Cut-off Frequencies Induced by the Length of Strain Gauges Measuring Impact Events


  • R. Othman

    1. Institut de Recherche en Génie Civil et Mécanique (GeM), Ecole Centrale de Nantes BP92101, F-44321 Nantes cedex, France and Structural Impact Laboratory (SIMLab), Centre for Research-based Innovation, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway
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Abstract:  The finite length of strain gauges may induce filtering effects when measuring impact events. In this study, we are interested in quantifying these effects. Precisely, we determined the cut-off frequencies of strain gauges cemented on visco-elastic bars and measuring impact-induced strain waves. This study shows that the cut-off frequencies increase with the bar’s wave velocity and decrease with the bar’s diameter. The asymptotic value, corresponding to an infinite bar diameter, is reached rapidly (bar diameter ≈ 15 mm). Moreover, we showed that the mode cut-off frequencies are more severe (lower) than the gauge length cut-off frequencies for bar diameters greater than 8 mm.