ABSTRACT A Vibration-Based Method for assessing the integrity of welded structures is presented. The proposed technique relies on fitting theoretical predictions of a lumped mass-based model of the welding with experimental measurements obtained from modal analysis. Experiments are performed in various test platens that are soldered at one or two locations and exhibit distinct welding qualities, achieved by using different control parameters in the welding process. The inertia added during the soldering execution is modelled by a lumped mass that connects to the structural element via linear springs. The associated rigidities play the role of fitting parameters and are adjusted to reproduce the (three) measured natural frequencies by means of optimisation algorithms. This method is successful in characterising the platens tested and provides an accurate and consistent (with the expected welding quality) quantification of their effective mechanical properties at the bond. We note that this is beyond the qualitative evaluation achieved with other extended Non-Destructive Testing techniques. Such characterisation is possible even without particular knowledge of modal shapes, whose experimental determination is difficult in any real structure, although different resonant frequencies must be considered to achieve reliable estimates. Based on the present results, we suggest that this technique can be used for assessing the overall integrity of welded structures in a quantitative and a reliable manner.

中文翻译：

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一种基于振动的焊接结构完整性评估方法

摘要介绍了一种基于振动的焊接结构完整性评估方法。所提出的技术依赖于对基于集中质量的焊接模型的理论预测与从模态分析中获得的实验测量值进行拟合。在焊接在一个或两个位置并表现出不同焊接质量的各种测试压板中进行实验，通过在焊接过程中使用不同的控制参数来实现。在焊接执行期间增加的惯性由通过线性弹簧连接到结构元件的集总质量建模。相关的刚度起到拟合参数的作用，并通过优化算法进行调整以重现（三个）测量的自然频率。这种方法成功地表征了所测试的压板，并提供了其在接合处的有效机械性能的准确和一致（具有预期的焊接质量）量化。我们注意到，这超出了使用其他扩展无损测试技术实现的定性评估。即使没有对模态形状的特殊了解，这种表征也是可能的，尽管必须考虑不同的共振频率才能实现可靠的估计，但在任何实际结构中都很难对其进行实验确定。基于目前的结果，我们建议该技术可用于以定量和可靠的方式评估焊接结构的整体完整性。