Operation on matrix with inconsistent units

Forum|Forum|2 years ago
October 24, 2023
1 reply
2720 views

I have a stiffness matrix where units within columns and rows are inconsistent. I tried to inverse the matrix but it said " The matrix element units are not compatible with this operation". How can I fix this? If possible. Or I just did this wrong.

ps: I this question a few years ago. The very same question. However, the solution is no longer working.

Thank you for any inputs!

2_Beam-Equations.zip

Best answer by Werner_E

If you assign suitable units to the zero values

then your matrix k.free ends up like this

and can be inverted without errors

T

terryhendicott

21-Topaz II

Hi,

Typical structural stiffness matrices are of multiple units for various elements. Inversion or decomposition of the matrices will result in unit inconsistent equations.

For this reason it is best to work in a consistent set of units so the value of the stiffness matrix elements are correct but without units.

A consistent set of units for imperial system is fps. This is from a commercial software suite.

You need to divide the stiffness matrix entry values to these consistent units.

1_231024-Beam-Equations.zip

Y

yoohooos

Author

12-Amethyst

So working unitless on the whole worksheet? I mean, one of the top reason people use Mathcad is so they don't have to worry about units. Working with scalars, excel is thousands times more appropriate and robust.