89 research outputs found
Temperature robust PCA based stress monitoring approach
Get PDFIn this paper, a guided wave temperature robust PCA-based stress monitoring
methodology is proposed. It is based on the analysis of the longitudinal guided wave propagating
along the path under stress. Slight changes in the wave are detected by means of PCA via statistical
T2 and Q indices. Experimental and numerical simulations of the guided wave propagating in
material under different temperatures have shown significant variations in the amplitude and the
velocity of the wave. This condition can jeopardize the discrimination of the different stress
scenarios detected by the PCA indices. Thus, it is proposed a methodology based on an extended
knowledge base, composed by a PCA statistical model for different discrete temperatures to
produce a robust classification of stress states under variable environmental conditions.
Experimental results have shown a good agreement between the predicted scenarios and the real
onesPostprint (author's final draft
Flow estimation in a steel pipe using guided waves
Get PDFIn this investigation, a flow rate estimation guided wave based scheme in pipes is
proposed. The effect of the fluid over the propagation of longitudinal waves has been
experimentally studied by using several laminar flows of water transported by a steel pipe. Results
have shown a decrease of the guided wave pattern repeatability and the signal energy as the flow
rate increase as a result of the energy leakage from the pipe to the fluid. A Matlab® script is used to
excite the PZT actuator via picoscope 2208 of Picotech®, the captured signal is acquired also by the
picoscope and the data is processed in Matlab. The test bench utilized is composed by a 1” sch 40
A-106 pipe, a needle valve and a centrifugal pump provides the flow energy. A couple of PZTs are
used in a picth-catch configuration to produce and capture the longitudinal waves along the cross
section of the pipe.Postprint (author's final draft
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