FE Damage Analysis Research Articles

Predicting ductile fracture of cracked pipes using small punch test data

This paper proposes a numerical method to simulate ductile fracture of a cracked pipe using small punch test data. The method is using FE damage analysis method based on the multi-axial fracture strain energy density model. The parameters in the damage model can be extracted solely from small punch test data, using which compact tension and circumferential through-wall cracked pipe tests are simulated. To validate the proposed method, simulation results are compared with TP316L experimental data. For the compact tension test, faster crack growth is predicted but for the pipe test, good agreement is obtained. The effect of the stress triaxiality on the prediction accuracy is discussed.

The effect of material ductility on notch fracture resistance: Numerical study

In this work, the effect of material ductility on the notch fracture resistance is quantified using FE damage analysis based on a multi-axial fracture strain model. Material properties of SUS316 stainless steel with three different levels of cold work (5%, 20% and 40%) are used to represent materials with different strength and ductility. Using validated FE damage analysis, notch fracture resistance data for these three materials with three different notch radii (0.2 mm, 0.4 mm and 0.8 mm) are generated numerically. Examination of notch fracture resistance data suggests that fracture initiation resistance (corresponding to 0.2 mm crack growth) depends almost linearly on notch radius. A linear dependence of the normalized fracture resistance of a notched specimen (with respect to that of a cracked one) on the material ductility is also found. The results are useful to estimate notch fracture resistance from the material ductility and the J-resistance curve obtained from a cracked specimen.

Numerical validation of burst pressure estimation equations for steam generator tubes with multiple axial surface cracks

This paper provides further validation of the burst pressure estimation equations for multiple axial surface cracked steam generator tubes, recently proposed by the authors based on analytical local collapse load approach against systematic FE damage analysis results of Alloy 690 tubes with twin axial surface cracks. Wide ranges of the relative crack depth and multiple crack configurations are considered. Comparison shows good agreements, giving sufficient confidence of the proposed equations.

Ductile Crack Growth Modeling under Low Cycle Fatigue Loading Condition

This paper presents a numerical method using FE damage analysis to simulate ductile tearing in CT specimen under low cycle fatigue loading conditions. To define a cyclic material properties, the nonlinear kinematic hardening model is adopted. The damage model is defined based on the ductility exhaustion concept using the multi-axial fracture strain energy concept. The proposed model is then applied to simulate two cyclic fracture toughness tests with different R-ratios. Simulated results show overall good agreement with experimental results.

Creep failure simulations of 316H at 550 °C: Part II – Effects of specimen geometry and loading mode

In this paper, the FE damage analysis method, proposed in Part I, is applied to simulate creep crack growth in six different types of cracked specimens of 316H at 550°C. Comparison with experimental results shows that simulated creep crack growth rates agree well with experimental data. Shortcomings of the present method to predict creep crack initiation is briefly discussed.