Combined Mode Fracture Toughness Measurement by the Disk Test

1978 ◽  
Vol 100 (2) ◽  
pp. 175-182 ◽  
Author(s):  
Hideo Awaji ◽  
Sennosuke Sato
Keyword(s):  
Fracture Toughness ◽  
Internal Crack ◽  
Mode I ◽  
Mode Ii ◽  
Mode Fracture ◽  
Fracture Toughness Measurement ◽  
Circular Specimen ◽  
Combined Mode ◽  
Toughness Measurement ◽  
Disk Test

The disk test in which a circular specimen with an internal crack is subjected to diametral compression is used to investigate combined mode I and mode II fracture. The stress intensity factors in the disk test are calculated numerically by means of the boundary collocation procedure and the dislocation method. Special care was taken to analyze the effect of the compression anvils. This method has the advantage, of allowing successive measurement of mode I, mode II and the combined mode fracture toughness under the same conditions. Some kinds of graphite, plaster and marble are examined to obtain the fracture toughness values, KIC, KIIC and the combined mode fracture criterion.

A Micromechanics Based Representation of Combined Mode I and II Toughness of Brittle Materials and Interfaces

1993 ◽  
Vol 115 (1) ◽  
pp. 101-105 ◽  
Author(s):  
J. Ahmad
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Brittle Materials ◽  
Mode I ◽  
Mode Ii ◽  
Mode Fracture ◽  
Bimaterial Interfaces ◽  
Mode Ii Fracture Toughness ◽  
Micromechanics Modeling ◽  
Combined Mode

The work of Evans and Hutchinson (1989) on micromechanics modeling of combined mode fracture is used as the basis for proposing an expression for combined Mode I and Mode II fracture toughness of brittle monolithic materials as well as bimaterial interfaces. The results of the proposed expression are compared with experimental data.

Microstructural Effects on Fracture Toughness of Polycrystalline Ceramics in Combined Mode I and Mode II Loading

1989 ◽  
Vol 111 (1) ◽  
pp. 174-180 ◽  
Author(s):  
D. Singh ◽  
D. K. Shetty
Keyword(s):  
Fracture Toughness ◽  
Mode I ◽  
Mode Ii ◽  
Mixed Mode Fracture ◽  
Transgranular Fracture ◽  
Pure Mode ◽  
Polycrystalline Alumina ◽  
Polycrystalline Ceramics ◽  
Mode Ii Loading ◽  
Combined Mode

Fracture toughness of polycrystalline alumina and ceria partially stabilized tetragonal zirconia (CeO2-TZP) ceramics were assessed in combined mode I and mode II loading using precracked disk specimens in diametral compression. Stress states ranging from pure mode I, combined mode I and mode II, and pure mode II were obtained by aligning the center crack at specific angles relative to the loading diameter. The resulting mixed-mode fracture toughness envelope showed significant deviation to higher fracture toughness in mode II relative to the predictions of the linear elastic fracture mechanics theory. Critical comparison with corresponding results on soda-lime glass and fracture surface observations showed that crack surface resistance arising from grain interlocking and abrasion were the main sources of the increased fracture toughness in mode II loading of the polycrystalline ceramics. The normalized fracture toughness for pure mode II loading, (KII/KIc), increased with increasing grain size for the CeO2-TZP ceramics. Quantitative fractography confirmed an increased percentage of transgranular fracture of the grains in mode II loading.

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