Critical thinking and design are fundamental principals of engineering. The use of modern technology like 3D printing now provides another avenue to explore creativity and facilitate rapid prototyping. The included files represent an update to an educational science activity(Egg Drop Challenge) that reinforces principles of design, benefits of material, and influence of 3D printed infill percentages with modern adaptation. The CAD model of the egg can be used to inspire creative mechanisms or housings that can enclose and protect an egg from high force or impact. Students can use the model of the egg or dimension their own egg to build a truly unique and customized enclosure and practice fundamental elements in the design process (dimensioning, drawing, sketching).The idea in this lesson plan is to observe the effects of different infill percentages and the effects the infill percentages experience as force is applied to the construct. The two egg container components are designed to encase the egg and maintain a static position with the flat surfaces. The flat bottom surface of the containers allows the egg to be positioned on a flat surface, while the contoured cap maintains a flat top to allow loading conditions. The demonstrative lesson will provide a visual representation of the effects of infill percentage. Not only can this process be performed for infill percentage, but the orientation of the models can also influence the loading capabilities and can also be tested.
To visualize the effects of various infill and measure the force response, print 3 different sets of containers with infill percentages of 10%, 50%, and 100%. To demonstrate the effects of orientation, print another set with infill percentage of 10% in an orientation opposite of the first set of containers. This second set of containers will demonstrate the influence of orientation. With the printed containers, apply a known force or weight incrementally to the desired container with respective infill percentage and record the response until the egg is broken. Repeat the process for the remaining containers to see the effects of infill percentage. The visualization and experimentation can be conducted at the beginning of class to instill the characteristics of each property with the students.
To incorporate design elements with CAD, have the students create custom egg enclosures for different infill percentages. Separate the students based on the previously studied infill percentages to see how the effect of infill percentage shapes design. Groups with the lower infill percentage may need to create creative enclosures to provide greater support. The main design requirements are: the enclosure must have a flat top, the enclosure must have a flat bottom, and the enclosure must fit an egg. Additional design constraints can be imposed based on academic standing or age i.e. volume, cost of material, print time. These elements can actually shape the design and may even dictate the infill percentages (i.e. time). These constraints can impose realistic demands much like those in industry or teach the students to meet deadlines.
If the instructor has access to various materials like rubber or NinjaFlex, an additional lesson might involve designing rubber like enclosures or caps to observe the effects of dampening characteristics. The 3D printed models can be designed to accommodate the rubber enclosures and the loading can commence much like the previous test.