Up Time Magazine- February/March 2008 - (Page 80) 68 66 64 62 60 58 56 Change of the Critical Frequency in Experiment A and B Experiment A Experiment B Crack Condition (from intact to worse) Figure 7 - Changes of critical speeds as the crack conditions change serious crack condition. Filler fully tightened and Filler partially tightened (more serious than Filler fully tightened) stand for the middle cracked conditions. Both tables have demonstrated that as the crack grows, the critical speed decreases due to the reduced stiffness. The overall trend of these results matches the theory of shaft crack quite well. Figure 7 clearly shows this trend for the changes of critical speeds in different crack conditions. Figure 8. Frequency analysis of 1X and 2X frequency responses 1X and 2X Frequency Response Using the analysis functions in the VibraQuest software package, as shown in Fig. 8, it is easy to obtain the 1X and 2X frequency response for each steady-state test in Experiments B and C. Because the critical speeds of the rotor systems were around 60 Hz to 65 Hz, when the running speed is 2000 rpm (33.33 Hz) in the tests, 2X will be close to the resonance frequency. So both the 1X and 2X components need to be analyzed. When the running speed is 4000 rpm (66.67 Hz), 1X is close to the resonance frequency and 2X will be far away from it. Therefore, only the 1X frequency response has been analyzed. Tables 3 through 6 show the results of 1X and 2X frequency response for all cases of Experiments B and C. Comparing these results shows that normally the 1X and 2X frequency responses of the cracked shaft are larger than that of the intact shaft. This means the crack in the shaft has changed and amplified the 1X and 2X vibration responses. This result is consistent with the theoretical consequence about the shaft crack which has been mentioned before in the introduction. Summary A shaft crack is a slowly growing fatigue fracture of the rotor. Damage of a crack failure can cause serious injury and major downtime. 80 february/march 2008 http://www.sdtnorthamerica.com http://www.sdtnorthamerica.com
Table of Contents Feed for the Digital Edition of Up Time Magazine- February/March 2008 Up Time Magazine- February/March 2008 Contents Upfront Upclose: Lessons Learned from the Walter Reed Story Information Technology: Parenting and Asset Performance Infrared: It's Alive! Lubrication: A Sense of Change Maintenance Management: PdM, Standardized Motor Testing: Being Well Connected Precision Maintenance: How to be Marketable Reliability: The Voyage of Wells Dairy Ultrasound: Two is Better Than One Vibration: Diagnosing a Cracked Shaft Upgrade: A Different Kind of Journey Up Time Magazine- February/March 2008 Up Time Magazine- February/March 2008 - Up Time Magazine- February/March 2008 (Page Cover1) Up Time Magazine- February/March 2008 - Up Time Magazine- February/March 2008 (Page Cover2) Up Time Magazine- February/March 2008 - Up Time Magazine- February/March 2008 (Page 1) Up Time Magazine- February/March 2008 - Up Time Magazine- February/March 2008 (Page 2) Up Time Magazine- February/March 2008 - Up Time Magazine- February/March 2008 (Page 3) Up Time Magazine- February/March 2008 - Up Time Magazine- February/March 2008 (Page 4) Up Time Magazine- February/March 2008 - Contents (Page 5) Up Time Magazine- February/March 2008 - Upfront (Page 6) Up Time Magazine- February/March 2008 - Upfront (Page 7) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 8) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 9) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 10) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 11) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 12) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 13) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 14) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 15) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 16) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 17) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 18) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 19) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 20) Up Time Magazine- February/March 2008 - Upclose: Lessons Learned from the Walter Reed Story (Page 21) Up Time Magazine- February/March 2008 - Information Technology: Parenting and Asset Performance (Page 22) Up Time Magazine- February/March 2008 - Information Technology: Parenting and Asset Performance (Page 23) Up Time Magazine- February/March 2008 - Information Technology: Parenting and Asset Performance (Page 24) Up Time Magazine- February/March 2008 - Information Technology: Parenting and Asset Performance (Page 25) Up Time Magazine- February/March 2008 - Information Technology: Parenting and Asset Performance (Page 26) Up Time Magazine- February/March 2008 - Information Technology: Parenting and Asset Performance (Page 27) Up Time Magazine- February/March 2008 - Information Technology: Parenting and Asset Performance (Page 28) Up Time Magazine- February/March 2008 - Information Technology: Parenting and Asset Performance (Page 29) Up Time Magazine- February/March 2008 - Infrared: It's Alive! (Page 30) Up Time Magazine- February/March 2008 - Infrared: It's Alive! (Page 31) Up Time Magazine- February/March 2008 - Infrared: It's Alive! (Page 32) Up Time Magazine- February/March 2008 - Infrared: It's Alive! (Page 33) Up Time Magazine- February/March 2008 - Lubrication: A Sense of Change (Page 34) Up Time Magazine- February/March 2008 - Lubrication: A Sense of Change (Page 35) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 36) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 37) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 38) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 39) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 40) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 41) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 42) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 43) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 44) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 45) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 46) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 47) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 48) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 49) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 50) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 51) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 52) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 53) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 54) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 55) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 56) Up Time Magazine- February/March 2008 - Maintenance Management: PdM, Standardized (Page 57) Up Time Magazine- February/March 2008 - Motor Testing: Being Well Connected (Page 58) Up Time Magazine- February/March 2008 - Motor Testing: Being Well Connected (Page 59) Up Time Magazine- February/March 2008 - Motor Testing: Being Well Connected (Page 60) Up Time Magazine- February/March 2008 - Motor Testing: Being Well Connected (Page 61) Up Time Magazine- February/March 2008 - Precision Maintenance: How to be Marketable (Page 62) Up Time Magazine- February/March 2008 - Precision Maintenance: How to be Marketable (Page 63) Up Time Magazine- February/March 2008 - Precision Maintenance: How to be Marketable (Page 64) Up Time Magazine- February/March 2008 - Precision Maintenance: How to be Marketable (Page 65) Up Time Magazine- February/March 2008 - Precision Maintenance: How to be Marketable (Page 66) Up Time Magazine- February/March 2008 - Precision Maintenance: How to be Marketable (Page 67) Up Time Magazine- February/March 2008 - Reliability: The Voyage of Wells Dairy (Page 68) Up Time Magazine- February/March 2008 - Reliability: The Voyage of Wells Dairy (Page 69) Up Time Magazine- February/March 2008 - Reliability: The Voyage of Wells Dairy (Page 70) Up Time Magazine- February/March 2008 - Reliability: The Voyage of Wells Dairy (Page 71) Up Time Magazine- February/March 2008 - Reliability: The Voyage of Wells Dairy (Page 72) Up Time Magazine- February/March 2008 - Reliability: The Voyage of Wells Dairy (Page 73) Up Time Magazine- February/March 2008 - Ultrasound: Two is Better Than One (Page 74) Up Time Magazine- February/March 2008 - Ultrasound: Two is Better Than One (Page 75) Up Time Magazine- February/March 2008 - Ultrasound: Two is Better Than One (Page 76) Up Time Magazine- February/March 2008 - Ultrasound: Two is Better Than One (Page 77) Up Time Magazine- February/March 2008 - Vibration: Diagnosing a Cracked Shaft (Page 78) Up Time Magazine- February/March 2008 - Vibration: Diagnosing a Cracked Shaft (Page 79) Up Time Magazine- February/March 2008 - Vibration: Diagnosing a Cracked Shaft (Page 80) Up Time Magazine- February/March 2008 - Vibration: Diagnosing a Cracked Shaft (Page 81) Up Time Magazine- February/March 2008 - Upgrade: A Different Kind of Journey (Page 82) Up Time Magazine- February/March 2008 - Upgrade: A Different Kind of Journey (Page 83) Up Time Magazine- February/March 2008 - Upgrade: A Different Kind of Journey (Page 84) Up Time Magazine- February/March 2008 - Upgrade: A Different Kind of Journey (Page 85) Up Time Magazine- February/March 2008 - Upgrade: A Different Kind of Journey (Page 86) Up Time Magazine- February/March 2008 - Upgrade: A Different Kind of Journey (Page 87) Up Time Magazine- February/March 2008 - Upgrade: A Different Kind of Journey (Page 88) Up Time Magazine- February/March 2008 - Upgrade: A Different Kind of Journey (Page Cover3) Up Time Magazine- February/March 2008 - Upgrade: A Different Kind of Journey (Page Cover4)
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