The Effects of Contact Conditions on the Onset of Shear Instability in Cold-Spray
- PDF / 774,017 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 2 Downloads / 194 Views
Fanchao Meng, Huseyin Aydin, Stephen Yue, and Jun Song (Submitted November 17, 2014; in revised form February 4, 2015) Using ABAQUS/Explicit, the effects of contact conditions between the particle and substrate, including tangential friction, normal constraint, and contact geometry on the plastic deformation during the coldspray process are studied. It was found that the onset of shear instability, an event often used to indicate the establishment of bonding, is very sensitive to the choice of contact conditions. This suggests that the onset of shear instability does not serve as an accurate means to identify the plasticity threshold responsible for bonding. On the other hand, it is demonstrated that the evolution of the overall equivalent plastic strain (i.e., PEEQ) and the overall von Mises stress, being linearly proportional to each other, are both independent of contact conditions. Furthermore, it is shown that an energy value, defined as the product of the PEEQ and the von Mises stress integrated over all particle elements, can quantitatively represent the energy dissipated via plastic deformation while being independent of contact conditions. The PEEQ and associated energy value as defined may provide robust tools to assess the plasticity and the consequent bonding during cold-spray.
Keywords
adiabatic shear instability, cold-spray, contact conditions, finite element analysis, Johnson-Cook model
1. Introduction Cold gas dynamic spray is a rapid fabrication process where micron-sized solid powders are accelerated by an expanding gas stream to impact and adhere to a substrate (Ref 1). Upon the impact, the particle undergoes substantial plastic deformation and subsequently bonds with the substrate. During the cold-spray process, the particle temperature values remain well below the melting temperature, which brings a few significant advantages in comparison to other thermal spray-type technologies, such as minimal substrate modification, avoidance of in-flight oxidation, and chemical degradation (Ref 2, 3). These advantages make cold-spray particularly useful for applications in aerospace, corrosive environments, and biocompatible implants (Ref 4-7). Cold-spray also promises potential alternatives for electroplating, soldering, painting, and 3D prototyping (Ref 8, 9).
Electronic supplementary material The online version of this article (doi:10.1007/s11666-015-0229-z) contains supplementary material, which is available to authorized users. Fanchao Meng, Huseyin Aydin, Stephen Yue, and Jun Song, Department of Mining and Materials Engineering, McGill University, Montreal, QC H3A 0C5, Canada. Contact e-mails: [email protected], [email protected], [email protected], [email protected], and jun.song2@ mcgill.ca.
Journal of Thermal Spray Technology
One key question revolving around cold-spray is when and how the particle/substrate bonding occurs. Although the actual bonding mechanism in cold-spray remains not well understood, it is commonly accepted that the bonding in cold-spray is attributed
Data Loading...
