Two of the objectives of manufacturing research conducted at our group are
1) to better understand the mechanics of deformation/failure in the forming process and therefore design a forming process that maximizes material usage, and
2) to better detect/understand process variations and therefore have a systematic approach to increase the robustness of a process.
These two objectives ultimately require a creation of an integrated system, which needs predictive modeling, sensors and process innovation. We have been practicing this overarching goal on sheet metal forming, composite sheet forming, and recently on microforming.
Laser micromachining is a relatively new method for creating surface textures. The process uses laser pulses of high energy density to ablate localized surface sites through rapid heating and vaporization; accumulated material removal allows the creation of a wide array of surface texture geometries. Northwestern’s state-of-the-art laser micro-machining and surface engineering system integrates a pico-second laser with the technology of numerical-controlled precision machining. Enhancements are currently being added, including instrumentation for direct visual and spectroscopic observation of the workpiece surface and the laser plume and temperature and strain measurements of the workpiece at high temporal and spatial resolution. Research work using this system focuses on gaining an understanding of laser-material interactions and applications of laser micromachining and material processing. Current projects concentrate on surface texture optimization for improving the friction and wear properties of contacting parts.
Microforming as a subset in micro-manufacturing which is defined as fabricating submicron to micro sizes three-dimensional features, has found applications in connecting pins, medical devices, optical lenses, etc. We designed a handheld microforming apparatus. The apparatus has allowed us to show the effect of material microstructure and specimen size on the geometry of deformed pins and on the frictional behavior in the process.
Sheet metal forming or stamping is one of the most widely used processes in the manufacture of automobiles (about 300 parts per vehicle) and is also employed in the production of aircraft, appliances, and many other products. Our past ten years work in this area contributes the knowledge in both computational modeling and experimental testing. We bridge applied mechanics, control and manufacturing together for solving the complex forming challenges.
Composite sheet forming has great potential as a valuable alternative to facilitating mass production of structural composites in automotive components. Structural composites contain continuous or long fiber reinforcements, which yield outstanding mechanical and physical properties including high specific strength and low specific weight. Stamping could reduce the cycle time by at least four times in comparison to liquid molding, which is currently the most common method of forming complex structural composite products in medium volumes. Research in this area is relatively new, with many of the preliminary results leading to more questions than answers as we move from concept to realization. Our work focuses on material characterization and we have co-organized an international benchmark test for examining the capabilities of various models and testing methods.