Interactive dynamic force analysis using constraint-based approach

This paper discusses the interactive dynamic force analysis of a planar mechanism using the constraint-based approach. The constraint network provided by the design tool, which includes geometric, dimensional and algebraic constraints, is utilized to impose relations among the skeleton-form mechanism and associated velocity, acceleration and force polygons. The slider-crank mechanism in a reciprocating engine is selected to demonstrate this new approach, with an emphasis on inertia forces and the effect of different mechanism positions on them. When one of links in the mechanism is dragged to produce an input motion, the imposed constraints force all the vector polygons to animate their shapes and sizes in tandem with the animated motion of skeleton mechanism. With such a powerful animation feature, the dynamic force analysis as exhibited in this study proves to be effective. In addition, the design evaluation involving dimension modification can be swiftly performed for any link in the mechanism to study its effect on inertia forces.