SSA Blog

Our first webinar of 2015 “The Composite Webinar” will be held on 30th January 2015 at 10:30  

Composite materials are a great alternative to metallic materials when looking for weight saving and improved performance. However, the difficulty to accurately model complex composite structures often leads to oversized structures and underestimated mechanical performance.

Performing Contact Analysis can be one of the more complex non-linear finite element challenges in the daily life of a structural engineer and in our opinion remains the single biggest challenge in simulation. As we have many involvements with people performing these non-linear contact analysis for their finite element model, we notice that there are a lot of challenges which often are not addressed well because a lack of convergence and ever reducing time-steps. This is where we see a lot of trial and error approaches with the hope on a possible solution.  Unfortunately many times the “hope” ends in a hugely stressful situation where you need to ask another company to do the analysis for you because you can’t seem to get it running properly.

Many engineers tend to forget that setting-up a contact analysis simulation takes quite some understanding of the actual physics and behavior behind this. The reason people tend to forget, probably exists due to easy and user-friendly CAD integrated Finite Element Software for which the user requires less knowledge and just applies the contact to their model. The downside of these CAD-Integrated simulation tools is that they focus on the average engineer performing slightly simple validations which most of the time are linear statics anyway. Using linear static analysis for contact behavior can produce nice colourful results, but can be completely off with respect to accuracy and the values like contact pressure or reaction forces. And even if the CAD-integrated FEA software would have the ability to perform non-linear analysis, often the solver capabilities are not powerful enough to provide the structural engineer with confidence and enough options to obtain convergence and get the job done to solve their contact challenge.

For some time now manufacturing process simulation has been a fairly routine activity.  All you have to do is read Richard’s last posting.  Casting, forging, injection moulding and stamping simulations are all commonplace, especially at what you could call the top end of the industrial market. But what doesn’t seem to be commonplace is coupling these to structural simulation packages; at least from where I’ve been sitting for the last year or two. But then SSA customers are by definition one step below the major industrial group level, and I may have missed something.

Quite simply we need to simulate the performance of the components we actually end up with, rather than those we’ve optimistically designed based on geometry and matweb style material definitions.  I often try and visualize what my car might look like if I could see the residual stress fields, but I suspect I may be alone in that.  And then you could visualize other factors such as material directionality and compromised properties like density and material thickness. Generally these are ignored when it comes to the structural simulation of the actual part. With a little additional effort we could map the production simulation results into the FEA models we are already using. We recently paid somebody to do some marketing for us and they came up with the slogan “joined up thinking” which pretty much hits this nail on the head