Location

La Jolla, CA

Start Date

1-1-1983 12:00 AM

Description

High performance weldments for critical service applications require 100% inspection. Balanced against the adaptability of the ultrasonic method for automated inspection are the difficulties encountered with nonhomogeneous and anisotropic materials. This research utilizes crystals and bicrystals of nickel to model austenitic weld metal, where the anisotropy produces scattering and mode conversion, making detection and measurement of actual defects difficult.

Well characterized samples of Ni are produced in a levitation zone melting facility. Crystals in excess of 25 mm diameter and length are large enough to permit ultrasonic measurements of attenuation, wave speed, and spectral content. At the same time, the experiments are duplicated as finite element models for comparison purposes.

Finite element models permit easy description of boundary conditions, geometry, and loading. Direct integration of the wave equation is done with the Newmark-Beta and Wilson-Theta Methods. The usual problem with the large number of degress of freedom can be alleviated with the use of Guyan reduction.

Two-dimensional comparisons showing mode conversion and a plate with a flaw are made. The continued development of this computational tool should increase understanding of quantitative ultrasonic inspection.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

2A

Chapter

Section 5: Weldments

Pages

257-270

DOI

10.1007/978-1-4613-3706-5_15

Language

en

File Format

application/pdf

Included in

Manufacturing Commons

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Jan 1st, 12:00 AM

Finite Element Modeling of Ultrasonic Inspection of Weldments

La Jolla, CA

High performance weldments for critical service applications require 100% inspection. Balanced against the adaptability of the ultrasonic method for automated inspection are the difficulties encountered with nonhomogeneous and anisotropic materials. This research utilizes crystals and bicrystals of nickel to model austenitic weld metal, where the anisotropy produces scattering and mode conversion, making detection and measurement of actual defects difficult.

Well characterized samples of Ni are produced in a levitation zone melting facility. Crystals in excess of 25 mm diameter and length are large enough to permit ultrasonic measurements of attenuation, wave speed, and spectral content. At the same time, the experiments are duplicated as finite element models for comparison purposes.

Finite element models permit easy description of boundary conditions, geometry, and loading. Direct integration of the wave equation is done with the Newmark-Beta and Wilson-Theta Methods. The usual problem with the large number of degress of freedom can be alleviated with the use of Guyan reduction.

Two-dimensional comparisons showing mode conversion and a plate with a flaw are made. The continued development of this computational tool should increase understanding of quantitative ultrasonic inspection.