Matching simulation and experiment
A big development in Additive Manufacturing is to integrate electronic and optical functionalities in the printing process. This is what the Ampere project was all about. Reden has contributed by simulating the 3D printing of the polymer parts. These simulations show the effect of print parameters on the shape distortions and residual stresses in the product, which may affect the final product performance.
For real-worlds parts, a technique called photoelasticity can be used to visualize the stresses in a transparent material. Polarized light in a plane polariscope is used. External applied stresses or residual stresses from printing can then be studied from the colorful images. For our simulated digital doubles, we can already look into the material to find the stresses, there is no need for polarized light. But how can we compare this field of numbers with the colorful photo elastic images?
Quantifying colorful images
Reden developed a method to create a photo elastic image from simulated 3D stress fields for validation of FEM simulations. This is illustrated with a test case of a 3D printed tensile specimen with a central hole. An increasing load is applied. The sample is illuminated from the bottom with a white, fluorescent lamp. The uneven clamping at the bolts leads to slip of the sample and a complex stress field. In the video above, you can see that the simulated and measured photo elastic images lead to similar results, thus validating the analysis. This method can be applied to many more cases, but it has some limitations as it requires transparent materials, and the resolution depends on the stress levels and sample thickness.
