Driving a Spring Load with a Piezoelectric Actuator

When a piezo-actuator (whether amplified or non-amplified) is actuated against a spring load, it converts electrical energy into both motion and force.  This force will vary according to the amount of expansion/contraction achieved by the piezo-actuator under the applied electrical field.  When activated with an applied electric field, the piezo-actuator moves against the spring load until it reaches a force balance condition.  If at this point the spring load were to be removed, the stored potential energy within the piezo-actuator would be converted completely into additional motion.  Therefore, when working against a spring load, the amount of displacement that the piezo-actuator can produce in the spring load is less than the piezo-actuator’s free zero-load displacement.   The amount of displacement that the spring can be compressed or stretched is a function of the spring stiffness and the piezo-actuator stiffness. 

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