(frequency Hz vs Temperature ) in Constant amplitude cyclic test

[Wazy01]

Hi

In axial fatigue test usually argued using specific frequency. the Q always Why did you use this frequency ? if that frequency could affect the temperature of the sample

ASTME606 states that "Higher load frequencies in the range of 20 to 35 Hz can be used to shorten the overall test time and cost. As per ASTME606, the frequency or strain rate should not increase the test sample temperature by more than the room temperature plus 2.

My question is using frequency such as in the range above say 25HZ in axial fatigue test, does this induce heat/ increasing in the temperature in the metal sample such as steel, how much could this increase the temperature? are we talking about a number of one order increase or twice the room temperature? do anyone have an experience to answer or can guide me to paper or technical report

using steel with other plastic composites, this question need an attention as if the temperature increase to a point of debonding.

Thanks

 

[EdStainless]

We used to do bending fatigue tests on high strength wire samples.
They were bowed and then rotated.
We typically did this in fish tanks full of oil. This provided lubrication for the bearings, constant temperature, and dampened vibration of the samples. Tests typically ran for a couple of days until fracture.
Out of curiosity we did some in open air. They didn't last 8 hours and were hot enough to burn you.
You could estimate the worst case by calculating the energy that it takes to deform the sample and assume that it all ends up as retained heat. It is enough to impact the results.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[rb1957]

"My question is using frequency such as in the range above say 25HZ in axial fatigue test, does this induce heat/ increasing in the temperature in the metal sample such as steel," ... not if you comply with the ASTM (RT +2deg).

usual answer to your usual question would be "typical practice".

run the test at various frequencies. If you notice heat at 20Hz, go lower. How many cycles predicted ? Could you increase the load to reduce the fatigue life ?

another day in paradise, or is paradise one day closer ?

 

[Wazy01]

Dear Edstainless,
Thank you so much for sharing your experience in the way controlling the temperature during test. The two cases just reflects how much this factor/temperature during the test could effect the results. In the literature, for my case it seems to me it common to do the test (uniaxil fatigue tests of cracked steel plates specimen) in a room temperature in a range of frequency of 10-30HZ. Non stopped at this point where the sample temperature has to be monitored or checked. I agree it missed and it is important to consider.
Regards

 

[Wazy01]

Dear rb1957,
Thanks for your comments!
Yes, I agree that I have to measure the sample temperature to know the accurate answer to my questions, and then we know if the temperate of the sample is within RT+2 of ASTM.
I thought I might get a sense of how much could the temperature rises at this frequency.
It seems hard to find accurate answer as the sample size, and the loading range are another factors.

Regards

 

[MintJulep]

using steel with other plastic composites, this question need an attention as if the temperature increase to a point of debonding.

ASTM E606 applies to homogeneous materials.

If you are testing composites and worrying about temperature rise inducing debonding between various materials then you need to look elsewhere for guidance.