Experimental Modal Analysis

By Prof. Subodh V. Modak | IIT Delhi

Learners enrolled: 331 | Exam registration: 23

ABOUT THE COURSE:

This course is about the fundamentals and basic concepts of Experimental Modal Analysis (EMA) and its applications. EMA, also known as Modal Testing, is a technique for experimentally determining the natural frequencies, mode shapes, and damping factors of a physical system or structure. One primary application of EMA is for the avoidance of resonant operation and troubleshooting vibration and noise problems. Another important application is in validating and updating structural dynamic FE models. EMA also enables deriving an experimental mathematical model of a physical system, which can be used for response simulation, force identification, structural modification, and structural control. The course will start from the theoretical basis of EMA, followed by signal processing for modal analysis. Then it will cover how the frequency and impulse response functions (FRFs and IRFs) can be measured by exciting the structure and measuring the input force and output response and how the modal parameters can be estimated from these measured FRFs and IRFs. In the end, the course will briefly cover Phase resonance testing, Operational Modal Analysis, and applications of EMA.

INTENDED AUDIENCE:

• BE/B. Tech/ME/M. Tech/MS/PhD students of Mechanical, Aerospace, Automotive, Civil, and Naval architecture disciplines

• Practicing engineers and professionals

PREREQUISITES: Basic mechanics

INDUSTRY SUPPORT: Automotive, aerospace, machine tool, and marine industries; Modal testing is widely used in many other industries, and they also may be interested.

Summary

Course Status :	Completed
Course Type :	Elective
Language for course content :	English
Duration :	12 weeks
Category :	Mechanical Engineering
Credit Points :	3
Level :	Undergraduate/Postgraduate
Start Date :	24 Jul 2023
End Date :	13 Oct 2023
Enrollment Ends :	07 Aug 2023
Exam Registration Ends :	18 Aug 2023
Exam Date :	29 Oct 2023 IST

Note: This exam date is subject to change based on seat availability. You can check final exam date on your hall ticket.

Page Visits

Course layout

Week 1: Introduction, need and applications of EMA, lumped parameter models, Analytical modal analysis of SDOF undamped and damped systems; Free and forced response, FRF

Week 2: Analytical modal analysis of undamped and damped MDOF systems; eigenvalue problem (EVP), free response, Forced response, FRF matrix, modal space, modal response

Week 3: IRF, Convolution integral, FRF characteristics, FRF types, FRF Plots, stiffness and mass lines; modal contributions; antiresonances

Week 4: Signal processing for experimental modal analysis, Fourier series, Fourier transform, Discrete Fourier Series, Discrete Fourier transform

Week 5: Time sampling; aliasing, sampling theorem, quantization, windowing; window functions, random signals, correlation, spectral density, white noise

Week 6: FRF measurement with an impact hammer, FRF estimation, Impact hammer, response measurement, accelerometer, mounting and selection, LDV

Week 7: Auto and cross spectrums, H1- H2 estimates, spectrum averaging, coherence function, FRF measurement simulation, boundary conditions, calibration

Week 8: FRF measurement with shaker, electromagnetic shaker, shaker-structure interaction, force transducer, impedance head; FRF measurement simulation, pseudo-random, periodic random, burst random, chirp excitation

Week 9: Modal parameter estimation using SDOF curve fitting, Peak-picking method, Circle fit method, Line fit, residuals

Week 10: Modal parameter estimation using MDOF curve fitting, RFP, Global method, Complex exponential method, Stabilization diagram, SVD, Eigensystem realization algorithm

Week 11: Phase resonance testing, Operational modal analysis

Week 12: EMA applications, local structural modification, Response simulation, Force identification, Coupled structural analysis, MAC correlation, FE Model validation and updating

Books and references

1) Ewins, D.J., Modal Testing: Theory, Practice and Application, 2000, Research studies press, England
2) Modak, S.V., Analytical and Experimental Modal Analysis, 2023, CRC Press, Taylor & Francis Group (Under publication)

Instructor bio

Prof. Subodh V. Modak

IIT Delhi

Prof. Subodh V. Modak is a Professor in the Department of Mechanical Engineering at the Indian Institute of Technology Delhi. His research and teaching interests include Experimental modal analysis, Vibration, Finite element model updating, Acoustics, Active noise control, and Control engineering. He has contributed significantly to leading and reputed journals like Mechanical Systems and Signal Processing, Journal of Sound and Vibration, Journal of the Acoustical Society of America, Applied Acoustics, and AIAA Journal.

Course certificate

The course is free to enroll and learn from. But if you want a certificate, you have to register and write the proctored exam conducted by us in person at any of the designated exam centres.

The exam is optional for a fee of Rs 1000/- (Rupees one thousand only).

Date and Time of Exams: 29 October 2023 Morning session 9am to 12 noon; Afternoon Session 2pm to 5pm.

Registration url: Announcements will be made when the registration form is open for registrations.

The online registration form has to be filled and the certification exam fee needs to be paid. More details will be made available when the exam registration form is published. If there are any changes, it will be mentioned then.

Please check the form for more details on the cities where the exams will be held, the conditions you agree to when you fill the form etc.

CRITERIA TO GET A CERTIFICATE

Average assignment score = 25% of average of best 8 assignments out of the total 12 assignments given in the course.
Exam score = 75% of the proctored certification exam score out of 100

Final score = Average assignment score + Exam score

YOU WILL BE ELIGIBLE FOR A CERTIFICATE ONLY IF AVERAGE ASSIGNMENT SCORE >=10/25 AND EXAM SCORE >= 30/75. If one of the 2 criteria is not met, you will not get the certificate even if the Final score >= 40/100.

Certificate will have your name, photograph and the score in the final exam with the breakup.It will have the logos of NPTEL and IIT Madras .It will be e-verifiable at nptel.ac.in/noc.

Only the e-certificate will be made available. Hard copies will not be dispatched.

Once again, thanks for your interest in our online courses and certification. Happy learning.

- NPTEL team

SWAYAM Helpline / Support