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35 to a library of over 24,000 of- the-shelf bearings, and ofers over 120 oil- and grease-based bearing lubricants for selection. The cable module computes the vibration and tension of cables in cable-based transmissions. This helps analyze cable slippage against load performance, cable compliance against system output speed, and winching efects when changing cable lengths. Last, there's the new electric motors module. The module covers DDC (shunt or series), DC brushless, stepper, and AC synchronous motors. Motor torque can be defned either by Easy5 controls and systems simulation from MSC Software or by MATLAB and Simulink from MathWorks ( mathworks.com ). The results help in motor sizing, predicting motor torque, analyzing position control, and producing a realistic drive signal for the rest of the machine components. Damping and fracturing; two banes in automotive design Among the many improvements in MSC Marc ( mscsoftware. com/product/marc ), a general-purpose, nonlinear FEA program, are new tools for analyzing elastomers (linear elastic and hyperelastic materials), such as tires, seals, and elastomeric bearings. The analysis focuses on the damping characteristics of elastomers in products that create and transmit mechanical vibrations and other types of noise. Specifcally, Marc now includes the Bergstrom-Boyce model for analyzing time-dependent and large strain viscoelastic behaviors, and the Marlow model for analyzing rubbers and frequency-dependent material behaviors. Fracture analysis, says Ted Wertheimer, MSC Software director, product management, is "really the birthplace of nonlinear FE because nobody wants a failure." Sure enough, Marc gives fracture and durability analysis plenty of attention. By using adaptive meshing capabilities, analysts can now put cracks anywhere in a solids model without worrying about splitting element faces and having to regenerate the mesh. (For instance, analysts can rotate surface cracks without having to regenerate the surrounding mesh.) As the cracks grow, analysts can specify the delamination along element faces: stay on the material interface, on the element set interface, or on automatic interface. This is all possible using higher order solid elements, particularly tetrahedral elements, which leads to better and more accurate simulations of crack propagation. Another enhancement involves interference ft. "The real motivation for this was where mesh was signifcantly overlapping one another," says Wertheimer. This overlap could be by design or because of faws in the model or the mesh. "If the overlap was over the contact tolerance, there was nothing we could do," continues Wertheimer. Now, a pop-up menu in Marc lets analysts specify how to resolve these interferences between parts: move parts relative to each other or scale them to a particular point or coordinate system. Fatigue, another bane New to MSC Nastran, a general-purpose FEA program, is Nastran Embedded Fatigue (NEF; mscsoftware.com/product/ msc-nastran-embedded-fatigue ). "What was once a post- processing exercise is now an integral part of the analysis process," says Wertheimer. NEF yields benefts way beyond eliminating the need to export results to a separate fatigue- analysis program. For instance, analysts can optimize the tradeofs of part weight and fatigue life; one example from MSC led to a 24% mass reduction, while increasing fatigue life by 14%. Second, durability calculations are now signifcantly faster and easier to perform; for example, a fatigue analysis that typically took 8 hours now only took 38 minutes, and only two fles were processed instead of 200. NEF is comple- mentary to MSC Patran pre/post-processing software. NEF can use material data for either stress life (S-N) or strain life (E-N), crack initiation, and safety factors. This release of Nastran also analyzes the poroelastic behavior of trim components, which are used to dampen vibrations and improve passenger cabin comfort. The analysis inspects the vibroacoustic performance (that is, frequency response) of a vehicle by simulating the fuid-solid interaction (air and the trim components) within the passenger cabin (the acoustic cavity). In short, the analysis leads to improved noise, vibration, and harshness properties of components and the entire vehicle. This analysis combines Nastran body-in-white with Patran, then adds the trim component material and the acoustic cavity to get the frequency response. Nastran can handle various trim material coupling connections: glued, sliding, open, or closed. t Here's a truck cab with 96,793 nodes, 580,758 degrees of freedom, and 91,783 elements. Using MSC Nastran Embedded Fatigue (NEF), fatigue analysis is faster (the conventional method, with fatigue analysis done in post-processing, required 118.79 minutes to solve; with NEF, 24.55 minutes—4.8 times faster), requires less disk space (the conventional method requires 282,660 MB of disk space; NEF, 31 MB—a 99% reduction), and is both simpler and easier (the conventional method requires 191 fles; NEF, 2 fles—a 99% reduction in number of fles). 0514ADP FEATURE FEA.indd 35 4/22/2014 1:31:24 PM