PSI - Issue 5

Terekhina Alena et al. / Procedia Structural Integrity 5 (2017) 569–576 Terekhina Alena et al. / Structural Integrity Procedia 00 (2017) 000 – 000

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model parameters we compared with the real tests result with the model results for different strain rate as in Figure 4b model and experimental stress values are very much similar.

3.3. The Theory of Critical Distances based on elasto-plastic analysis

The stress fields requiring to calculation of the value of the critical distance and the effective stress according to definitions TCD were determined by solving Finite-Element models done by the finite-element package Abaqus SE. The cylindrical un-notched specimens and samples with sharp stress concentrators under different strain rates were used for determining the value of the critical distance. The value of the critical distance for elasto-plastic analysis is a constant equal 0.24 mm (Figure 5), while with linear-elastic analysis, the critical distance is a function of the strain rate.

Fig. 5. Local elasto-plastic stress fields under different strain rate.

By making use value of critical distances the effective stress for intermediate (stress concentrator radius ρ =1 mm) and blunt (ρ=2 mm) notched specimens was then calculated, in the incipient failure condition, according to Point Method of the Theory of Critical Distances (equation 6). The results of this final re-analysis are summarized in Figure 6, where the error is calculated according equation:

( ) nom

( ) nom

eff  

  

 

0

Error

(8)



( ) nom

0