PSI - Issue 41

Alexandru Isaincu et al. / Procedia Structural Integrity 41 (2022) 646–655 Alexandru Isaincu / Structural Integrity Procedia 00 (2019) 000 – 000

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The simulations were performed considering an orthotropic material with the properties provided in Tab. 1. The numerical models are shown in Fig. 5 for both symmetric and asymmetric loading.

Fig. 5. ECT specimen deformation in FRANC2D under (a) symmetrical loading conditions and (b) asymmetrical loading conditions.

A total number of 1820 eight-nodded plane stress elements connected in 3749 nodes were used for each model. Singular elements were considered around the crack to model the square root singularity at the crack tip. The orientation of the orthotropic material was changed in steps of 15°, between 0° and 90°. The SIF’s values were obtained using the displacement extrapolation technique. In all cases, a constant force of 1000 N was applied at the top part of the specimen. The variation of Y I and Y II with fiber orientation angle is shown in Fig. 6, for PPA material, side by side with the values corresponding to homogeneous material (red dotted lines). A linear isotropic material model, with E 1 as Young’s Modulus (corresponding to 0° fiber orientation), was used in FRANC2D to generate that value.

Fig. 6. Variation of non- dimensional SIF’s with the ori entation angle for PPA GF33 (left) and PPS GF40 (right).

Comparing the two materials, insignificantly small variation in terms of geometrical factors can be distinguished for both Y I and Y II . An increasing trend can be seen for Y I with the increase in the fiber orientation. For Y II , up to 45°, there is an increasing trend. This tendency changes between 45° and 90°. For both materials, the Y I orthotropic solution at 45° overlaps with the homogeneous solution. Because the variation of Y II is minimal, at all angles, the orthotropic solution is close to the homogeneous one.