Why can't I get the same natural frequencies, which are calculated by the exported [K] and [M] matrices, compared to the ANSYS Modal analysis result?

First of all, I created a simple solid cubic structure with coarse mesh in ANSYS WB Modal modulus. With the boundary condition is set as 1 face fixed, the first 5 natural frequencies (fn) given by...

24 June 2020 9,980 13 View