A Frame Stress Calculator

An aircraft in flight is subjected to a moment about its frame due to the aerodynamic loading of the wings and tail. In industry, it is common to neglect any resistance to bending that the aircraft shear panels have and only consider the stringers.

My program, bendframe does just that. You provide it a file containing stringer information and the program does the rest.

The Program: bendframe

I considered writing a cgi script so that anyone could play with the 'bendframe' program, but I decided that it would be best not to strain the freeshell servers more than I already have. Therefore I decided to provide source code and allow anyone who wants to compile it themselves.

'bendframe' was compiled with g++ on freeBSD 5.4 _STABLE, but with nominal tweeking should be compatible on virtually every operating system.

The Stringer File

The information about the stringers is kept in a file called "stringers.frame" that must be in the same directory as the executable. The organization of this file is critical.

Each stringer gets a line to itself. Information may be deliminated with spaces or tabs. In the first column should go the stringer's name, and consists of characters. The second column contains the area of the stringer in square milimeters. The third column contains the vertical distance to the stringer from the base of the frame. E.g.

stringer1 600 350
stringer2 600 335
stringer3 650 310
stringer4 600 285

Known Bugs

First, this section might give someone the idea that this is a professionally written program. It is not. This program was a hack that I just happen to be proud of enough to post online. It gets the job done.

Currently the only known bug is that it is unable to handle more than 100 stringers. If you need more, then it is a very simple act of changing the initialization values to a higher number. If that sounds tacky to you, I've already made all components effected by this bug dynamically allocatable, so all that is left for you to do is write an array resizing function. If I ever encounter a time when I have more than 100 stringers I promise to do just this.

I encourge people to make changes to this code. I also encourage you to not notify me about them. Unless you think it's a wicked cool change. Then please do!

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© 2006 Nic Reveles