PSI - Issue 24

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Lorenzo Bergonzi et al. / Procedia Structural Integrity 24 (2019) 213–224 Lorenzo Bergonzi et al. / Structural Integrity Procedia 00 (2019) 000–000

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5 (b) full-size and mini specimen profiles are superimposed, showing the same starting point for the two different fillets kind.

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MaCh3D Full-Size MaCh3D S-Size with spline

Total contact force - Normalized

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Position along specimen axis [mm]

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Figure 5. Contact force along specimen profile for full-size MaCh3D and miniaturized S-Size specimen (a). Superimposed full-size and miniaturized geometry (b).

3.3. Stress distribution in specimen section In Figure 6 (a) are reported the contours of $$ $$_"#$ ⁄ in correspondence of fillet region and rectilinear section, being 1.00 the maximum value. It is shown how maximum stress are localized in correspondence of fillet region for smaller radii, whilst increasing its value, the higher stress levels interests a wider specimen portion which entails a more even distribution.

(a) (b) Figure 6. Stress $$ intensity in correspondence of fillet and parallel regions (a) and in detail the end of fillet region with a contour limited between 1.00 and 0.95 for the spline profile (b). In Figure 6 (b) it is shown the stress contour for the specimen with spline fillets: it is evident how stress is evenly distributed along the rectilinear section. In the magnified detail, legend is limited between 0.95 and 1.00, showing slightly higher stress value in correspondence of transition zone between spline and parallel trait. Stress distribution in correspondence of specimen middle plane and at the end of the fillet was evaluated and compared with ASTM E8M Type I, ASTM E8M type V and ASTM E8M sheet type. ASTM E8M Type V was considered due to the fact it has reduced section and overall dimensions similar to MaCh3D S-Size. Both axial stress ( $$ ) and Von Mises stress ( 'F ) were taken into account. In particular, comparison between principal and Von Mises stress indicates presence of stress triaxiality in the considered regions for some configurations. Stress values were