pyNastran  0.5.0
pyNastran BDF Reader/Writer, OP2 Parser, and GUI
inertiaFormulas Namespace Reference

Functions

def bar
 The purpose of this code is to automatically generate the moment of inertia equations.
def cross
 y b1 ^ b3 | b2 a---p1--b | | | h1 k--l | c-----d | | | | o---------p2-> x h2 | | j--i f-----e | | h3 | | h-------g
def box
 y ^ | w1 | w2 w3 | a-----p1------b | | | h1 | e--|----f | | | | | | | | | | | h2 | | o-------|--> x | | | | | h-------g | | | h3 d-------------c
def Box1
 y ^ | w1 | w2 w3 | a-----p1------b | | | h1 | e--|----f | | | | | | | | | | | h2 | | o-------|--> x | | | | | h-------g | | | h3 d-------------c
def T
 y ^ | a---k-p1-l---b | | | h1 | | | h---g | d---c | | | | o----------> x | | | | h2 j f----e i w1 w2 w3
def Ixx
 from http://en.wikipedia.org/wiki/Second_moment_of_area J_{xx} = {1}{12} {i = 1}^{n-1} ( y_i^2 + y_i y_{i+1} + y_{i+1}^2 ) a_i J_{yy} = {1}{12} {i = 1}^{n-1} ( x_i^2 + x_i x_{i+1} + x_{i+1}^2 ) a_i J_{xy} = {1}{24} {i = 1}^{n-1} ( x_i y_{i+1} + 2 x_i y_i + 2 x_{i+1} y_{i+1} + x_{i+1} y_i ) a_i
def add
def sub
def subx
def suby
def addx
def addy

Function Documentation

The purpose of this code is to automatically generate the moment of inertia equations.

only the locations of The nodes of the elements are required, as well as the triangular sections that are generated. For example, [1,a,b] means a positive triangular section (+1) with the 3 nodes at a, b, and <0,0>. This is easily understood if the triangle creates an area. Some are positive, some are negative, but if you sum them all up you get the total area of the section. This allows you to generate the moments of inertia for complex sections.

y ^ | 1----|----2 | | | | | | h | o----------> x | | | | 4---------3 b

b = w1 h = h1

Definition at line 55 of file inertiaFormulas.py.

References addx(), cross(), Ixx(), subx(), and suby().

y ^ | w1 | w2 w3 | a-----p1------b | | | h1 | e--|----f | | | | | | | | | | | h2 | | o-------|--> x | | | | | h-------g | | | h3 d-------------c

# given #a-d = D2 #(f-g)_y = D3 #d-c = D1 #(g-c)_x = D4

Definition at line 178 of file inertiaFormulas.py.

References addx(), Box1(), Ixx(), subx(), and suby().

Referenced by cross().

y ^ | w1 | w2 w3 | a-----p1------b | | | h1 | e--|----f | | | | | | | | | | | h2 | | o-------|--> x | | | | | h-------g | | | h3 d-------------c

# given #a-b = D1 #a-d = D2

#(b-f)_y = D3 #(g-c)_y = D4 #(g-c)_x = D5 #(d-h)_x = D6

Warning:
inertia is wrong b/c 0 is assumed to be <0,0> when it should be the output of the first inertia calculation

Definition at line 243 of file inertiaFormulas.py.

References addx(), Ixx(), subx(), suby(), and T().

Referenced by box().

y ^ | a---k-p1-l---b | | | h1 | | | h---g | d---c | | | | o----------> x | | | | h2 j f----e i w1 w2 w3

# given a-b = D1 (b-e)_y = D2 a-h = D3 f-e = D4

Todo:

Area seems off

Inertias should be relative to the CG

Warning:
wrong...

Definition at line 308 of file inertiaFormulas.py.

References addx(), addy(), Ixx(), subx(), and suby().

Referenced by addy(), and Box1().

def inertiaFormulas.Ixx (   sections)

from http://en.wikipedia.org/wiki/Second_moment_of_area J_{xx} = {1}{12} {i = 1}^{n-1} ( y_i^2 + y_i y_{i+1} + y_{i+1}^2 ) a_i J_{yy} = {1}{12} {i = 1}^{n-1} ( x_i^2 + x_i x_{i+1} + x_{i+1}^2 ) a_i J_{xy} = {1}{24} {i = 1}^{n-1} ( x_i y_{i+1} + 2 x_i y_i + 2 x_{i+1} y_{i+1} + x_{i+1} y_i ) a_i

Definition at line 353 of file inertiaFormulas.py.

References add(), and sub().

Referenced by bar(), box(), Box1(), cross(), and T().

def inertiaFormulas.add (   p1,
  p2,
  s1 = 1,
  s2 = 1 
)

Definition at line 407 of file inertiaFormulas.py.

References sub(), and subx().

Referenced by Ixx(), subx(), and suby().

def inertiaFormulas.sub (   p1,
  p2 
)

Definition at line 412 of file inertiaFormulas.py.

References suby().

Referenced by add(), and Ixx().

def inertiaFormulas.subx (   p1,
  p2x 
)

Definition at line 415 of file inertiaFormulas.py.

References add(), and addx().

Referenced by add(), bar(), box(), Box1(), cross(), and T().

def inertiaFormulas.suby (   p1,
  p2y 
)

Definition at line 418 of file inertiaFormulas.py.

References add(), and addy().

Referenced by bar(), box(), Box1(), cross(), sub(), and T().

def inertiaFormulas.addx (   p1,
  p2x 
)

Definition at line 421 of file inertiaFormulas.py.

Referenced by bar(), box(), Box1(), cross(), subx(), and T().

def inertiaFormulas.addy (   p1,
  p2y 
)

Definition at line 424 of file inertiaFormulas.py.

References T().

Referenced by cross(), suby(), and T().

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