Effect of micro-cracks in nonhomogeneous stress field on fracture instability in structural components

Bohumir Strnadel; Vratislav Mareš; Bohumir Strnadel; Vratislav Mareš

doi:10.3934/matersci.2016.4.1534

AIMS Materials Science

2016, Volume 3, Issue 4: 1534-1543. doi: 10.3934/matersci.2016.4.1534

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Effect of micro-cracks in nonhomogeneous stress field on fracture instability in structural components

Bohumir Strnadel ^,,
Vratislav Mareš

Center of Advanced Innovation Technologies VŠB-Technical University of Ostrava, 17. listopadu 15, 708 00 Ostrava-Poruba, Czech Republic

Received: 08 September 2016 Accepted: 07 November 2016 Published: 14 November 2016

The paper analyses the effects of statistical distribution in sizes of micro-cracks on scatter of fracture toughness of steels under brittle conditions. The results are utilized for reliability assessment of selected functional parts. The reliability considered as a complementary probability of brittle fracture initiation is discussed in dependence on the character of statistical distribution of micro-crack sizes, mechanical properties of steel, mechanisms of energy dissipation during cracks propagation, variation of loading, stress state of functional part and its service life. This probability approach is compared with deterministic reliability access originating from computation of safety factor. Its rational evaluation as a function of acceptable probability of fracture instability provides high economical effects saving materials and energy.
- microcracks,
- HRR stress field,
- brittle fracture,
- stress intensity factor,
- fracture probability,
- reliability,
- structural component
Citation: Bohumir Strnadel, Vratislav Mareš. Effect of micro-cracks in nonhomogeneous stress field on fracture instability in structural components[J]. AIMS Materials Science, 2016, 3(4): 1534-1543. doi: 10.3934/matersci.2016.4.1534

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Abstract

The paper analyses the effects of statistical distribution in sizes of micro-cracks on scatter of fracture toughness of steels under brittle conditions. The results are utilized for reliability assessment of selected functional parts. The reliability considered as a complementary probability of brittle fracture initiation is discussed in dependence on the character of statistical distribution of micro-crack sizes, mechanical properties of steel, mechanisms of energy dissipation during cracks propagation, variation of loading, stress state of functional part and its service life. This probability approach is compared with deterministic reliability access originating from computation of safety factor. Its rational evaluation as a function of acceptable probability of fracture instability provides high economical effects saving materials and energy.

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