Consider a slider-crank mechanism as shown in the following figure. The crank is considered to be rigid and the connecting link is assumed to be flexible. The link connects the crank to the sliding block (or piston). The simplified finite element model of the slider-crank mechanism is also shown.
The slider-crank mechanism has these characteristics:
The rigid crank is modeled with an MPC184 Rigid Beam element.
The rigid crank is connected to ground with a "grounded" MPC184 Revolute Joint element.
The connecting link is flexible and modeled with BEAM188 elements.
The rigid crank and the connecting link are connected to each other by a MPC184 Revolute Joint element.
The connecting link moves within a "grounded" MPC184 Slot Joint that approximates a slider block.
As a quick first attempt, you can model the flexible mechanism with some simple approximations to the flexible and rigid parts. You can also model the connecting link in detail to study the deformation, stresses, etc.
Mechanical APDL offers an extensive library of beam, shell, solid-shell, and solid elements for modeling the flexible parts, and the extensive contact capability to model the rigid part and any other contact conditions. Joint elements implemented via the Lagrange multiplier method offer the required kinematic connectivity between any two parts or components.
Mechanical APDL offers a rich suite of beam, shell, and solid elements to model the flexible structural components. Each element has a prefix that identifies the element category and a unique number (for example, BEAM188 and SHELL181).
To model mass and rotary inertia, use the MASS21 element. The element is also appropriate for use in a lumped approximation of rigid bodies.
Detailed information about element selection for flexible components is available in the Basic Analysis Guide and the Element Reference.