Yang Ting, Venkatesh T A, Dao Ming
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
Nanomaterials (Basel). 2023 May 9;13(10):1584. doi: 10.3390/nano13101584.
In applications involving fretting wear damage, surfaces with high yield strength and wear resistance are required. In this study, the mechanical responses of materials with graded nanostructured surfaces during fretting sliding are investigated and compared to homogeneous materials through a systematic computational study. A three-dimensional finite element model is developed to characterize the fretting sliding characteristics and shakedown behavior with varying degrees of contact friction and gradient layer thicknesses. Results obtained using a representative model material (i.e., 304 stainless steel) demonstrate that metallic materials with a graded nanostructured surface could exhibit a more than 80% reduction in plastically deformed surface areas and volumes, resulting in superior fretting damage resistance in comparison to homogeneous coarse-grained metals. In particular, a graded nanostructured material can exhibit elastic or plastic shakedown, depending on the contact friction coefficient. Optimal fretting resistance can be achieved for the graded nanostructured material by decreasing the friction coefficient (e.g., from 0.6 to 0.4 in 304 stainless steel), resulting in an elastic shakedown behavior, where the plastically deformed volume and area exhibit zero increment in the accumulated plastic strain during further sliding. These findings in the graded nanostructured materials using 304 stainless steel as a model system can be further tailored for engineering optimal fretting damage resistance.
在涉及微动磨损损伤的应用中，需要具有高屈服强度和耐磨性的表面。在本研究中，通过系统的计算研究，对具有梯度纳米结构表面的材料在微动滑动过程中的力学响应进行了研究，并与均质材料进行了比较。建立了一个三维有限元模型，以表征不同接触摩擦程度和梯度层厚度下的微动滑动特性和安定行为。使用代表性模型材料（即304不锈钢）获得的结果表明，具有梯度纳米结构表面的金属材料在塑性变形表面积和体积方面可减少80%以上，与均质粗晶金属相比，具有卓越的微动损伤抗性。特别是，梯度纳米结构材料可根据接触摩擦系数表现出弹性或塑性安定。通过降低摩擦系数（例如，304不锈钢中的摩擦系数从0.6降至0.4），梯度纳米结构材料可实现最佳的微动抗性，从而产生弹性安定行为，即进一步滑动时，塑性变形体积和面积在累积塑性应变中的增量为零。以304不锈钢为模型系统的梯度纳米结构材料的这些发现可进一步定制，以实现工程上的最佳微动损伤抗性。
