RADIAL-THRUST

Description

Figure 1. Connection type RADIAL-THRUST.

The RADIAL-THRUST connection does not impose kinematic constraints. An orientation at node a is required to define the axis of the rectangular coordinate system, ${\mathbf{e}}_3^a$. The position of node b relative to node a is given by the radial and axial-direction distances

The RADIAL-THRUST connection has two available components of relative motion, $u_1$ and $u_3$. The radial displacement $u_1$ measures the change in distance from node b to the axis of the cylindrical coordinate system and is defined as

where $r_0$ is the initial radial distance from node b to the axis. The thrust displacement $u_3$ measures the change in distance from node a to node b along the cylindrical axis and is defined as

where $l_0$ is the initial distance along the axis from node b to node a. The connector constitutive displacements are

The kinetic force is

where the radial unit vector is

The radial resistance of the RADIAL-THRUST connector is analogous to a single spring in the ${\mathbf{e}}_1^a$–${\mathbf{e}}_2^a$ plane. Loads applied in this plane and perpendicular to the current radial unit vector will initially encounter no resistance and may lead to numerical singularity and/or zero pivot warnings from the solver during static analyses. If the numerical singularities cause convergence difficulties, one modeling option is to overlay the RADIAL-THRUST connector with a CARTESIAN connector with a very small elastic stiffness.

Summary