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1.2  Key areas

• Area 1: Experimental modal analysis
• Area 2: Test/analysis correlation
• Area 3: Basic finite element analysis
• Area 4: Advanced FE analysis (model reduction, component mode synthesis, families of models)

This section is intended for people who don't want to read the manual. It summarizes what you should know before going through the SDT demos to really get started.

You can find a primer for beginners at http://www.sdtools.com/help/primer.pdf.

Self contained code examples are distributed throughout the manual. Additional demonstration scripts can be found in the sdt/sdtdemos directory which for a proper installation should be in your MATLAB path. If not, use sdtcheck path to fix your path.

The MATLAB doc command no longer supports non MathWorks toolboxes, documentation access is thus now obtained with sdtweb FunctionName.

The SDT provides tools covering the following areas.

Area 1: Experimental modal analysis

Experimental modal analysis combines techniques related to system identification (data acquisition and signal processing, followed parametric identification) with information about the spatial position of multiple sensors and actuators.

An experimental modal analysis project can be decomposed in following steps

• before the test, preparation and design (see section 2.2)
• acquisition of test data, import into the SDT, direct exploitation of measurements (visualization, operational deflection shapes, ...) (see section 2.1)
• identification of modal properties from test data (see section 2.3)
• handling of MIMO tests and other model transformations (output of identified models to state-space, normal mode, ... formats, taking reciprocity into account, ...) (see section 2.4)

The series of gart.. demos cover a great part of the typical uses of the SDT. These demos are based on the test article used by the GARTEUR Structures & Materials Action Group 19 which organized a Round Robin exercise where 12 European laboratories tested a single structure between 1995 and 1997.

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Figure 1.1: GARTEUR structure.

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• gartfe builds the finite element model using the femesh pre-processor
  
• gartte shows how to prepare the visualization of test results and perform basic correlation
  
• gartid does the identification on a real data set
  
• gartsens discusses sensor/shaker placement
  

Area 2: Test/analysis correlation

Correlation between test results and finite element predictions is a usual motivation for modal tests. Chapter 3 addresses topology correlation, test preparation, correlation criteria, modeshape expansion, and structural dynamic modification. Details on the complete range of sensor definitions supported by SDT can be found in  4.6. Indications on how to use SDT for model updating are given in section 6.5.

• gartco shows how to use fe_sens and fe_exp to perform modeshape expansion and more advanced correlation
• gartup shows how the upcom interface can be used to further correlate/update the model

Area 3: Basic finite element analysis

Chapter 4 gives a tutorial on FEM modeling in SDT. Developer information is given in chapter 7. Available elements are listed in chapter 9.

A good part of the finite element analysis capabilities of the SDT are developed as part of the OpenFEM project. OpenFEM is typically meant for developers willing to invest in a stiff learning curve but needing an Open Source environment. SDT provides an integrated and optimized access to OpenFEM and extends the library with

• solvers for structural dynamics problems (eigenvalue (fe_eig), component mode synthesis (section 6.3), state-space model building (fe2ss), ... (see fe_simul);
• solvers capable of handling large problems more efficiently than MATLAB;
• a complete set of tools for graphical pre/post-processing in an object oriented environment (see section 4.4);
• high level handling of FEM solutions using cases;
• interface with other finite element codes through the FEMLink extension to SDT.

Area 4: Advanced FE analysis (model reduction, component mode synthesis, families of models)

Advanced model reduction methods are one of the key applications of SDT. To learn more about model reduction in structural dynamics read section 6.2. Typical applications are treated in section 6.3.

Finally, as shown in section 6.4, the SDT supports many tools necessary for finite element model updating.