PSI - Issue 41

Victor Rizov et al. / Procedia Structural Integrity 41 (2022) 94–102 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

101

8

 1 1 / G G and 

    1 1 / ratios. The strain

calculations of the strain energy release rate are carried-out at various

 1 1 / G G ratio at three 

    1 1 / in Fig. 4. It is evident from Fig.

energy release rate is displayed as a function of

4 that when     1 1 / ratios increase, the strain energy release rate decreases. Figure 5 illustrates the effect of crack location along the beam width on the strain energy release rate at three   2 2 / G G ratios. The crack location is characterized by b b / 1 ratios. The inspection of curves in Fig. 5 indicates that the strain energy release rate is maximal when the crack is located near the vertical mid-plane of the beam. One can observe also in Fig. 5 that the strain energy release rate reduces when   2 2 / G G ratio increases. The influence of     2 2 / ratio on the strain energy release rate is displayed in Fig. 6 at three h b / ratios.  1 1 / G G and 

    2 2 / ratio (curve 1 – at /

1.4 = h b , curve 2 – at /

1.7 = h b and

Fig. 6. The strain energy release rate displayed as a function of

curve 3 – at /

2.0 = h b ).

    2 2 / ratio causes reduction of the strain energy release rate. The

It can be seen in Fig. 6 that increase of

increase of h b / ratio leads also to reduction of the strain energy release rate (Fig. 6). 4. Conclusions

Delamination of inhomogeneous beam structure of rectangular cross-section loaded in torsion is analyzed with taking into account the creep behaviour. The beam is built-up by two longitudinal vertical layers. A delamination crack is located between layers inside the beam. The two layers are continuously inhomogeneous along the length of the beam. Besides, the layers have different width. Since the delamination is inside the beam, the latter is treated as an internally statically undetermined structure in order to determine the torsion moments in the crack arms. These torsion moments are then used to derive the strain energy release rate by considering the time-dependent strain energy cumulated in the beam structure. For verification, the strain energy release rate is determined also by analysing the compliance of the beam under creep. A parametric study of the strain energy release rate is performed.