Description:

This spring features a square cross section throughout the legs then as it transitions to the U-bend it changes to a rectangular cross section that spans 49.201mm. The overall thickness of the spring is 0.275 cm and has a 3.5 cm radius of curvature. The hooks are a customizable feature that can range from 0.15 cm to 0.30 cm based on the infant.

Mechanical Characterization:

To determine whether the force produced by the spring is within range we conducted a test on the Instron that compressed our spring to 1 cm. Figure 2 depicts these results in the form of a displacement versus force graph. From the results it was determined that the spring could reach a maximum of about 15N and in duration testing it could retain a force that was in the required range for 10 hours of compression. This design stood out because after extensive testing the spring never showed signs of yielding or unsteady loss of force.

Manufacturing:

All the prototypes for force testing was manufactured with a 3D printer using PLA filament. However, we experimented with two printers which gave us varying results for the same spring on default settings. While at 15% infill for Prusa gave us a completely filled spring, the same for Bambu produced a hollow one. Even after changing the settings of the Bambu printer to create a spring that is filled, the material properties determined by the dogbone test revealed that this printer makes springs that are too flexible. So the best printer for our team and the design was the Prusa MK4 and if another printer is selected for future research it is crucial to experiment with the printer settings.

Product Demonstration: