Location

Santa Cruz, CA

Start Date

1-1-1984 12:00 AM

Description

Machining damage in hot pressed (NCI32) silicon nitride, due to surface grinding and polishing, has been simulated by dragging a Knoop indentor across the surface of optically polished samples. The reflection coefficient of the cracks thus generated was measured versus frequency, and was found to be in excellent agreement with the theoretical calculations of Achenbach and Brind1. We found that the long slot-like cracks were closed at the top (about 20% of the total crack depth), which was due to the residual stress introduced when the samples were scratched. By taking into consideration the crack closure, and with the results of our scattering measurements, we were able to make failure stress predictions with an accuracy of better than 10%.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

3A

Chapter

Chapter 2: Ultrasonics

Section

Scattering

Pages

229-237

DOI

10.1007/978-1-4684-1194-2_21

Language

en

File Format

application/pdf

Share

COinS
 
Jan 1st, 12:00 AM

Measurement of Surface Machining Damage in Ceramics

Santa Cruz, CA

Machining damage in hot pressed (NCI32) silicon nitride, due to surface grinding and polishing, has been simulated by dragging a Knoop indentor across the surface of optically polished samples. The reflection coefficient of the cracks thus generated was measured versus frequency, and was found to be in excellent agreement with the theoretical calculations of Achenbach and Brind1. We found that the long slot-like cracks were closed at the top (about 20% of the total crack depth), which was due to the residual stress introduced when the samples were scratched. By taking into consideration the crack closure, and with the results of our scattering measurements, we were able to make failure stress predictions with an accuracy of better than 10%.