ACCELEROMETER

Connection type ACCELEROMETER provides a convenient way to measure the relative position, velocity, and acceleration of a body in a local coordinate system. All kinematic quantities are measured relative to node a. The position, displacement, velocity, and acceleration are reported in the coordinate system of node b. Each node of the connector can translate and rotate independently, although fixing the first of the two nodes to ground is more common. With the first node fixed, connection type ACCELEROMETER provides a convenient way to measure the local components of the velocity and acceleration in a coordinate system fixed to a moving body (for example, an accelerometer).

Connection type ACCELEROMETER is available only in Abaqus/Explicit. It is the translation counterpart to connection type ROTATION-ACCELEROMETER, which measures relative angular position, velocity, and acceleration. ACCELEROMETER connections cannot be used in two-dimensional and axisymmetric analyses in Abaqus/Explicit.

This page discusses:

See Also
Connector Elements
Connector Element Library
In Other Guides
*CONNECTOR BEHAVIOR
*CONNECTOR SECTION

ProductsAbaqus/ExplicitAbaqus/CAE

Description

Figure 1. Connection type ACCELEROMETER.

The ACCELEROMETER connection does not impose kinematic constraints. It defines three local directions at node a and three local directions at node b. The ACCELEROMETER connection's formulation is similar to that for the CARTESIAN connection. The ACCELEROMETER connection measures the position of node b relative to node a

x=e1a⋅(xb-xa);    y=e2a⋅(xb-xa);    and    z=e3a⋅(xb-xa).

The coordinate system at node b rotates with the rotation of node b, and the kinematic quantities are reported in this rotated coordinate system as shown in Figure 2.

Figure 2. Kinematic quantities in rotated coordinate system.

There are no available components of relative motion for the ACCELEROMETER connection. The connector displacement components are

u1=x-x0,    u2=y-y0,    and    u3=z-z0,

where x0, y0, and z0 are the initial coordinates of node b relative to node a.

The ACCELEROMETER connection measures velocity and acceleration in the local directions at node a as if node a were an inertial frame. In contrast to the CARTESIAN connection, the ACCELEROMETER connection reports all the computed quantities (such as displacement, position, velocity, and acceleration) in the local directions at node b. Let Ti⁢j be the transformation from eia to eib. Then the ACCELEROMETER connection measures velocity and acceleration as

vi=Ti⁢j⁢d⁢ujd⁢t    and    ai=Ti⁢j⁢d2⁢ujd⁢t2,

where the derivatives above are time derivatives in a system moving with eia.

In two-dimensional and axisymmetric analyses u3=0.

Summary

ACCELEROMETER
Basic, assembled, or complex: Basic
Kinematic constraints: None
Constraint force output: None
Available components: None
Kinetic force output: None
Orientation at a: Optional
Orientation at b: Optional
Connector stops: None
Constitutive reference lengths: None
Predefined friction parameters: None
Contact force for predefined friction: None