Recent advances in mechanical and civil engineering are noticed in many innovative designs that frequently employ cold-formed High Strength Steels (HSS). Typical mobile cranes benefit from the advanced properties of these steel grades in a bent configuration. Here, the majority of load-carrying members are produced through cold-bending and subsequent welding procedures. These cold-foring processes induce residual stresses and strains that must be considered when assessing the structural integrity and service life of bent sections in an assembly. Finite Element Analysis (FEA) offers a unique solution here to reproduce the bending process accurately. However, this analysis must be verified using representative validation methods. If these methods remain scarce, basic or incomplete, the credibility of a sensitive FE model may be compromised. In the present paper, a series of model validations are proposed that rely on the global and local response of the material during or after bending. A benchmark specimen and an air bending set-up have been developed from a numerical design of concepts and fine-tuning of tool dimensions, ensuring the appropriate bending conditions. Local validation is pursued using stereo Digital Image Correlation (DIC) to capture the strain fields, generated during plastic bending of a 12 mm thick S690QL plate. The crux of the problem is twofold: firstly, strain calculation methods used in DIC and FEA are fundamentally different, hampering a correct and honest comparison. Secondly, consistent point-to-point comparisons of experimentally acquired (DIC) and numerically computed (FEA) strains are more susceptible to uncertainties related to processing settings and differences in coordinate frame. Moreover, the main advantage of the introduced ground truth validation is the ability to level the FEA data through identical filters as the DIC experiment. Unlike a direct comparison, this levelling approach auto-adopts an unconditionally equal strain calculation, based on nodal displacement fields, independently of a local (shell) or global (solid) element formulation. This paper aims at clarifying the need for this ground thruth validation in pursuance of higher fidelity FE-models for metal forming simulations.

机械和土木工程领域的最新进展在许多采用冷弯高强度钢（HSS）的创新设计中得到了体现。典型的移动式起重机得益于这些钢种在弯曲状态下的先进性能。在这里，大多数的承载构件是通过冷弯和随后的焊接程序生产的。这些冷锻过程会产生残余应力和应变，在评估组件中弯曲部分的结构完整性和使用寿命时必须考虑这些残余应力和应变。此处的有限元分析（FEA）提供了一种独特的解决方案，可以准确地重现弯曲过程。但是，必须使用代表性的验证方法来验证此分析。如果这些方法仍然缺乏，基本或不完整，则可能会损害敏感的有限元模型的可信度。在本文中，提出了一系列模型验证，这些验证依赖于材料在弯曲过程中或弯曲之后的整体和局部响应。通过概念的数值设计和工具尺寸的微调，开发了基准试样和空气弯曲装置，以确保适当的弯曲条件。使用立体声数字图像关联（DIC）来捕获12毫米厚S690QL板塑性弯曲期间产生的应变场，以进行局部验证。问题的症结是双重的：首先，DIC和FEA中使用的应变计算方法根本不同，从而妨碍了正确和诚实的比较。其次，实验获得的（DIC）应变和数值计算（FEA）应变的一致点对点比较更容易受到与处理设置和坐标系差异有关的不确定性的影响。此外，引入的地面真实性验证的主要优点是能够通过与DIC实验相同的滤波器对FEA数据进行均衡。与直接比较不同的是，这种找平方法基于节点位移场自动采用无条件相等的应变计算，而与局部（壳）或整体（固体）单元的配方无关。本文旨在阐明对用于金属成型模拟的更高保真度有限元模型进行地面验证的必要性。引入的地面真实性验证的主要优点是能够通过与DIC实验相同的滤波器对FEA数据进行均衡。与直接比较不同的是，这种找平方法基于节点位移场自动采用无条件相等的应变计算，而与局部（壳）或整体（固体）单元的配方无关。本文旨在阐明对用于金属成型模拟的更高保真度有限元模型进行地面验证的必要性。引入的地面真实性验证的主要优点是能够通过与DIC实验相同的滤波器对FEA数据进行均衡。与直接比较不同的是，这种找平方法基于节点位移场自动采用无条件相等的应变计算，而与局部（壳）或整体（固体）单元的配方无关。本文旨在阐明对用于金属成型模拟的更高保真度有限元模型进行地面验证的必要性。