Hello All,
I'm looking into measuring crack growth rate using the DCPD method and was wondering if it is possible to use a "bench top power supply" and a multimeter with higher accuracy? Or do I need to have specialized equipment for DCPD measurement?
The materials I'm interested are iron alloys and aluminum alloys.
Compact tensions specimen thickness =< 13mm
Cheers,
Rashiga
Hi, you don't need any special equipment. We don't use it in our lab either. But it is easier to buy a DCPD. On the other hand, you are a little proud when the system finally runs. :)
We use a nanovoltmeter and a PC with a self-written software in Labview.
You have to measure on your sample the voltage drop at your crack ("active signal") and the voltage at a spot without crack ("reference signal"). In addition, total voltage and total current.
We do the evaluation with Matlab. In the standards, you will find the corresponding formulas for the ratio of electrical voltage to crack length.
I recommend the insertion of striations during the crack propagation test for a better correlation of the crack length. A reference test may be necessary.
Regards,
Michael
Hi Michael Harwarth
Many thanks for your reply.
Would you be kind enough to share the model number of the voltage supplier and the nano-voltmeter?
Furthermore, could you elaborate on what you meant by the insertion of striations?
Thank you
Kind Regards,
Rashiga
For a correct assessment of the crack depth, accurate calibration curves for the geometry at hand are required. therefore it needs to be done continiously. potential drop technique is a robust method to provide continuous in situ crack growth monitoring of real power-plant components.
Syed Khaja Naimuddin thank you for your insights.
Do you have any input on the question I asked?
Hi Rashiga Walallawita
our nanovoltmeter is Keithley Nanovoltmeter Model 2182A.
Sorry, I didn't read your first question carefully. What I wrote only works if you combine creep and fatigue tests. But still you have a total length of the crack, which you then have to calibrate to your voltage signal.
Kind regads,
Michael
please refer to this paper you will get some information,
The Development of Crack Measurement System Using the Direct Current Potential Drop Method for Use in the Hot Cell Dosik, KIM, Sangbok, AHN and Key-soon, LEE Korea Atomic Energy Research Institute, Irradiated Materials Examination Facility P. O. Box 105, Yusong, Korea, 305-600
please refer to paper from atomic energy research institute korea they have good study on this,
The Development of Crack Measurement System Using the Direct Current Potential Drop Method for Use in the Hot Cell Dosik, KIM, Sangbok, AHN and Key-soon, LEE Korea Atomic Energy Research Institute, Irradiated Materials Examination Facility P. O. Box 105, Yusong, Korea, 305-600
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