The design concept has been provisionally approved, the team is coming together—and the project is ON! What is the plan for FINITE ELEMENT ANALYSIS? Modern design strategy incorporates FEA from the outset.
Finite Element Analysis at Project Initiation
Early in the design cycle, details of the hardware will not be fully understood. This should not delay starting the model. In fact, a completely logical approach to FEA modeling is to begin with the initially determined basic shape and function. In this case, model development precedes the overall design, and favorable model results then lead to a green light for actual hardware design. As the actual design comes together, the model may be adjusted—and a very accurate, predictive capability emerges.
From this point forward, design revisions then can be “tested” (meaning modeled or simulated) in advance of “cutting metal.” Whether it is a straightforward linear static stress analysis, or a transient coupled multi-physics heat transfer, fluid flow and stress analysis, it is well worth having the model in place early in the process to allow the rapid evaluation of changes before undergoing the expense and time of a physical build. Sometimes, the model will even indicate that the design team should pursue another solution or direction. Design concepts should always be proven before the next step commences.
The predictive capability of a good model is so powerful that entire industries have adopted the extensive use of FEA. The Japanese auto industry and the network of component suppliers are a perfect example. Rather than consuming resources, time, and materials designing something that may or may not work, sophisticated design teams develop models, first. Glew Engineering has performed multiple FEA analysis for the Japanese automotive supply chain. Usually, the drive for FEA analysis starts at the top, with the large company possessing the desire and discipline to minimize risk and maximize project speed.
The concept of continuous modeling represents a very mature approach to real world hardware design. Over time, key elements of the design, including the materials, the environment and the resulting thermal exposures, all come to light. By folding actual test data back into the model, accuracy and understanding are improved. Ultimately, continuously modeling throughout various design phases provides excellent predictive capability. Effects such as changing materials, improving thermal contact, re-routing cooling channels, adding radiation shields, etc., can be simulated with high speed and low cost and sufficient accuracy (relative to generating a physical prototype).
And what does “sufficient accuracy” mean? This is an ongoing discussion to hold with the modeler. The needed precision of the results drives the development of the model. Accuracy dictates the fineness of the mesh, and therefore the actual computation time. In addition, accuracy determines the precision required for the many physical parameters and material properties utilized in the model.
Note that material properties can likely be obtained by the
modeler, but often, materials testing is still needed. FEA may rely on more than the basic parameters, especially for nonlinear analysis. Design engineers may have their own background data, providing material properties for their own specific materials of interest in the required temperature range.
Finite Element Analysis As a Response
Sometimes the FEA is initiated in response to some design shortcoming or even a field failure. This situation places tremendous pressure on all involved: designers as well as the modeler. Furthermore, this unfortunate circumstance describes a situation where best-known design methods such as FEA were known to the parties involved, but for some reason were not employed from the beginning.
In response to this time critical situation, all logistical elements become pressure packed. The transfer of CAD packages, obtaining all relevant materials parameters, etc. are critical path activities placing great stress on all involved. Key steps to validate the model cannot be given adequate time.
For such reasons, finite element analysis has its rightful place at the beginning of the design. Besides, haven’t you always wanted to tell an attractive stranger you meet at a party that you “model for a living”?