This CAREER project will utilize a combined fundamental and applied research approach to create effective hyperplastic (high strain rate) and superplastic (elevated temperature with small grain size) microforming processes. At the macroscale, these processes are too slow and energy intensive to be practical for high production rate applications, but at the microscale due to the reduced energy and force requirements, these processes will provide for a low cost, compact processing technique. However, basic research on size effects, which prevent optimized macroforming processes to be simply miniaturized to components on the microscale, must be conducted with respect to material and processing parameters. This knowledge will then be applied to devise effective microforming processes that will produce more accurate parts faster, for less cost, and with higher aspect ratios. The anticipated specific scientific and technological outcomes are: (a) scientific understanding of the size effects on material behavior and process parameters, (b) development of models and methods to aid microcomponent designers, and (c) creation of effective microforming systems based on the microfactory concept.
Several broader impacts will be created through this research. First, the knowledge gained through this research at the microscale will lead to the advancement of microscale systems for energy generation, environmental monitoring, and biomedical applications and thus will benefit society as a whole. Also, the undergraduate and graduate students will benefit from the integration of research results into course material, international experiences, and involvement in this industrial relevant, multidisciplinary research. Finally, the nature of the hyperplastic and superplastic forming lends itself to high school outreach activities, which the PI is actively involved, through physics principles such as impact mechanics and chemistry principles such as grain size and structure.
The goals of this CAREER project were to investigate electrically-assisted forming (EAF) and electromagnetic forming (EMF) processes to produce microscale components. At the macroscale, these processes have been shown to alleviate some of the size effects (e.g., increased springback and data scatter) that cause difficulties when miniaturizing forming components and processes. A better fundamental understanding of EAF was obtained by varying the grain and specimen size (Siopis and Kinsey, 2010); alloying elements (Dzialo et al., 2010); and level of deformation (Siopis et al., 2011) of samples. In addition, the variations in strain gradients due to miniaturization through the diameter of extruded specimens (Parasiz and Kinsey, 2010) and through the thickness of 3-point bent samples were determined (Wang et al., 2012). Such variations in strain gradients in bent samples, which lead to sporadic springback angles, were alleviated using EAF (Jordan and Kinsey, 2013). For EMF, miniaturized samples were formed (VanBenthysen et al., 2008) but the importance of specimen planar area was identified and systematically investigated (VanBenthysen et al., 2013). The PI was also involved in a review paper based on his expertise in EMF (Psyk et al., 2011). Finally, a possible connection between the EAF and EMF processes (i.e., that the eddy currents induced in workpieces during EMF being analogous to the electrical current that is applied during EAF) was investigated (Kinsey et al., 2013) and found not to exist. This research resulted in eight journal publications (and another two currently under review) and ten peer-reviewed conference papers. One Ph.D. student, five Master’s degree students, 11 undergraduate students, and one post-doctoral fellow have worked on this research grant. An essential research tool (i.e., a Digital Imaging Correlation system) to generate full field strain data from experiments for many of these research efforts was obtained from a separate NSF Major Research Instrumentation grant (#0821517). Several broader impacts were created through this research. First, the knowledge gained has set the stage for advancement in microforming components, which have applications in the energy generation (e.g., bipolar plates), environmental monitoring (e.g., channel structures), and biomedical (e.g., textured surface) applications. Such innovations will benefit society as a whole. Also, the undergraduate and graduate students have benefited from the integration of research results into course materials, collaborations with national laboratories, and involvement in this industrially relevant, multidisciplinary research. Finally, several Research Experience for Undergraduates and Research Experience for Teachers participants were involved in the work thus extending the educational benefits, including outreach to K-12 education. One teacher developed an electromagnetic levitation device, which is related to EMF, and others have used the metallic microstructural aspects in their chemistry and physical science courses.
