VRCIM

DDEX - Dynamics Data EXtraction

DDEX - Rigid Body Dynamics Data EXtraction from Computer Aided Design Systems  


This project aimed to create a pre-process module, named DDEX, for rigid body Dynamic Data EXtraction from Computer Aided Design geometric models. It was developed to be used as part of the design analysis cycle of the International Space Station (ISS).

DDEX was developed to be a part of the Synergistic Engineering Environment (SEE). The SEE is being used at the National Aeronautics and Space Administration as an advanced engineering analysis and planning tool for space operations. The SEE software integrates accurate geometric models of spacecraft, such as the International Space Station, with engineering data to allow users to perform real-time interactive engineering analysis. ISS being an International project, coordination among all engineers was an important issue, as were the maintenance and modification of the development tools. SEE was aimed to address all these issues.

The official Design Analysis Cycle (DAC) model of the ISS consists of over one hundred configurations representing different stages of the station. Each configuration consists of up to 28 rigid bodies while each rigid body is an assembly formed by subassemblies and elements. There are over four hundred individual elements within a CAD model of the station. DDEX generates a text file with all the parameters required by the analysis tool. The focus in this research was on two CAD Systems: 1) IDEAS and, 2) Pro/Engineer.

In order to perform a rigid body dynamics analysis of the space station, we need to obtain mass properties, inertia properties, and the locations and orientations of joints from the CAD model of the station. This information is also required by the visualization part of the application to simulate the analysis data generated by the dynamics analysis tools. In addition, in order to display the station with a high level of detail within the ISS SEE, a program is desired to automatically generate the high-fidelity geometry files of all elements from the CAD model of the station. The DDEX module was designed to achieve these goals, without human intervention.

Two I-DEAS model files consisting of over 80 DAC 8 configurations were obtained from NASA LaRC.  Once the DDEX files are extracted using the module,  the user can load a configuration into the ISS environment by choosing the corresponding DDEX file from the configuration library. The user can also import an individual element from the element library, move the elements within the configuration, and save the modified configuration into a new DDEX file. The new DDEX file is then fed into the dynamics tools for the calculation of rigid body dynamics analysis for the new configuration. The main application then simulates the results. Thus, DDEX has contributed significantly to the SEE program

 

 

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