week5-xue bai

     Last week in class we listened a speech about how to find use information about our bridge design. Mr. Jay Bhatt come and shows some useful book that we could look at. I also got to know that our library have a lot of useful thing I can look at to improve my knowledge of bridge. Then we learn about the basic rule about the k’nex bridge design. like how long should it be and how to find out how many weight it can keep with out break it. The cost of the bridge is also a big part we get look at the sheet of the cost of each part. The last part of class we get a change to play with the K’nex.

     Next class we would really start built our own bridge. We would try to finish the bridge in class. Try to find the best bridge with can hold more weight and cost less.

     The k’nex is different from the WPBD by many ways. The k’nex did allow you to changer any of the size of the bridge. You have only one size over all. Also the really K’nex bridge did allow you to text it over and over to get a best type. The WPBD would tell you which part is weak and need to improve, but K’nex will not. K’nex is more really, it is a really thing than just a program. It also made it harder because it is really not ideally any more. You need to think more carefully of every peace. There would be a lot of unexpected problem appear, but I am ready to handle it.       

A2 - Hayes

The reasoning of my shape is because I like the results I have gotten in WPBD using a top and bottom truss. Although I do wish the top was more arch like but I found it difficult to make but given more time and experimentation I believe it will become more arch like in the future. It was shaped to be fairly condensed using short pieces as they were more stable in testing also it is not too expensive as the longer pieces are and it does not require too many gussets as if done using shorter length peices.

Side View

 Top View

 I felt it was unneeded to put the lenghts and dimensions as it is color coded and each color has a fixed length. White: 1.25", Yellow: 3.375", Red: 5"

The gussets are blue dots and are all made of two 180 degree grooved gusset plates put together so the cross bars can be added to attatch the two sides. the only exception is there are 5 gussets per side that are 180 degree grooved gusset plate and 360 degree grooved gusset plate together, these are used in the middle where the gusset has bar located to the top, bottom, and both side.



Height: 6.77"
Lenght: 25.25"

Cost Table

There were not many changes as I wanted to keep it as simple as possible but some of my changes are as followed. The base was made of five red bars, I changed to six yellow as I feel the shorter ones will be more stable and offer more connections on the upper level. Second the highest level was just like the middle but I changed it to be like the bottom in hope that it would be more stable and also to cut cost. Also the bars that connect the two sides was red but I changed it to yellow bars as it would condense it and also cut cost a bit. These were the major changes.

I learned that some time material is predetermined in length and thus options are limited and some designs require tweaking or may not be possible.

   - Kyle Hayes

A2-Xue

By the experience of using WPBD I know that the single line up is the most effect way of building the bridge. This time with the K’nex I am also try to make a simple line bridge. I use 3.375’’ as my basic chord. I find out that the 3.375’’ is the most effect length. Short that that would cost a lot of the join and long that is too long that cannot hold enough weight. I use two different triangles in the middle. In the really middle are four small triangles and the one beside it is three. By the WPBD experience I got know that the middle is the place than get most of the force, so I put more chord to support the weight. On the side witch is not that much force I cut out some of part. 
  

side view

top view

 bridge hight =3.375

bridge length=23.625

cost of the bridge

At first I use all 1.125’’ chord as a base. Then I find out it is too short and also the K’NET connect is not work really well and it also cost a lot of more money. Then I change the 1.125 to 3.375. it use less chord than the 1.125. About the link part I first use all 360 degree grooved gusset plate. Then I find out that 180 degree grooved gusset plate can do the same job with lower lost. I lower my cost a lot by these two steps.

By design this bridge I get a basic idea what a K’nex bridge would look like. It is different that the WPBD. In the WPBD the program would allow you to change different length and size of the bridge. In the K’nex it only have same size and 5 length. It lowers the possibility to design a bridge. I did not have the chance to try the bridge and see how it works out. I think this bridge would be reasonable good.         

Week 5 - Kyle Hayes

I was sick and unable to attend class this week and therefore I am unable to provide my experience, however I did go over the slides and look up the constraints and pieces and cost of the pieces and I feel that I have a fair understanding of what happened without being there.

The K’NEX will be more restrictive, there is only one material, and there are predesigned lengths and thicknesses, where on WPBD this could be customized. Similarities are obviously they will both test designs and help analyze information; WPBD will give values where as the K’NEX will only tell us that it broke here therefore it needs to be strengthened. WPBD is under perfect conditions and is only a simulation but K’NEX will be a real prototype and will not work perfectly, there will be many small factor that affect each individual piece as each piece is different. I feel that unexpected results may occur with the K’NEX due to all the small factors and the lack of full customization. The K’NEX design will be much more challenging due to the constraints and predetermined lengths and it will much harder to lower cost as you would have to change the design and shape rather than the material thickness and type. Overall I find the two to be fairly different, they both test bridges but have very different styles of design and testing.

Next week we will begin using the K’NEX and start with our individual designs which will be tested and then what we individually gathered will come together in the end to form one final team bridge.

-          Kyle Hayes

Week 4 - Yilei Jiang

    Last week, the major thing we did was building a bridge design via West Point Bridge Design, which is a program to design a virtual bridge. Because of this designed bridge, I knew the basic knowledge of  bridge building components, such as span, material, placement of the travel surface in relation to the structure, and form. The other thing I knew was the cost of a bridge design played an important role. Related to reality, the cost also always decides that a contract is signed or not. 
     
     There's a thing that only can happen in West Point Bridge Design, not in our real world. During the testing, the truck passed every time whatever the bridge I designed looks like. Sometimes, my bridge was down to the bottom of canyon. It's not a serviceable bridge in the real world. 
      
     Next week, we will get the K'Nex and I will put the knowledge I learnt from WPBD on K'Nex. We can use K'Nex as a model to build a low-cost and serviceable bridge. K'Nex is not like WPBD. It is a model made up of solid materials(members), which means it has its own tension and strength capacities. How to hold heavy objects with the K'Nex bridge is the goal during these weeks. 

week4-BaiXue

Last week in class we are try to make a bridge with the lowest cost. At first we are doing two side bridge, but it end up with a high cost. By effect with the bridge that showed in class, we end up with a bridge that is one side and the price of around 240,000. Next week, we may have a guest speech that is about the bridge. For the end of the next class, I would know better about bridge and how to build the bridge.

We are now using West Point Bridge Designer to designer bridge. When comes the point of when we building the real bridge to build, which we use K’NEX. K’NEX is not a good quality thing to build a bridge. By using K’NEX, we are not able to change the size of the part. There also limited length of the part. It limited the shape that could make. Fuser more the connect part of the K’NEX is very weak and easy to get apart. What the WPBD can do may not happen in the really world. The support point of the bridge is also something to think about. On the WPBD there is no problem with the support point. When we made the real bridge there would be a lot of question come out. The WPBD is more about an idea world. One the real bridge there would be a lot of thing that unexpected happed.               

Week 4- Kyle Hayes

This week we gathered our group’s designs and tried to find the best parts of the three and create an even better bridge. we did manage to cut a few thousand dollars in cost, down to around$240000. We wanted to make a bridge that was only either a top truss or a bottom truss which did work and was a bit cheaper that of a bridge with a top and bottom truss. In my personal opinion I prefer the top and bottom truss bridge, although more complicated I found it to be less challenging to make and might give more strength on the actual model. With a bit more experimenting I came to the conclusion to use only hollow bars because they are cheaper and always stronger, the reasoning was explain be a TA that it is because it has a higher moment of inertia and thus will hold more weight. Also that when the bridge is is arched the weight wwill be distributed better and thus arch trusses can suport more weight.

WPBD is a very useful tool to make bridge design and test tension and compression. However I do not like using it for a model for the K’NEX competition. The K’NEX will not be joined perfectly like on WPBD also the K’NEX are all solid made of the same material and can’t be thickened so the fact that these can be changed and the goal in WPBD is to make the cheapest bridge not cost to strength ratio. If the bridge in the model is made solid, out of the same material, and same thickness then this can be more useful but they way it is being used is not very accurate for this assignment.  Two other problems with WPBD are there are no other forces, such as wind or age and rust; WPBD is only for the ideal conditions. The second is that the load added is fix, the weight added is limited to the one truck, which tell if it held or fell and the tension each piece was at, if more weight could be added and to a fixed location it would actually provide a defined weight limit and the cost of the bridge which would give a ratio used in our competition. WPBD is a very nice tool to make designs and see if there geometrically stable but not great when some conditions are fixed and real life is not ideal.

Next week we will use the knowledge gained by the guest speaker and use that to help with the next bridge design. We will also try a final analysis using WPBD before we start building the K’NEX model based on all the information gathered.

         - Kyle Hayes