balsawood bridge (3 Viewers)
- Thread starter viraj30
- Start date
wingman
Let's Rock N' Roll
Big Croc, you made your arch bridge from particle laminate board. This material is thinly layer plyboard in a cross directional grain direction. This material is actually stronger than many 'normal' timbers out there! It's manufactured to be a cheap and strong substitute for functionality. It looks like a great design! Good work! If you had to improve it, the two top strips on the top of deck, if you stood them upwards (on their sides) the bridge still be stiffer even more so!
Balsa timber is a very weak timber. its one of the weakest woods available actually. It's density is low and thus it is lightweight and good to work with in modelling. you wont be able to build the arch of the bridge with balsa, it doesnt have flexibility like plyboard.
Viraj, if your project is only balsa wood, pins and silicon carbide paper (isnt that sand paper???) then your only option is trusses (just like your house roof).
Like a true engineer, consider everything. But first ask yourself these questions:
How is the bridge supported over the span in the test (need to know this to transfer the weight to your foundations)?
Where will the weight in test be loaded (centre point or uniform)?
Any material/cost limitations?
Can you glue?
Other materials allowed?
Can you pin your bridge onto foundation testing bay?
Find these answers out and it will start bringing up ideas in your head of what to build.
I remember doing this for my HSC year also. REMEMBER! the best design will still suck if you dont build it correctly. Reinforce everything (double up on pins!)
Good Luck!
Balsa timber is a very weak timber. its one of the weakest woods available actually. It's density is low and thus it is lightweight and good to work with in modelling. you wont be able to build the arch of the bridge with balsa, it doesnt have flexibility like plyboard.
Viraj, if your project is only balsa wood, pins and silicon carbide paper (isnt that sand paper???) then your only option is trusses (just like your house roof).
Like a true engineer, consider everything. But first ask yourself these questions:
How is the bridge supported over the span in the test (need to know this to transfer the weight to your foundations)?
Where will the weight in test be loaded (centre point or uniform)?
Any material/cost limitations?
Can you glue?
Other materials allowed?
Can you pin your bridge onto foundation testing bay?
Find these answers out and it will start bringing up ideas in your head of what to build.
I remember doing this for my HSC year also. REMEMBER! the best design will still suck if you dont build it correctly. Reinforce everything (double up on pins!)
Good Luck!
Cruiseshipfan
New Member
- Joined
- Apr 30, 2012
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- HSC
- 2012
I know this is old but I did the assessment task this year and it only held 60KG but collapsed because of a crack caused by a scratch or something in the wood and a unbalanced load. It involved glueing 3 sticks of 5x5 balsa side by side to get a 15x5 then you make a 10x5. Then uses these to make a T beam. It is actually very strong and could support 60kg by itself. Then create another identical t beam and then join it via truss to the other t beam. Repeat this as many times as you can but make sure you have enough balsa left over to stop it from twisting.