I\'m building a skateboard. How to get the factor of safety? -------------------

Question

I'm building a skateboard. How to get the factor of safety?

----------------------------------------------------------

I designed the board to stand a load up to 210 lb. I did a bending test in a rectangular wood sample with 11.2 mm thick and 24.7 mm wide.

The length between the brackets that hold the sample in the bending test machine was 70 mm (actual length of the sample). I got a maximun bending stress of 136 MPa before the fracture. The maximun load before fracture (that related to the maximum bending stress) was 4007.7 N.

----------------------------------------------------------

* I was wondering if the factor of saferty is simply 4007.7lb/210lb= the real maximum load/the desired load I designed.

* Do I need to consider the dimensions of the board in determining the factor of safety?

* simply, what is the factor of saferty for my skateboard?

----------------------------------------------------------

thanks in advance guys.

Explanation / Answer

The value of maximum load before fracture i the bending machine itself was for the skateboard you designed,of which you got the corresponding maximum bending stress.

Maximum Bending Stresses vary from one cross-section to the other depending on the Flexure Formula.

For this case it was for your rectangular shaped skateboard.

It is okay if you take the factor of safety to be 4007.7lb/210lb=19.08

And you dont need to worry about the Dimensions because the values you got on the machine were for this dimension only.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.