The materials be yielded due to its particles separated to a critical value K0 which is effected by the factors of three-dimensional stress, loading history, external environment etc.

• 本文从材料构成的基本物理概念出发,简要说明了材料的屈服是受三向应力、荷载历史、外界环境等的作用,材料内部紧密相连的质点间的距离增大到某临界值K_0所致。