SEM Modal Analysis Technical Division presents

Modal Parameter Estimation Round Robin

IMAC XXIX 2011 Jacksonville, FL

Modal parameter estimation (MPE) is a common activity for experimental structural dynamicists. Many MPE algorithms are documented and compared in the history of the IMAC proceedings. MPE is the final step to determine the modal parameters for a particular structure under test. MPE is calculation intensive and several commercial and custom software tools exist to automate the calculations and guide users through the MPE process.

The purpose of the Modal Parameter Estimation Round Robin is to compare MPE results from a wide range of participants using various commercial and custom implementations of MPE algorithms. To ensure consistency, the same data sets will be available to each participant. The organizers will then collect and compare results. At a special session of IMAC 28, participants will have the opportunity to present their work, and the organizers will present a comparison of results.

Each standard data set will contain:

• Numeric Data (Universal File Format)
• Single or multiple reference frequency response functions (FRFs)
• Corresponding ordinary coherence functions
• Geometry information (point identification and 3-D coordinates, connectivity)
• Descriptive Information
• Boundary condition(s)
• Excitation technique
• Data acquisition conditions and parameters

The organizers request that the participants provide:

• Numeric Results
• Scaled mode shapes, natural frequencies, and damping information (UFF type 55)
• Synthesized FRFs for the measurement DOFs included in the original data set (SDF or UFF type 58)
• Descriptive Results
• Software used
• MPE algorithm(s) used
• General comments about the user confidence in the results

The organizers will compare the submitted results using several methods:

• Modal Assurance Criteria (MAC) to establish mode correspondence
• Statistics of natural frequencies for corresponding mode shapes
• Statistics of damping values for corresponding mode shapes
• Comparison of synthesized FRFs
• Individual
• Multivariate Mode Indicator Function (MIF)
• Sum of the square amplitude

Several data sets are available on the Michigan Technological University web site ( www.me.mtu.edu/imac_mpe). Participants are required to submit MPE results for the calibration data sets, to identify any overall scaling bias. Users can then choose from any combination of the other data sets.

Description of available data sets:

• Calibration 1 – Proportionally damped lumped parameter model
• Calibration 2 – Non-proportionally damped lumped parameter model
• Calibration 3 – Constant Modal Damping
• Plexiglass plate - 25 responses / 3 inputs
• Dryer cabinet – 300 responses / 4 inputs
• Automobile – 398 responses / 3 inputs
• Aerospace data - 240 responses / 5 inputs

Click on a each link set for a description of the data and download information.

For further in formation please contact:

Chuck Van Karsen (cdvankar@mtu.edu) or Jim DeClerck (jdeclerck@mtu.edu)