MVLF Unité de Vibrations Libres et Forcées

The Free and Forced Vibration Unit, "MVLF", has been developed to cover a range of demonstrations and experiments which provide the user with an understanding of the free and forced vibrations of a simple spring-mass-damper system. Simple adjustments can be made to the unit and the motion of the mass can be readily observed and recorded on the pen recorders provided.

A feature of the unit which approaches the problems of forced damped vibrations for the first time, is the simple way in which it is presented so that free and forced vibration phenomena can be readily observed.

Experiments can be carried out by the students to investigate the relationship between the mass of the body, the stiffness of the spring and the period/frequency of oscillation and to observe the effect of viscous damping on the system.

The basic components of the unit consist of a rigid frame with vertical mass carriage guides, an upper mounting plate for the spring, a lower mounting plate for the damper and a variable speed motor and drive unit for the forced vibration experiments. The mass carriage is constrained by rollers which run along on the vertical guides to provide a single degree of freedom with minimum uncontrolled damping.

Frequency of the oscillations can be measured with an optical sensor.

Two pens, attached to the vibrating frame, and two paper strips provide a means of producing amplitude/time recordings and amplitude/phase recordings.

Two methods of forcing vibrations are provided: a rotating out-of-balance mass and a periodic displacement to the point of support of the spring.

Springs of various stiffness and suitable masses are supplied. The damper is adjustable to provide a wide range of damping.

A control console attached to the frame contains the speed control unit and a frequency indicating meter.