Biomedical Engineering Reference
In-Depth Information
summarized in Table 9. Results from these tests do not show significant
differences in hardness values before and after impacts.
Table 9. Summary of Average Hardness Values (HRE)
Sample Pre-impact Post-impact
1 103.9 103.5
2 105.6 104.4
3 94.4 93.7
4 94.8 94.3
Reproduced with permission. Copyright retained by Inderscience Publishers.
4.
D
ISCUSSION
The study of high-speed impacts of solid particles into substrates, and the
resulting investigation of the effects of these impacts on the surface of the
substrate material, has only recently begun to be investigated. To allow for
further research to continue in this area, it is desirable to develop a device
capable of accelerating particles to supersonic speeds, where it becomes
possible to bond particles into substrates for selected materials and particle
sizes. The pneumatic device developed in this study proves to be capable of
this, and is simple and cost effective to operate when compared to traditional
cold spray devices. By using different types of burst disc materials, velocity
can be controlled to allow for further investigative research. A vacuum cannon
was used to successfully record velocity at three positions along its barrel. The
purpose of doing so was twofold: sensors used to record data proved reliable
and capable of being incorporated in the design of the velocity measurement
device for the smaller pneumatic device. In addition, data obtained
experimentally was compared to predicted values using a first order analytical
model. The experimental data correlates well to the analytical data, although
the number of velocity data points was limited to four for each barrel position.
At this point the analytical model was also compared to a computational model
using FLUENTTM CFD software. The FLUENTTM model predicted much
lower velocities than those velocities predicted by the analytical model.
Although the general trends of the velocity data seem similar in nature, it is
possible the FLUENTTM model has errors that are beyond the scope of this
study. The subsonic pneumatic gun proved capable of precise control of exit
