Constitutive dependence in finite-element modelling of crack closure during fatigue

• The influence of choice of constitutive relation on the prediction of crack-opening stress for fatigue cracks using the finite-element method is investigated and compared with experimental results. Two different experimentally obtained stress–strain relations for IN718 at 550 °C were used for fitting material parameters to the linear kinematic and the Bodner–Partom viscoplastic constitutive models. In addition, one reference material description and one Bodner–Partom with parameters fitted to both types of experiment was used, i.e., in total six constitutive descriptions. Experimental values for crack-opening stress were found by the potential drop method for the two load cases analyzed. Two different load cases, load control and displacement control, have been examined. It turns out that the correlation between experimental and analytical crack-opening stress vary significantly with material description, opening criteria in the simulation and load case. The investigation shows that care must be taken when choosing material description and opening criteria for crack propagation simulations.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Teknisk mekanik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Applied Mechanics (hsv//eng)

Keyword

fatigue

finite-element modelling

Bodner-Partom

crack closure

material model

IN718

Publication and Content Type

art (subject category)

ref (subject category)