While working on the GrabCAD Amarok bracket contest, I found a few things that you should know when planning to do multiple iterations of design analysis in Autodesk Inventor 2012. It’s a remarkable tool, and a little thought ahead of time can make the process much less stressful.
The Process Used
The process I used was to employ Parametric Dimension mode in Inventor’s Stress Analysis Environment to establish an approximate safe range of feature sizing using slightly refined mesh settings and reduced model complexity in order to produced fast, but approximated results. (I say fast, there is nothing fast about a laptop performing this).
I went on to use the similar settings in Single Point mode, in order to evaluate more detailed structural features as I continued to look for areas to reduce the mass.
I continued to use Single Point with carefully evaluated settings to perform a slow , exhaustive analysis of the completed part. Some weaknesses were detected and the corner rounds reduced and structural radii increased in order to bring the design back to my desired conditions.
This article will discuss various aspects of the refinement process, and include warnings throughout related to oversight in order to help users to avoid mistakes that could send the design back to the beginning. It ran rather long, and I have decided to chop it up over three parts:
- A Word about Parametric Analysis
- Model Preparation
- Stress Analysis
A Word about Parametric Analysis
Inventor Stress Analysis offers Single Point and Parametric Dimension options. Single point runs the model as it is, but the parametric option permits an array or parameter variations to be tested against specific criteria. This is great when fighting the strength to mass relationship battle, which is exactly what the contest was all about. What Inventor will do is test each possibility you propose, and then stores the results of each model variation for you to review. Various report filters include Maximize, that will filter the results as desired.
On the Inventor Stress Analysis Environment Ribbon you should find the Parametric Table button that will activate a form that you can use to customize you parameters as you need. You select the parameters to include from the assembly tree in the Stress Analysis Browser.
The selected parameters are then displayed in the parameter table, in the state as they exist in the current model. Ranges applied to these values create the width of the array, and the number of evaluations to be run. Note the sliders in the image above, that permit you to review each of the parametric results easily.
|This sounds like a great feature, so why don’t I use this all the time?
TIME! It is extremely time consuming to run through each possibility, and takes a great deal of memory and processing power. I don’t care how much power you have, if you run 19 variations, it will take a little while. Try running a hundred.
So what I did was run one array, and get the range of happiness in the design. I stayed within this range, and further refinements were evaluated as Single Point analysis. Running the Parametric Dimensions over and over is a huge waste of time since we have already evaluated them once before.