The restraint modulus kr is introduced to represent the exterior restraint . kr and the restraints coefficient cr have the same physical essence and can convert into one another ; but the former is more convenient for establishing the equations of the force equilibrium and the compatibility of deformation 新模型采用约束模量k _ r表示外约束，它与约束程度系数c _ r在本质上统一，可互相转化，但在形式上利于建立力平衡和变形协调方程，方便问题的分析。
