ASME VIII 2-2025 5.2.1.3 分析方法的限制
下面是AS ME VIII2-2025中的一段原话，我们翻译一下，然后重点说一下需要注意的地方。
5.2.1.3 Limitations on A nalysis Methods.
5.2.1.3.1 Limitations on Elastic An alysis With Heavy-Walled Components. The use of elastic stress an alysis combined with stress classification procedures to demonstrate structural integrity for heavy-wall ( ≤4)pressure containing components, especially around structural discontinuities, may produce nonconservative results and is not recommended. Thereason forthenon-conservatis m is that the nonlinear stress distributions associated with heavy wall sections are not accurately represented by the implicit linear stress distribution utilized in the stress categorization and classification procedure. The misrepresentation of the stress distribution is enhanced if yielding occurs. For example, in cases where calculated peak stresses are above yield over a through thickness dimension that is more than 5% of the wall thickness, linear elastic a nalysis may give a nonconservative result. In these cases, the elastic–plastic stress an alysis procedures in 5.2.3 or 5.2.4 shall be used. 5.2.1.3.2 Limitations on Primary Stress Limits and Limit Load An alysis. The following limitations apply equally to the elastic stress a nalysis method of 5.2.2 and the to the limit-load an alysis method of 5.2.3: (a) The effect of strain-controlled loads resulting from prescribed non-zero displacements and temperature fields is not considered. The magnitude of deformations and strains is not physical due to the assumptions made in these an al ysis methods. For physically meaningful deformations and strains, the elastic–plastic stress an alysis method of 5.2.4 shall be used [see 5.2.4.3(b)]. (b) Components that experience reduction in stiffness with deformation, e.g., a pipe elbow under in-plane bending, shall be evaluated using the elastic–plastic stress a nalysis method of 5.2.4 and protection against collapse from buckling in 5.4.
5.2.1.3 分析方法的适用限制
5.2.1.3.1 厚壁构件弹性分析的限制
对于R/t径比≤4 的厚壁承压构件，尤其在结构不连续区域，采用弹性应力分析 + 应力分类法验证结构完整性，可能得出 ** 偏危险（非保守）** 结果，不推荐使用。产生非保守结果的原因：厚壁截面真实的非线性应力分布，无法被应力分类法默认的线性应力分布准确表征；若材料发生屈服，该偏差会进一步加剧。例如：计算峰值应力超过屈服强度，且贯穿壁厚区域厚度大于总壁厚 5% 时，线弹性分析结果偏危险，必须采用 5.2.3 或 5.2.4 的弹塑性应力分析流程。
5.2.1.3.2 一次应力限值与极限载荷分析的通用限制
以下限制同时适用于 5.2.2 弹性应力分析法和 5.2.3 极限载荷法：
(a) 未考虑由强制位移、温度场引起的应变控制载荷；受分析理论假定影响，求解的变形与应变不符合工程实际。如需获得真实有效的变形和应变结果，应采用 5.2.4 弹塑性应力分析法（见 5.2.4.3 (b)）。
(b) 随变形发生刚度衰减的构件（如平面弯曲工况下的弯管），应采用 5.2.4 弹塑性应力分析法，并同时按 5.4 要求开展屈曲垮塌防护校核。
