Force-versus-time graphic display unit for impact tester - uses optical detector coupled to digital analyser and includes digital plotter

摘要

The hammer force measuring system consists of a bar pattern attached to the hammer and a double optical detector which provides two phase-shifted pulse trains as the hammer passes it. The displacement increments and direction signal control a counter. The displacement increment time values are stored and the counter is stopped when the hammer returns. The digitised values are passed to an analiser which carries out the necessary differentiation. This comprises a series of dividers, adders/dividers subtractor/dividers, a multiplier and a final adder. Finally, the time-related force products are displayed on a digital plotter.