Determination of true stress-strain data behond the necking point and fracture loci of vintage steel pipes, using digital image correlation and finite element analysis

使用数字图像相关和有限元分析确定老式钢管颈缩点和断裂位点后面的真实应力应变数据

• 批准号: 490975-2015
• 负责人: Weck, Arnaud
• 金额: $ 2.62万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=618360
• 关键词: Determination; true; stress; strain; data

Manufacturing, transportation, power generation and many other industries strongly rely on a high supply of oil and gas products. Pipelines are the main means of transportation and delivery of these vital products. However, like any structural system, they are vulnerable to through life damage and degradation. Depending on many factors, pipeline industry has defined and standardized a wide variety of assessment and inspection techniques to consider the integrity of their systems. Generally, the significance of features (e.g. dents, cracks, wrinkle and buckles) and metal loss (e.g. corrosion) determine the severity of the maintenance period to assure a safe integrity for the system. In recent years, particular interest was aimed at vintage (manufactured before 1970) steel pipe materials to investigate their micro- and macro-structural behaviors to large deformations, under different loading conditions (such as uniaxial tension, compression and bending). The consideration of large deformations/displacements in a pipeline system could result in the generation of large strains in the pipe material. Normally, very large strains (beyond the uniaxial necking point) exist in regions with features such as wrinkle or local buckling. These high levels of induced strains can lead to damage accumulation in the pipe and endanger the integrity of the pipeline system. In order to obtain better pipeline deformation predictions, feeding more reliable material properties to an FE model is of great importance. The main purpose of this work is to conduct uniaxial tensile testing, using a Digital Image Correlation (DIC) technique, to obtain Lankford coefficients, stress-strain curves over a large range of strains (beyond the necking point), and the fracture strains for different stress-triaxialities (fracture locus). In order to consider the material anisotropy, tests will be conducted for a variety of vintage steel pipe materials at two different pipe orientations, axial and circumferential. The effect of sample size on the resulting mechanical behavior will also be investigated.

制造业、运输业、发电业和许多其他行业严重依赖石油和天然气产品的高供应。管道是运输和交付这些重要产品的主要手段。然而，像任何结构系统一样，它们很容易受到终身损坏和退化的影响。根据许多因素，管道行业已经定义和标准化了各种各样的评估和检查技术，以考虑其系统的完整性。通常，特征（例如凹痕、裂纹、褶皱和褶皱）和金属损失（例如腐蚀）的重要性决定了维护周期的严重性，以确保系统的安全完整性。近年来，人们对老式（1970年以前制造）钢管材料特别感兴趣，以研究它们在不同载荷条件（如单轴拉伸、压缩和弯曲）下大变形的微观和宏观结构行为。考虑管道系统中的大变形/位移可能导致管道材料中产生大应变。通常情况下，非常大的应变（超过单轴颈缩点）存在于具有褶皱或局部屈曲等特征的区域。这些高水平的诱导应变会导致管道中的损伤累积，并危及管道系统的完整性。为了获得更好的管道变形预测，提供更可靠的材料属性的有限元模型是非常重要的。这项工作的主要目的是进行单轴拉伸试验，使用数字图像相关（DIC）技术，以获得Lankford系数，应力-应变曲线在很大范围内的应变（超过颈缩点），和断裂应变为不同的应力三轴（断裂轨迹）。为了考虑材料的各向异性，将在轴向和周向两个不同的管道方向上对各种老式钢管材料进行测试。还将研究样品尺寸对所得力学行为的影响。