ASME VIII 2-2025 5.5.1.6棘轮
5.5.1.6 Ratcheting.
Undercertaincombinations ofsteady state andcyclic loadings there is apossibility of ratcheting (see 5.5.5). A rigorous evaluation of ratcheting normally requires an elastic–plastic an alysis of the component; however, under alimited numberof loading conditions, an approximate an alysis is utilized based on the results of an elastic stress an alysis (see 5.5.5.2). Protection against ratcheting shall be performed and shall include all operating loads listed in the User’s Design Specification and shall be performed even if the fatigue screening criteria are satisfied (see 5.5.2.1). Pro tection against ratcheting is satisfied if one of the following three conditions is met: (a) The loading results in only primary stresses without any cyclic secondary stresses. (b) Protection against ratcheting is demonstrated by satisfying the elastic stress an alysis rules of 5.5.5.2. (1) Method A —Elastic Stress An alysis. In Method A, the membrane-plus bending stress range from an elastic stress an alysis is compared to an allowable value. See 5.5.5.2.1. (2) Method B — Elastic Stress A nalysis With Bree Diagram. In Method B, elastic stress an alysis results are used in conjunction with the Bree Diagram. See 5.5.5.2.2. (c) Protection against ratcheting is demonstrated by satisfying the elastic–plastic stress an alysis rules of 5.5.5.3.
5.5.1.6 棘轮效应
在稳态载荷与循环载荷的特定组合下，构件可能出现棘轮效应（见 5.5.5）。
对棘轮效应的精确评定通常需要对构件进行弹塑性分析；但在少数载荷工况下，可基于弹性应力分析结果采用近似评定方法（见 5.5.5.2）。
必须进行防止棘轮效应校核，且应包含用户设计规格书中列出的所有运行载荷；即使已满足疲劳筛选准则（见 5.5.2.1），仍需进行棘轮评定。
满足以下任一条件，即认为构件具备防止棘轮失效的能力：
(a) 载荷仅产生一次应力，且无任何循环二次应力。
(b) 通过满足 5.5.5.2 的弹性应力分析规则，验证防止棘轮效应：
(1) 方法 A — 弹性应力分析将弹性分析得到的薄膜加弯曲应力范围与许用值比较，见 5.5.5.2.1。
(2) 方法 B — 基于 Bree 图的弹性应力分析将弹性应力分析结果结合 Bree 图进行评定，见 5.5.5.2.2。
(c) 通过满足 5.5.5.3 的弹塑性应力分析规则，验证防止棘轮效应。
5.5.1.7 Joint Alignment and Weld Peaking.
If a fatigue screening or fatigue an alysis is required, the effects of joint alignment (see 6.1.6.1) and weld peaking (see 6.1.6.3) in shells and heads shall be considered in the determination of the applicable stresses
总结：每个人对标准的解读都不一样，理解也不一样，书读百遍，其义自见。在失效评定中，二次应力的作用和地位越来重要了，需要重点关注。
