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Articles 1 - 5 of 5
Full-Text Articles in Materials Science and Engineering
Characterization Of Waviness In Wind Turbine Blades Using Air Coupled Ultrasonics, Sunil Kishore Chakrapani, Vinay Dayal, David K. Hsu, Daniel J. Barnard, Andrew Gross
Characterization Of Waviness In Wind Turbine Blades Using Air Coupled Ultrasonics, Sunil Kishore Chakrapani, Vinay Dayal, David K. Hsu, Daniel J. Barnard, Andrew Gross
Sunil Kishore Chakrapani
Waviness in glass fiber reinforced composite is of great interest in composite research, since it results in the loss of stiffness. Several NDE techniques have been used previously to detect waviness. This work is concerned with waves normal to the plies in a composite. Air‐coupled ultrasonics was used to detect waviness in thick composites used in the manufacturing of wind turbine blades. Composite samples with different wave aspect ratios were studied. Different wavy samples were characterized, and a three step process was developed to make sure the technique is field implementable. This gives us a better understanding of the effect …
A Clamped Dual-Ridged Waveguide Measurement System For The Broadband, Nondestructive Characterization Of Sheet Materials, Milo W. Hyde Iv, Michael J. Havrilla
A Clamped Dual-Ridged Waveguide Measurement System For The Broadband, Nondestructive Characterization Of Sheet Materials, Milo W. Hyde Iv, Michael J. Havrilla
Faculty Publications
A novel two-port probe which uses dual-ridged waveguides for the nondestructive, broadband characterization of sheet materials is presented. The new probe is shown to possess approximately 2 to 3 times the bandwidth of traditional coaxial and rectangular/circular waveguide probe systems while maintaining the structural robustness characteristic of rectangular/circular waveguide probe systems. The theoretical development of the probe is presented, namely, by applying Love’s equivalence theorem and enforcing the continuity of transverse fields at the dual-ridged waveguide apertures, a system of coupled magnetic field integral equations is derived. The system of coupled magnetic field integral equations is solved using the method …
Experimental Verification Of The Linear Relationship Between Stress And The Reciprocal Of The Peak Barkhausen Voltage In Astm A36 Steel, Orfeas Kypris, Ikenna Nlebedim, David Jiles
Experimental Verification Of The Linear Relationship Between Stress And The Reciprocal Of The Peak Barkhausen Voltage In Astm A36 Steel, Orfeas Kypris, Ikenna Nlebedim, David Jiles
Orfeas Kypris
This study presents an experimental validation of a model theory for determining the relationship between a nondestructive measurement parameter and a property of interest. It was found that the reciprocal of the peak envelope amplitude of the Barkhausen emission voltage follows a linear relationship with stress. A linear relationship between stress and the reciprocal of the root mean square voltage was also obtained. These observations represent an important step towards improving the use of Barkhausen signals for magnetic non-destructive evaluation of stress as a function of depth in ferromagnetic load bearing structures.
Theory Of Thin-Skin Eddy-Current Interaction With Surface Cracks, Nicola Harfield, John R. Bowler
Theory Of Thin-Skin Eddy-Current Interaction With Surface Cracks, Nicola Harfield, John R. Bowler
Nicola Bowler
Eddy-current non-destructive evaluation is commonly performed at relatively high frequencies at which the skin depths are significantly smaller than the dimensions of a typical crack. A thin-skin analysis of eddy currents is presented in which the electromagnetic fields on the crack faces are described in terms of a potential which obeys a two-dimensional Laplace equation. Solutions of this equation for defects in both magnetic and non-magnetic materials are determined by applying thin-skin boundary conditions at the crack perimeter. The impedance change of an eddy-current coil due to the defect is then calculated by numerical evaluation of one-dimensional integrals over the …
Low‐Frequency Perturbation Theory In Eddy‐Current Non‐Destructive Evaluation, Nicola Harfield, Y. Yoshida, John R. Bowler
Low‐Frequency Perturbation Theory In Eddy‐Current Non‐Destructive Evaluation, Nicola Harfield, Y. Yoshida, John R. Bowler
Nicola Bowler
A method is presented by which series solutions for the impedance change in an eddy‐current test probe due to closed cracks in a non‐magnetic, conducting half‐space can be derived at low frequency. The series solution is applicable for flaws whose dimensions are much smaller than the electromagnetic skin‐depth. The problem is formulated using an approach in which the flaw is represented by an equivalent distribution of current dipoles. The electric field scattered by the flaw is then written as an integral, over the flaw, of the product of the dipole density distribution and an appropriate Green’s function. Terms in the …