The BUSHING statement defines a massless bushing with linear stiffness and damping properties.

The BUSHING statement defines a massless bushing with linear stiffness and damping properties. The BUSHING statement applies a force and torque to two parts. You specify a marker on each part for force or torque application.

Each force consists of three components in the coordinate system of the J marker, one in the x-axis direction, one in the y-axis direction, and one in the z-axis direction.

Likewise each torque consists of three components in the coordinate system of the J marker: one about the x-axis, one about the y-axis, and one about the z-axis. The force is linearly dependent upon the relative displacement and the relative velocity of the two markers. The torque is dependent upon the relative angle of rotation and the relative rotational velocity of the parts containing the specified markers.

A BUSHING statement has the same constitutive relation form as a FIELD statement. The primary difference between the two statements is that certain coefficients (Kij and Cij, where i j) are zero for the BUSHING statement. Only the diagonal coefficients (Kii and Cii) are defined for a BUSHING.

Fx, Fy, and Fz are the measure numbers of the translational force components in the coordinate system of the J marker. The terms x, y, and z are the translational displacements of the I marker with respect to the J marker measured in the coordinate system of the J marker. The terms Vx, Vy, and Vz are the time derivatives of x, y, and z, respectively. The terms F1, F2, and F3 represent the measure numbers of any constant preload force components in the coordinate system of the J marker.

Tx, Ty, and Tz are the rotational force components in the coordinate system of the J marker. The terms a, b, and c are the relative rotational displacements of the I marker with respect to the J marker as expressed in the x-, y-, and z-axis, respectively, of the J marker. The terms , , and are the angular velocity components of the I marker with respect to the J marker, measured in the coordinate system of the J marker. The terms T1, T2, and T3 are the measure numbers of any constant torque in the coordinate system of the J marker.

Adams Solver (FORTRAN) applies an equilibrating force and torque to the J marker, as defined by the following equations:

Fj=-Fi

Tj = - Ti - x Fi

is the instantaneous deformation vector from the J marker to the I marker. While the force at the J marker is equal and opposite to the force at the I marker, the torque at the J marker is usually not equal to the torque at the I marker because of the deformation.

The BUSHING only models linear bushings. The GFORCE or FIELD (with a FIESUB) may be used to model nonlinear bushings.

This BUSHING statement describes a bushing with translational spring rates of 5000 units in both the x-axis and the y-axis directions of Marker 22 and of 2000 units in the z-axis direction of Marker 22. The corresponding damping rates for the force are 5 units in both the x- and y-axis directions of Marker 22 and 2 units in the z-axis direction of Marker 22. The rotational spring rates are 50000 units about the x- and y-axis of Marker 22. The corresponding damping rates for the torque are 50 units in both the x- and y-axis directions of Marker 22 and zero units in the z-axis direction of Marker 22. Since the z components of KT and CT are zero, the I marker can rotate about the z-axis of the J marker without generating any torque. There are no FORCE or TORQUE values because there is no initial load (preload) associated with the input positions of the markers.

See other Forces available.