How can I get the internal forces, forces, reaction and displacement?

[Martin15135215]

Currently, I have this code with units mm and N:

import trusspy as tp

M = tp.Model(log=0)

# create nodes
with M.Nodes as MN: 
    MN.add_node(1, (0, 0, 0))          # mm
    MN.add_node(2, (0, 0, 3000))       # mm
    MN.add_node(3, (-4000, 0, 3000))   # mm
    MN.add_node(4, (-4000, 0, 6000))   # mm

# create element
with M.Elements as ME:
    ME.add_element(1, [2, 1])
    ME.add_element(2, [2, 3])
    ME.add_element(3, [2, 4])
    ME.assign_geometry("all", [1000]) # Area mm²
    ME.assign_material("all", [1000]) # E-Modulus N/mm²
   

# create displacement (U) boundary conditions
with M.Boundaries as MB:
    MB.add_bound_U(1, (0, 0, 0)) # support
    MB.add_bound_U(2, (1, 0, 1)) # smooth pin
    MB.add_bound_U(3, (0, 0, 0)) # support
    MB.add_bound_U(4, (0, 0, 0)) # support


# create external forces
with M.ExtForces as MF:
    MF.add_force(2, (100000, 0, -100000)) # N

M.build()

M.run()

print(f"""
{M.Results.R[-1].element_force} N
""") 

[adtzlr]

Hi Martin, sorry that the examples in the docs aren't clear enough. Unfortunately, my free time is very limited right now and it will take me a few days to answer your question.

[adtzlr]

Please have a look at the comments in the code-block:

import trusspy as tp

M = tp.Model(log=0)

# create nodes
with M.Nodes as MN:
    MN.add_node(1, (0, 0, 0))  # mm
    MN.add_node(2, (0, 0, 3000))  # mm
    MN.add_node(3, (-4000, 0, 3000))  # mm
    MN.add_node(4, (-4000, 0, 6000))  # mm

# create element
with M.Elements as ME:
    ME.add_element(1, [2, 1])
    ME.add_element(2, [2, 3])
    ME.add_element(3, [2, 4])
    ME.assign_geometry("all", [1000])  # Area mm²
    ME.assign_material("all", [1000])  # E-Modulus N/mm²


# create displacement (U) boundary conditions
with M.Boundaries as MB:
    MB.add_bound_U(1, (0, 0, 0))  # support
    MB.add_bound_U(2, (1, 0, 1))  # smooth pin
    MB.add_bound_U(3, (0, 0, 0))  # support
    MB.add_bound_U(4, (0, 0, 0))  # support


# create external forces
with M.ExtForces as MF:
    MF.add_force(2, (100000, 0, -100000))  # N

# TrussPy is a nonlinear truss analysis - it incrementally searches for the equilbrium
# by scaling given external forces. If you are not interested in the deformation path,
# set the number of increments ``incs`` to one, the allowed increase in displacements to
# infinity or a high value ``du`` and the increase of the load-proportionality-factor
#  ``dlpf`` to one.
M.Settings.incs = 1  # evaluate only one increment
M.Settings.du = 1e8  # turn off max. incremental displacement
M.Settings.dlpf = 1  # apply the load proportionality factor in one increment

M.build()
fig, ax = M.plot_model(force_scale=0.01, view="xz")

M.run()

# results of last solution
res = M.Results.R[-1]  

# verify the applied load-proportionality-factor of the result
# assert res.lpf == 1.0  

# (element) truss forces in N
# see https://trusspy.readthedocs.io/en/latest/theory/truss.html#kinetics
res.element_force

# (nodal) displacements in mm
# see e.g. https://trusspy.readthedocs.io/en/latest/theory/equilibrium.html
res.U

# (nodal) fixing forces in N
# see https://trusspy.readthedocs.io/en/latest/theory/assembly.html
res.r

[Martin15135215]

Thanks for the hint!