Moments of Inertia and Deflection for Aluminium Doors and Windows

[strawhats2000]

Hi,

I am looking for research tips, all the possible notes and calculations on Moments of Inertia and Deflection for Aluminum Doors and Windows (Casement and Sliding).

I have the cad sections, the moments of inertia already calculated for the sections as well as section modulus. From this, I want to interpret and apply those basic calculations to determine height and width limits for the doors and windows.

The aluminium aloys is 6060 or ALMGSIO,5 with young modulus 70,000 MPa.

I have to draw graph showing dimensional limits as per wind pressure of 800 pascals, 1200 pascals and 1600 pascals, somtimes more. The Deflection is 1/150 (What does that mean?)

The main problem is that I have only seen those calculations in a few french-based catalogues and the few verbal explanations I received seemed illogical and so far not a single data on the net.

Any hints will be of great help.

Regards,

Nicolas.

 

[MiketheEngineer]

While you can do a simple (or even complex) structural analysis for this - my experience is that these companies test the "He$$" out of them to get verified and best results possible in order to qualify for storms, hurricanes, etc.

 

[strawhats2000]

How would you do the simple structural analysis? Where would you start given that you have the cad profiles, the moments of inertia on both x and y, the section modulus, the weight, the area, the centroid to name but a few?

 

[dhengr]

Strawhats:
How do you want your college engineering degree, in one paragraph or two? We’ll send it right out. Those basic calcs. are a first year college engineering problems, with a bunch of engineering and product experience, judgement and testing thrown in for the final solution, tabulations and graphs.

A few CAD profiles do not an engineer make...., and you shouldn’t need your CAD program to calc. the section properties either. I’d suggest you get a couples text books on Engineering Mechanics and Strength of Materials and study them, or take a few courses on these subjects if you are going to do this kind of work. Alternatively, go to a senior engineer or your boss for this kind of help, they should know what you know and what you don’t know, if for no other reason than to keep you and the company out of trouble. Those kinds of local mentoring experiences are almost always more meaningful, rewarding and lasting than coming here for this level help, or the quick answer. If you can run a CAD program these probably are problems which you could do with some ongoing help from someone right at your company, so they can watch your progress and correct you quickly when you are going astray. They have a vested interest in seeing you do well and in seeing you doing your work correctly.

 

[strawhats2000]

Hi,

The very least I need is tips for research. I have number of structural, mechanical engineering books as well as 2-3 books on Strength of Materials. The issue is that I found moments of inertia application wrt to openings nowhere in those books, nowhere else. How come?

I have serious doubt on just adding profile inertia and insert in an excel sheet and the graphs popping up. I don't want to just do that without having a deeper understanding on the application.

Regards,

Nicolas.

 

[MiketheEngineer]

Might be second year engineering!! Moments of inertia are easy to calc or find a program to help you.

TRY Google. Me thinks you might be in over your head and need to seek professional help....

 

[dhengr]

Strawhats:
The reason you are having doubts and troubles, is that you apparently don’t understand your own problem at a fairly fundamental level. While you may have some books, it appears that you haven’t bothered to studied them to really understand the subject. While you may have a CAD and EXCEL program they won’t do you much good either if you don’t have the fundamentals down pat. They might help you do engineering, but they don’t make you an engineer, and they won’t do engineering for you if you don’t know what you are doing. Given your level of questions, you have to do some serious studying on you own, or get help from your boss, because we don’t teach elementary engineering fundamentals at E-Tips. You are probably not going to find a solved textbook problem that exactly addresses your situation. You have to use some engineering intuition, imagination, judgement and experience to understand how to break this problem down into its simplest parts, and then rebuild them, put them back together again, understanding how they interact, to start to arrive at your solution. The reason I needled you a bit about your engineering education, is that that is where these abilities come from when you are starting out. Some of the judgement and experience will come from a senior engineer or your boss until you gain some of your own. The reason you didn’t find anything about moments of inertia w.r.t. openings, in a textbook, is that they are only related to each other through the dissection and putting back together process mentioned above.

For starters, answer these questions.... How does the pane of glass act in the Al. frame? How does it load the frame? Is it pinned or fixed in the frame? Does it add any torsional loading to the frame? Is the glass itself strong enough, and for what pressures and at what sizes? What impact loading can it take, say a 2x4 projectile, at what mass and speed?

How is the sash frame or door frame supported in its structural frame in the bldg.? Are these four sash or door frame pieces separate beams, and then do they also act as a unitized frame for the whole door? What loads does the glass pain impart on these Al. frame members, and what are their stresses and deflections? How do your CAD moments of inertia fit into this picture?

You have to answer these types of questions for every different size of sash or door, for each different pressure level; each variable that can change must literally be iterated through its whole range of values, sizes or lengths, etc. Once you understand the fundamental of the subject and your specific problem, and really understand the calcs. involved, really well, you can write an Excel program to help you with this calc. process. At the same time, you test a couple of your std. units at different pressures, different support options (two hinges or three, etc.), different sizes, etc. Then you compare these test results to your calc’ed. results, and mostly you adjust your calc. approach to match the test results, because you pretty much can’t argue with a well thought out test result, but you may have made some erroneous assumptions in your first go round at your calc. approach. Pretty soon you become a valuable drafter, tech. or engineer, with some real judgement and experience, but the computer or a few programs won’t do this for you. You must learn it and earn it.

 

[dvd]

I don't think a door really does that well with beam theory. I would liken it to a plate, possibly with a rectangular hole for a window, and solve using plate theory. Looks reasonable for FEA.

As far as analysis, if it is really that important, then buy a door and test in the lab. Should be fairly easy to uniformly load to achieve the required pressures. Not sure which is cheaper: to test or to model.