The Science of Squish

by Michael Mullaney on May 26, 2011

Think about metal. More specifically, think about a metal component in a Boeing 787, or your other favorite airliner.

To make that component, raw metal was heated up and distorted (molded, drilled, carved) into a specific shape. Every step in this production process has an impact on the metal’s nanoscale and microscale structure. Even though we can’t see the cause-and-effect with our naked eyes, it’s happening.

All of these microstructural changes have a cumulative effect on the overall metal component. The changes may alter the component’s strength, or its resilience to wear and tear and fatigue.

As a result, it’s imperative that engineers designing aircraft understand these microstructural changes in order to know precisely how the component will function, and how often it needs to be replaced.

These are the kinds of questions that interest Professor Antoinette Maniatty. A big part of her impressive research portfolio at Rensselaer is modeling metals to better understand how microstructural changes occur and affect the material’s ability to withstand different forces or loads.

We talk a lot on The Approach about computer modeling. The picture above, provided by Maniatty, is a stellar example of how it works and why it’s critically important.

What you see on the left is a very small section of aluminum.  All metals are made up of many “crystal grains.” In the image, each colored section represents a grain, or single crystal. Notice that the colors, which represent the structure (or lattice orientation) of the different grains, are quite distinct from one another.

Now, kindly move your attention to the image on the right. This is what the section of aluminum would look like after being squished, or compressed, to about half its original size. I can guess what you’re thinking, and no, “squish” is not a technical engineering term.

Many things happened as a result of being squished. First, the like-colored grains are no longer the same size. Second, the colors are no longer distinct. You can see colors starting to blend together, which represents the distortion of the structure of the crystal grains.

Maniatty says these kinds of models and simulations are absolutely necessary in today’s world. Creating a system to do physical experiments, squishing actual pieces of metal thousands and tens of thousands of times, would be eminently time-consuming and cost millions of dollars. It would be a big game of trial and error.

By using computer modeling techniques like the one described above, however, it’s far less costly and the engineers are able to better define the problem and coax more knowledge and data out of the results.

Click here for more information on Maniatty’s research.