Optimising vibration influence on detect defects on low-carbon steel plates using liquid penetrant testing technique

Liquid Penetrant Testing (LPT) is a time-honored Non-Destructive Testing (NDT) technique for identifying surface defects in materials. This study takes a fresh approach, exploring the dynamic impact of vibrational frequencies on LPT indications in welded low-carbon steel plates. The primary goal of this paper is to investigate the influence of vibrational frequencies on LPT indications and to devise and execute traditional vibration experiments for LPT. The method involves applying vibration to a 250 mmx150 mmx5mm dimension welded low-carbon mild steel plate and detecting the defect indication accordingly. The results, particularly at 93 Hz frequency, reveal a distinct indication of defect detection; it exhibits a significantly higher amplitude response, suggesting it is in resonance with the system's natural frequency. At 93 Hz resonance, the LPT indicators also had the largest area of the indicator with the shortest dwell time required. In conclusion, the resonance of vibrational frequency with the natural frequency of the desired testing material is a crucial factor in LPT, as it can enhance the wetting of the surface and capillary forces while significantly reducing the dwell time required for the penetrant indications to resurface. These findings not only contribute to our understanding of LPT but also open up avenues for further research in this field.