Week 6 Blog Post

Over the course of last week, week 5, we worked more with Knex. We put together some great ideas from everyone in the group to create one group bridge. We, as a group, decided to spend a little more money, using a lot of pieces, and attempt to build a bridge that can hold very large amounts of weight. We were able to test the bridge and were very happy with the results. Our bridge was able to hold more weight than could be fit in the testing bucket. In regards to the difference between Knex and WPBD, I stand by my previously stated differences. The biggest differences are still the physical presence of the Knex bridge and the overdramatized bridge movements in WPBD.
There are many differences between working with Knex and building a real steel bridge spanning about twenty feet. The first and most important difference is that in the construction of a Knex bridge, no lives are in danger. With the Knex bridge, a small scale model is created to simply test how much weight the bridge can hold versus the estimated cost of producing the bridge in real life. Another major difference between creating a Knex bridge and a real bridge is that the Knex bridge will not be exposed to weather and other natural effects that factor into a bridge's functionality such as wind, rain and extreme heat. These factors would also wear down a standard bridge over time by means of corrosion.
This week, we plan to do more testing on our bridge and edit it accordingly. We will possibly remove some less important pieces that could save us some money. Depending on the outcome of the tests, we may decide to alter the bridge's design slightly. I would like to do a little more testing of our bridge's ability to distribute weight and make necessary adjustments. My biggest fear is that the bridge will not be able to evenly distribute the weight of the bucket. Regardless, I am excited to continue working on our bridge in lab this week.

Week 6

In week 5 we finally got to start working with Knex.  When making our 2’ bridge we combined all of our ideas together.  We took designs similar to the ones we drew and the ones we created in Westpoint Bridge Design.  Our design was a little bit expensive.  Apparently it only costs $250,000, I think I may cost more but I did not do the estimate.  Our first design started out with a bunch of cubes put together to span 2’.  We tested this design out and there was not enough weight to break it.  After we brought the original bridge back to our station we added a top piece that covered the middle.  This design now looks similar to the one I made in Westpoint Bridge Design but with different trusses. 

            My views of the similarities and differences have not changed at all.  Obviously there are going to be a lot of differences between a Knex bridge and a 20’ real bridge.  The first thing that comes to mind when comparing the two is the materials that are used.  Cement and steel are a lot different then plastic.  The real bridge will be able to hold a larger weight because of the stronger materials that it has.  Another thing is that the Knex really limits what designs you can make.  There are only certain angles that you can make with Knex but on a real bride you can make what ever angle you would like.  In the real world a bridge cannot simply be tested like the Knex to see how much weight it can hold.  Engineers need to be 100% sure that their bridge can hold X weight otherwise lives are being put in danger. 

        -John Watson

A2- LaChance

When approaching this assignment I knew right off the bat that the design I had for the WPBD program was not going to be transferred into KNex, so I decided to go back to the basics. First I looked and the model bridges that were given to us in the WPBD program and made to one that seemed to be the most structurally sound out of the three with some modifications. Instead of just having one beam go from corner to corner of each box I decided that and 'X' formation would be sturdier. I also used a select few of the materials available because it made the building of the actual bridge easier. After taking some measurements the bridge came out to be 2' long x 3" wide x 3" tall.

After fiddling with the materials I discovered that the 'X' formations placed on the top and bottom of the bridge seemed to as effective as just a beam connecting to opposite corners. So to cut down on cost even further I switched out the 'X' formations on the top and bottom for the yellow 3.375" chord. In the whole design process I have learned that ideas will have to change because not all ideas that you have when designing something can be just transferred into building the bridge. Your ideas may be interfered with depending on the materials available. Also, after seeing the designs of my fellow partners I believe that there will not be too much arguing between what the final design should be.

Week 5 Blog Post

During our engineering lab last week, librarian Jay Bhatt came in to talk to us. Some people had submitted questions to him about anything regarding this class which unfortunately he did not have a sufficient amount of time to cover many of the questions.  What he was able to tell us was how to go about using the library resources to guide us on making our bridges.  He also gave us his contact information so that if we needed to we could ask him any questions.  Also in lab we discussed how we may not be able to make the designs we did in WPBD due to the constraints of the KNex pieces.  We were also given the following parameters; the bridge had to be at least two feet long and have a flat surface for a block to place on top of the bridge.  After listening to everything that had to be said beforehand, each group went back to their tables and began to get a feel for the KNex and how they can be used.
When messing around with possible structures there were some visible differences.  WPBD is able to show the stresses put on each point of the bridge but the Knex has to forces in 3 dimensions instead of 2. Because we can’t measure the stresses using the KNex it would be impossible to find out what would need to be changed unless we test it.  In WPBD you could use different types of materials and beams, but with KNex there are only different sizes of the chords that we can use. I personally enjoy working with KNex so I have the mindset that this part of the lab will be pretty exciting.
-Robert LaChance

A2-Tillman

This bridge is based off of a simple but effective bridge design I came up with while using West Point Bridge Designer. This is a simple truss bridge with the addition of small top and bottom supports. These supports are present to provide support to the middle of the bridge so it does not split down the center when weight is place on it. The bridge is the minimum length at two feet long with eight inch height and six inch width.

Over the course of this design, I simplified my bridge to cut down on costs. I moved the bulk of my bridge to the center of the bridge instead of overtop as in my original design in WPBD. In addition to this, I changed my trusses from triangles to "X" designs. I did this to provide the bridge with added support. I also strengthened many of the beams to provide extra support. 

While designing this bridge, I learned the importance of the materials used. I also learned that designing a bridge takes patience. A great amount of testing is required when designing any bridge. The most important thing I learned is to listen to my teammates. Everyone in my group has great ideas and if we put all of our great ideas together, we should come out with the most effective bridge design at the lowest possible cost. 

A2-Watson

1.  I based my design off one of my first bridge designs in Westpoint Bridge Design.  From the side you can see a bunch of triangles.  These triangles alternate from being right side up to up side down.  In the middle of the design you can see the two supports make an X.  I felt that the middle of the bridge would be the weakest point so I crossed two supports there.  I used three different types of beams and 3 different types of gusset plates.  The beams I use were 1-1/4, 2-1/8, and 3-3/8.   The gusset plates I used were 180-degree grooved gusset plates, 360-degree gusset plates and, 45-degree gusset plates.


2.  Elevation View

3.  Plan View

4.  Cost

5.  My design changed once during drafting.  The one thing I did change was the crossing beams in the middle.  Like I said above I did this to add strength to what I thought to be the weakest part of the bridge.

6.  While doing the design I learned that you do not want to put too much in because it will raise the cost of the bridge.  I do wish that I had Knexts to bring home because it is hard to imagine in your head what will fit and what will not.

Week 5 Blog Post

Last week the engineering librarian Jay Bhatt came in to talk to us.  The previous week we had submitted questions and he briefly touched base on some of them.  He explained how to use the library and other tools we might need in order to research bridges.  He also said to contact him if we had any questions.  Before he came in and talked we discussed issues concerning the Knex bridges.  We went over how much each piece would cost and the constraints of the bridge.  The bridge had to be at least two feet long and have a flat surface for a block to placed.  After we broke up into smaller groups we got to play around and get the feel for the Knex. 

            Knex and Westpoint bridge design are similar in that you get a feel for creating a bridge and you can play with different designs.  What Westpoint bridge design lacks in is that it is unrealistic but the Knex make up for this.  In Westpoint bridge design the bridge would bend unrealistically.  The Knex will not bend like this and will break before they even get to that point.  In Westpoint bridge design you could play around with different types of materials and beams, but when using Knex we are limited to the same type of plastic and beam, they only differ in size.  One other thing that I noticed is that the Knex bridges are much more time consuming to make.  It is also hard to tell where the breaking points are on the Knex bridges.  Since this part of the project is more hands on I feel like we will learn a lot more.  I can’t wait to start building!

-John Watson