88 lines
2.6 KiB
Python
Executable File
88 lines
2.6 KiB
Python
Executable File
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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"""\
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Tube
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"""
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from __future__ import absolute_import, division, print_function, unicode_literals
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from math import sqrt
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__author__ = "Daniel Weschke"
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__copyright__ = "Copyright 2019 Daniel Weschke"
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__credits__ = ["Daniel Weschke"]
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__license__ = "MIT"
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__version__ = "2019.02.07"
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__maintainer__ = "Daniel Weschke"
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__email__ = "daniel.weschke@directbox.de"
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__status__ = "Production" # "Prototype", "Development", "Production"
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VERSION = """\
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%(prog)s version {version} {copyright}
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For Unicode characters check the file encoding that the console is using.
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Windows user may execute the command "chcp 65001".""".format(
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version=__version__, copyright=__copyright__)
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EPILOG = """\
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"""
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def critical_buckling_stress(r, nu, E, t):
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"""\
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Critical buckling stress of a thin tube loaded with external pressure p.
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r mean radius (r_a + r_i)/2
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nu Poisson's ratio
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E Young's modulus
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t thickness
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"""
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return (E/(4*(1-nu**2))*(t/r)**3)
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def allowable_stress(sigma, S):
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"""\
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Allowable stress.
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sigma stress
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S safety factor, elastic buckling stress state S = 3
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"""
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return sigma/S
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def main():
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"""\
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Main function
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"""
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import argparse
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parser = argparse.ArgumentParser(
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description=__doc__, prefix_chars='-', epilog=EPILOG,
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#usage="%(prog)s [OPTION]... NAME",
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formatter_class=argparse.RawTextHelpFormatter,
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)
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parser.add_argument('-v', '--verbose', action="store_true", help="Verbose output")
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parser.add_argument('-V', '--version', action='version', version=VERSION)
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parser.add_argument('-D', '--debug', dest='debug', action='store_true', help=argparse.SUPPRESS)
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subparsers = parser.add_subparsers(help='', dest='case')
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parser_a = subparsers.add_parser(
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'buckling', help="critical buckling stress", prefix_chars='-',
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description="Critical buckling stress of a thin tube loaded with external pressure p.")
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parser_a.add_argument('NU', type=float, help='Poisson\'s ratio')
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parser_a.add_argument('R', type=float, help='mean radius')
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parser_a.add_argument('E', type=float, help='Young\'s modulus')
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parser_a.add_argument('T', type=float, help='thickness')
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parser_a.add_argument('S', nargs='?', type=float, default=3., help='safety factor [default for elastic stress state: 3]')
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args = parser.parse_args()
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if args.debug:
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print(args)
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if args.case == 'buckling':
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p_crit = critical_buckling_stress(args.R, args.NU, args.E, args.T)
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print("p_crit =", p_crit)
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print("p_allow =", allowable_stress(p_crit, args.S))
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return 0
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if __name__ == "__main__":
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import sys
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sys.exit(main())
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