Mass and Stiffness Matrices for MDOF Torsional System

cma4h

1. The problem statement, all variables and given/known data
I'm trying to figure out the mass and stiffness matrices for the following system:


2. Relevant equations
J1 = 3600 kg-m^2
J2 = 200 kg-m^2
J3 = 800 kg-m^2
J4 = 4800 kg-m^2
G (shear mod) = 8e10 Pa

3. The attempt at a solution

I've tried this setup:
M =
|J1 0 0|
|0 J2+J3 0|
|0 0 J4|

K =
|k1 -k1 0|
|-k1 k1+k2 -k2|
|0 -k2 k2|

where ki = GπDi⁴/(32Li)

but I don't think that is correct. Any ideas? Thanks.
1. The problem statement, all variables and given/known data



2. Relevant equations



3. The attempt at a solution
1. The problem statement, all variables and given/known data



2. Relevant equations