The aim of this research was the development and application of the following structural strain approaches for predicting the low-cycle fatigue life of AA 5083 welded joints: Finite Element equivalent structural strain approach and Digital Image Correlation equivalent structural strain approach. The first one was already applied for the low-cycle fatigue life prediction of welded joints, while the second approach is here proposed for the first time.

Low-cycle fatigue tests were conducted at displacement ratios equal to minus one and zero.

The Digital Image Correlation technique was used to analyze the local behaviour in proximity of the welded fillet and to obtain a notch equivalent strain range–number of cycles curve.

Furthermore, a complete indipendent experimental procedure to evaluate the equivalent structural strain range, using the Digital Image Correlation technique, was proposed.

A Finite Element analysis, with the advantage of being mesh insensitive and requiring only the elastic parameters, was performed in order to apply the Finite Element equivalent structural strain approach.

The two structural strain approaches were used to predict the fatigue life, obtainining good agreement with the ASME mean curve representing over 1000 experimental data.

本研究的目的是开发和应用以下结构应变方法来预测 AA 5083 焊接接头的低周疲劳寿命：有限元等效结构应变方法和数字图像相关等效结构应变方法。第一种方法已经应用于焊接接头的低周疲劳寿命预测，而第二种方法在这里是首次提出。

低周疲劳试验是在位移比等于负一和零的情况下进行的。

数字图像相关技术用于分析焊接角附近的局部行为并获得缺口等效应变范围 - 循环次数曲线。

此外，还提出了使用数字图像相关技术评估等效结构应变范围的完整独立实验程序。

为了应用有限元等效结构应变方法，进行了有限元分析，其优点是网格不敏感且只需要弹性参数。

两种结构应变方法用于预测疲劳寿命，与代表 1000 多个实验数据的 ASME 平均曲线非常吻合。