/FRAME/MOV
Block Format Keyword Describes moving frames. Relative motion with respect to a reference frame.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
/FRAME/MOV/frame_ID | |||||||||
frame_title | |||||||||
node_ID1 | node_ID2 | node_ID3 | Dir |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
frame_ID | Reference frame identifier
- must be different from all skew identifiers. (Integer, maximum 10 digits) |
|
frame_title | Reference frame
title (Character, maximum 100 characters) |
|
node_ID1 | Node identifier
N1 (Integer) |
|
node_ID2 | Node identifier
N2 (Integer) |
|
node_ID3 | Node identifier
N3 (Integer) |
|
Dir |
Default = X (Text) |
Comments
- Let a moving reference frame .
- For each time t, the frame position and orientation are determined via its original position and a rotation (orientation) matrix .
- Let be the instantaneous rotational velocity of .
- For each time t,
the local coordinates
of a point M with respect to
the frame are related to its coordinates
into the global system, as:
(1) - The relative displacement
of M between time 0 and
t, with respect to the frame is related to its
displacement with regard to the global system, as:
(2) - The relative velocity of
M with respect to the frame is related to its velocity
with regard to the global system, as:
(3) Where, is the driving velocity; that is the velocity of the point coincident with M at time t and fixed with respect to the reference frame.
- The relative acceleration of
M with respect to the frame M is
related to its acceleration with regard to the global system,
as:
(4) Where, is the driving acceleration and is the acceleration, due to Coriolis forces.
- For a moving reference frame, the
reference frame position and orientation vary with time and are defined by
N1, N2 and
N3.The axis definition depends on the input for Dir.
- When Dir=X
node_ID1 amd node_ID2 define
node_ID1 and node_ID3 define - When Dir=Y
node_ID1 and node_ID2 define
node_ID1 and node_ID3 define - Case Dir=Z
node_ID1 and node_ID2 define
node_ID1 and node_ID3 defineThe skew is defined by , and
- When Dir=X
- In a 2D analysis N1 and N2 define .
- Reference frame identifier must be different from all skew identifiers.