Abstract: The present invention relates to a method for making a device for monitoring the structural integrity of structures such as beams, plates and shells, made of isotropic, anisotropic and/or laminated material, and to such a device. The method provides to define a asymmetric directivity function D(k1,k2) that has, in the domain of wave numbers, a plurality of maxima arranged on different concentric circumferences having center in the origin of the axes. Then a load distribution in spatial coordinates f(x1,x2) is computed by inverse Fourier transform of the directivity function D(k1,k2). Then therefore the device is made with the electrodes, whose shape is obtained by gathering the values of the load distribution f(x1,x2) in the plane having for coordinates the set of real numbers and imaginary numbers, defining at least two sectors of said plane that comprise at least one real value and one imaginary value.

Abstract: The present invention relates to a piezoelectric sensor (1,100) comprising a piezoelectric material (10) interposed between a first (11) and a second (12) electric contact element. The first electric contact element (11) comprises at least two sensing areas (110, 111) spatially separated along a sensing direction. It also describes a sensor node that includes the piezoelectric sensor, a system and a method for monitoring the integrity of a structure using said piezoelectric sensor.

Abstract: The present invention relates to a method for making a device for monitoring the structural integrity of structures such as beams, plates and shells, made of isotropic, anisotropic and/or laminated material, and to such a device. The method provides to define a asymmetric directivity function D(k1,k2) that has, in the domain of wave numbers, a plurality of maxima arranged on different concentric circumferences having center in the origin of the axes. Then a load distribution in spatial coordinates f(x1,x2) is computed by inverse Fourier transform of the directivity function D(k1,k2). Then therefore the device is made with the electrodes, whose shape is obtained by gathering the values of the load distribution f(x1,x2) in the plane having for coordinates the set of real numbers and imaginary numbers, defining at least two sectors of said plane that comprise at least one real value and one imaginary value.

Abstract: The present invention relates to a piezoelectric sensor (1,100) comprising a piezoelectric material (10) interposed between a first (11) and a second (12) electric contact element. The first electric contact element (11) comprises at least two sensing areas (110, 111) spatially separated along a sensing direction. It also describes a sensor node that includes the piezoelectric sensor, a system and a method for monitoring the integrity of a structure using said piezoelectric sensor.