CREEP-RECOVERY BEHAVIOR FOR EIGHT DATES CULTIVARS AT TWO DIFFERENT MATURITY STAGES

Creep-recovery characteristics of some selected Saudi dates cultivars, namely Barhi, Khudari, Khlass, Serri, Sukkari, Suffri, Saqie, and NubotSaif were investigated at two maturity stages that is, Khalal and Rutab. The results revealed the significant effect of date cultivar and stage of maturity on the creep-recovery behavior for the dates. At the end of creep period, the strain values ranged from 0.02-0.09 mm/mm for Saqie and Barhi cultivars, respectively at Khalal stage, and from 0.36-0.64 mm/mm for Saqie and Khlass cultivars, respectively at Rutab stage. Burgers four-element model was used to predict experimental data and it was highly satisfactory in predicting experimental data with determination coefficients ranged from 0.920- 0.994. Barhi cultivar showed great susceptibility for deformation and medium ability to recover it regardless of its high toughness.