-I want to calibrate an economical self-designed four-point bending setup. (Please refer to the image)
-The plan is to test specimens on my setup and the standard Bending setup with specimen dimensions designed for my setup for calibrating the setup and test standard dimension specimens on my setup and the standard Bending setup for calibrating the specimen. Tensile tests are also carried out for confirmation of the Calibration results.
Hello! I suppose the calibration method depends of parameter (material property) you are planning to evaluate using your setup and what sort of measurement equipment you have. For instance if it is deflection of the specimen you can measure it using your setup and specimen and standard setup and specimen for the same material, compare the results and calculate calibration factor.
For more apropriate advises you should provide some more information (at least general) about the test
Nice setup, by the way. I like those aluminum bars, it must be wery rigid!
It looks like the load application system can be further improved.
Anyway, you should be able to calculate the theoretical bending stress and it might be possible to measure the deformation by digital image correlation.
Hey Yurij thank you! I will be using it to determine the effect of temperature distribution in the Selective Laser Sintering (SLS) bed on the material properties of PA 12.
I would be using a load cell to measure the force acting on the specimens. The setup is designed according to the DIN standards. The load will be acted with the help of a screw and the number of rotations needed to fail the specimen will help me determine the deflection of the specimen.
Hello Preetham! I think that measurement of deflection through the number of rotation of the screw is not precise enough. It would be better to use some extensometer or inductive displacement sensor. In this case you will be able to plot load – displacement curve and obtain more information about material behavior under loading. Digital image correlation (DIC) is also good, but I think it is too complicated technique if you are planning to measure deflection only. On the other hand using DIC you can obtain strain distribution map of the entire specimen surface (as finite element analysis can provide), and it would be completely different level of research. But you will need to rebuild you setup in such way that you can place a digital camera under the specimen.
For some examples of practical use of DIC in experimental mechanics you can read my articles:
https://www.researchgate.net/publication/257619818_Application_of_the_Method_of_Digital_Image_Correlation_to_the_Construction_of_Stress-Strain_Diagrams
https://www.researchgate.net/publication/276269276_Determination_of_the_Local_Strains_Near_Stress_Concentrators_by_the_Digital_Image_Correlation_Technique
Article Application of the Method of Digital Image Correlation to th...
Article Determination of the Local Strains Near Stress Concentrators...
Dear Preetham,
pl have a look at the load path components, there should not be any deflections in the load path components. When the load path components do not deflect, accurate measurements of deflection( dial gauge of LC 0.001 mm ) and load (load cell of 10 N resolution) you can check the stresses induced in this setup and compare with the standard setup.
Hey Yurji! Thanks a lot for the articles. I will go through them.
Dear Pramod,
Thank you for your response. I was having that problem earlier but now I am using a bush under the top profile similar to the one above it in order to accurately guide the load application. I am also using parts with smaller tolerances in order to prevent any deflections of the load path components.
In that case you should change the device......instead of having a devise that push to applie the loads, you should pull in that points and the external supports you should hang the beam....... send me youe emanil and i will attach teh set up you need......in the way you are workins is only for solid specimens and thick enough to support the loads....not for your specimen
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