/TH/ACCEL

Block Format Keyword

/TH/ACCEL - Time History - Accelerometer

Description

Describes the time history for accelerometers.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/TH/ACCEL/thgroup_ID
thgroup_name
var_ID1	var_ID2	var_ID3	var_ID4	var_ID5	var_ID6	var_ID7	var_ID8	var_ID9	var_ID10
Obj_ID1	Obj_ID2	Obj_ID3	Obj_ID4	Obj_ID5	Obj_ID6	Obj_ID7	Obj_ID8	Obj_ID9	Obj_ID10

Field	Contents
thgroup_ID	TH group identifier (Integer, maximum 10 digits)
thgroup_name	TH group name (Character, maximum 100 characters)
var_ID1, ...n	Variables saved for TH (see table below) (Character, maximum 8 characters)
Obj_ID1, ...n	Identifiers of the objects to be saved (Integer)

Keyword	Object saved	Variables
ACCEL	Accelerometer	AX, AY, AZ, WX, WY, WZ

Keyword	Variable Group	Saved TH Variables
ACCEL	DEF W	AX, AY, AZ WX, WY, WZ

•	AX: acceleration in direction X

•	AY: acceleration in direction Y

•	AZ: acceleration in direction Z

•	WX: integral of acceleration in direction X

•	WY: integral of acceleration in direction Y

•	WZ: integral of acceleration in direction Z

•	Let the nodal acceleration vector with laboratory expressed in the global skew system, the nodal acceleration vector with laboratory projected onto the moving skew.

Let the nodal velocity vector with laboratory expressed in the global skew system, the nodal velocity vector with laboratory projected onto the moving skew.

Let R(t) the orientation matrix of the skew at time t, so that:

Derivating vs versus time leads to:

th_nodal_velocity_result

This shows that derivating the nodal velocity with laboratory projected onto the moving skew, vs does not give as a result the nodal acceleration with laboratory projected onto the moving skew, .

The vector WX, WY, and WZ available for output in the accelerometer is the following:

th_vector_eq

Derivating to this output will give a value of nodal acceleration with laboratory projected onto the moving skew, the integration-derivation acting as another filter other than the 4-pole Butterworth, which is used in the accelerometer and computes the filtered accelerations AX, AY, and AZ.

1.	Available names are listed in the two tables above.

In the first table, TH-variables are listed. If a TH-variable is requested, this variable is written.

In the second table, variable groups are listed. If a variable group is requested, all the associated TH-variables are written at once.