This is the bed frame that I have build now, the part in red is something I have created but did not dare to attach it yet.

enter image description here

I have used Spruce wood for everything, and the long side of the frame is attached to the short side via dowels and two large wood screws on each side.

Now my question is about the load on the frame that I created (see the arrow pointing to the rectangular shaped object).

My feeling says that I need to add extra support to that frame, and that I need to add extra support between the three components as well to create a stable frame. However, to gain trust in my schema I would like to calculate some stresses, or deflections that the beams will undergo due to the static load and dynamic load of me and my partner.

I have found some equations to calculate some part of the load, but I dont think this will capture all the stresses. Can somebody point me in the right direction?

PS: Thanks for the tips and the comments guys, I hope the question is now better suited for this forum.

  • 1
    As it's formulated, this question isn't really suitable for a home improvement network. While there are some engineering-minded folks around, this type of math isn't really what we do here. Instead, describe your design or post a diagram and we can discuss viability based on real-world experience. – isherwood Dec 20 '18 at 19:21
  • Did you mix units of measure? – Lee Sam Dec 20 '18 at 21:59
  • Check the value for Young's Modulus. It looks way too low, and the units are wrong. Values I'm finding are around 10 GPa - 10,000,000,000 N/m2. – Mark Dec 20 '18 at 23:09
  • I think I indeed mixed up the Youngs Modulus. And will add more pictures of my current situation – zwep Dec 21 '18 at 8:15

I see a few issues to consider: 1) load transfer, and 2) impact load vrs. Working stress, 3) you’re only considering deflection

1) The load isn’t transferred equally to the four sides. Rectangular shapes accept the load to the long sides more than the short sides, especially if the bulk of the load (your rear end) is located in the center of the rectangle.

2) You are using working stress formulas and the stress/strain on your bed is more of an impact load (less than 1 day load). You should be able to double the “ultimate” load.

3) Maximum loads are determined by extreme fiber in bending, shear (horizontal and vertical), and ACCEPTABLE deflection. You’re only considering deflection.

I’m away from my office, so I don’t have access to my college notes, (I just use span tables for everyday use now,) but will return in a week or so and will answer more directly at that time.

Meanwhile, it looks like you’re using a 1x12. (See “I”.) What unit is it?

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    Thanks for your comment. I have changed my question to a more practical introduction, however I am still very much interested in the correct equations/physics behind such calculations as well as some practical advice. This is my first DIY project, so I am kinda new to this. – zwep Dec 21 '18 at 8:38

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