Quality assurance of test pieces as a basis for adequate significance of test results

Badenheim, D.; Hoffmann, Michael J.; Oberacker, R.

doi:10.1002/mawe.200400855

Cited by 1 publication

(1 citation statement)

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“…An attractive feature of this approach is that failure occurs from pre‐existing processing related cracks. A difficulty with this approach is the large scatter in the data at each stress rate, requiring a large number of samples to characterize the values of n and B, the subcritical crack growth parameters, as well as adequate surface finishing .…”

Section: Discussionmentioning

confidence: 99%

Dynamic fatigue behaviour of a steatite ceramic

Oliveira

Reboredo

Fernandes

2016

Materialwissenschaft Werkst

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Dynamic fatigue of a low dielectric loss steatite was investigated. To this end, the values of n and B, the so-called subcritical crack growth (SCG) parameters were experimentally determined. The steatite exhibited the expected dynamic fatigue behaviour, so that the stress corrosion susceptibility parameter, n, of 24 was obtained. In addition, the material/environment parameter B, which is a constant for a given test environment, was also attained. These parameters are instrumental in predicting the lifetime of components under stress. When the applied load is such that the resulting strength equals half of the inert strength (σ i ), defined as the strength of a sample tested in an inert environment or at a fast stress rate, i.e. where no subcritical crack growth occurs, the time to failure (t f ) of the material was found to bẽ 140 h. Measurement of the fracture toughness of steatite is also of upmost importance and so it was determined using three test methods. A value of K Ic = 1.91 ± 0.29 MPa m 1/2 was attained by the indentation fracture method through measurement of the cracks emanating from the Vickers indentation. This value is in good agreement with those determined using the K Isc (surface crack in flexure) test method (2.21 ± 0.07 MPa m 1/2 ) and fractography analysis test method (2.00 ± 0.44 MPa m 1/2 ). Differences in test procedure and analysis causing the values from each test method to be different are discussed. Keywords: Steatite / fracture toughness / dynamic fatigue / slow crack growth / flexural strength Schlüsselwörter: Steatit / Bruchzähigkeit / dynamische Ermüdung / langsames Risswachstum / Biegefestigkeit

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Section: Discussionmentioning

confidence: 99%