Howard
Duan
H
Cardboard Bridge Project
As an extension of what we learned in class, groups of 3 students were asked to build a 990mm span cardboard bridge. The bridge has to pass tests. First, it must support a 400N train, secondly it will then support 2 point loads of 250N increased until failure.
Our group was determined to pass at least the first test. In order to achieve this requirement, we had to consider different configurations of the cross section. Finally, not wanting to waste a key stakeholder’s time, we settled on a PI configuration. The key stakeholder in mind was ourselves; I believe that the purpose of the project is to employ the use of all the plate buckling equations we did. Taking the initiative, I worked in tandem with another team and created a simple span bridge. I then drew rough sketch on paint and communicated the design to my team mates. From then on, work was efficient and fast.
For this project, we did not spend much time on problem identification and preliminary design, as we knew we had a tight deadline, in addition to other work. So, we focused only on the necessary requirement of passing the first test. And the design chosen did indeed fulfill that requirement.
Vex Robotics
Perhaps my first exposure to structured engineering desing. I partook in a team of 4 core members that represented our school for the first time in a VEX competition. As a learning exercise, we tried to follow a simplfied flow chart emobodying a model of engineering design.
Our team experienced the most difficulty in idea generation. This is due in part to a hostile atmosphere created by unconstructive criticisms. Had the team followed some key rules in idea generation, eg. suspension of judgement, I believe we could have accomplished so much more. Instead, I found myself working in the last days before the competition, desparately trying to construct an imperfect design.
Since then, I like to think I've learned how to work in teams, at least in one aspect. That is, communicating my ideas persuasively. Though the team's failure can be attributed in some part to dynamics, I think had I used AutoCad Inventor to demonstrate my ideas, there would be much more constructive criticisms and hopefully better idea generation.
Other Works
3D Prototyping
In Gr 11 our school received a new package of Autodesk software, among them the first versions of Inventor 3D modelling. My teacher and I worked in tandem on developing 2D drawings into 3D models on Inventor. After the first project, I was astounded by the capabilities of the program; there was so much I can model and test and everything was automated, from finite element analysis, to bill of materials creation.
I later experimented and discovered for myself what Inventor allowed me to do. One of the most inspiring moments came when I was modelling a Wankel engine (rotary engine) and was stumped on how to model the casing, an epitrochoid. Then I realized I can force the shaft and the rotor to spin in the desired way, trace the path of a vertex, and use that as the sketch for my casing, and it worked! (Link to Wankel and other animations here) This is when an imperfect triangle and cylinder worked to create a perfect shape, just like the one used in real engines. In effect, I’m proud of this instance of lateral thinking to accomplish a task which at the time was beyond my math capabilities.
Ultimately, any CAD program is just a tool to help the engineer design, so I supplemented another hobby – amateur rocketry – with CAD. I began to use the NASA amateur rocket modeller, the shape became much better defined and precise. All my designs culminated in a two stage rocket designed to attach easily and detach as the explosive charge (originally meant to deploy the parachute on a model rocket) pushed and ignite the second half. I planned to export the file into STL and 3D print my prototype, but the prohibitive costs, combined with the uncertainty in the design, prevented me from doing so. Nevertheless, I learned to integrate design into models and then into (hypothetically) a physical prototype for testing.
In Praxis II, I had undertaken an RFP with a group of 3 other students. More detail can be found here. I made extensive use of AutoCad Inventor to model and plan our solutions. It gave us a sense of the scale of the solutions, and how different parts would fit together.
We finally decided upon a modular design of roller conveyors, the assembly of which can be seen in the video to the right, made with Inventor's Presentation feature.
This video, along with many other visuals, greatly aided communicating with our assessors and intrested memebers of the public.
This isn't all that can be done with 3D modelling, however; I also did stress analysis tests on virtual models using expected forces, this helped us focus our design to match the physical requirements more closely.
In another aspect, 3D modelling also made easier communication with manufactureres, in our case we consulted with a machinist at one of the UofT machine shops. I created an engineering drawing with the relevant drawings and info straight from the model, and feedback we received told us our design was easily manufactured due to similar parts that fit together, per the picture Above.
