As long as l/d is between 1/4 and infinity then you can use equation 12-16 (10th edition Shigley) to interpolate between the lines. Basically, you calculate a weight for each of the four lines that are shown on the charts based on your actual l/d and multiply that weight by the value given on each line at your Sommerfeld number. For example, lets say you have a S = 0.1 and l/d = 1.25 (which isn't on the chart). If you want to find the minimum film thickness using Figure 12-16 you would solve equation 12-16 as: ho/c = (1/(1.25^3))*(-0.125(1-1.25)(1-2.5)(1-5)*0.74+0.33(1-2.5)(1-5)0.34-0.25(1-1.25)(1-5)0.2+0.04167(1-1.25)(1-2.5)(0.11)) = 0.391 I hope that makes sense and the parentheses are all correct. :)
Useful video to learn calculate hydrodynamic journal bearing. What about hydrostatic ? Journal with fed lubrications and groove?
Thank you. A hydrostatic video is a great suggestion! I will add that to the list of videos for the future.
How can I solve it when the l/d ratio does not appear in the tables? .....How is Raimondi and Boyd's interpolation applied?
As long as l/d is between 1/4 and infinity then you can use equation 12-16 (10th edition Shigley) to interpolate between the lines. Basically, you calculate a weight for each of the four lines that are shown on the charts based on your actual l/d and multiply that weight by the value given on each line at your Sommerfeld number. For example, lets say you have a S = 0.1 and l/d = 1.25 (which isn't on the chart). If you want to find the minimum film thickness using Figure 12-16 you would solve equation 12-16 as:
ho/c = (1/(1.25^3))*(-0.125(1-1.25)(1-2.5)(1-5)*0.74+0.33(1-2.5)(1-5)0.34-0.25(1-1.25)(1-5)0.2+0.04167(1-1.25)(1-2.5)(0.11)) = 0.391
I hope that makes sense and the parentheses are all correct. :)
you forget to screenshare after 20 minutes
Yeah, I think I notice it around the 25 minute mark and go back and quickly summarize what was missed. Sorry about that!!