Integrated Piezoelectric Sensing and Actuation System for Crack Detection and On-Demand Repair in Steel Structures

Steel structures operating in demanding environments require instrumentation capable of detecting structural damage and supporting timely intervention. This paper presents a compact wireless system that integrates piezoelectric sensing, decision-making, and localized on-demand repair. A surface-mounted piezoelectric transducer (PZT) transmitter–receiver pair is bonded to a steel plate, while an Arduino controller drives the transmitter with a 5 V, 10 kHz signal and acquires the sampled receiver response. Damage is identified through relative changes from a baseline established for the intact plate. Upon detection, a motor-driven miniature valve releases low-viscosity adhesive from an internal reservoir through a silicone tube for gravity-fed delivery to the damaged region. The system also logs and transmits data for MATLAB R2025b-based post-processing. A 3D-printed PLA/TPU housing integrates the sensing, control, power, and repair components while mechanically separating sensing and actuation functions. Coupled-field harmonic simulations in ANSYS were used to evaluate the electromechanical response of the bonded PZT pair and support the experimental design. Experimental frequency sweeps characterized the intact-system response, while controlled slot-width tests at 10 kHz showed a systematic decrease in the sampled receiver-response index with increasing defect width. Repair performance was further supported by partial recovery of the sampled response, together with morphology and bond-strength evidence showing continuous adhesive filling and mechanically meaningful bonding. The results demonstrate the feasibility of integrating piezoelectric sensing, decision-making, and localized on-demand repair within a single portable system for steel structures.