CARNEGIE MELLON Department of Electrical and Computer EngineerJ Manufacturing Mechatronics Using a Recursive Mask and Deposit ( MD ) Process
A new technology for manufacturing mechatronics is described. The technique is based on recursive masking and deposition of thermally sprayed materials. Using these methods, structures can be created that embed and interconnect electronic components, resulting in highly integrated mechatronic devices. A simple, electromechanical artifact was designed and produced to assess the feasibility of these techniques. The details and limitations of this project are discussed and areas of future research are identified which are aimed at realizing the full potential of this emerging manufacturing process.
Thermal spray shape deposition
This paper describes a new spray-forming process based on thermal spray shape deposition. Shape deposition processes build three-dimensional shapes by incremental material buildup of thin, planar crosssectional layers. These processes do not require preformed mandrels and can directly build three-dimensional structures of arbitrary geometric complexity. The basis for the thermal spray approach is to spray each layer using a disposable mask that has the shape of the current cross section. Masks can be produced from paper rolls, for example, with a CO2 laser. In addition to applications for rapid prototyping, this approach makes possible the fabrication of composite structures and integrated electronic/mechanical assemblies that are not feasible with conventional manufacturing technologies.
Neutron Residual Stress Measurements on Rail Sections for Different Production Conditions
Rail sectioning with subsequent neutron diffraction experiments has been used to assess residual stresses in the rails. In this study we present the results of neutron stress measurements performed at the NIST Center for Neutron Research (NCNR) on rail sections from rails that were produced under various conditions. Specifically, these are air-cooled, air-cooled and roller-straightened, head-hardened and head-hardened and roller-straightened. More significantly, a head-hardened and roller-straightened rail was also studied after service to elucidate evolution of the service-induced residual stresses. In the latter case both a transverse-cut slice and the central region of a 0.53 m long piece were studied. Measurements on this piece are the first in which triaxial stresses have been determined for an intact rail. Neutron strain measurements with 3×3×3 mm3 spatial resolution were successfully employed for transversally cut slices to verify the difference in the stress state depending on the production process. Although examination of slices allows determination of only two-dimensional stresses in the plane of the slice, additional measurements on obliquely-cut slices, which were also carried out, and utilization of FEM gives the possibility of reconstructing the full triaxial stress distribution. Together, these approaches provide a better understanding of rail fabrication and the possibility of improving the durability and safety of rails in the future.Copyright © 2004 by ASME