residual compressive stress on the surface increases first and then decreases. When τ is set to be around 360 ns, the residual compressive stress reach maximum.
In the case that the time interval τ is fixed to be 320 ns, the calculated radial residual stresses distributing on the surface with respect to different η are shown in Figure 7. It can be seen from Figure 6 that in general the residual compressive stress on the surface increases with the rising of the attenuation factor η, but the stress nearby the edge of spot varies oppositely due to the aggregation of the stress wave. When η is 0.9, there are small residual tensile stresses appearing near the edge of the spot. When η is too small, the composite shock wave no longer plays a significant role. These results indicate that an appropriate value of η should be set for the effective composite shock wave.
The simulations show that the main parameters of the composite shock wave, formed in the cavity, have an important influence on the strengthening effect. In order to provide guidance for the design of the cavity, further theoretical research needs to be
Figure 7. The calculated radial residual stresses distributed on the surface of the workpiece with respect to different η (τ=320 ns)
carried out. The experimental work is also under way, and the new progress will be reported soon.
The authors are with Ningbo Institute of Materials Technology & Engineering (NIMTE).
Small is the new BIG
Newport Motion Solutions for Laser Micromachining Enable: • Tight Focal Planarity
• Optimized Path Control • Nanometer Scale Line Uniformity
• Trajectory-Based Laser Triggering
Scribing Lithography Additive Newport Motion Solutions now include Drilling Ablation Smarter Motion Controllers. For more information call (877) 835-9620 or visit
www.newport.com
A-121401 Motion LMP-IDL-XY-LIA
hfpg.indd 1 12 LIATODAY FOCUS: SCIENCE & RESEARCH SEPTEMBER/OCTOBER 2016
9/8/16 2:57 PM
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28