Analysis of a system for the measurement of impact loads

A reinforced flat plate supported on load cell force transducers is proposed as a system for measuring the dynamic force of an impact test. The system is mathematically modeled as a beam on elastic supports loaded at its midspan by a half sine pulse. Analytical expressions are derived for the force vs time in the load cells and are shown to be functions of three parameters, the ratio of the load duration to the fundamental frequency of the system, the ratio of support stiffness to beam flexural stiffness and the ratio of the distance between supports to the total beam span. The results of calculations made for a range of parameters are presented and discussed. It is shown that the load cells should not be located at the end of the beam. Optimum results are obtained by placing them directly under what would be the nodal points of the fundamental beam vibration mode if the beam were in a free-free condition. As an example, a hypothetical impact test including estimates for peak force and duration is considered and a drop table suitable for the test is designed