SimQuake Final Testing
By: Andrew Sack, Annalisa DeBari, James Liao, Sahana Karthik
Our product is a small table-like structure with a platform that is able to move back and forth with different speeds. The purpose of this device is to simulate an earthquake, so the students can test the stability of their structures, which are built using spaghetti and marshmallows.
Our device is consists of an acrylic base, on which there are two rectangular wooden blocks mounted rigidly by hot glue, providing support for a gear and a rack. Only a part of the gear has teeth, and the rack is oval-shaped with teeth along the inner circumference. Using this mechanism, the rotational motion from the gear can be translated into linear motion by the rack. Powered by Lego EV3 motors, the rotating gear can move the rack back and forth, which in turn moves the platform back and forth.
Both the gear, rack, and platform were made using the laser cutter. The motors are mounted rigidly underneath the platform within a 3D-printed base, which is tightly hot glued to the base. The platform is mounted on top of the oval rack, so it moves along with the rack.
The shake table worked very well on testing day. Students were able to press the button and shake their structures. The speed was an input variable in the code so it was easy for Andrew to change the speed to challenge the kindergarten students' structures if it was able to stand for a while when the table was shaking. Occasionally the gear and rack mechanism got stuck but it was easily reset within seconds. The wooden material on the central gear was a good choice since the acrylic gears' teeth kept breaking prior to testing day.
The flow of the whole setup improved greatly the second time as the team had a better strategy of managing the students. The clear table top on the device was a nice feature so the students could see the gear and rack mechanism. The students enjoyed creating and testing their structures on the shake table, and were motivated to go back and improve their design. After testing for a bit, the students learned about the engineering process and how engineered devices require many cycles of testing. The group assessed the students’ understanding of the engineering design process via some questions about engineered products. Overall, the product reliability improved and the students enjoyed using it.