The input signal a in [m/s2] moves the 1D translational flange connector flange with a predefined acceleration, i.e., the flange is forced to move relative to the support connector with this acceleration. The velocity and the position of the flange are also predefined and are determined by integration of the acceleration.
The acceleration "a(t)" can be provided from one of the signal generator blocks of the block library Modelica.Blocks.Source.