Adam Frisch
Member
Hi.
I'm all new to this, but in my efforts to get my head around certain structures for my design, I need your help. I have access to Birch on my own land, but this could apply to any wood. Here is a list of structural properties for various woods.
http://www.csudh.edu/oliver/chemdata/woods.htm
Now if you look at Birch wood it for the yellow variety gives a Modulus of Rupture of 11.88kg/mm2. This is, as I understand, the breaking or bending force required to break a cross section of 1mm2 of the wood. So one square millimeter would need 11.88kg to break it off.
But here's what I don't get - common sense says there's no way that could be the case. A toothpick is probably about 2-3 square millimeters in cross section and it certainly does not take 22-33kg to break that. Maybe a tenth of that.
What am I not getting?
And is there a good online site that even a dummy like me can get this explained? I have a degree in civil engineering from 15 years ago, but I can't recall a single thing since I never went into that kind of work.
Thanks.
I'm all new to this, but in my efforts to get my head around certain structures for my design, I need your help. I have access to Birch on my own land, but this could apply to any wood. Here is a list of structural properties for various woods.
http://www.csudh.edu/oliver/chemdata/woods.htm
Now if you look at Birch wood it for the yellow variety gives a Modulus of Rupture of 11.88kg/mm2. This is, as I understand, the breaking or bending force required to break a cross section of 1mm2 of the wood. So one square millimeter would need 11.88kg to break it off.
But here's what I don't get - common sense says there's no way that could be the case. A toothpick is probably about 2-3 square millimeters in cross section and it certainly does not take 22-33kg to break that. Maybe a tenth of that.
What am I not getting?
And is there a good online site that even a dummy like me can get this explained? I have a degree in civil engineering from 15 years ago, but I can't recall a single thing since I never went into that kind of work.
Thanks.