Accession Number:

ADA071892

Title:

Compressive Strength and Indentation Damage in Ceramic Materials.

Descriptive Note:

Technical rept. 31 May 78-31 May 79,

Corporate Author:

SOUTHWEST RESEARCH INST SAN ANTONIO TEX

Personal Author(s):

• Lankford,James , Jr.
• Davidson,David L.

Report Date:

1979-05-31

Pagination or Media Count:

54.0

Abstract:

The threshold loads and crack sizes for indentation cracking were investigated for a number of ceramics using scanning electron microscopy and acoustic emission. It was found that the cracking behavior could be predicted, using a fracture mechanicsdimensional analysis approach modified to take into account the stress field at an elastic-plastic indentation. Selected area electron channeling was used to characterize the extent of subsurface damage produced in ceramics during grinding and polishing operations. It was found that polishing damage depths can be correlated using a simple model based on a sliding elastic-plastic indenter. Finally, the effect of temperature and strain rate upon material removal and cracking threshold was analyzed, using recent experimental compressive strength and crack growth measurements as inputs to current predictive models. The results are shown to have surprising implications with regard to dynamic, high temperature indentation particle impact. Author

Descriptors:

• *DEFORMATION
• *CRACKING(FRACTURING)
• *CERAMIC MATERIALS
• *MICROCRACKING
• COMPRESSION
• TEMPERATURE
• DAMAGE
• THRESHOLD EFFECTS
• ELECTRONIC SCANNERS
• ELASTIC PROPERTIES
• ELECTRON MICROSCOPY
• CRACK PROPAGATION
• SURFACE PROPERTIES
• PLASTIC PROPERTIES
• GRINDING
• POLISHING

Subject Categories:

• Ceramics, Refractories and Glass
• Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE