PSI - Issue 12

Simonetta Boria et al. / Procedia Structural Integrity 12 (2018) 317–329 Simonetta Boria et al./ Structural Integrity Procedia 00 (2018) 000 – 000

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Fig. 1. SEM micrographs of agglomerated cork CR12-J at different magnifications.

The typical stress – strain curve obtained from compression test on cork is reported in Fig. 2. It is characterized by three common stages, namely a linear elasticity at low stresses due to cell wall bending, a long collapse plateau due to elastic buckling of cell walls and finally a densification stage where the collapse of cells and compaction of the successive cell walls take place (Fernandes et al. (2014)). From the curve in Fig. 2, the compressive modulus (calculated as the average slope of the stress – strain curve in the elastic stage) and the collapse stress (calculated as the intersection of the lines fitting the plateau and the elastic stages) were obtained and reported in Table 1. It is worth mentioning that the stress was found to be not constant during the collapse propagation in agglomerated cork, which is likely due to structural heterogeneities.

Fig. 2. Representative compression stress – strain curve for agglomerated cork.

Table 1. Mechanical properties of agglomerated cork in compression. Modulus (MPa)

Strength (MPa)

CR-12J

17.00 ± 1.83

0.78 ± 0.06