The jet engine is modeled in Catia but stress, CFD, and thermal simulations, along with an optimization routine, were run in sequence in MD Nastran.

The jet engine is modeled in Catia but stress, CFD, and thermal simulations, along with an optimization routine, were run in sequence in MD Nastran.


Software developer MSC.Software, Santa Ana, Calif., says it has developed a method that lets design teams use one model for a wide range of simulations, such as motion, CFD, and thermal, as well as to represent linear and nonlinear aspects. The program is called MD Nastran, according to MSC Vice President Product Development Enterprise Computing Reza Sadeghi. It solves the many-model problem for a thorough simulation.

Ordinarily, each simulation would require a separate model. After each simulation, the user takes its outputs and treats them as inputs for the next program. This is especially so when the programs involve, for example, lumped masses to simulate a rigidbody system and solid models to predict stresses. "The software lets users model the accurate behavior of their products in a unified software environment, with just one representation of the model," says Sadeghi.

Preprocessing involves instructing what each program will calculate and where it will apply that to the next. Sadeghi adds that after setting up several different disciplines, optimization functions can be added that will run the sequence several times looking for a best user-defined output from each. For instance, if the design is an engine, simulations might run through vibration dynamics, thermal and stress simulations, and pumping efficiency. The optimization routine could be programmed to hunt for the lightest-weight block, maximum allowable stresses and heat, and greatest efficiency.

Simulations can progress from a simple point analysis, to one done at subsystems level, and eventually a system level. "You'd begin with the controls that drive the system, which may cause components to move. The simulations could be simultaneous, loosely coupled, or staggered, depending on the type of interaction required," says Sadeghi.

He adds that his company will expand the simulation capability of MD Nastran to include analysis for crash, acoustics, aeroelastics, and manufacturing verification. Sadeghi says MSC.Software has studied assembly modeling to more accurately reproduce the behavior of welds, bonds, bolts, and press fittings. And because models are growing larger, MD Nastran will run under 64-bit versions of Windows and Linux. Thanks to software from Engineous Inc., Cary, N.C., the simulation loop can include analysis programs developed by
other companies as well.

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