Vesion 1.1

Version 1.1 - Mode tracking and structural damping

This version mainly features a mode tracking method and the addition of structural damping.

Changes

• Add mode tracking
• Add structural damping
• Refactor interface

Notes

Mode tracking
A mode tracking algorithm has been added so that modes are correctly identified at all times. This removes spurious oscillations in damping which may happen when modes cross or coalesce.
Structural damping
Structural damping can now be added by using the complex proportional stiffness method.
Refactoring
The solution files have been merged into a single file. The partial gradients can now be accessed through the OpenMDAO API. A test case for partials has also been added.

Tests

• Ubuntu 22.04 (gcc 11, python 3.10)

pypk/solution.py

@@ -62,8 +62,8 @@ class Solution:
         """Find the flutter speed and display it
         """
         found = False
-        self.f_speed = np.inf
-        self.f_mode = np.inf
+        self.f_speed = -1.
+        self.f_mode = -1
         for ivel in range(len(self.speed) - 1):
             if (found):
                 break
@@ -82,9 +82,8 @@ class Solution:
         """Write results to disk
         sfx : filename suffix
         """
-        hdr = '{:>8s}, {:>10s}, {:>10s}, {:>10s}'.format('Mach', 'u_f', 'mode', 'AGG(g)')
-        np.savetxt(f'results_{self._name}{sfx}.dat', np.array([self._mach, self.f_speed, self.f_mode, self.damp_agg]).reshape(1,4), fmt='%10.4f', delimiter=', ', header=hdr)
-        hdr = '{:>9s}'.format('u_inf')
+        hdr = 'Mach={:.2f}, u_f={:.2f}, mode={:d}, AGG(g)={:.2f}\n'.format(self._mach, self.f_speed, self.f_mode, self.damp_agg)
+        hdr += '{:>9s}'.format('u_inf')
         for j in range(self.n_modes):
             hdr += ', {:>11s}'.format(f'f_{j}')
         for j in range(self.n_modes):