Pinjonelement

Pinjonelement, or pin joint element, is a constraint element used in kinematic and multibody simulations to connect two rigid bodies at a single point. It acts as an ideal hinge, transmitting only forces at the connection and not bending moments, thereby allowing relative rotation about a specified axis.

In two-dimensional modeling, a pin joint constrains both translational degrees of freedom, leaving one rotational degree of freedom in the plane. In three-dimensional modeling, a standard pin (revolute) joint constrains three translational degrees of freedom and two rotational degrees of freedom, leaving a single rotational degree of freedom about the joint axis. The orientation of the joint axis defines the axis of allowed rotation, which can be fixed to a reference frame or attached to one of the connected bodies.

Modeling approaches for pinjonelement typically use constraint equations or penalty methods, sometimes implemented via Lagrange multipliers to enforce the joint conditions. The element can be formulated to provide reaction forces at the pin while not transmitting bending moments, making it suitable for simulating linkages, robotic joints, and many mechanical assemblies.

Applications of pinjonelement include the analysis of mechanism kinematics, multi-body dynamics, and structural simulations where hinge-like connections are needed. It is widely used in mechanical design, robotics, vehicle suspensions, and finite element analyses of articulated systems.

Limitations of the ideal pin joint include the neglect of friction, clearance, or play found in real joints; these non-idealities may be added in more detailed models as needed. See also revolute joint and hinge.