Member Portal

The buttons below provide quick and easy access to Renew your members and update your personal profile.
Renew Your Membership
As a member you have exclusive access to our Member Directory. Click the button below to browse the listings.
Member Directory


Papers and Abstracts


Your SEM membership allows exclusive access to dozens of technical and academic journals.
Member Only Journal Access
Free Articles from Experimental Techniques
The Society for Experimental Mechanics, Inc. regularly publishes multiple series of articles in addition to the technical articles that appear in Experimental Techniques. The Society is pleased to make these articles available for non-commercial use.
Back to Basics
Modal Space

Sometimes the mode shapes appear to be rotated from what is expected. Are the modes wrong? (Jan/Feb 2008, Vol. 32, No. 1)

Bolted joints are common in structures. Can the frequency change significantly due to joints? (Nov/Dec 2007, Vol, 31, No. 6)

The stability diagram has poles that are not indicated by the MMIF or CMIF; are they really modes? (Sep/Oct 2007, Vol. 31, No. 5)

How do you interpret the stability diagram? And how do data points affect the fit? (Jul/Aug 2007, Vol. 31, No. 4)

How do you select the reference location for a modal test? What needs to be considered? (May/Jun 2007, Vol. 31, No. 3)

What is the difference between all the mode indicator functions? What do they all do? (Mar/Apr 2007, Vol. 31, No. 2)

What is MRIT??? I hear people talk about it for impact testing. (Jan/Feb 2007, Vol. 31, No. 1)

Someone told me that operating modal analysis produces better results, and that damping is much more realistic (Nov/Dec 2006, Vol. 30, No. 6)

What is a good MAC value so that I know my model is right? (Sep/Oct 2006, Vol. 30, No. 5)

Is there any problem running a modal test to 2 KHz but only analyzing up to 500 Hz? (Jul/Aug 2006, Vol. 30, No. 4)

What effect can the test set up and the rigid body modes have on the higher flexible modes of interest? (May/Jun 2006, Vol. 30, No. 3)

Can modal parameters be extracted for heavily damped modes when you can’t see them in the measured FRFs? (Mar/Apr 2006, Vol. 30, No. 2)

Should the measurement bandwidth match the frequency range of interest for impact testing? (Jan/Feb 2006, Vol. 30, No. 1)

I ran a shaker test with a simple beam, but some of the modes don’t look right – What’s wrong? (Nov/Dec 2005, Vol. 29, No. 6)

Sometimes my impact force is very smooth just as expected, but often it looks like it is oscillating – Why is that? (Sep/Oct 2005, Vol. 29, No. 5)

Why does my stability diagram of a component on a system show modes that the SUM and MIF don’t show? (Jul/Aug 2005, Vol. 29, No. 4)

When I perform impact testing, the input spectrum looks distorted – do you think my FFT analyzer has a problem? (May/Jun 2005, Vol. 29, No. 3)

I know that certain shaker excitations have different characteristics – but, which is the best to use? (Mar/Apr 2005, Vol. 29, No. 2)

Once I have set up a good measurement, is there any reason to watch the time and frequency results for every FRF? (Jan/Feb 2005, Vol. 29, No. 1)

Do mode shapes of a plate have any particular predetermined order? (Nov/Dec 2004, Vol. 28, No. 6)

I find overload and underload of the digitizer and range settings difficult to understand. (Sep/Oct 2004, Vol. 28, No. 5)

Is there any way to scale mode shapes without a drive point measurement? (Jul/Aug 2004, Vol. 28, No. 4)

Do I need to have an accelerometer mounted in the X, Y, and Z directions to do a modal test? (May/Jun 2004, Vol. 28, No. 3)

Number of points needed for a Modal test and the necessity of defining the entire shape. (Mar/Apr 2004, Vol. 28, No. 2)

What's the difference between local and global curve fitting? (Jan/Feb 2004, Vol. 28, No. 1)

Why do some measurements have antiresonances and others do not? (Nov/Dec 2003, Vol. 27, No. 6)

I ran a Modal test on a portion of a structure of concern and many modes look the same! What did I do wrong? (Sep/Oct 2003, Vol. 27, No. 5)

Must you have multiple references in order to find pseudo repeated roots? (Jul/Aug 2003, Vol. 27, No. 4)

Is it really necessary to reject a double impact? (May/Jun 2003, Vol. 27, No. 3)

Why are calibration and mode shape scaling important, and does it make a difference? (Mar/Apr 2003, Vol. 27, No. 2)

Is it better to collect averaged FRF data for a Modal test, or collect time data and process it afterwards? (Jan/Feb 2003, Vol. 27, No. 1)

What are some of the major mistakes people make in Modal tests so I don't make the same ones. (Nov/Dec 2002, Vol. 26, No. 6)

Is there any real advantage to MIMO testing? Why not just use SISO and then move the shaker? (Sep/Oct 2002, Vol. 26, No. 5)

Can you explain the basic steps to acquire data for Modal testing? (Jul/Aug 2002, Vol. 26, No. 4)

What's the difference between a complex mode and a real normal mode? (May/Jun 2002, Vol. 26, No. 3)

Which window is most appropriate for the various types of Modal tests performed? (Mar/Apr 2002, Vol. 26, No. 2)

Can the test setup have an effect on the measured Modal data? Do the setup boundary conditions and accelerometers have an effect? (Jan/Feb 2002, Vol. 26, No. 1)

Should I use all collected measurements when estimating modal parameters? Let's discuss this. (Nov/Dec 2001, Vol. 25, No.6)

What are some of the most important things to consider when impact testing? Let's discuss this. (Sep/Oct 2001, Vol. 25, No.5)

Is there any benefit to using multiple references? I thought that only one reference was necessary. Let's discuss this. (Jul/Aug 2001, Vol. 25, No.4)

When impact testing, can the use of the exponential window cause any problems? Let's discuss this. (May/Jun 2001, Vol. 25, No.3)

Does it make any sense to use the actual operating load as excitation force for modal test if the force is a random signal? (Mar/Apr 2001, Vol. 25, No.2)

I hear about SVD all the time. Could you explain it simply to me? (Jan/Feb 2001, Vol. 25, No.1)

Why is mass loading and data consistency important for modal parameter estimation? (Nov/Dec 2000, Vol. 24, No.6)

Someone told me SDM will never work because you don't have all the mode shapes of the system. (Sep/Oct 2000, Vol. 24, No. 5)

How many points are enough when running a modal test? (Jul/Aug 2000, Vol. 24, No.4)

I ran one test with an X-excitation and can see some of the modes, and another test with a Y-excitation and see some different modes. Could I use an oblique angle instead? (May/Jun 2000, Vol. 24, No. 3)

I showed some mode shapes to someone and they asked if the design was OK. (Mar/Apr 2000, Vol. 24, No. 2)

I'm still overwhelmed by all this modal stuff - give me the big picture! (Jan/Feb 2000, Vol. 24, No. 1)

I heard someone say "Pete doesn't do windows" What's the scoop? (Nov/Dec 1999, Vol. 23, No. 6)

Are you sure you can get mode shapes from one row or column of H? (Sep/Oct 1999, Vol. 23, No. 5)

What's the difference between operating deflection shapes and mode shapes? (Jul/Aug 1999, Vol. 23, No. 4)

I still don't understand curvefitting. How do I get mode shapes from FRFs? (May/Jun 1999, Vol. 23, No. 3)

Curvefitting is so confusing to me! What do all the different techniques mean? (Mar/Apr 1999, Vol. 23, No. 2)

Which shaker excitation is best? Is there any difference? (Jan/Feb 1999, Vol. 23, No. 1)

Should I always use a hard tip for impact testing so the input spectrum is flat over all frequencies? (Nov/Dec 1998, Vol. 22, No. 6)

Is there any difference between a roving hammer and roving accelerometer test? (Sep/Oct 1998, Vol. 22, No. 5)

Is there any difference between a modal test with a shaker excitation or impact excitation? (Jul/Aug 1998, Vol. 22, No. 4)

Could you explain the difference between the time domain, frequency domain and modal space? (May/Jun 1998, Vol. 22, No. 3)

Could you explain modal analysis for me? (Mar/Apr 1998, Vol. 22, No. 2)

Optical Methods

Measuring Phase Difference—Part VI: Phase Unwrapping and Determining Displacement (Nov/Dec 2011, Vol. 35 Is. 6)

Measuring Phase Difference—Part V: Phase Calculations (Sep/Oct 2011, Vol. 35 Is. 5)

Measuring Phase Difference—Part IV: Phase-Stepping Algorithms (Jul/Aug 2011, Vol. 35 Is. 4)

Measuring Phase Difference—Part III: A Phase-Shifting Setup (May/Jun 2011, Vol. 35 Is. 3)

Measuring Phase Difference—Part II: Compensation (Mar/Apr 2011, Vol. 35 Is. 2)

Measuring Phase Difference—Part I: The Problem (Jan/Feb 2011, Vol. 35 Is. 1)

NEXUS (Nov/Dec 2010, Vol. 34 Is. 6)

Photoelasticity XV—Three-Dimensional Photoelasticity (Sep/Oct 2010, Vol. 34 Is. 5)

Photoelasticity XIV—Reflection Photoelasticity (Jul/Aug 2010, Vol. 34 Is. 4)

Photoelasticity XIII—Stress Trajectories (May/Jun 2010, Vol. 34 Is.3)

Photoelasticity XII—Recording Isoclinic Fringes (Mar/Apr 2010, Vol. 34 Is. 2)

Photoelasticity XI—Polariscope Calibration (Jan/Feb 2010, Vol. 34 Is. 1)

Photoelasticity X—Transfer of Stress Data From Model to Prototype (Sep/Oct 2009, Vol. 33 Is. 5)

Photoelasticity IX—Fringes to Stress and Display of Results (Jul/Aug 2009, Vol. 33 Is.4)

Photoelasticity VIII—Recording and Numbering Isochromatic Fringes (Mar/Apr 2009, Vol. 33 Is. 2)

Photoelasticity VII—Basic Polariscope Setups (Jan/Feb 2009, Vol. 33 Is. 1)

Photoelasticity VI—The Circular Polariscope (Nov/Dec 2008, Vol. 32. Is. 6)

Photoelasticity V—Fringe Patterns (Sep/Oct 2008, Vol. 32. Is. 5)

Photoelasticity IV—Observables and Interpretation (May/Jun 2008, Vol. 32. Is. 3)

Photoelasticity III—Theory (Mar/Apr 2008, Vol. 32. Is. 2)

Photoelasticity II—Birefringence in Materials (Jan/Feb 2008, Vol. 32. Is. 1)

Photoelasticity I—Birefringence and Relative Retardation (Nov/Dec 2007 | Vol. 31. Is. 6)

Speckle Brightness Distributions (Sep/Oct 2007, Vol. 31. Is. 5)

Speckle Size Estimates (May/Jun 2007, Vol. 31. Is. 3)

Subjective Speckle (Mar/Apr 2007, Vol. 31. Is. 2)

Objective Speckle (Jan/Feb 2007, Vol. 31. Is. 1)

Demonstrations of Laser Speckle Phenomena (Nov/Dec 2006, Vol. 30. Is. 6)

Reflection Moiré (Sep/Oct 2006, Vol. 30. Is. 5)

Projection Moiré (Jul/Aug 2006, Vol. 30. Is. 4)

Shadow Moiré (Mar/Apr 2006, Vol. 30. Is. 2)

Parametric Analysis of Geometric Moiré (Jan/Feb 2006, Vol. 30. Is. 1)

Basic Strain Measurement by Geometric Moiré (Nov/Dec 2005, Vol. 29. Is. 6)

Geometric Moiré Phenomena and Simulations (Jul/Aug 2005, Vol. 29. Is. 4)

Laser Doppler Interferometry (May/Jun 2005, Vol. 29. Is. 3)

The Optical Doppler Effect. (Mar/Apr 2005, Vol. 29. Is. 2)

Fourier Optical Processing (Jan/Feb 2005, Vol. 29. Is. 1)

Diffraction at a Clear Aperture (Nov/Dec 2004, Vol. 28. Is. 6)

Diffraction Theory—Part III (Sep/Oct 2004, Vol. 28. Is. 5)

Diffraction Theory—Part II (Jul/Aug 2004, Vol. 28. Is. 4)

Diffraction Theory—Part I (Mar/Apr 2004, Vol. 28. Is. 2)

Complex Amplitude (Jan/Feb 2004, Vol. 28. Is. 1)

The Diffraction Problem (Nov/Dec 2003, Vol. 27. Is. 6)

Michelson Interferometry (Sep/Oct 2003, Vol. 27. Is. 5)

Colored Interferometry Fringes (May/Jun 2003, Vol. 27. Is. 3)

Another Classic Interferometry: Young's Experiment (Mar/Apr 2003, Vol. 27. Is. 2)

A Classic Interferometry: Newton's Rings (Jan/Feb 2003, Vol. 27. Is. 1)

Some Basic Methods of Interferometry (Nov/Dec 2002, Vol. 26. Is. 6)

Path Length and the Generic Interferometer (Sep/Oct 2002, Vol. 26. Is. 5)

Interference of Light Waves (Jul/Aug 2002, Vol. 26. Is. 4)

The Nature and Description of Light (May/Jun 2002, Vol. 26. Is. 3)

Unifying Concepts in Teaching Optical Methods (Mar/Apr 2002, Vol. 26. Is. 2)

Automotive Applications
Computational Validation

The Need for Computational Model Validation (Mar/Apr 2001, Vol. 25, No. 2)

What Are Validation Experiments? (May/Jun 2001, Vol. 25, No. 3)

A Framework for Assessing Confidence in Computational Predictions (Jul/Aug 2001, Vol. 25, No. 4)

Dynamic Strain Measurement
Education Notes
Experimental Techniques Addressing Product Quality
Innovative Measurement Techniques
Strain Gages
Structural Integrity
Technology Applications
Testing of Acoustic Stringed Musical Instruments

Modern Vibration Measurement Techniques for Bowed Stringed Instruments (Jul/Aug 2001, Vol. 25, No. 4)

The Mechanics of Guitars (May/June 2001, Vol. 25, No. 3)

Mechanics of Stringed Instruments (Mar/Apr 2001, Vol. 25, No. 2)

Testing of Acoustic Stringed Musical Instruments - An Introduction (Jan/Feb 2001, Vol. 25, No. 1)

Wireless Technology