ISSN: 0090-3973
Published Online: 25 January 2006
Page Count: 10

A Two-Parameter Method for Determining the Fracture Toughness of Materials from Subsized Specimens
Santarelli, EL
Professor, Universidad Nacional del Comahue,

(Received 29 November 2004; accepted 15 November 200)

Abstract

The fracture toughness of brittle materials can be determined easily using the Linear Elastic Fracture Mechanics (LEFM) approach, and the only demand for change is the desire to decrease specimen size requirements. Specimen size effect on the normally measured K^Q and P^MAX/P^Q values was revisited in order to establish the suitability of a relationship between these parameters. A linear dependence was confirmed from experimental data of materials as different as isotactic polypropylene, AISI 4140 steel, a titanium alloy, and an aluminum alloy. The load ratio was interpreted as a second parameter, and thorough this dependence, K^Q values measured on subsized specimens were extrapolated to linearity conditions P^MAX/P^Q = 1, determining a value identified as K^1.0. When some simple conditions were met, this K^1.0 value matched the toughness of evaluated materials. For the analyzed materials, this toughness parameter could be obtained from subsized specimens with important size reduction compared with that needed for K^IC valid value determination. Moreover it permitted a simple characterization of material as difficult to characterize as isotactic polypropylene, which initially motivated this study.

Keywords:
linear elastic fracture mechanics (LEFM), fracture toughness, subsized specimens, polypropylene, 4140 steel

Paper ID: JTE13151
DOI: 10.1520/JTE13151
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