D.H. Lammlein PhD Dissertation - Vanderbilt University
D.H. Lammlein PhD Dissertation - Vanderbilt University
D.H. Lammlein PhD Dissertation - Vanderbilt University
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Figure 102: Tapered retraction procedure performed in a bead on plate configuration. A<br />
snubbed nose, cupped nose, 100º conical tool was used. The final segment of the<br />
retraction is essentially flush with the sphere surface (i.e. no indentation). ................... 116<br />
Figure 103: Tapered retraction procedure performed in a butted configuration after and<br />
over a full, circumferential weld ..................................................................................... 117<br />
Figure 104: Experimental setup for rotary FSW of hemispherical butted sections. ....... 117<br />
Figure 105: Dynamometer data for a butted configuration, sphere weld (1000rpm,<br />
10.4ipm, 0.095” depth) using a 100º conical tool (snub-cup). The top frame shows<br />
measured force(blue) and desired force (green). The desired force is presented for<br />
comparison and not used in the control algorithm. The middle panel shows measured<br />
torque(blue) and desired torque (green). Toque is highly sensitive to plunge depth. The<br />
desired depth is followed closely by maintaining weld torque via vertical adjustments of<br />
tool position. The weld is a full circumferential weld and the eccentricity of the setup can<br />
be seen in the lower frame which shows the vertical position of the tool relative to its<br />
initial calibration on the material surface. ....................................................................... 119<br />
Figure 106: Dynamometer data for a butted configuration, sphere weld (1000rpm,<br />
10.4ipm, 0.095” depth) using a 100º conical tool (snub-cup). The weld is a full<br />
circumferential weld and the eccentricity of the setup can be seen in the lower frame,<br />
which shows the vertical position of the tool relative to the machine stage. The<br />
eccentricity was generally around 0.02” but varied in its manifestation from weld to weld.<br />
The desired torque is closely maintained. From approximately 159 to 203 seconds the<br />
spinning tool is being gradually lowered (plunged) into the material at approximately<br />
0.002” per second. From 203 to 209 seconds the vertical and rotary (traverse) motors are<br />
stopped during a brief dwell period prior rotary motor engagement. Reductions in axial<br />
force from 188 to 203 seconds are due to material softening [27]. ................................ 120<br />
Figure 107: Surface appearance for full-penetration, supported welds made with the<br />
cupped shoulder, threaded probe tool. Samples are taken from the steady-state, steadydepth<br />
portion of each weld. ............................................................................................. 122<br />
xiii