PSI - Issue 52

Vinit Vijay Deshpande et al. / Procedia Structural Integrity 52 (2024) 391–400 Author name / Structural Integrity Procedia 00 (2019) 000 – 000 5 these responses, effective stress invariants namely pressure, P and von Mises stresses, are calculated from the two macroscopic stresses 11 and 22 using the expressions given below: = 11 + 22 + 33 3 = √ 1 2 √( 11 − 22 ) 2 +( 22 − 33 ) 2 +( 33 − 11 ) 2 . Here, 33 =0 as only biaxial compression is being studied. The evolutions of effective pressure and von Mises stress during the course of the simulation are shown in Fig. 4a-b. It can be seen that as the maximum pressure increases, the maximum von Mises stress also increases indicating increase in strength as the pressure is increased 395

Fig. 4. Evolution of effective (a) pressure and (b) von Mises stress during the course of simulation for the selected 5 load cases.

Fig. 5. (a) Damaged regions indicated by black colored regions in the microstructures; (b) evolution of number of damaged regions in the foam microstructure as a function of effective von Mises stress for the 5 load cases.

An interesting insight into the damage mechanisms is obtained by tracing the number of damaged regions developed in the foam microstructure as a function of the effective von Mises stress. A single damaged region is defined by the adjacent finite elements that are fully damaged (refer black color regions in Fig. 5a). As the loading is increased, new