Week 7 Assignment: Analysis desires

During this week in lab my group came in with a design that had been previously tested but we knew we needed to make stronger. The first thing we did was added a deck truss to our original design because we knew that the weak spot on the bridge was the gusset plates in the middle. The deck added support for that area and gave it extra strength. When we tested the bridge we found that it held more weight with the deck, in the end holding about 19 pounds. The cost of our current bridge is about $320,000 so getting the cost down is also something that we need to do. This coming week we will be brainstorming our ideas about the 3 foot bridge we will be designing in the upcoming weeks, taking the things we learned about our previous bridge and working from there.

If I could know any numbers for this project I would definitely want to know the compression and tension forces (just like in WPBD) at each gusset plate. It seems like many of the problems are found at the gusset plate and so that’s where I think the most research and calculations would need to be performed. I would also want to know maybe if there is a way to calculate the maximum weight that a bridge could hold with certain values.  

Kelsey McSorley

Week 6: K'NEX Build Process

      Unfortunately, due to personal health issues and concerns, I was unable to participate in last week’s lab. Melissa, Kelsey and I met and filled me in on last week’s instructions. From what I understand, both of them built individual, full-scale bridges, while keeping in mind the final objective of the most successful cost to weight ratio.  Although I was unable to participate in this lab, I collaborated with Melissa over the week to enhance her bridge. Through trial and error, we discovered that the angle in which the gussets are arranged provided a more stable product. Our meticulousness in this effort also promoted symmetry throughout our entire design. In testing, I believe this change was able to add three more pounds to its stable condition without adding any more components.

      My opinions about WPBD compared to K’NEX remain the same. Both provide very different methods of construction. WPBD provides a virtual experience, whereas K’NEX is completely tangible. WPBD operates in a way that uses proposed materials and beam sizes to appear as realistic as possible. The results from testing have induced accuracy within the force/compression readings, which, upon careful analysis, can be used to further success in future designs. K’NEX, on the other hand, is limited in its materials but can be physically tested to its limit and thus analyzed from its breaking point. Also, one major difference in provided materials is that WPBD lacks gusset plates. Gusset plates are essential to a bridge’s construction as they join members of a bridge together yielding stability. 

Chelsea Moss

Week 6

This past week during lab we got to experiment with the Knex a second time. We were asked to build a bridge that we thought had the best cost to weight ratio. Kelsey and I designed separate bridges. I decided that I was going to try and create a simple design with the smallest length of members to lower cost. I did not have time to test my bridge during class but I did bring my bridge home to experiment and fix it. This week I have been working on a new design that will lower cost but maintain strength.

My opinions about the differences between the WPBD program and Knex have not changed. However, I see many differences between working with and designing a real bridge and a Knex bridge.   Knex limit the types of beams, members and gussets you can use. When building a real bridge a person can use any types of beams, gussets and members they want, in any shape or color. Plastics also react and bend differently than steel which is the most common material used in bridge construction. The differences between the materials also determine how they will react to outside forces like inclement weather and wind gusts. Also when someone isemplyed to design a bridge they are often given a time contraint I feel these are the greatest  and most important differences. 

Week 6 Assignment: Knex Process

During this week in our lab sections we spent our time constructing individual bridges from the knex. Melissa and I decided to each construct our own bridge and then test them both to see which held the most weight. With my original design not being long enough, I had to add another component to my bridge, causing it to be unsymmetrical. This caused my bridge to fail after only 5 pounds of weight. We decided after testing to go along with Melissa’s bridge design (even is minor tweaks had to be made). This week we brought our bridge home with us along with some pieces we can use to make modifications if needed. We plan to test and modify the bridge as much as needed to make it as strong as it can be.

            My statements about last week stand the same. I still agree that you can use your hands to feel and test the strength and compression of the bridge, and I still agree that we can easily find where the mistakes are made. We learned that while testing it, it would easily break at the weak spots and they could be easily determined. I also still do agree that making repairs is much harder with Knex. After breaking the bridge with testing and determining where the repairs needed to be made, if one piece had to be changed out for length the whole bridge needed to be changed. Obviously, if this were a real bridge we would need to be 100% positive that the bridge was sturdy because it would cost hundreds of thousands of dollars to construct and if it broke a new design would have to be made. With Knex, there are no repercussions for breaking it and making it all over.

Kelsey McSorley

A2 - Chelsea Moss

Week 5: WPDB vs. K'NEX

dkgjskdjgdlkdksgjs

A2-Mercado

1)

The design of my bridge is fairly simple. I wanted to keep the design simple to lower the cost which is what I learned from experimentation with West Point Bridge Designer. My truss consists mostly of alternating triangles according to the side. All the triangles point inward and the center square is an X. The top are all X’s inside squares.  I also tried to utilize smaller beams because they were cheaper. My design is very abstract and based on how I perceive loads to be experienced thus the X  centers are at areas where there is more load.  My main concern is the question as to whether my abstract idea will work at all.

2)

 Elevation View

3)

 Plan View

4)

 Bill of Materials

5)

As of right now my bridge did not change much because I have not tested it yet. If and when I get to test my design I will change the design accordingly.  I took

6)

                I learned that designing a low cost bridge is not easy at all. Many of the gusset plates are very expensive especially the connection plates.  This makes the price of the bridge skyrocket.  In order to make a good bridge that is low in cost a lot of testing must be done.