Main research group: Prof. W. Ostachowicz, Prof. M. Krawczuk, Dr M. Palacz, Mr T. Wandowski, Mr P. Malinowski

The main objective of the research carried out in the area of the development and optimisation of sensor networks for damage detection is a search for optimal sensor placements for structural health monitoring purposes. When the positions of the sensors are chosen optimally in a structure then measured data carry most information useful for damage detection. In order to solve the problem of the optimal sensor placements a good optimisation procedure is required. Very effective tools, which can be applied here, are the methods of genetics algorithms (GA) or neural networks (NN).

In the case of GA the optimisation search procedures simulate natural evolution. Possible candidate solutions are coded as chromosomes. Random operations based on natural selection principles are used to evolve the initial population. In order to obtain "better" offspring the genetic operations such like: selection, reproduction, crosover, and mutation are employed. For proper realisation of these operations a right objective function must be determined. For solution of the problem of optimal piezo transducers (PZT) placements in a real structure chromosomes, which are binary coded, are used. Each substring in every chromosome represents one coded variable, which may be: position x and y of a sensor, position x and y of damage. The objective function may be based on the relation between energy transmitted and/or received for every relevant sensor. Then for every sensor an index can be introduced and based on such an index "the best" sensor (position) can be identified. Also as the objective function a function expressing the difference between a well-known position of a defect in a mathematical model, and calculated position of the defect, can be used. In this case "the best" sensor is such a sensor for which the objective function is equal zero or is near to zero.

Aircraft equipped with a network of piezo transducers

Calculated sensor indices indicating their ability for damage detection

Damaged glass/epoxy composite beam with piezo transducers