The code has specifically set the speed of the actuator (0.025 to 0.075 mm/ min) for the testing but the equipment that i am using is not digital, its manual and normally used to produce load until flexural failure. I am testing for post-crack toughness and i need the load to be slow and steady, not swift and abrupt, so that i can analyse the post-crack behaviour - which complicates the problem since the equipment will produce load upon activated until flexural failure.
Is it still adhering to the code, if i prepare 4 controlled & identical specimens. In which 1 of them is used to test for the deflection mm/min using an LDVT. Then that speed will be used for the other 3 assuming that the deflection tested in specimen 1 applies to the other 3.
Please note that ASTM specification C1609 requires a testing machine with "closed-loop control". This means that the machine has internal displacement sensors, as well as computerized control that continuously checks the feedback signals from the sensors to ensure that they are within the specified target. In this case the target is the loading speed.
It may be possible, using the procedure you have identified, to produce loading that simulates the ASTM specification. However, you should verify with your client that this simulation is acceptable to them. If you are conducting the tests for the purpose of research, you should record loading speed (or calculate it from the displacement history) to demonstrate that you were able to simulate conditions that satisfy the "spirit" of the ASTM specification.
Having made the preceding statement, I caution you that you should carefully investigate if your equipment can simulate the ASTM C1609 loading conditions. ASTM C1609 is ultimately seeking "stability" of loading when a brittle specimen cracks and deflects beyond first cracking. Those are difficult conditions to simulate.
I also suggest that you read "Loading rate concerns in ASTM C1609" by Nemy Banthia. You can find the paper on ResearchGate at https://www.researchgate.net/publication/274294001_Loading_rate_concerns_in_ASTM_C1609.
I hope this information helps you.
Article Loading rate concerns in ASTM C1609
Please note that ASTM specification C1609 requires a testing machine with "closed-loop control". This means that the machine has internal displacement sensors, as well as computerized control that continuously checks the feedback signals from the sensors to ensure that they are within the specified target. In this case the target is the loading speed.
It may be possible, using the procedure you have identified, to produce loading that simulates the ASTM specification. However, you should verify with your client that this simulation is acceptable to them. If you are conducting the tests for the purpose of research, you should record loading speed (or calculate it from the displacement history) to demonstrate that you were able to simulate conditions that satisfy the "spirit" of the ASTM specification.
Having made the preceding statement, I caution you that you should carefully investigate if your equipment can simulate the ASTM C1609 loading conditions. ASTM C1609 is ultimately seeking "stability" of loading when a brittle specimen cracks and deflects beyond first cracking. Those are difficult conditions to simulate.
I also suggest that you read "Loading rate concerns in ASTM C1609" by Nemy Banthia. You can find the paper on ResearchGate at https://www.researchgate.net/publication/274294001_Loading_rate_concerns_in_ASTM_C1609.
I hope this information helps you.
Article Loading rate concerns in ASTM C1609
With reference to my answer to your previous question: you say your machine is manually controlled. Does this mean that you can control the loading or load rate (generally a hydraulic powered machine) or the crosshead displacement or displacement rate (generally a simple screw machine)? If it is the former, you will never be able to properly carry out a test compatible with most FRC testing standards. If it is the latter, it may be possible to at least perform a close approximation by calibrating the machine using an LVDT or similar. The previous contributor has provided an excellent reference.
Attached is a link that explains how ASTM C1609 should be run. As mentioned in previous posts, the standard specifies that the test must be performed in servo-control, at very slow net deflection rates, more specifically, it needs to be controlled at rates finer than 0.001 in/min (0.0254 mm/min).
http://www.admet.com/testing-applications/testing-standards/astm-c1609-concrete-bend-strength-testing/
Sheikh Mohd Iqbal S. Zainal Abidin ......Good question… Please check references below.. hope it will be helpful for you…
Regards…
https://fsel.engr.utexas.edu/images/resources-pdfs/FSEL-Flexural-StrengthTesting-Rev-00.pdf
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