1. A process for determining the force acting on a test piece and the parameters of the test piece reacting under the force, comprising the steps of: (a) exposing the test piece to the effect of the force increasing in a linear manner; (b) measuring continuously the resultant changes in parameters and the force needed for this purpose, and comparing the ascertained values with predetermined values; and (c) determining the measured value pair when there is equality between at least one measured value and the associated reference value.