Fracture testing of a layered functionally graded material

Michael R. Hill, R. Doug Carpenter, Glaucio Paulino, Zuhair A. Munir, Jeffery C. Gibeling

Research output: Contribution to journalConference articlepeer-review

Abstract

This paper describes measurements of the K1 R-curve for a layered ceramic-metallic functionally graded material (FGM) composed of Ti and TiB phases. Single edge notch bend specimens were fabricated for crack propagation perpendicular to the graded layers from the brittle to the ductile side of the FGM. The precracking method and residual stresses affected the measured toughness. A new reverse bending method produced a sharp precrack without damaging the material. A representative sample indicates R-curve behavior rising from Kmeas, = 7 MPa·m1/2 in the initial crack-tip location (38% Ti and 62% TiB) to 31 MPa·m1/2 in pure Ti. Residual stresses acting normal to the crack-plane were measured in the parent plate using the crack compliance technique. The residual stress intensity factor in the SE(B) specimen determined from the weight function was -2.4 MPa·m1/2 at the initial precrack length. Thus, the actual material toughness at the start of the test was 34% less than the measured value.

Original languageEnglish (US)
Pages (from-to)169-184
Number of pages16
JournalASTM Special Technical Publication
Issue number1409
StatePublished - 2002
EventFracture Resistance Testing of Monolithic and Composite Brittle Materials - Oralando, FL, United States
Duration: Nov 14 2000Nov 14 2000

Keywords

  • Fracture toughness
  • Functionally graded material
  • R-curve
  • Residual stress

ASJC Scopus subject areas

  • Engineering(all)

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