The Dynamic stiffness of toothbrushes

摘要

Using strain gauges, the method to be described measures the lateral force required to produce a standard deflection of toothbrush tufts. A deflector bar which remains stationary is attached to a cantilever which is stressed by the pressure of the brush moving across the deflector bar. The resulting strain is measured by using strain gauges which are connected via a Wheatstone bridge to an oscilloscope. Movements of the oscilloscope beam represent changes in the force exerted by the brush and are photographed on moving film.The effects on stiffness of changes in the rate of strain, length, diameter, wetness and temperature of nylon were investigated separately, and a standard test was devised which could assist in more accurate labelling of toothbrushes.