This paper aims to provide a state-of-the-art review on impact damage detection techniques in structures using strain data. An overview of impact detection systems is provided. These include sensors, specimens, and impact sources used for developing and testing strategies. The review is focused on approaches that use impact strain data (passive approach) to determine simultaneously the location and/or energy of an impact at the time it occurs. These approaches can be classed into two main groups, one based on analytical models and the other based on data-driven models. The former uses a first-principle model obtained from physical laws, whereas the latter describes complex relationships between input and output data obtained by experiments or simulations. Although some weaknesses and strengths are cited, we did not attempt to compare these approaches, and we do not comment the quantitative results.

Peer Reviewed