trussSolver.py

# To do
# - add command line flags, for data input and flags for what sort of solve, also add help flag
# - error handling, check statically determinant and files correct format
# - write a solver for beams and frames
# - enclose parts of this script into functions
# - write a visualisations function using tikz
# - can add calculation for stress in members if material data is given

# Loading Libraries
import numpy as np
import pandas as pd
import sys

# Taking Command Line Flags
for i in range(0,len(sys.argv)):
    if sys.argv[i] == "-h":
        print("The arguments should be; nodes elements reactions external \nCheck the documentation for format")
        quit()

# Loading Data
nodes = np.array(pd.read_csv(sys.argv[1]))
elements = np.array(pd.read_csv(sys.argv[2]))
reactions = np.array(pd.read_csv(sys.argv[3]))
external = np.array(pd.read_csv(sys.argv[4]))

# Calculating
geometryMatrix = np.zeros((len(nodes) * 2, len(nodes) * 2))

for i in range(0, len(elements)):
    member = elements[i, 0]
    nodeFrom = elements[i, 1]
    nodeTo = elements[i, 2]

    dx = nodes[nodeTo - 1, 1] - nodes[nodeFrom - 1, 1]
    dy = nodes[nodeTo - 1, 2] - nodes[nodeFrom - 1, 2]
    dis = np.sqrt(dx ** 2 + dy ** 2)

    geometryMatrix[(2 * nodeFrom - 1) - 1, member - 1] = dx / dis
    geometryMatrix[(2 * nodeTo - 1) - 1, member - 1] = -dx / dis
    geometryMatrix[(2 * nodeFrom) - 1, member - 1] = dy / dis
    geometryMatrix[(2 * nodeTo) - 1, member - 1] = -dy / dis

for i in range(0, len(reactions)):
    reaction = reactions[i, 0]
    node = reactions[i, 1]
    direction = reactions[i, 2]

    if direction == 'y' or direction == 'Y':
        geometryMatrix[(2 * node) - 1, (len(elements) + reaction) - 1] = geometryMatrix[(2 * node) - 1, (
                    len(elements) + reaction) - 1] + 1

    elif direction == 'x' or direction == 'X':
        geometryMatrix[(2 * node - 1) - 1, (len(elements) + reaction) - 1] = geometryMatrix[(2 * node - 1) - 1, (
                    len(elements) + reaction) - 1] + 1

externalForces = np.zeros((len(nodes) * 2, 1))

for i in range(0, len(external)):
    node = external[i, 0]
    force = external[i, 1]
    direction = external[i, 2]

    externalForces[(2 * node - 1) - 1] = -force * np.cos(direction * np.pi / 180)
    externalForces[(2 * node) - 1] = -force * np.sin(direction * np.pi / 180)

results = np.dot(np.linalg.pinv(geometryMatrix), externalForces)

# Printing
for i in range(0, len(elements)):
    print("The force in member %d is %5.2f kN" % (i + 1, results[i]))

for i in range(0, len(reactions)):
    print("The reaction at %d in the %s direction is %5.2f" % (
    reactions[i, 1], reactions[i, 2], results[(len(results) - 3) + i]))

# Visualising
f = open("results.tex", "w")
doctext = [r'\documentclass[preview,border={20pt 20pt 20pt 20pt}]{standalone}', r'\usepackage{tikz,pgfplots}', r'\usepackage{fancyvrb}',r'\usepackage{xcolor}' r'\begin{document}', r'\begin{figure}[h]',r'\centering',r'\begin{tikzpicture}', r'\end{tikzpicture}', 
r'\end{figure}', r'\begin{Verbatim}[commandchars=\\\{\}]',r'\end{Verbatim}',r'\end{document}']

for i in range(0,len(doctext)):
    f.write(doctext[i]+'\n')
    
    if i == 6:
        for j in range(0,len(nodes)):
            f.write('\draw node('+str(nodes[j,0])+')[mark size=1pt, color = red] at ('+ str(nodes[j,1]) +','+ str(nodes[j,2]) +') {\pgfuseplotmark{*}};\n')
            f.write('\draw node[above, red] at ('+ str(nodes[j,1]) +','+ str(nodes[j,2]) +') {' +str(nodes[j,0])+ '};\n')
        
        for j in range(0,len(elements)):
            f.write('\draw[thick] ('+str(elements[j,1])+') -- node[above, blue]{'+ str(elements[j,0]) + '} ('+str(elements[j,2])+');\n')

        for j in range(0,len(reactions)):
            f.write('\draw[thick] ('+ str(reactions[j,1]) + ') -- ++(-0.25,-0.4330127019) -- ++(0.5,0) -- ('+ str(reactions[j,1]) + ');\n')

    elif i == 9:
        for i in range(0, len(elements)):
            f.write("The force in member " + r'\textcolor{blue}' + "{%d} is %5.2f kN\n" % (i + 1, results[i]))

        for i in range(0, len(reactions)):
            f.write("The reaction at " + r'\textcolor{red}' +"{%d} in the %s direction is %5.2f\n" % (
            reactions[i, 1], reactions[i, 2], results[(len(results) - 3) + i]))