Abaqus is itself a powerful tool for Finite Element Analysis, but coupling it with Dassault Systèmes Isight can open up new worlds of capabilities when it comes to design optimization. Isight is a system integration tool that is designed to execute other engineering software codes; providing inputs, executing models, parsing results, linking them into integrated networks. It is able to drive the input to each component in the loop and extract the outputs, and it contains a suite of tools for both design exploration and optimization once a linked model has been constructed. This post will demonstrate the capabilities of Isight by driving an Abaqus model and determining the maximum load that a chain can withst1 Modeland before any of its material experiences plastic stresses.

The FE model is relatively straightforward with geometry modeled in Abaqus while taking advantage of planar symmetry, one link is modeled and an assembly is created with two instances of it used to form the interlocking links. Symmetry conditions are applied on both the XY & YZ planes, a contact pair is created to enable the two links to interact with each other, and the distal cross-sectional face is fixed while a Reference Point is used to apply a point force to the proximal face. Material properties are assigned based on the elastic-plastic stainless model found in this Abaqus tutorial. At this point the CAE model is saved so that it can be referenced with Isight, however it should first be solved so that we know it has been properly set up and will result in plastic deformation. That result is shown below, where the extreme deformation due to plastic stresses under the high load is immediately apparent.

1b Initial Condition

 

After opening Isight and creating a new file3 Isight Model an Abaqus component is dropped onto the hanger and configured. This is as simple as choosing the applied force as an input parameter and the equivalent plastic strain value (PEEQ) as an output parameter. Once this is complete the loop can be executed with any applied force as the input and the plastic strain be extracted automatically.

To determine the maximum load that the chain can sustain before any plastic deformation will occur we simply need to optimize for the force that will result in a slightly positive but non-zero value for PEEQ. This is accomplished by dropping an Optimization onto the top of the hanger and suitably configuring it as shown in the image below.

 

4 Optimization Setup

The Hooke-Jeeves algorithm is chosen with most options left at the default values and the output parameter PEEQ selected as the goal with a target of 0.01. A max load of 70,000 is set as the initial condition and the model is ready to be optimized.

5 Optimization Result

After it completes the results can be analyzed by bringing up a plot of the Optimization History. Here you can see that the plastic strain rapidly drops from its initial value down to zero, and then Isight is quickly able to hone in on the load that yields our positive but negligible value of 0.01.

To extract the force, simply switch to the History tab to see the optimal point that was determined in the optimization.

Now we can use this force for an input in Abaqus and examine the results, which are shown below.

2 Plastic Strain Results

As you can see essentially none of the chain is yielding and we have found that maximum load that it can withstand with plastic stress. Hopefully this example has made it clear how simple a tool Isight is to use, and just how powerful its capabilities are in engineering design optimization. If you have any questions please feel free to contact us, and if you would like to get access to the files used please complete the form below.

Thanks

Gary

info@optimaldevice.com

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