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湿膨胀系数用于预报谷物堆密度和研究谷粒应力裂纹产生原因等研究。文献中，计算此系数的参照体积和参照长度都取含水量为零状态下的值。这对计算谷粒湿应力会有误差，应当取初始状态下的值。理论上３个互垂方向的线膨胀系数之和应等于体膨胀系数，而且与方向无关，前者和已发表的实验结果基本一致，后者则不很一致。该文基于二相材料的假定，提出了理论湿膨胀系数，它对实验测定工作有指导意义。该文指出水分迁移会给谷粒造成损伤，应用损伤力学理论研究这个问题将是很有意义的。
The coefficient of wet expansion is used to predict the bulk density of grains and to study the causes of grain stress cracks. In the literature, both the reference volume and the reference length used to calculate this coefficient are taken as zero water content. This error in calculating the grain wet stress, it should take the value of the initial state. In theory, the sum of the linear expansion coefficients of three mutually perpendicular directions should be equal to the body expansion coefficient, and has no relation with the direction. The former is basically consistent with published experimental results, while the latter is not very consistent. Based on the assumption of two-phase material, this paper proposes the theoretical wet expansion coefficient, which is of guiding significance for the experimental determination. This paper points out that the migration of water will cause grain damage, and it is very meaningful to study the problem of damage mechanics theory.