Accuracy assessment of thickness measurement by an impulse hammer

Abstract

To improve hammering test on a hull inspection, thickness estimation method by an impulse hammer was developed with numerical expression of impact behavior of a ball on an elastic plate. Impulse load signals of an impulse hammer striking steel plates were collected and the relationship between plate thickness and characteristic values of the signals were examined. Impact, peak load and minmax ratio (-minimum derivative/maximum derivative) of the signal show significant dependency on plate thickness. In case of the impact, the reproducibility was better than the others. The accuracy of thickness estimation which was examined by multi-value regression estimates with 1st-4th powered impact values was found to be within ±0.5mm in thickness range of 6mm-19mm.