Designing a Balsa Wood Beam: Max Strength, Min Weight

[Struggling]

Hi for school i need to design a balsa wood beam. Winner is judged be strength to weight ratio.

i have searched around and found all the stress and strain values for balsa wood at different densitys etc...

now my dilemma is that i have to use formulas to design this beam before it is built. Iam having trouble getting started.

would anyone be able to point me in the right direction? iam a little confused as to were to begin, so much needs to be taken into consideration such as widths,lengths,density, forces etc etc

and how do i find the beam design that will hold the most amount of force?

beam needs to be 500mm long with 25mm supports on either side. total length 550mm

width and depth no more than 100 mm and the beam is said to have failed once deflection reaches 50mm.

please help thanks

 

[saltydog]

Hi for school i need to design a balsa wood beam. Winner is judged be strength to weight ratio.

i have searched around and found all the stress and strain values for balsa wood at different densitys etc...

now my dilemma is that i have to use formulas to design this beam before it is built. Iam having trouble getting started.

would anyone be able to point me in the right direction? iam a little confused as to were to begin, so much needs to be taken into consideration such as widths,lengths,density, forces etc etc

and how do i find the beam design that will hold the most amount of force?

beam needs to be 500mm long with 25mm supports on either side. total length 550mm

width and depth no more than 100 mm and the beam is said to have failed once deflection reaches 50mm.

please help thanks

Make a beam with a nested architecture: Construct cross-beams to reinforce the length, construct smaller cross-beams which reinforce the smaller cross-beams, make even smaller cross-beams which reinforce the smaller cross-beams. Keep nesting it until you get tired or run into a constraint.

 

[quicknote]

To design a balsa wood beam with maximum strength and minimum weight, there are a few key factors to consider:

1. Material properties: As you have mentioned, the stress and strain values for balsa wood at different densities will be important in determining the strength of the beam. It is also important to consider the direction of the grain in the wood, as this can affect its strength.

2. Beam dimensions: The length, width, and depth of the beam will all play a role in its strength and weight. Generally, a longer and thicker beam will be stronger but also heavier. It will be important to find the right balance between these dimensions to achieve the desired strength to weight ratio.

3. Supports: The supports on either side of the beam will also impact its strength. Make sure to consider the type and placement of the supports in your design.

To get started, you can use formulas such as the Euler-Bernoulli beam equation and the moment of inertia equation to calculate the maximum load the beam can withstand before failure. These equations take into account the material properties and dimensions of the beam.

Next, you can use a finite element analysis (FEA) software to simulate the beam under different load conditions and find the optimal design. FEA software allows you to input different dimensions and materials to see how they affect the beam's strength and weight.

Finally, once you have a design that meets the given requirements, you can test the physical beam to validate your calculations and make any necessary adjustments.

In conclusion, designing a balsa wood beam with maximum strength and minimum weight will require careful consideration of material properties, dimensions, and supports. Using formulas and FEA software can help guide your design process, but physical testing will be necessary for final validation.