Femap, Solid Edge, Synchronous Technology

One of the questions many design/engineering organisations face is whether to invest in CAD-embedded FEA or go for standalone general purpose FEA like Femap with NX Nastran.  Each has its merits, and in this post we outline why either or both would be the right choice.

Why Solid Edge Simulation?
The major advantage of Solid Edge Simulation is that it provides a high level of integration with the design model.  Femap has excellent standalone geometry capabilities, however, they are not as extensive and as easily editable as geometry in Solid Edge.  Similarly Solid Edge includes Synchronous Technology for even more geometry editing power.  Solid Edge Simulation (available as an SE add-on or included at the SE Premium level) allows direct update of the simulation model based on changes within parts or assemblies.  It also includes a collection of FEA idealisations (eg. midsurfacing), where the geometry analysed can include some configuration differences (whilst still being fully associated) compared to the design model.  Add the fact that Solid Edge Simulation includes shape optimisation, glue, contact, bolt pre-load, and uses the NX Nastran solver, it is clear that SE Simulation has a fairly significant arsenal of industrial grade analysis for the design engineer.  Compared to Femap, quite a few models up to a certain level of depth/complexity can be analysed, revised and optimised faster than they could in Femap with NX Nastran, with the end result being a final CAD design model in Solid Edge.

Why Femap with NX Nastran?
By contrast, however, Femap provides engineering depth far beyond Solid Edge Simulation, and is superior to all others in many, many ways.  Femap is “analyst grade” FEA.  The supported physics in its NX Nastran solver also far exceed that available in Solid Edge Simulation.  Below is a small sub-set of incremental capability.  Of course, Solid Edge Simulation creates a 100% complete run-ready Femap with NX Nastran geometry / analysis model, so having both provides the best of all worlds.  Some of the contrast is related to methods / techniques.  For example, if a design requires a substantial cut-shut change with significant alterations to part or assembly topology, then Femap’s geometry creation/editing may hold its own against making the FEA modification in a CAD-embedded system.
Some incremental capabilities in Femap with NX Nastran include:

  • Closer control over all FEA entities.
  • Substantially more mesh operations , mesh controls and live mesh tools.
  • Brick elements, springs, dampers, gaps, bushes, crack-tip elements, advanced links.
  • Non-linear materials (eg. yield, creep, hyperelastic), directional materials (eg, for composites).
  • Plate and solid layups and composites, element offsets, membranes, non-structural mass.
  • Many more load types: equation-based loads, data-surface loads, loads from results, load combo’s.
  • More model checks: mesh mass, sum-forces, plate normals, element quality, geometry quality, element shrink, free edges of mesh and geometry, label/highlight anything.
  • Faster analysis changes if changes are based on property (eg. plate thickness; beam section).
  • More physics: non-linear static and transient, inertia relief, sub-modelling, multi-case analysis, non-linear buckling, sequential loading (eg. for unloaded residual stresses and permanent deflection), fluid modes analysis, frequency response, advanced thermal (transient including enclosure radiation).
  • Advanced glue, contact and controls: plate-to-solid, plate-to-plate, edge-to-edge, plate thickness on/off, initial interferences and separations on/off.
  • Advanced results visualisation: double sided plate results, free-body diagrams, XY graphs including results-vs-results, data tables (including rapid sort, filter, highlight), advanced vector/tensor results, advanced results display controls, live or permanent results transformations, stress linearisation (ASME). full beam cross-section results, results arithmetic / advanced maths, results enveloping (worst case results from multi-case analysis), failure indices in composites and interlaminar shear stresses.
  • Ability to work with other analysis solvers.
  • Options for even more advanced physics, such as Advanced Non-Linear (eg. for crashworthiness, drop test and metal forming), Rotor Dynamics, Aero-Elasticity and Computational Fluid Dynamics.
  • Easy automation of repetitive tasks.

These distinctions provide a guide to situations where one or other of these solutions provides unique advantages.  Solid Edge Simulation provides the advantage of having the FEA update with the design model and (via shape optimisation) the ability for the FEA to drive the design model.  This is particularly good for parts and assemblies of cast or machined solids where geometry updates can efficiently transfer through to the FEA model.
Femap with NX Nastran has the advantage of engineering depth, general-purpose capability, and the fact that in many cases the simulation can be more effective when unconstrained by a CAD model.  These cases may include large scale structures and assemblies of beams and/or mid-surface plates, where the geometry complexity is substantially greater than what is needed for efficient FEA, or where the complexity of the physics, loads, materials, properties, results dictates a comprehensive in-depth solution.

Why Both?

The value of both combined was shown (in part) in one of our webinars, available at http://www.cadcentral.co.nz/learn/videos-webinars.  Part 2 of this webinar is scheduled for later in 2014 (November) in our scheduled of many varied analysis and modelling topics.

Solid Edge combined with Femap has the very productive ability to launch a “connected” instance of Femap from within Solid Edge.  This opens a Femap model which already includes the part / assembly geometry directly from Solid Edge. Femap can then add all the Loads, Constraints, Mesh Controls, Material Properties, Connection Regions and all sorts of other “geometry associated” entities, plus the analysis setup to run the analysis.  However, if changes are made within Solid Edge parts or assembly, that change is carried through into the Femap model and the associated setups are preserved.  This means that the traditional limitations of standalone FEA are overcome via a tight connection with the CAD assembly.  This is the ultimate combination of design-team connection to advanced standalone analysis.

If interested in more details, please contact us via info@cadcentral.co.nz.

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