Impact Localization in Smart Composite Plates Using Embedded PZT Sensors

This project investigated the experimental and theoretical analysis of impact localization in smart composite plates using embedded piezoelectric (PZT) sensors.

The study aimed to develop a cost effective and reliable method for detecting impact locations in composite structures, which is an important aspect of structural health monitoring in engineering applications such as aerospace and mechanical systems.

The project focused on designing and fabricating passive smart composite plates using low cost PZT patch sensors instead of more expensive piezoelectric materials. The composite plates were manufactured using a hand lay up method at low temperature to prevent damage to the sensors and ensure stable performance. Two main configurations were developed, including a composite plate with one embedded PZT sensor and another with two embedded PZT sensors. The fabrication process, illustrated on page 3, involved preparing materials, embedding sensors within fiberglass layers using a cut out method, and curing the composite structure.

An experimental impact test system was developed to analyse the behaviour of the composite plates under different loading conditions. As shown in the experimental setup on pages 6 and 7, impact forces were generated by dropping a rod from different heights onto the composite plate. The resulting mechanical stress waves propagated through the material and were detected by the embedded PZT sensors, which converted these mechanical signals into electrical voltage signals displayed on an oscilloscope.

The results demonstrated a clear relationship between impact force, pressure, and sensor output voltage. As illustrated in the graphs on page 7, the pressure on the sensor increased with increasing impact force, while the output voltage also increased accordingly. However, both pressure and voltage decreased as the distance between the impact point and the sensor increased. This indicates that the system can effectively estimate the distance of the impact location based on sensor output.

For the single sensor configuration, the project showed that the impact location lies on a circular locus centred on the sensor, where the radius is determined by the measured voltage. For the dual sensor configuration, a more accurate localization method was developed. The impact location was determined by calculating the intersection of two circles, each centred on a sensor, with radii derived from the respective sensor voltages. Mathematical models and equations presented on pages 8 to 10 were used to calculate the coordinates of the impact point with improved accuracy.

The findings confirmed that embedded PZT patch sensors can effectively detect and localize impacts in composite structures using a passive sensing approach. Compared to traditional bonded sensors, embedding the sensors provides better protection, improved durability, and more stable signal performance.

In conclusion, this project demonstrated that low cost PZT based smart composite systems can provide an efficient and practical solution for impact detection and structural health monitoring. The proposed method offers a reliable, accurate, and economically viable approach for real world engineering applications.