Method of protection of acceleration transducers from unmeasurable effects

Abstract

Firstly, reduction in the DS is achieved at too high a cost. The thickness of the packing is comparable with that of the transducer base. This invariably leads to reduction in the impact strength of the object surface-adhesive-~packing-adhesive-transducer joint since the side component of the impact acceleration creates an additional moment by acting on such a system. This can lead to failure of the joint. Secondly, even the use of these packings produces a relatively small reduction in the sensitivity to deformation (in impact mode, about I0 times for packing thickness hp = 3 mm) which in many cases is not enough. Finally, the method in the technical description practically does not ensure protection of the transducer from the unmeasurable high-frequency overlaps which can lead to the so-called phenomenon of "zero shift" [3]. This, in turn, leads to partial or total loss of the measuring information. In order to extend the field of application of the transducers and to ensure reliable measurements, efforts were made to establish methods of mounting piezoelectric acceleration transducers which effectively lower (eliminate) the effect of the unmeasurable actions. Specialists point to the mechanical filter UA 0559 made by the Danish firm "Briule and Kier" in the form of a component adapter between the object surface and the transducer body, the main component of which, is the rubber packing and to the method of mounting the transducer on plasticized epoxy compound, i.e., a method in which the elastic adhesive layer in essence acts as a mechanical filter [2]. As in the case of textolite packings, use of this filter leads to increase in transverse sensitivity of the transducer and decrease in the cohesive strength for side impact. It is not possible to use the epoxy compound proposed in [2] in our case since the joint has to be subjected to heat treatment. What is most important in this is the fact that such a method has limited scope for varying the filtering properties, whereas, conditions of the tests often compel investigators to intensify one or the other effect of protection from the unmeasurable actions.