BodyBox

A rigid body with uniform mass calculated by the given density and extent. [1]

Modeling Approach

The rigid body box has two frames, frame_a and frame_b located at, notionally, two ends. The shape is specified by length,width,and height, located at r_shape. Specify inner width and height to form a rectangular cylinder.

Required Parameters

name	type	description
r	SIunits.Position	vector from frame_a to frame_b such that {1, 0, 0} describes a 1<unit> long box with the length in the x direction.

Optional Parameters

name	type	default	description
r_shape	SIunits.Position	{0,0,0}	vector that locates the box's shape (length, width, height) in frame_a
r_shape	SIunits.Position	{0,0,0}	vector that locates the box's shape (length, width, height) in frame_a
length	SIunits.Length	length(r-r_shape)	Length of box
lengthDirection	Modelica.Mechanics.MultiBody.Types.Axis	r-r_shape	Vector in length direction of box, resolved in frame_a
width	SIunits.Distance	length/defaultWidth	Width of box
innerWidth	SIunits.Distance	0	Width of inner box surface (0 <= innerWidth <= width)
widthDirection	Modelica.Mechanics.MultiBody.Types.Axis	{0,1,0}	Vector in width direction of box, resolved in frame_a
height	SIunits.Distance	width	Height of box
innerHeight	SIunits.Distance	innerWidth	Height of inner box surface (0 <= innerHeight <= height)
density	SIunits.Density	7700	Density of matieral (e.g., steel: 7700 .. 7900, wood : 400 .. 800)
mo	SIunits.Mass	min=0, =density*length*width*height	Mass of box without hole
mi	SIunits.Mass	min=0, =density*length*innerWidth*innerHeight	Mass of hole of box
m	SIunits.Mass	(min=0) =mo-mi	Mass of box
r_CM	SIunits.Position	=r_shape+normalize(lengthDirection)*length/2	Position vector from origin of frame_a to center of mass, resolved in frame_a
angles_fixed	Boolean	false	if angles_start is used as initial values, else as guess values
angles_start	SIunits.Angle	{0,0,0}	Initial values of angles to rotate frame_a around 'sequence_start' axes into frame_b
sequence_start	Types.RotationSequence	{1,2,3}	Sequence of rotations to rotate frame_a into frame_b at initial time
w_0_fixed	Boolean	false	if w_0_start are used as initial values, else as guess values
w_0_start	SIunits.AngularVelocity	{0,0,0}	Initial or guess values of angular velocity of frame_a resolved in world frame
z_0_fixed	Boolean	false	if z_0_start are used as initial values, else as guess values
z_0_start	SIunits.AngularAcceleration	{0,0,0}	Initial values of angular acceleration z_0 = der(w_0)
enforceStates	Boolean	false	if absolute variables of body object shall be used as states (StateSelect.always)
useQuaternions	Boolean	true	if quaternions shall be used as potential states otherwise use 3 angles as potential states
sequence_angleStates	Types.RotationSequence	{1,2,3}	Sequence of rotations to rotate world frame into frame_a around the 3 angles used as potential states

Public Fields

name	type	description
frame_a	Interfaces.Frame_a	Coordinate system fixed to the component with one cut-force and cut-torque
frame_b	Interfaces.Frame_b	Coordinate system fixed to the component with one cut-force and cut-torque
r_0	SIunits.Position	Position vector from origin of world frame to origin of frame_a
v_0	SIunits.Velocity	Absolute velocity of frame_a, resolved in world frame (= der(r_0))
a_0	SIunits.Acceleration	Absolute acceleration of frame_a resolved in world frame (= der(v_0))
R	Frames.Orientation	Orientation object from frame_a to coordinates system spanned by r and widthDirection
I	SIunits.Inertia	Inertia tensor of body box with respect to center of mass, parallel to frame_a