Getting started

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1.2 Getting started

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/pdf/Bristol_Primer.pdf.

The SDT demonstrations are located in the sdtdemos directory which for a proper installation should be in your MATLAB path. Executing demosdt at the MATLAB prompt will also add the demo directory to your path if needed. Many of these demonstrations are associated to manual pages. You can easily access the proper page with your favorite web browser by typing the doc commands listed in the demos at the MATLAB prompt.

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.

Figure 1.1: GARTEUR structure.

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

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, done outside the SDT, followed parametric identification) with information about the spatial position of multiple sensors and actuators.

To get started with a modal analysis project read chapter 3.

Area 2: Test/analysis correlation

Correlation between test results and finite element predictions is a usual motivation for modal tests. Chapter 4 addresses topology correlation, test preparation, correlation criteria, modeshape expansion, and structural dynamic modification. Indications on how to use SDT for model updating are given in section 6.4.

Area 3: Basic finite element analysis

Finite element analysis capabilities of the SDT are now developed as part of the OpenFEM project. SDT extends this library with

solvers for structural dynamics problems (eigenvalue, component mode synthesis, state-space model building, ...);
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;
high level handling of FEM solutions using cases;
interface with other finite element codes through the FEMLink extension to SDT.

Chapter 5 gives a tutorial on FEM modeling in SDT. Developer information is given in chapter 7. Available elements are listed in chapter 8.

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 6.1. Typical applications are treated in section 6.2.

Finally, as shown in section 6.3, the SDT supports many tools necessary for finite element model updating.

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