作　　者： ; ;

机构地区： 内蒙古农业大学食品科学与工程学院

出　　处： 《农业工程学报》 2008年第3期31-37,共7页

摘　　要： 为解决河套蜜瓜在储运过程中因静载产生的机械损伤问题,通过对不同条件下完整形态的河套蜜瓜静载破坏时损伤体积的测定和分析,研究了河套蜜瓜机械特性以及各试验因素、机械特性参数对破坏损伤体积的影响。试验结果表明,屈服极限和变形能在随载荷速率增大而增加的过程中有极值现象存在,而破坏极限与破坏能则随载荷速率增大而持续增加;随果实硬度降低,屈服极限、变形能、破坏极限、破坏能等指标均明显降低;试验获得了完整近球形蜜瓜果实的应力-应变曲线,应力-应变曲线反映出完整形蜜瓜在受压初期载荷增长滞后于受压面积的增长。试验结果同时表明,河套蜜瓜准静载机械特性参数、影响因素如载荷速率、果实硬度、加载部位等对果实受压产生的机械损伤均有明显影响,缓慢加载使果实内部微观组织较早出现破坏,易扩大损伤体积,受压后果实的损伤体积较大;垂直受压使果实破坏后产生的损伤体积大于果实水平受压时的损伤体积。建立了完整形河套蜜瓜准静载机械特性参数、影响因素与蜜瓜果实损伤体积的回归方程。数据分析表明,所建立的回归方程是有意义的,可以用其预测和控制河套密瓜储运过程中的静载损伤。机械特性参数之间均存在一定相关性,其中生物屈服极限与变形能的相关程度最高(r=0.870),生物屈服极限与破坏极限的相关程度最小(r=0.366)。 The mechanical properties of Hetao muskmelons and the effective factors, such as loading rate, fruit＇s stiffness and compressing position, were experimentally studied in order to solve the problem of damage due to quasi-static loading during storage and transportation. The results show that with the increasing loading rate, the yield force Fy and deforming energy Uy increase and reach maximum values, but both the break force Fb and break energy Ub continue to increase. The values of Fy and Uy, Fb, Ub obviously decrease with the decrease of fruit＇s stiffness. Stress-strain curves of about spherical body of intact Hetao muskmelon fruit under quasi-static loading were originally developed. These curves indicate that the stress increase lags behind the increase of the contact area of the sample at early compressing stage. The results also reveal that the damage volume is significantly affected by both the mechanical property parameters and the effective factors. The micro tissues of the fruits under compression at a smaller loading rate are more easily destroyed, which lead to damage diffusion. The fruits compressed in the vertical stem direction are more easily to get to state of yield than that of compression in the horizontal stem direction, resulting in much serious damage degree. Both the linear regression equations of the relationships between the mechanical property parameters and damage volumes, and the linear regression equations of the relationships between the effective factors and damage volumes are innovatively developed. Statistic analysis indicate that the above equations are all meaningful and suitable for predicting and controlling the damage due to quasi-static loading during storage and transportation. Moreover, correlation exits between the mechanical property parameters. Statistic analysis indicate that Fy presents a significant positive correlation with Uy, with a highest coefficient r of 0.870, and Fb presents a least correlation with and Fy, with a coefficient r of 0.366.

关 键 词： 河套蜜瓜 静载 机械特性 损伤体积

领　　域： [农业科学]