Tensegrity Material Analysis

material.py

#!/usr/bin/env python

import numpy as np


'''
Notes:
- Tensile strength of 7x19 1/4" galvanized steel wire rope ~ 7000 lbs
'''


# TUNABLE PARAMETERS
# Length
L = 20 * 12  # Length in inches
K = 1.0  # Column effective length factor -- taken to be 1.0 for pinned at both ends


def buckling(D, W, E):
    '''
    Calculate the euler critical buckling load of a round tube column
        - D - outer diameter (in)
        - W - wall thickness (in)
        - E - Modulus of elasticity (ksi)
    '''
    # Inner diameter (in)
    d = D - 2 * W
    # Moment of Inertia (in^4)
    inertia = np.pi * ((D ** 4) - (d ** 4)) / 64
    # Euler Critical Buckling Load (lbf)
    return 1000 * (np.pi ** 2) * E * inertia / ((K * L) ** 2)


for E in (10000, 30000):  # Modulus of elasticity for [aluminum, steel]
    for D in [3, 3.5, 4, 5]:  # Outer diameter
        for W in [.063, .083, .095, 0.1, 0.12, .125, .18, .187, .25]:  # Wall thickness
            buckle = buckling(D, W, E)
            if buckle >= 4000:
                mat = {10000: '6061', 30000: 'A500'}[E]
                print(f'D {D:0.2f} W {W:0.3f} mat {mat} buckling {buckle:.0f}')
                break