Localized Finishing of Freeform Geometries using Dynamic Magnetic Field-Manipulated Magneto-Viscoelastic Fluids

使用动态磁场操纵磁粘弹性流体对自由形状几何形状进行局部精加工

• 批准号: 1538501
• 负责人: Satish Bukkapatnam
• 金额: $ 12万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1538501&HistoricalAwards=false
• 关键词: Localized; Finishing; Freeform; Geometries; using

Demand for biomedical prosthetic implants (e.g., total hip joints) is growing by 5 percent annually and this market is expected to exceed $35B by 2019. Local finishing of targeted regions of the surfaces of various joints is essential for their life assurance. The industry largely depends on laborious and expensive manual or chemical etching methods for localized finishing. This award supports fundamental research that can lead to new machine tools that use magnetic energy and abrasive-mixed magnetic "blob" (semisolid globule in a nonmagnetic fluid) for localized finishing of surfaces. These machine tools can be vital for affordable manufacturing of custom, functional free-form parts (e.g., durable, single piece prosthetic components). The focus of this research is on the effects of the composition of the magnetic fluid as well as the spatio-temporal variation of the external magnetic fields on the selectivity and material removal rates over 1-10 sq. cm area on freeform parts made of diamagnetic or weak paramagnetic materials. The first research objective is to establish quantitative relationships connecting the rheological properties of magnetic fluid blobs with their colloidal compositions and the spatio-temporal variation of external magnetic fields: This knowledge is essential to select magnetic field patterns that can create gradients conducive for optimal flow and selectivity of magnetic fluids, and make a blob exert appropriate down pressures. To achieve this objective, an experimental study will be conducted employing a specialized rheometer instrumented with array of magnets, Gauss meters, as well as force and vibration sensors. The rheometer provides a controlled means to estimate both the magneto-viscoelastic properties of the abrasive granular fluid (based on rubber elasticity theory) as well as the material removal rates for different fluid compositions and workpiece surfaces, and measure the induced magnetic field, forces, and the down pressure. The second objective is to establish a relationship between the localized magnetic field gradients induced over a magnetic blob and the applied spatio-temporal magnetic field: The resulting knowledge will provide guidance to realize sharp magnetic gradients at specified locations, and design magnetic enclosures capable of creating these patterns. To achieve this objective, a novel implicit viscoelastic modeling approach will be employed. This approach uses the property relationships gathered from the first objective to provide a computationally efficient means to capture the blob behaviors, including smooth transition from a magneto-elastic solid like response to that of a magneto-viscoelastic fluid.

对生物医学假体植入物（例如全髋关节）的需求每年增长 5%，预计到 2019 年该市场将超过 $35B。各种关节表面目标区域的局部精加工对于保证其生命至关重要。该行业在很大程度上依赖于费力且昂贵的手动或化学蚀刻方法来进行局部精加工。该奖项支持基础研究，这些研究可以开发出使用磁能和磨料混合磁性“斑点”（非磁性流体中的半固态小球）对表面进行局部精加工的新型机床。这些机床对于经济实惠地制造定制、功能性自由形状零件（例如耐用的单件假肢部件）至关重要。本研究的重点是磁性流体的成分以及外部磁场的时空变化对抗磁性自由曲面零件在 1-10 平方厘米区域内的选择性和材料去除率的影响或弱顺磁材料。 第一个研究目标是建立将磁性流体团的流变特性与其胶体成分以及外部磁场的时空变化联系起来的定量关系：这一知识对于选择磁场模式至关重要，该磁场模式可以创建有利于最佳流动的梯度和磁性流体的选择性，并使斑点施加适当的向下压力。为了实现这一目标，将使用配备磁铁阵列、高斯计以及力和振动传感器的专用流变仪进行实验研究。流变仪提供了一种受控手段来估计磨料颗粒流体的磁粘弹性特性（基于橡胶弹性理论）以及不同流体成分和工件表面的材料去除率，并测量感应磁场、力、和下行压力。第二个目标是建立磁团上感应的局部磁场梯度与所施加的时空磁场之间的关系：由此产生的知识将为在指定位置实现尖锐的磁梯度提供指导，并设计能够创建的磁外壳这些图案。为了实现这一目标，将采用一种新颖的隐式粘弹性建模方法。该方法使用从第一个目标收集的属性关系来提供一种计算有效的方法来捕获斑点行为，包括从磁弹性固体响应到磁粘弹性流体响应的平滑过渡。