Tbuelna recommended me to look at Vacuumelt Nitralloy N from Latrobe based on my spline. I've been looking at the vacuumelt; however, I called Latrobe the other day, and they seemed to imply 300M was easier to procure, so I got a quote for that. I've been following a number of shaft and...
You guys beat me to it. I think I am looking at improper fatigue properties. I'll post back when I learn more about my material, hopefully in the next day or so.
@tbuelna, good points. Yeah, I wish I had more experience with FEA modeling this type of system. I've already noticed that small...
Hello everyone, I designed a spline in this thread: http://www.eng-tips.com/viewthread.cfm?qid=373420
Now I'm doing an FEA torsional analysis of my shaft to check for fatigue issues. I modeled the spline along with the shaft. Peak stress is showing to be about 80MPa (12ksi) localized around the...
Dear all, I am simulating a shaft for an electric motor using ANSYS MAPDL rotordynamic tools. I have a shaft with multiple stepped diameters made of Beam188 elements. I was wondering how Beam188 analyzes the stress distribution in this stepped geometry. Are stress concentrations considered? If...
Ok, I'm starting to understand now. These surface measures are more about fatigue/fretting prevention, as opposed to stress/design. I think that clears up most of my confusion.
And thank you for the material recommendations. That will keep me going in the right direction.
Regards,
PR
Terry,
Thanks for your comments. Your knowledge and wisdom is vast. You're extremely helpful. I've been kind of (by kind of, I mean a lot) stressing out the last couple days trying to understand this material relationship to this spline. So I can make more informed decisions in the future...
Terry,
It is indeed quite high. For the spline calculations I went with 1million start-stop cycles and 1billion revolutions. The result was about 5ksi compressive stress. If this was for a long lifetime production environment, I'd want more, but the dyno manufacturer and I agreed we believe...
Looks like I'm ok now. I spoke with the dyno manufacturer yesterday. Using the average torque instead of peak torque, the stress goes down considerably. There's still some uncertainty with the factors, but we think with the material selected, we should be in good shape.
Thanks for taking the...
@mfgenggear, I'm new to this topic. Machinery guide describes the stresses as different, so I can only assume there may be different solutions to each stress problem. This is a demanding application, so it's critical that I be as precise as possible.
@tbuelna
Here's the material being used on...
Yes, this is a bi-directional motor, so that will have to be considered. Machinery guide also makes note of a parallelism variation. Would that not give enhanced load capacity bi-directionally?
"Regarding your question about modifying the section properties of the area backing the spline...
Hi Terry, thanks for the response!
[sad] Lead variation looks complicated. [sad] I'll have to look more into that. The Machinery Handbook doesn't seem to mention too much about that. If you know of any design references for that, I'd appreciate them.
Do I need a flexible type joint? You mean...
Dear all,
I am designing a flexible spline for an experimental application. I'm looking at ANSI B92.2M in the machinery guide. My root stresses appear to be too high. I am using the maximum effective length and my maximum diameter is restricted. If I could choose a larger diameter, this...
Hey Guys!
Is it possible to directly assign a mass in Creo?
I'm making a space model. I don't have all the features or internals of the component. I just want to assign the part mass "4". Do I really have to adjust the density to the part volume to get the right mass? That seems really...
Thanks for all the resources everyone, very helpful.
Tomwalz, what exactly do you mean by bond line? Thickness of the epoxy section or bond area?
Just for an update, I am remaking my samples today. I should have results sometime next week. The plan is to try a roughed bond surface. If that's...
Well, it's not as dramatic as that. A crack formed around the edge is all. Yeah, in most places there will be thinner sections of epoxy, but that's not the part I'm worried about at this time. This test was performed to see if any degradation would happen to the epoxy itself, and so far no...
Hi MintJulep,
This is a bond failure. I'm doing some R&D on potting of electrical stator cores, so no, the expansion will not be uniform, but full thermal simulation with thermal expansion integration is a bit beyond the project scope at the moment. I may try to break the material later. I'll...
Hmmmm,
according to that document, I need to determine the max allowable strain. The manufacturer may have that, or I could probably determine it on my own. As long as I use the same prep techniques, and as long as I ensure that thermal strain + elastic strain is less than the allowable...
I thought that to at first. MATWEB says 1018 has CTE of 12e-6 in/in-C. Epoxy datasheet says the expansion coefficient is about 31.
I've filled a steel cup with epoxy. So I believe both materials experience thermal expansion over the same length. Would that not suggest that they epoxy expanded...
I won't be able to mate materials that have precisely equivalent expansion coefficients. Is there a rule of thumb for when the linear expansion coefficient will be close enough? I guess not, because that would depend on the quality of the bond and surface prep as you have suggested. Assuming a...
