This article considers the processes of the accumulation of irreversible strains in an elastoviscoplastic material of a thick-walled cylindrical tube in the framework of small strains. The material is deformed under the action of uniform inner pressure changing with time. Irreversible strains accumulate in the material by means of two different mechanisms, namely creep and plastic flow. Initially, whereas stresses increase in the deformed body due to mechanical influence, irreversible strains are produced as creep strains because of the viscous material properties. When the stress state reaches a loading surface, the production mechanism of irreversible strains becomes plastic. When unloading, this sequence in the production mechanisms is opposite, i.e. the fast plastic mechanism is replaced by the slow viscous one. The continuity in the growth of irreversible strains is provided by the corresponding setting of creep and plastic potentials. The possibility of the use of these potentials in the form of piecewise linear functions is investigated. It makes possible to use the developed mathematical formalism of the ideal plasticity theory. The creep and plastic flow processes under increasing and constant inner pressures are considered. The unloading process and repeated plastic flow under decreasing inner pressure, the stress relaxation after the full removal of a loading force are investigated. The reversible and irreversible strains, stresses and displacements in the medium are calculated. The laws of the motion of elastoplastic boundaries in the cylindrical layer are determined.

本文考虑了在小应变的框架下不可逆应变在厚壁圆柱管的弹黏塑性材料中积累的过程。材料在均匀的内部压力随时间变化的作用下变形。不可逆应变通过两种不同的机制在材料中累积，即蠕变和塑性流动。最初，由于机械影响而使变形体内的应力增加，但由于粘性材料的特性，产生了不可逆的应变作为蠕变应变。当应力状态到达加载表面时，不可逆应变的产生机理就变成可塑性。卸货时，生产机构中的这一顺序是相反的，即快速的塑料机构被缓慢的粘性机构所代替。不可逆应变增长的连续性是由蠕变和塑性势的相应设置提供的。研究了以分段线性函数形式使用这些电势的可能性。它可以使用理想可塑性理论的发达的数学形式主义。考虑了不断增加的内部压力和恒定内部压力下的蠕变和塑性流动过程。研究了卸载过程以及在降低的内部压力下反复进行塑性流动，完全消除加载力后的应力松弛情况。计算了介质中可逆和不可逆的应变，应力和位移。确定圆柱层中弹塑性边界运动的定律。