A minimax sensor placement approach for damage detection in composite structures

This article proposes a new method for optimal placement of sensors for detecting damages in composite structures. The problem is formulated as a minimax optimization in which the goal is to find the coordinates of a given number of sensors so that the worst (maximum) probability of nondetection of the sensor network is made as good as possible (minimized). It is shown that a minimax approach can more efficiently place the sensors on complex geometries, compared to existing placement methods that consider average probability of detection. The method allows one to account for characteristics of sensors by assuming that the effectiveness of a sensor decreases with the distance from damage via an experimentally determined sensor probability of detection function and sensor noise in sensor network optimization. The formulation also enables to account for nonuniform likelihood of damages on the structure, which often arises due to irregular loading or boundary conditions, using a damage probability density. Numerical examples and an experimental validation study involving a Lamb-wave sensing system are presented to show the effectiveness of the proposed method.