CAD for FEA today

Also read:
CAD for FEA in the BAD old days
CAD for FEA in the GOOD old days

In the first half decade of the new century, I saw enthusiasm over FEA and CFD leveling out a bit. It wasn’t so much that companies didn’t see the value in CAE… it was simply that the “new car smell” had worn off. Every fresh-faced engineering graduate was fully aware of the term Finite Element Analysis. Most could even spell CFD. The same was mostly true for the grizzled gray-hairs in engineering management.

Most companies engaging in CAE had at least 5 years of experience with the technology. They might have dropped one brand for another in that time, but they had experienced good time savings over the old build-break-test-repeat process in the prototyping lab. CAE became a validated activity. Expectations surrounding the effort and time required to complete this kind of work started to bake in to the collective consciousness:

“Yes, I’d say it takes about 3 weeks to get all the parts for a physical prototype and complete a test in the lab.”

“Yes, I’d say it takes about 1 week to simplify a CAD assembly (or maybe redraw it from scratch), get it meshed, and run the FEA simulation.”

For the most part, people engaged in CAE were happy with the status quo. They had experimented with different methods for handling geometry and had settled on the best strategies given the toolsets at hand. However, a new technology was about to change the game in the late 2000s.

Direct Modeling found traction and began to build momentum around 2007. Just as many engineers in the late 1980s were fairly unaware of CAE, however, most professionals in the late 2000s are unaware of Direct Modeling. That is changing at an exponential rate right now, largely due to the simultaneous efforts of Siemens (Synchronous Technology), PTC (CoCreate), and SpaceClaim. Each is building 3D tools based on a history-free, Direct Modeling methodology, and pouring significant effort and marketing dollars to raise awareness for the category.

As a side note, it is interesting that each company has a completely different philosophy and marketing message surrounding the category.
Check out this Direct Modeling round-table discussion, for example.

How does Direct Modeling change the CAD for CAE game?

Traditional CAD tools are history-based design systems. If you look on the left side of the screen, you’ll see a history/feature tree. That tree is essentially a recipe of operations that went into building the object you see. The CAD software has to replay that recipe (in order) to regenerate the part. Since there are many dependencies and parent child relationships in that history tree, making significant unplanned changes can easily break the model and cause regeneration failures.

Direct Modeling does not rely on a recipe regeneration process. It enables engineers to directly manipulate an otherwise “dumb” model on the fly without the need to decode the original designer’s CAD recipe.

This is a huge advantage for CFD and FEA users who spend a significant amount of time simplifying and defeaturing manufacturing-ready models for simulation.

These folks have mostly accepted the painful process of doing that in CAD as a necessary evil. Their managers have, as well. After all, 1 week of simulation sounds much better than 3 weeks of expensive lab testing! Up to this point, there hasn’t been a viable way to speed up that 1 week process, so everyone is happy with the status quo.

I generally see the CAD simplification phase of CAE speed up by 2-10x with Direct Modeling. If analysis engineers are asking the design department to do this simplification, the savings can be even bigger as you cut out an inefficiency loop in the workflow. Most importantly, we are talking valuable man-hour savings here.

Most companies these days are working hard to ferret out new time, cost, and resource savings as a response to the tough economy. If you are in that boat, I suggest you take a fresh look at how much manual effort and time your analysts are spending on geometry prep for CAE. If that process takes more than half a day, seek out a Direct Modeling vendor and ask for a baseline demonstration on your CAD geometry. Then prepare to find an easily quantifiable improvement in an unexpected area of your process.

8 comments

  1. dude, solid post, as always..

    I think the acceptance of direct modeling, as with everything, will come with time. Engineers are reluctant to take the plunge on something new until we over analyze, over think, over test a new technology. By the time we are comfortable, it is not new anymore. I suppose that is ok as I don’t see this mindset changing anytime soon.

    But any guy that is looking to do FEA or CFD on more than a simple part will quickly understand what direct modeling brings to the table.

    I don’t see it as a one or the other (direct vs. history). It will be a combo of the two. I think the more the line between each is blurred, the more people will accept it.

  2. dude, solid post, as always..

    I think the acceptance of direct modeling, as with everything, will come with time. Engineers are reluctant to take the plunge on something new until we over analyze, over think, over test a new technology. By the time we are comfortable, it is not new anymore. I suppose that is ok as I don’t see this mindset changing anytime soon.

    But any guy that is looking to do FEA or CFD on more than a simple part will quickly understand what direct modeling brings to the table.

    I don’t see it as a one or the other (direct vs. history). It will be a combo of the two. I think the more the line between each is blurred, the more people will accept it.

  3. Great series, Jeff. I never fully understood the ramifications of direct modeling. It was always obscured by competing ISV jargon. As competitors lash out at one another, customers seeking a deeper understanding of process and benefits are left on the sidelines.

    Your series, and especially this article, fill a much-needed void in a clear and concise way.

  4. Great series, Jeff. I never fully understood the ramifications of direct modeling. It was always obscured by competing ISV jargon. As competitors lash out at one another, customers seeking a deeper understanding of process and benefits are left on the sidelines.

    Your series, and especially this article, fill a much-needed void in a clear and concise way.

  5. Jeff,
    The direct-modeling approach is a breath of fresh air. It seems like a much better approach, at least to me. I’m looking forward to trying out SpaceClaim’s software, thanks for the hookup.
    BTW, you’re blog is excellent, very crisp.
    I’ll let you know how things go.

    1. Thanks John! It’s a chore to stay crisp and concise, but I try.

  6. Jeff,
    The direct-modeling approach is a breath of fresh air. It seems like a much better approach, at least to me. I’m looking forward to trying out SpaceClaim’s software, thanks for the hookup.
    BTW, you’re blog is excellent, very crisp.
    I’ll let you know how things go.

    1. Thanks John! It’s a chore to stay crisp and concise, but I try.