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Application of the PCA to Guided Ultrasonic Waves to Evaluate Tensile Stress in a Solid Rod

J. Q. MÉNDEZ, R. V. MEJA, J. L. Q. PINEDA, L. E. MUJICA, M. RUIZ

Abstract


In this work, the use of Principal Component Analysis (PCA), through T2 and Q-statistics, is proposed to evaluate the tensile stress in a bar rod by means of ultrasonic guided waves. This method can be potentially used in-situ and real time for continuous condition monitoring. The specimen tested is a 1020 steel bar of 1” cold finished with yield strength of 441 MPa. Piezoelectric transducers are used in a through-transmission configuration to excite and detect axis-symmetric waves at the free ends of the bar. The load on the bar is performed using a MTS® testing machine in load control to maximum load of 80% of the yield strength. A dedicated Matlab® software is utilized to perform ultrasonic signal generation, signal acquisition and processing. A 5 cycles Gaussian-modulated sinusoidal pulse is used to generate narrow-band waves. Data captured by the piezoelectric sensor for each load condition are projected into the PCA model. The first two projections, Qstatistic and T2-statistic indices are analyzed. Results of each load scenario are presented and discussed demonstrating the feasibility and potential of using this formulation in the evaluation of the tensile stress in structural elements.

doi: 10.12783/SHM2015/226


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