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Thread: Help with structural calculations

  1. #1
    Engineer
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    Help with structural calculations

    I am embarking on a DIY project requiring some structural aluminium work, which I need to design for maximum rigidity and minimal weight.

    Can someone please point me in the direction of a good website, where I can learn about how to calculate forces and deflections on beams etc, so I can get a handle on this. My mathematical skills are very good, and I did do similar calculation work to this about 40 years ago but never maintained the skills. I will be working with small section aluminium channel, box section and tube up to say 150mm maximum section size and 1metre maximum length.

    Thanks in anticipation.
    Pete.

  2. #2
    Technical Fellow jboggs's Avatar
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    This site has that information if you will just look around. Its not just a forum. Kelly has done a wonderful job of compiling engineering reference information.

  3. #3
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    Thanks very much.

    I've had a look at the engineering calculators tab and can see that some of those resources will be useful to me.

    I really need to get right back to basics with this and properly refresh myself with the methodology behind it all, so I can apply it to my project. Can you point me to somewhere for help on this please?

  4. #4
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by PS2112 View Post
    Thanks very much.

    I've had a look at the engineering calculators tab and can see that some of those resources will be useful to me.

    I really need to get right back to basics with this and properly refresh myself with the methodology behind it all, so I can apply it to my project. Can you point me to somewhere for help on this please?
    With all due respect - Engineers Edge (this website has 30,000 + free webpages of solutions and tools) is probably the most comprehensive resource available.

    Also, there is now a premium membership available with another 5,000 + pages of resources and tools.

    Are setting up to post a link to your website?

    See:

    Search Engineers Edge

    Beam deflection Equations and Stress

    Strength of Materials Basics

    Yield Strength Basics

    and thousands and thousands of other webpages on www.engineersedge.com.

    Don't forget the engineering and manufacturing instructional videos...

    Engineering and Manufacturing Videos

    Don't see what your looking for there?

    Buy a book from the Engineering Book Store

    If you can't find what your looking for here on Engineers Edge - tell me and i'll either find it (on this website) or create a webpage to address the technicals..
    Last edited by Kelly Bramble; 11-28-2015 at 12:09 PM.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  5. #5
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    Thank you very much Kelly.

    It seems like I am already in the right place on this forum

    As a newbie to both engineering and this forum, I will obviously need some time to find my way around to get the help I need. I can certainly now see that you have a vast amount of information and resources here. As per jboggs above, I will have to have a good look round and will surely find all the help I need.

    What an excellent forum and website you have.

    I will probably be asking a few silly questions shortly

    Cheers,
    Pete.

  6. #6
    Lead Engineer Cake of Doom's Avatar
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    The only silly question is one that's not asked.

    What is the purpose of your design?

  7. #7
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    Quote Originally Posted by Cake of Doom View Post
    The only silly question is one that's not asked.

    What is the purpose of your design?
    My hobby and passion for the last 45 years has been astronomy. I have owned, modified or built various telescopes over the
    years and now the largest one I use has a 14" mirror. My current 14" telescope is as tall as me, fatter than me and about as heavy, and therefore is quite a handful to strip down to fit in the car to transport to dark sky viewing sites 30 miles or more from home. I have recently purchased a 20" mirror set to build into an even larger telescope that will have double the light grasp of my 14". The 20" primary mirror alone weighs 20 kilos, and needs to be held rigidly and accurately in place relative to the other optical components, and the whole design needs to dismantle and be transported by myself without help. On previous smaller telescope builds, the weight has not been a problem, so the tendency has been to over engineer, obviating the need for any calculations. If this big telescope is going to be transportable and properly usable, the design needs to be very smart in every way. In order to design on the limits of minimum weight for maximum rigidity, I really need to get my head around the structural calculations. Otherwise I will have a massive dinosaur that will rarely venture out under the stars. Most people construct these type of telescopes from wood, but I am leaning toward aluminium and possibly even some carbon fibre. I would hope, that over the next year or so, I can design and build this 20" telescope to be of similar weight and ease of use as my current 14".

    Here are some photo's. First, my 14" telescope, second a wooden design, third something more along the lines of what I want to build...
    https://dl.dropboxusercontent.com/u/...43825small.jpg
    https://dl.dropboxusercontent.com/u/104047272/Dob.jpg
    http://www.stardazed.com/MoonsilverIV.html
    Attached Images Attached Images
    Last edited by PS2112; 11-30-2015 at 05:31 PM. Reason: Formatting

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