Strength and stiffness
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- čas přidán 11. 09. 2024
- Find out what engineers mean by the words "strength and stiffness" and watch a bending test on a wooden joist. We do lots of tests like this because we need to calibrate our non-destructive methods of measurement.
This video was recorded in 2006 and was originally on google video.
This is such a big relief for me. I am trying to build my own bedframe and to be honest I didn't believe a lot of these DIY CZcams channels saying that a 2x6 price of lumber was strong enough for a bedframe.
Good for you for doing research and verifying what was said. It's what should be done. 👍
I am doing the same. What did you find out? I was thinking about constructing an 80" x 60" queen platform frame using 1x6's for siderails and middle support, 1x4's for slats with 1.6" gap, and 1x6's for legs (2 in each corner and 1 under center of each siderail and center support).
According to the chart 2 of these spanning what i believe to be 8 feet could support 700 lbs while sagging only 1/4". Ultimate breaking strength would be over 4000 lbs.
This video just eased my worries, I used 4 4x4s with 2x4 support beams to make a bedframe. Based on this the metal bunk bed part that I added would probably break before my bedframe does. The metal part is hollowed out.
It's stronger, because of the fact it's hollow. No?
@@TsunamiDragonEX Metal is decently more dense and hollowing it out does make it more flexible however since the metal bars are directly below my bed it adds more stress the middle bars which are most likely to break first over time.
Initially watched the video because I originally thought wood was somewhat weak so I was scared.
About 2,200 lbs. Impressive. What was the span?
5
Thank you Ma'am for your valuable explanation and effective animation. It really gives a crystal clear concept reflection !!! 👍
#KEEP UP THE GOOD WORK💐 😄🍫
In Vietnam, we prefer the term Modulus of Elasticity / Rupture.
Mostly because strength and stiffness are quite similar when translated into Vietnamese, and even more difficult to tell them apart when we also have the 'hardness' of wood.
Thanks for the insight.
Vietnam is gay
Very cool! Thanks. I will be using this to design a raised bed on wheels.
I'm not sure that that is the definition. You seem to be talking about Elasticity vs Modulus of Rupture.
Chernobieff Piano - terminology varies from place to place. It's not even consistent within the European Standards - but 'bending strength' is the term used in EN 408, rather than Modulus of Rupture. The stiffness is 'Modulus of Elasticity in bending'. Here we use the basic terms 'strength and stiffness' to try and keep things simple.
Ok, i'll agree that terminology is inconsistent. So if you have a piece of lumber, let's say a 2" x 4", will the strength (MOR) be the same in either direction? Can you demonstrate strength and stiffness separatly?
I don't really understand what you mean by "either direction".
The piece of timber will be able to sustain different loads depending on which orientation it is in (since you can place it in the machine flatwise or edgewise - and two ways up for each) and also depending on where the defects (knots, inclined grain etc) are along the length. The European standards (EN 384 and EN 408) require the worst defect (a guess) placed centrally in order to try and get the lowest bending strength measurement - with the board (normally) placed edgewise - but a random way up. Other standards around the world specify random positioning of worst defect - and sometimes different testing spans. This means that a piece of timber can have different bending strengths depending on how you test it. Hopefully all the possible bending strengths for a single piece are quite similar - but since you can only break it once, it's hard to say what the reality is.
This is different from timber having different material strengths in different directions (along the grain, radial, tangential) and under different actions (compression, tension, shear).
Stiffness can be measured in the same test, and is also affected by orientation and test span - and also depending on how you measure it (e.g global vs local in EN 408). It is a separate property to strength (but often correlated with it).
Nice video, but it would have been more informative with the dimensions of the beam.
Looks like a true dimension 2x6 to me but I could be wrong. Of course they also didn't give us the measure of the gap or the location the force was applied either so trying to figure out just what this 1000kg really means is pointless. Then again I don't think that is the point of their video so 🤷♂️
This is youtube treasure
Hi, great video presentation. Thank you. If you are still in the field, can you please tell me the strength of a plank in the other direction; on the flat/wide side? Thank you.
It didn't break because of pure force but because of bending stress right?
do you know the dimension of that beam?
13x88
@@BurningTirez
in mm? 1/2" x 3.5"?
it looks more like a 2x6 or 2x8
what is the span. This is terrible science.
That piece of wood was...knot...very strong.
3 seconds in and I had to pause and call you guys out on making the hottie talk about stiff wood.
well played
Thanks guys! ✨🌎
Now add some wood glue and try it again
good old windows xp days.
Keep it up ms....you are so sweet.
Even with captions I don’t know what she’s saying 😂
british
magnificent
Girls with hard hats on . Mmm
span and dimension please?
with units
2x6x6 if I had to guess. Species and quality are equally important.
👍🏼
Can't understand a word she's saying!
She gets stiffness
great video. NOT