Shock Transducer with Hall Sensing Element Ioan Gavril Tarnovan, Bogdan Tebrean, Titus Eduard Crisan Departament of Electrical Measurement, Faculty of Electrical Engineering, Technical University of Cluj-Napoca, Str.C.Daicoviciu nr.15, 400020 Cluj-Napoca, Romania, E-mail: ioan.tarnovan@mas.utcluj.ro Abstract - The aim of this paper is to show a determination method for mechanical shocks, using as sensing element an analogical Hall effect transducer. In the first part of the paper there will be enunciated the used physical principle, mentioning the conservation laws of mechanical energy and in following part we will describe the experimental setups and the behavior of the implemented captors. We will also analyze the factors that can generate errors or they can disturb the measurement process. There will be presented the sensors as well as a implementation method of the sensor in complex integrated parts which contain the signal processing circuits and the sensing element. We can consider this transducers not a replacement to the present methods (piezoresistive, tensometric, optical, etc), but a viable alternative which is easy to implement. I. Theoretical Approach The measurement of the aperiodical vibration or of the mechanical shocks is made in present technical applications with the help of the piezoresistive, tensometric, optical transducers. The analogical Hall effect transducers, used in different mechanical configurations, can help us to distinguish a vast area of shocks and vibrations parameters. It is very well know the fact that when a probe, which is in free fall condition, meets on it’s trajectory an obstacle, for example a cantilever beam, an energetic transfer will be made between this two parts of the system. Figure 1. The transformation of the gravitational potential energy in elastic potential energy Practicaly, the potential energy stored, during the time of the displacement, will be transferred to the beam according with following formula: 2 2 1 ) ( y k y h mg ⋅ ⋅ = + (1) - where: - m – the probe’s mass [Kg] - h – the throwing height [m] - y – the displacement of the beam [m] - k – the elastic constant [N/m] - g – the gravitational acceleration [m/s 2 ] We have considered for the beam’s potential energy calculation the behavior of a classic elastic spring due to the fact that the relative displacement is small and the load is end concentrated type. According with the physical phenomena mentioned previously and considering that over the action of the weight G there aren’t any effects or another exterior force, we can calculate the weight, respectively the mass of the probe with is in free fall condition, knowing the value of the elastic constant k, of the the throwing height h and of the the displacement of the beam h (which is measured with the aid of the Hall effect transducer). (2) (3) ) ( 2 2 y h g y k m + ⋅ ⋅ ⋅ = ) ( 2 2 y h y k G + ⋅ ⋅ =