Experimental Modal Analysis Training
Experimental Modal Analysis TrainingCourse Description
This 4-day Experimental Modal Analysis Training is designed for test engineers involved in acquisition and reduction of vibration data for the development of a modal model. Practical aspects of modal analysis theory, digital signals processing, excitation techniques and modal parameter estimation are addressed.
• Basic fundamental background of experimental modal analysis
• Digital signal processing techniques necessary for performing a modal test
• How to successfully conduct an impact test for acquisition of frequency response functions
• How to specify shaker excitation techniques for modal testing
• Techniques for the reduction of measured data to form a modal model
• Approaches for validation of the derived model
• Techniques for the quality assessment of acquired data
With onsite Training, courses can be scheduled on a date that is convenient for you, and because they can be scheduled at your location, you don’t incur travel costs and students won’t be away from home. Onsite classes can also be tailored to meet your needs. You might shorten a 5-day class into a 3-day class, or combine portions of several related courses into a single course, or have the instructor vary the emphasis of topics depending on your staff’s and site’s requirements.
Overview. Troubling shooting noise and vibration problems.
Modal Testing Considerations. Overview of modal test setup and conduct of test. Practical considerations for the setup of a test.
Experimental Modal Theory. Single degree of freedom equations. Time and Laplace domain formulations. Definition of poles and residues. Development of the system transfer function and the point to point frequency response function.
Experimental Modal Theory. Multiple degree of freedom systems. Time and Laplace domain formulations. Modal Space. Modal vector orthogonality and vector independence. Superposition of sdof systems.
Digital Signal Processing for experimental modal analysis. Identification of sampling and quantization problems. Discussion on aliasing, leakage and the need for windows. The use of rectangular, hanning, and flattop windows; measurement distortion due to the use of windows. Frequency response estimators. Description of auto power spectrum, cross power spectrum, frequency response function and coherence.
Excitation Techniques – impact excitation. The selection of hammer tips. The need for pre-trigger delay. Double impact problems. The proper selection and use of force/exponential windows for impact testing. Examples of impact setup with proper and improper setups.
Excitation Techniques – shaker excitation. The use of random and deterministic excitations for experimental modal testing. Identification of specialized excitation techniques such as pseudo-random, burst random, sine chirp and digital stepped sine for the efficient excitation of structures without the need for window functions.
Transducers and calibration.
Modal Parameter Estimation. Concepts in parameter estimation. Single degree of freedom methods vs. multiple degree of freedom methods. The use of the time and the frequency domain representations of data. Identification of local, global and polyreference curvefitting methods. Commonly implemented commercial curvefitting techniques.
Validation of extracted modal parameters.
Practical discussion on real world testing – problems and pitfalls.
Case Studies. Acquisition of data for a simple structure followed by the data reduction through the use of commercially available software.
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