Assessment of mechanical properties of silkworm cocoons under quasi-static loading

Most agricultural products are viscoelastic, showing a complex behavior during transport, grading, and separation. Thus, it seems necessary to determine the mechanical properties of these materials to analyze their behavior and minimize losses. Accordingly, this study investigated the effect of hybrid type (154×153, 31×32, and 154×151), loading rate (10 and 20 mm/min), and loading direction (horizontal and vertical) on the mechanical properties of silkworm cocoons. A factorial experiment was used in a completely randomized design to analyze the data, and the means were compared by the multiple range Duncan test at a probability level (α) of 5%. The results showed the significant impact of the hybrid type, loading direction and speed, and their interaction on all mechanical properties of specimens. All mechanical properties of hybrids decreased as the loading speed increased from 10 to 20 mm/min. On the other hand, the rupture force, rupture energy, toughness, and deformation at rupture point were higher in horizontal loading than in vertical loading. According to the results, the highest rupture force (10.05 N) was measured for the hybrid 154×153. However, the highest rupture energy (2.78 J), deformation at rupture point (610 mm), and toughness (3.6×10-4 J/mm3) were measured for the hybrid 31×32 under horizontal loading at a loading speed of 10 mm/min. The lowest rupture force (3.83 N), rupture energy (0.27 J), deformation at rupture point (160 mm), and toughness (0.34×10-4 J/mm3) were obtained for the hybrid 154×151 under vertical loading at a loading speed of 20 mm/min.