This book chapter describes experimental investigations, which are the basis for the advancement of the LET method. Furthermore, the experiments provide objective data for the validation of numerical approaches used for theoretical determination of the exerted Lorentz force.

Chapter Contents:

• 4.1 Measurement procedure
• 4.1.1 Measurement principle
• 4.1.2 Measurement method
• 4.1.3 Experimental setup
• 4.1.3.1 Linear drive
• 4.1.3.2 2D-positioning stage
• 4.1.3.3 Sensor system
• 4.1.3.3.1 3-Axes force sensor
• 4.1.3.3.2 3-Axes acceleration sensor
• 4.1.3.3.3 1-Axis DiLET sensor
• 4.1.3.3.4 Incremental position encoder
• 4.1.3.4 DAQ and measurement control system
• 4.2 Validation procedure
• 4.2.1 DSP and basic statistics
• 4.2.1.1 Concepts of signal ensembles
• 4.2.1.1.1 Ideal signal ensemble
• 4.2.1.1.2 Artificial signal ensemble
• 4.2.1.2 Basics of signal alignment
• 4.2.1.2.1 Signal alignment based on external trigger signals
• 4.2.1.2.2 Correlation of time-continuous signals
• 4.2.1.2.3 Correlation of time-discrete signals
• 4.2.2 Autocorrelation on typical force signals
• 4.2.3 Program flowchart for DSP
• 4.2.3.1 Loading data
• 4.2.3.2 Static offset correction and tailoring
• 4.2.3.3 Filtering data
• 4.2.3.4 Aligning data
• 4.2.3.4.1 Arbitrary ensemble member as reference signal
• 4.2.3.4.2 QSA simulation as reference signal
• 4.2.3.5 Statistic evaluation of the signal ensemble
• 4.2.4 Experimental study
• 4.2.4.1 Design of experiment
• 4.2.4.2 Result of the force measurement F(t)
• 4.2.4.3 Result of the force DRS δF(t)
• 4.2.4.4 Result of the DiLET voltage measurement Vz(t)
• 4.2.4.5 Concluding remarks
• 4.2.5 Uncertainty analysis
• 4.2.5.1 Introduction and motivation
• 4.2.5.2 The Generalized Polynomial Chaos Method
• 4.2.5.2.1 β-distribution
• 4.2.5.2.2 Orthogonality
• 4.2.5.2.3 Normalization
• 4.2.5.2.4 Set of basis functions
• 4.2.5.2.5 Regression approach to determine the gPC coefficients
• 4.2.5.2.6 Postprocessing
• 4.2.5.3 Problem definition in LET
• 4.2.5.4 Uncertainty quantification of model parameters
• 4.2.5.4.1 Experimental LET setup
• 4.2.5.5 Results and discussion
• 4.2.5.6 Conclusions

Inspec keywords: force measurement; electromagnetic forces; eddy current testing

Other keywords: motion-induced eddy current techniques; LET measurements; exerted Lorentz force; nondestructive testing

Subjects: Mechanical variables measurement; Electromagnetic induction; Materials testing; Measurement of mechanical variables; Nondestructive testing: eddy current testing and related techniques