Effects of Time after Harvest and Rate of Loading on Mechanical Properties of Sweet Orange (Lemunzaki) Under Quasi-Static Loading

Some mechanical properties of a local variety of sweet orange (Lemun zaki) were determined under quasi-static compression loading using Instron Universal Testing Machine at three levels of time after harvest and three rates of loading. The mean load the cultivar can withstand without imposing internal injury when fresh at loading rates of 10, 5, and 1 mm/s were 188.803 ? 78.753, 188.552 ? 79.034, and 187.023 ? 76.954 N respectively. On the seventh day, the mean load was found to be 51.934 ? 18.259, 53.928 ? 18.809, and 52.745 ?18.563 N for the respective rates of loading; this further decreased to 44.399 ? 19.663, 44.273 ? 19.682, and 43.743 ? 18.927 N on the fourteenth day at the same loading rates respectively. The Stress and strain, secant modulus and energy were found to vary significantly with time after harvest at ? = 0.05 at rupture point.