal parameters of railway bridges. For this purpose, comparison and application of three different OMA methods including FDD, ARX, SSI-COV are discussed. The vibration measurements are conducted on two railway bridges in Northern Norway for using five triaxial accelerometers. The first bridge is a single-span bridge with the length of 50 m, while the second is a two-span bridge with a total length of 85m. OMA has been conducted on the free vibration responses after passage of different types of trains including light-weight railway vehicles and heavily loaded iron ore trains to evaluate the variation of the identified modal parameters with the chosen algorithm and the vibration source on the OMA results.</p>

Identification of Modal Parameters of an Elastic Rotor With Oil Film Bearings

1984 ◽  
Vol 106 (1) ◽  
pp. 107-112 ◽  
Author(s):  
Rainer Nordmann
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Design Process ◽  
Mechanical Engineering ◽  
Mechanical Systems ◽  
Rotating Machinery ◽  
Modal Parameters ◽  
Powerful Method ◽  
Oil Film ◽  
Engineering Problems

Investigations of the dynamic behavior of structures have become increasingly important in the design process of mechanical systems. To have a better understanding of the dynamic behavior of a structure, the knowledge of the modal parameters is very important. The powerful method of experimental modal analysis has been used to measure modal parameters in many mechanical engineering problems. But the method was mainly applied to nonrotating structures. This presentation shows improvements of the classical modal analysis for a successful application in rotating machinery with nonconservative effects. An example is given, investigating the modal parameters of an elastic rotor with oil film bearings.

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