Smart Slice Validation Series - Part 1 - Tensile Tests

The fundamental value of Smart Slice is reducing the time and costs associated with developing a part that meets end-use requirements. Traditionally, this is achieved with the print-test-revise iterative cycle, but this process is inefficient and requires upwards of 50 cycles per part in some instances. A more efficient approach is to employ virtual prototyping to validate different part designs prior to manufacturing and testing the part.

Our Smart Slice technology utilizes sophisticated optimization algorithms to adjust print settings (global and local) so that the part meets the design requirements while reducing print time and material usage. Instead of iteratively printing and testing design concepts over the course of days or weeks, the same can be done in hours or minutes with Smart Slice. Any software that predicts real-world scenarios must be validated against experimental data. And this is why we are putting together a series of posts where Smart Slice is compared to experimental data. We will start with a simple part and loading and increase complexity over time. It is important to establish credibility on basic parts and loadings first and then build up to more interesting real-world applications.

How We Validate Smart Slice with Tensile Specimens – Part A

We start with dogbone-shaped tensile specimens printed with BASF ABS Fusion+ and BASF PAHT CF15. The geometry of these specimens conforms to the guidelines in the ASTM D638 standard. There are no official standards for 3D printed tensile specimens so existing standards are commonly adapted for 3D printed parts. As shown in the image below, there are up to 3 configurations that were tested: XY0, XY±45, and XY90. XY refers to the parts being printed in the XY build orientation (flat on the print bed) and 0, ±45, and 90 refer to the raster angle (the angle between the direction of the extruded filament and the load direction). The raster angle is uniform for all layers of the XY0 and XY90 specimens and the raster angle alternates between +45 and -45 for layers in the XY±45 specimen. Finally, each layer is solid (there is no infill).

Raster Orientations

Raster angle profiles for standard dogbone tensile specimens. Note: the line widths have been increased for the purpose of clearly illustrating the raster angles. Actual line widths are smaller.

The specimens are loaded in tension and the experimental linear stiffness and yield load are obtained. The yield load refers to the load at which the load-displacement plot switches from linear to non-linear. In other words, the load where the stiffness of the part begins to decrease because of softening of the material. Using Smart Slice, we predicted the stiffness and global yield load for each configuration.

The results for both materials are shown below. In all cases, the Smart Slice trends match the experimental trends well. The predicted yield loads for BASF PAHT CF15 are lower than the experimental values. This is likely because the yield load predicted by Smart Slice can be conservative in the sense that the Smart Slice yield load corresponds to the load where yielding initiates at a single point in the model whereas the experimental yield load corresponds to the load where enough yielding has occurred to influence the stiffness of the part. In other words, yielding in the part is usually more widespread in the experimental yield load.

stiffness vs raster angle BASF ABS Fusion+

Smart Slice vs. experimental stiffness and yield load values for BASF ABS Fusion+.

stiffness vs raster angle BASF PAHT CF15

Smart Slice vs. experimental stiffness and yield load values for BASF PAHT CF15.

How We Validate Smart Slice with Tensile Specimens – Part B

Next, let us consider how Smart Slice performs across a wider variety of raster angles for a different material, 3DXTech ABS. The tensile specimens share the same geometry as the previous specimens, but the raster angles are uniform for all layers. For example, every layer of the XY30 specimen has a raster angle of 30 degrees (as opposed to alternating between +30 and -30 degrees).

The results below display again that Smart Slice is successful in reproducing the experimental trends. We see that the stiffness and yield load both decrease as the raster angle goes from 0 to 90. The ability to capture the yield load trend is particularly striking.

stiffness vs raster angle 3DXTech ABS

Smart Slice vs. experimental stiffness and yield load values for 3DXTech ABS.

Closing Remarks

These validation results demonstrate that Smart Slice generates trends that agree well with experimental trends. Stay tuned for future posts in our validation series to see how we are validating Smart Slice with different parts, materials, and loading scenarios.

Experiment Smart Slice Validation