4569846498

Multibody systems simulation software 115
{T C } 1
Z
GRF
Y
{F A } 1
{R AG } n
A
Z
C
X
O 1
G
Y
O n
{R BG } 1
m{g} 1
B
X
{T B } 1
{F B } 1
Fig. 3.36
Applied forces and torques on a body
The summation of applied forces resolved in the GRF as required in equation
(3.54) is obtained in this example by:
Σ{Fn A } 1 {F A } 1 {F B } 1 m{g} 1 (3.54)
The summation of moments about G is not so straightforward.
MSC.ADAMS performs the moment calculations about the axes of the
Euler-axis frame. It is therefore necessary to use the transformation matrix
[A n1 ] to transform forces and torques to the part frame O n and to use [B n ] T
to transform from the part frame to the Euler-axis frame:
{F A } n [A n1 ]{F A } 1 (3.55)
{F B } n [A n1 ]{F B } 1 (3.56)
{T B } n [A n1 ]{T B } 1 (3.57)
{T C } n [A n1 ]{T C } 1 (3.58)
It is now possible to calculate the moments at G due to the forces at A and
B working in the part frame:
{M A } n {R AG } n {F A } n (3.59)
{M B } n {R BG } n {F B } n (3.60)
The next step is to transform the moments and torques to the Euler-axis
frame and to summate as required in equation (3.61):
Σ{Mn} e [B n ] T {M A } n [B n ] T {M B } n [B n ] T {T B } n [B n ] T {T C } n (3.61)
3.3 Analysis capabilities
3.3.1 Overview
Once the model has been assembled the main code may be used to carry
out kinematic, static, quasi-static or dynamic analyses. Kinematic analysis
is applicable to systems possessing zero rigid body degrees of freedom.