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MBDynモデル集

## 2. 自由回転するブロック

### 入力ファイル

```# free_rotating_block.mbd

begin: data;
problem: initial value;
end: data;

begin: initial value;
initial time:   0.;
final time:     5.;
time step:      1.e-2;
max iterations: 10;
tolerance:      1.e-6;
end: initial value;

begin: control data;
structural nodes: 1;
rigid bodies:     1;
end: control data;

# Design Variables
set: real M   = 1.;   # [kg] Mass
set: real Lx  = 0.15; # [m] Width
set: real Ly  = 0.05; # [m] Thickness
set: real Lz  = 0.3;  # [m] Height
set: real Wx0 = 5.;   # [rad/s] Initial angular velocity along x axis
set: real Wy0 = 0.;   # [rad/s] Initial angular velocity along y axis
set: real Wz0 = 5.;   # [rad/s] Initial angular velocity along z axis

set: real Ixx = 1./12.*M*(Ly^2+Lz^2); # [kgm^2] Moment of inertia about x axis
set: real Iyy = 1./12.*M*(Lz^2+Lx^2); # [kgm^2] Moment of inertia about y axis
set: real Izz = 1./12.*M*(Lx^2+Ly^2); # [kgm^2] Moment of inertia about z axis

# Node Labels
set: integer Node_Block = 1;

# Body Labels
set: integer Body_Block = 1;

begin: nodes;
structural: Node_Block, dynamic,
0., 0., 0.,    # absolute position
eye,           # absolute orientation
null,          # absolute velocity
Wx0, Wy0, Wz0; # absolute angular velocity

end: nodes;

begin: elements;
body: Body_Block, Node_Block,
M,                   # mass
null,                # relative center of mass
diag, Ixx, Iyy, Izz; # inertia matrix

end: elements;
```