# Modal Mass Matrix. Tower

**URL:** <https://forums.nlr.gov/t/modal-mass-matrix-tower/1639>\
**Category:** Computer-Aided Engineering Software Tools\
**Created:** [June 12, 2017, 10:49am UTC](https://forums.nlr.gov/t/modal-mass-matrix-tower/1639 "2017-06-12T10:49:42Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\
**Post date:** [June 12, 2017, 1:03pm UTC](https://forums.nlr.gov/t/modal-mass-matrix-tower/1639/2 "2017-06-12T13:03:35Z")

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Dear Aitor,

As discussed in the following forum topic: [How to find the paramter of the first bending modal mass, damping, and stiffnees coefficients? - #2 by Jason.Jonkman](http://forums.nlr.gov/t/how-to-find-the-paramter-of-the-first-bending-modal-mass-damping-and-stiffnees-coefficients/1594/2), FAST v8 returns the linearized model in first-order form. So, while you can’t get the second-order mass and stiffness matrices (M and K), you can get the same terms normalized by the mass matrix i.e. [M^-1]\*[M] = I and [M^-1]\*K through the FAST v8 linearization analysis. This first-order form should also be amendable for controls design.

That said, a linearization analysis with FAST v7 can be used to obtain the mass and stiffness matrices.

Best regards,

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