LMS Virtual.Lab Correlation

Systematic validation from the bottom up -

To guarantee realistic high fidelity simulations, it is essential that simulation models meet stringent accuracy standards. Ensuring reliable simulation results requires component, subsystem and full-system models to be compared with experimental data, or alternatively validated models of similar structures. Building and validating system models from the bottom up is the only way to prevent accumulating inaccuracies. Besides more reliable what-if analyses, validated models provide a better understanding of assumptions made regarding material properties, connections, joints and boundary conditions.

Correlating structural characteristics -

Although static physical tests serve many design purposes, models used for vibro-acoustic simulations usually require systematic test-based validation of dynamic properties. LMS Virtual.Lab Correlation helps correlate physical test results and prepare structural tests. A comprehensive tool set significantly facilitates simulated and measured mode shape comparison and operational deflection shapes and response functions. Using the original FE model as a basis to provide optimal comparison positions, and the required number of excitation and response points helps avoid testing errors and redundancy.

Validation-driven model updating -

Deducing model improvements using validation output is not always obvious. To facilitate model updating driven by validations, LMS Virtual.Lab Correlation offers specialized features to identify specific locations that need improvement. For example, it runs sensitivity analyses that efficiently retain the most influential specified parameters. Users can also automatically update models using internal and external algorithms, such as Nastran Solution 200, which focuses on tuning modal frequencies and response functions.

Compare and validate FE models based on test data
Identify the cause of modeling errors
Define system targets and improve simulation models
Improve measurements by defining optimal sensor and excitation device location

Pre-Test

When preparing measurements for physical structures, one can use modal information of preliminary Finite Element models to define the optimal measurement set-up. For a modal test set-up, this means defining a set of

measuring points and excitation points. LMS Virtual.Lab Correlation provides tools to quickly carry out this pre-test analysis in a user-friendly way. The objective is to obtain a measurement set-up that guarantees high quality measurement data.

Correlation

Once good test data for the physical model is available, LMS Virtual.Lab Correlation allows its users to quantify the geometrical and dynamic (FRF and Modal) resemblance between the test model and its FE equivalent model. Several correlation metrics, like MAC and FRAC, are available to study (mode) shape or frequency response function correlation interactively. Specialized algorithms and post-processing tools allow to localize the problem locations of bad shape correlation and give insight in stiffness differences between the two models.

Sensitivity and Updating

After the dynamic correlation between two models has been quantified, LMS Virtual.Lab allows to easily setup and drive Nastran Sol200 to obtain the sensitivity of FE dynamic properties towards a set of design parameters as to decide which parameters to change to obtain better correlation results. Using Sol200 sensitivities, MAC and frequency difference sensitivities are derived to use for modal updating. A broad range of sensitivities can also be computed using LMS Virtual.Lab Optimization: the user can define a variety of dynamic properties to optimize for a very broad range of design parameters. Once the setup of design parameters (inputs) and correlation metrics (outputs) is in place, LMS offers the possibilities to carry out Design of Experiments, Response Surface Modeling and Updating with several local and global optimization algorithms.

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