New Technologies for Materials Processing - Industrial and ...

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Faculty News Moment (N-cm), Force (N) Temperature (C) 150 100 50 0 80 70 60 50 40 30 Energy dissipation 16.5 16.55 16.6 Time (s) Temperature models Chip formation Tissue damage 20 0 5 10 Sample x 10 4 Energy dissipation measurements, temperature modeling and experimental observations of processing and damage in thermal and mechanical loading of equine bone to repair orthopedic trauma. helps improve the lubrication and subsequent heat dissipation of tooling, which in turn increases the overall precision. Dr. Saldana’s group is currently using custom experimental platforms to address fundamental questions related to these effects in micro-scale machining configurations. Techniques based on such research already are being used in industrial practice, for example, to enable dramatically faster processing rates in the manufacture of medical components such as bone screws and femoral pins made from difficult-to-work, biocompatible material systems (e.g., titanium and steel alloys). Employing these same micro-scale perturbations, Dr. Saldana’s group is also accessing new domains for cutting-based processing. Two examples in this regard are the generation of alloy particulate that can be used in composite materials and also large-scale mechanical surface texturing. Surfaces with controlled micro-scale geometries are of primary interest to the automotive, energy and medical sectors due to the better operational performance they achieve. Although micro-fabrication routes are attractive options for their production, potential for large-scale surface texturing of structural components is 10
Faculty News Dr. Saldana’s work will help to obtain a better understanding of the interplay between the mechanics of surface texturing and surface integrity. Dr. Christopher Saldana works with students Cesar Moreno and Miguel Iturralde on the deformation processing research team. non-trivial in practice. However, industry interest in textured surfaces by mechanical processing has grown significantly. Dr. Saldana’s group has developed experimental texturing platforms and is currently mapping the capabilities and limitations of these systems, as well as answering fundamental questions regarding the performance of various textured surfaces. Dr. Saldana’s work will help to obtain a better understanding of the interplay between the mechanics of surface texturing and surface integrity. The process used to modify the shape of components and materials in typical manufacturing operations can also modify their atomic-level structure through deformation. The deformation conditions intrinsic to manufacturing processes can also have a positive effect when they are harnessed to impart materials with a nano-scale microstructure (measured in units of one-billionth of a meter). This is of interest to materials designers as it yields a multiple-fold increase in strength, among other unique properties. In this regard, Dr. Saldana has established high-rate processing protocols using very low temperatures that facilitate the generation of nano-scale microstructures otherwise unattainable with more established configurations. These techniques enabled the discovery of a case example of thermodynamically efficient strengthening, an elusive concept for this class of materials and an open problem for the advanced materials community. Dr. Saldana’s group is currently applying these model approaches to a broader set of engineering materials to determine the interplay of microstructure, strength, stored energy and thermal stability in fine-grained material systems. The overall goal is development of optimal nano-scale microstructure designs and processing routes for materials critical to next generation manufacturing, particularly high strength-to-weight (e.g. magnesium alloys) and bio-compatible material systems (e.g. titanium, steels). Two other areas wherein deformation processing plays an important role is in the processing of biological systems and granular materials. Common to many orthopedic surgical operations are machining processes such as cutting, drilling and sawing of bone and tissue. These biological materials are substantially more sensitive to the severity of the material removal process than conventional work systems. High temperatures during surgical processing can weaken the surrounding bone and tissue. Dr. Saldana is studying the severity of contact conditions during the manufacture of biological materials, such as in the cutting of bone, so as to inform, for example, the development of less damaging surgical procedures. With regard to granular media, Dr. Saldana has an active collaboration with the Indian Institute of Science to study deformations in granular materials, a core topic for the construction and pharmaceutical communities. Employing high-speed imaging and fluid dynamics algorithms, the team is working to elucidate the underlying mechanics of deformation and material flow, complementing the broader community’s efforts related to modeling, tool design and design of efficient granular processing methods. Dr. Saldana’s research areas present unique opportunities for fundamental improvements in manufacturing, while maintaining realistic connections to contemporary problems with broad scientific interest. Various modeling and experimentation capabilities housed within the department are central to this research, as are characterization facilities available through the Materials Research Institute at Penn State and with outside collaborators. 11
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