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Thread: Load Capacity of a Rectangular Tube

  1. #1
    Associate Engineer
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    Load Capacity of a Rectangular Tube

    Hello,

    I am looking to purchase two aluminum 6063 four feet rectangular tube of dimensions 4" x 2" x 1/4". I am going to be mounting linear guides and carriages on the tubes. I am also going to mount an aluminum plate (6061) 2.5' x 2' x 3/8" in dimension. This platform would be used to translate human subjects in the forward and backward direction to test their ****** response. The maximum weight for the human subjects to be eligible for the study is 300 lbs . I would like to know if this tube would be able to support that much weight. Just for your information. We will be inserting a rectangular flat bar within the tube to weigh it down. That way, once we take the flat bar out, the platform could be moved to another location easily.

    If this dimension for the tubes won't work, what are your suggestions?

    Thanks!
    Last edited by krishbaggy; 10-24-2012 at 11:52 AM.

  2. #2
    Technical Fellow
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    Hi and welcome.

    You have not supplied enough information. Do you have a sketch or drawing of the system?

    Is the plate attached to the tubes?

    How are the tubes supported?

    A whole bunch of stuff is needed before I (we??) can help with this.

  3. #3
    Associate Engineer
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    Hi there!

    I am sorry if my information was not clear. The top of my platform (2.5' x 2' x 3/8") will be mounted on four carriages that would be driven by the guides. The guides in turn would be mounted on the rectangular tubes of dimension 4" x 2" x 1/4".

    Thanks,
    BK

  4. #4
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by krishbaggy View Post
    Hello,

    I am looking to purchase two aluminum 6063 four feet rectangular tube of dimensions 4" x 2" x 1/4". I am going to be mounting linear guides and carriages on the tubes. I am also going to mount an aluminum plate (6061) 2.5' x 2' x 3/8" in dimension. This platform would be used to translate human subjects in the forward and backward direction to test their ****** response. The maximum weight for the human subjects to be eligible for the study is 300 lbs . I would like to know if this tube would be able to support that much weight. Just for your information. We will be inserting a rectangular flat bar within the tube to weigh it down. That way, once we take the flat bar out, the platform could be moved to another location easily.

    If this dimension for the tubes won't work, what are your suggestions?

    Thanks!
    Ok, just to estimate I took one tube (4" x 2" x 1/4") and looked to see if this one tube was adequate by itself.

    First, find the moment of inertia..

    Bottom most equation

    http://www.engineersedge.com/materia...a-gyration.htm

    I got 2.976237 in^4

    Then determine Modulus of Elasticity (elastic Modulus) for 6063.

    I used the average properties for aluminum found here:

    http://www.engineersedge.com/manufac..._materials.htm

    10.2 x 10^6 lb/in^2

    Then, I assumed a single point load in the middle and used the beam deflection calculator and equation here:

    http://www.engineersedge.com/beam_be...m_bending2.htm
    http://www.engineersedge.com/beam_be...flection_2.htm

    beam-calc.jpg

    So, comparing the calculated Stress at the center to the Yield Strength of 6063 Aluminum given at:

    http://www.engineersedge.com/materia...properties.htm

    Yield = 7,000

    One aluminum beam all by itself appears to be adequate to support the 300# load.

    I do not certify this and have only had one coffee this morning...
    Last edited by Kelly Bramble; 10-25-2012 at 01:25 PM.

  5. #5
    Administrator Kelly Bramble's Avatar
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    Also, you could do the same calculation for the plate after determining the moment and other geometry characteristics.

    For more engineering beam stress and deflection equations and calculators see:

    http://www.engineersedge.com/beam_calc_menu.shtml

  6. #6
    Principle Engineer
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    With all due respect, the problem is that the OP still hasn't given us a clue as to what the setup looks like.

    As usual a big guessing game.

    If the OP could give us a somewhat clearer picture of this maybe there is some hope.

    It is probably a simple problem which begs for a better description.

  7. #7
    Technical Fellow
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    I am with you Zeke, I quit after the OP's second post. It made less sense than the first.

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