Week 6 KNEX

Working with the KNEX for a week, I have come to the view that KNEX are alot better with building bridge. 

It gives you a wide range of connectors and different types of rods. With the KNEX we are actually able to test out out bridges, so the relativistic effects on a bridge are seen. the uneven weight distribution is put forth in front of you, unlike WPBD the full range of those defects are not seen. Here you are clearly able to see what connectors are bad and which are good. So that you know exactly which parts to replace and which to keep and where to change the structure of bridge if need be. Which WPBD did not show connector defects, it only showed uneven distribution in the rods. So, maybe changing a connector was not an option. Here it is, which also may keep cost down, since you are able to change a broader range of items. 

This week we will be testing the weight capacity of out bridges with sand, as well as the discussing and changes that might be needed to out bridge. We have done several modifications so far but our bridge still had about the same strucuture, a trapezoidal prism. This week we need to fix all of our connector issues that were presented to us last week. 

Week 6 - Knex Process

After working with the Knex for a week, I have noticed that my previous perspectives of the comparison between Knex and WPBD have slightly shifted. I have noticed that working with Knex gives you more options to design your bridge. Especially the connectors, WPBD is limited to one type of connector while Knex has variety of connectors. In addition, Knex consist of groove gussets that can be attached another groove gusset to strengthen the bridge. Some of the major flaw in the similarities and differences I had previously seen between Knex and WPDB programs is with testing the bridge. WPBD program provides a constant result because the bridge is being tested in a controlled testing field. The results from the Knex bridges can vary because the bridges are tested at an uncontrolled field. Therefore other factors can influence the end result of the bridge such as the position of the bridge and the placing of the weights on the bucket. Another discovery I made from working with the Knex was that the connectors and the chords starts to bend and becomes less stable, more we work with the Knex. Whereas, the joint and the membranes in WPBD programs remain stable and unchanged as they undergo more testing.

During the previous week in class, our group discussed about the design that will produce the most efficient bridge. For the rest of the class, we worked with the Knex to build one bridge as a team. We did several trial and error on our own and modified the design as went along. Although our bridge went through several modifications, the basic outline of the bridge remained as a trapezoidal prism. For the next week in class, we will be discussing the construction issues and conducting more Knex bridge testing.    

Week 6 - Knex Process

After spending another week with Knex to build a bridge, I believe that it is harder than I first assumed. First of all, it was difficult to choose which design or method the team will use to create the bridge because there are numerous different options. In addition, while building the bridge we encountered several problems, such as the parts not fitting with the design due to the limited sizes available. As we moved on fixing the problems, at the end it resulted with a very expensive bridge. The most important observation we saw about the Knex pieces is the 180 groove gussets. The most common procedure is to combine two of the 180 groove gussets to able to create a rectangular prism structure, but it turned out to be very expensive and unstable. Our bridge, which contained numerous 180 groove gussets, was extremely weak and unreliable even though it was expensive. Therefore, it is very important to understand all of the Knex pieces and use them efficiently. In West Point Bridge Design, all the parts played similar role, but the gussets were not as important as they are in Knex. In addition I realized that in WPBD, increasing the cost will increase that strength ratio, which does not occur with knex pieces.

Last week in lab, the groups were allowed to build a bridge based on their design from the A1 assignment using Knex pieces. My group decided to build one bridge as a team effort and incorporate everyone’s ideas. Our bridge was structured in a small rectangular prism with triangles as the web. It contained numerous pairs of 180 grooved gussets, which turned out to be unreliable. This week in lab, each group will test their final outcome of knex bridge and try to analyze how it fails.