{"id":368776,"date":"2024-05-27T19:04:44","date_gmt":"2024-05-27T19:04:44","guid":{"rendered":"\/forum\/forums\/topic\/problems-with-fatigue-calculations\/"},"modified":"2024-06-03T10:13:07","modified_gmt":"2024-06-03T10:13:07","slug":"problems-with-fatigue-calculations","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/problems-with-fatigue-calculations\/","title":{"rendered":"Problems with fatigue calculations"},"content":{"rendered":"
Hi all.<\/div>\n
I’ve done a fatigue test and have questions.<\/div>\n
I model a tungsten carbide drill tip that drills an SPG die, with a ring of solid body around the die for securing. The material of the die and ring is Mora-Columba concrete.<\/div>\n
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The units I use are: GPa, mm, ms.<\/div>\n
The rotation of the drill is set at a speed of rad\/ms.<\/div>\n
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I did a short calculation (2 hours), the drill rotated about 30 degrees during this time (the total solution to the problem was 60 hours).<\/div>\n
I checked the d3plot file. Adequate stress:<\/div>\n
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Next, I decided to do a fatigue analysis to check what it would look like.<\/div>\n
I got inadequate results:<\/div>\n
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1. The cumulative damage ratio is too high.<\/div>\n
2. Expected Fatigue Life – too small, the elements will only last 235 seconds under load? But they drill with such a drill for many hours or even the whole day. Tungsten carbide is a very durable material with high density.<\/div>\n
3. Expected fatigue cycles are generally empty. Why?<\/div>\n
Help me understand the results, what could I have done wrong?<\/div>\n
I also apply some basic fatigue tinctures:<\/div>\n
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SN curve for drill:<\/div>\n
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I also got this warning when I increased the starting point in the SN curve, I got the following results:<\/div>\n
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The damage has become less, it is gone, but the lifespan is still short.<\/div>\n
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PS. To reduce calculation time, I increased the density of the die, ring and drill by 4e10, can this make a difference? <\/div>\n
Please, help. Thank you.<\/div>\n","protected":false},"template":"","class_list":["post-368776","topic","type-topic","status-closed","hentry","topic-tag-fatigue","topic-tag-ls-dyna"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t