Emerging SHM Technologies

The very basis of SHM is its ability to monitor structures using embedded / attached sensors and to utilize the data to assess the state of the structure. Non-destructive evaluation sensors for SHM purposes have attained a modest degree of maturity and are able to monitor significantly large areas of structures. Following are the important SHM technologies:

• Piezoelectric sensors
• Magnetostrictive sensors
• Optical fiber sensors
• Dynamic response analysis using Laser Doppler Vibrometer

Piezoelectric sensors

Piezoelectric sensors convert mechanical energy into electrical energy and vice versa. This phenomenon enables them to detect impacts and deformations in a structure

Figure 5.1: Piezoelectric materials (a) in original state with poling direction (b) voltage generation under compression (c) under tension

Lead Zirconate Titanate (PZT) is the most commonly used piezoelectric material. It is used in the form of patches. Since it is a hard ceramic which is weak in tension it is not always possible to embed it into a structure. The most common piezo-polymer for sensing dynamic strain is PVDF. PVDF sensors are not likely to modify the stiffness of the host structure due to their own low stiffness. Being a polymer PVDF film can be shaped as desired according to intended application and can be formed into very thin films making it attractive for sensing purposes.