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本文根据弹塑性小变形理论推出压力容器内壁发生塑性变形时电测应力计算公式。得到压力容器内壁周向应力σ_t及经向应力σ_z为: 式中σ_i为应力强度,ε_i为应变强度,σ_i——ε_i曲线可用单向拉伸试验的σ——ε曲线来描述。测出内壁周向应变ε_t及经向应变ε_z可按上式用试差法求出σ_t夏σ_z。对于开式圆筒,因σ_z=0,推得: σ_t=(2σ_i/3ε_i)(ε_t-ε_z) (22)或σ_t=(σ_i/ε_i)ε_t-(P/2) (26)上二式中σ_i=(σ_t~2+σ_tP+P~2)(1/2) (23)按式(22)或式(26)用试差法可求得开式圆筒内壁周向应力σ_t。
In this paper, according to the elasto-plastic deformation theory, the formulae for calculating the electrical stress during the plastic deformation of the inner wall of the pressure vessel are introduced. The circumferential stress σ_t and radial stress σ_z of the inner wall of the pressure vessel are: where σ_i is the stress intensity, ε_i is the strain strength, and the σ_i—ε_i curve can be described by the σ-ε curve of the uniaxial tensile test. Measured circumferential strain ε_t and longitudinal strain ε_z of the inner wall can be calculated by trial and error method using the above formula σ_t summer σ_z. For an open cylinder, because σ_z = 0, it is derived: σ_t = (2σ_i/3ε_i) (ε_t - ε_z) (22) or σ_t = (σ_i/ε_i)ε_t - (P/2) (26) Medium σ_i=(σ_t~2+σ_tP+P~2)(1/2) (23) According to equation (22) or (26), the circumferential stress σ_t of the inner wall of the open cylinder can be obtained by trial and error.