Accession Number:

ADA113937

Title:

Requirements for Flexure Testing of Brittle Materials

Descriptive Note:

Final rept.,

Corporate Author:

ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MA

Personal Author(s):

Report Date:

1982-04-01

Pagination or Media Count:

54.0

Abstract:

Requirements for accurate bend-testing of four-point and three-point beams of rectangular cross-section are outlined. The so-called simple beam theory assumptions are examined to yield beam geometry ratios that will result in minimum error when utilizing elasticity theory. Factors that give rise to additional errors when determining bend strength are examined, such as wedging stress, contact stress, load mislocation, beam twisting, friction at beam contact points, contact point tangency shift, and neglect of corner radii or chamfer in the stress determination. Also included are the appropriate Weibull strength relationships and an estimate of errors in the determination of the Weibull parameters based on sample size. Error tables, based on many of the previously mentioned factors, are presented. Such data are utilized to rationally arrive at a 13-four-point nd a three-point beam of a specific geometry ratio and dimension that will result in minimization of errors during flexure testing. Although such beams are recommended for a military standard, they are termed reference standard beams. Beams of other loading configurations and dimensions are considered acceptable if statistical correlation to one of the reference standards is determined, and if error spans are reported when presenting flexure test data.

Subject Categories:

  • Ceramics, Refractories and Glass
  • Test Facilities, Equipment and Methods
  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE