Experimental validation and microstructure characterization of topology optimized, additively manufactured SS316L components
Experimental validation and microstructure characterization of topology optimized, additively manufactured SS316L components
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DOI：
10.1016/j.msea.2020.139050
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发表时间：
2020-03-03
期刊：
影响因子：
6.4
通讯作者：
Suresh, K.
中科院分区：
文献类型：
--
作者：
Rankouhi, B.;Bertsch, K. M.;Suresh, K.
拓扑优化（TO）和增材制造（AM）的集成有可能彻底改变现代设计和制造。然而，制造优化设计的实例很少有记录，甚至更少的实验测试设计的例子。缺乏验证与AM工艺对材料性能的影响相结合，在我们对工艺微观结构-性能关系的理解中留下了空白，这对于开发整体设计优化框架至关重要。在这项工作中，一个功能设计拓扑优化和制造使用定向能量沉积（DED）和选择性激光熔化（SLM）的方法。这是第一次在TO的上下文中直接比较这些AM方法。SS 316L和优化的组件在制造和热处理条件下的单轴位移控制拉伸载荷下的力学性能进行了研究，并与有限元建模（FEM）预测。优化的样品在测试样本中提供了压缩和拉伸载荷的区域。实验结果表明，有限元预测是保守的。微观结构分析表明，这种差异是由于在增材制造过程中形成的精细微观结构，这些微观结构在高应力水平区域强化了材料。此外，SLM样品表现出更高的屈服强度相比，DED样品由于更细化的晶粒尺寸和更密集的位错结构。TO结果对AM方法、后处理条件和机械性能差异敏感。因此，AM框架的TO可以通过并入微结构特征来最佳地优化，以考虑制造部件中的局部微结构变化。
The integration of topology optimization (TO) and additive manufacturing (AM) has the potential to revolutionize modern design and manufacturing. However, few instances of manufactured optimized designs are documented, and even fewer examples of experimentally-tested designs are available. The lack of validation combined with the influence of AM process on material properties leaves a gap in our understanding of processmicrostructure-property relationships that is essential for developing holistic design optimization frameworks. In this work, a functional design was topologically optimized and fabricated using both directed energy deposition (DED) and selective laser melting (SLM) methods. This is the first direct comparison of these AM methods in the context of TO. Mechanical properties of SS316L and the optimized components in as-fabricated and heat-treated conditions were investigated under uniaxial displacement-controlled tensile loading and compared to finite element modeling (FEM) predictions. Optimized samples provided regions of both compressive and tensile loading in the test specimen. Experimental results showed the FEM predictions to be conservative. Microstructural analysis revealed that this difference is due to refined microstructures formed during the additive manufacturing process that strengthen the material in regions with high stress levels. Moreover, SLM samples showed higher yield strength compared to DED samples due to a more refined grain size and denser dislocation structures. TO results are sensitive to the AM method, post-processing conditions, and differences in mechanical properties. Thus, a TO for AM framework can be best optimized with the incorporation of microstructure features to account for localized microstructural variations in fabricated components.