I have been trying to find the frequency of a 2d truss on PyAnsys. I did code it up but have not been able to get the desired answer. Below I have attached the truss that i want to solve using the PyAnsys.

Below is the Code that I used to get the frequency of the truss.

import ansys.mapdl.core as pymapdl

import numpy as np

# Start MAPDL

mapdl = pymapdl.launch_mapdl()

# Clear any existing data

mapdl.clear()

# Set up the model

mapdl.prep7()

# Define material properties

mapdl.mp('EX', 1, 68.95e9) # Young's modulus in Pascals

mapdl.mp('DENS', 1, 2767.05) # Density in kg/m^3 for modal analysis

# Define element type for 2D truss elements (LINK1)

mapdl.et(1, "LINK1")

# Define real constant (cross-sectional area)

area = 0.00007161 # Cross-sectional area in m^2

mapdl.r(1, area)

# Define nodal coordinates

nodes = [

(1, 0, 0), # Node 1

(2, 3.048, 0), # Node 2

(3, 6.096, 0), # Node 3

(4, 9.144, 0), # Node 4

(5, 9.144, 3.048), # Node 5

(6, 6.096, 3.048), # Node 6

(7, 3.048, 3.048), # Node 7

(8, 0, 3.048) # Node 8

]

# Create nodes

for node in nodes:

mapdl.n(*node)

# Define elements

mapdl.type(1) # Set element type to LINK1

mapdl.mat(1) # Set material number to 1

mapdl.real(1) # Set real constant set number to 1

elements = [

(1, 2), (2, 3), (3, 4),

(5, 6), (6, 7), (7, 8),

(2, 7), (3, 6), (4, 5),

(1, 7), (2, 8), (2, 6),

(3, 7), (3, 5), (4, 6)

]

for start_node, end_node in elements:

mapdl.e(start_node, end_node)

# Apply boundary conditions

mapdl.d(1, 'UX', 0) # Fix UX at Node 1

mapdl.d(1, 'UY', 0) # Fix UY at Node 1

mapdl.d(8, 'UX', 0) # Fix UX at Node 8

mapdl.d(8, 'UY', 0) # Fix UY at Node 8

# Apply loads for static analysis

load_magnitude = -44482.2 # Load in Newtons

mapdl.f(4, 'FY', load_magnitude) # Apply load at node 4

# Solve modal analysis

mapdl.finish()

mapdl.run('/SOLU')

mapdl.antype('MODAL')

mapdl.modopt('LANPCG', 10)

mapdl.solve()

mapdl.finish()

# Post-processing to extract natural frequencies

mapdl.post1()

frequencies = mapdl.post_processing.frequency_values

# Check and print frequencies

if frequencies.size > 0:

for mode, frequency in enumerate(frequencies, start=1):

print(f"Mode {mode} - Natural Frequency: {frequency:.2f} Hz")

else:

print("No natural frequencies were computed. Check constraints and setup.")

# Stop MAPDL

mapdl.exit()

How ever I am not getting the result I want. I have attached the modes that i got from SAP2000 and Ansys.