Wesley Heung

Objectives

The purpose of this assignment was to create a bridge from just the supplied materials that would carry a simulated train load across a span before being loaded to failure. The objective was to maximize the failure load of the bridge without failing any of the other requirements.

Design

As an example of a design project that involves several clear constraints and just one objective to maximize, this artifact clearly demonstrates some strengths and weaknesses of my design process.

To begin, the problem was broken down into many smaller problems. Did we want a column at midspan? What cross section would we choose? A plethora of promising designs occured when different combinations of answers to these questions were considered.

Using mathematical models, the designs were evaluated and thier performance was compared to the objective. Ways to improve designs quickly emerged: if a design failed from excessive shear, was there a way to convert some of the excess flexural strength reserve into some shear strength?

The design was built into a prototype. Even as construction continued, we searched for ways to improve the design. When it became clear that we would have excess material, we used some to reduce the criticality of our most critical loading factor.

Finally, our prototype was tested. Featuring a unique design incorporating a column, our bridge was predicted to fail due to one critical factor, long before any other types of failures. And it did. The bridge failed due to excessive glue shear with superficial damage to any other components, just as we expected.

Why didn't we reinforce this "weakest link" during our design and construction phase? In fact, we had attempted to reinforce the glue with an additional strip of material, but it was insufficient. After the competition, we learned from others superior techniques to prevent this exact type of failure. By incorportating the advice of others, we now have a new design with much improved performance.

This artifact demonstrates the importance of not just prototyping, but actually enhancing the design in another cycle. Even though we had identified a problem, we had no solution on which to work. Therefore, our design was effectively limited by that single problem.