Improvement of Omega Method for Creep Life Prediction
Improvement of Omega Method for Creep Life Prediction
复制标题
蠕变寿命预测Omega方法的改进
DOI：
10.2355/isijinternational.37.419
复制
发表时间：
1997
影响因子：
1.8
通讯作者：
H. Umaki
中科院分区：
文献类型：
--
作者：
K. Maruyama;I. Nonaka;K. Sawada;Hiroyuki Sato;J. Koike;H. Umaki
提出了由蠕变应变e-时间t数据预测持久寿命的Omega方法。该方法基于蠕变速率e的对数与应变之间的线性关系，即没有第一和第二蠕变阶段的蠕变曲线。然而，这种线性关系在真实的蠕变数据中很少成立。本文将原方程修改为如下形式：e= e0 + 1/Ω{In（1 + η t）-In（1-ηt）}其中e0、Ω、η和η是表征蠕变曲线的参数。括号中的第一项和第二项分别表示第一次蠕变和第三次蠕变。该方程适用于铁素体钢。对于Ine-e关系为曲线的蠕变曲线，方程的四个参数可以唯一确定。该方程能很好地再现蠕变曲线，并具有显著的主蠕变阶段。由于具有较高的重现性，修正后的蠕变断裂寿命预测公式在蠕变早期阶段的预测精度比原公式高。
Omega method has been proposed for predicting rupture life from creep strain e-time t data. The method is based on a linear relation between logarithm of creep rate e and strain, namely a creep curve without the primary and secondary creep stages. Such a linear relation, however, seldom holds in real creep data. In this paper, the original equation is modified to the following form: e=e 0 +1/Ω{In(l+ζt)-In(1-ηt)} where e 0 , Ω, ζ and η are parameters characterizing a creep curve. The first and second terms in the parentheses describe primary creep and tertiary creep, respectively. The equation is applied to ferritic steels. The four parameters of the equation can uniquely be determined for a creep curve with a curved In e-e relation. The equation can well reproduce creep curves with a prominent primary creep stage. Because of the high reproducibility, the modified equation can predict rupture life with higher accuracy at an earlier stage of creep than the original equation.