Hello,
We would like to know, what are the limitations of a Hounsfield Tensometer? How are the extensions and tensions of the specimens measured by the meter? And what is the source of inaccuracyin these measurements?
Thank you for your help,
Sam.
ANSWER
Hi Sam,
I assume you mean one of our current machines and not one of the old Hounsfield Tensometer which contained mercury.
To answer your question fully would take considerable time and the answers would be very long. Therefore, i will try to answer your questions briefly:-
As with all measurements, it is important to have an understanding of what you are measuring, why you are making the measurement and how the equipment makes the measurement. The equipment must be the right equipment for the job and used within its operating range. Our machines use strain gauge load cells to measure force and optical encoders to measure crosshead movement. Our current load cells are Grade 0.5 which means +/-0.5% accuracy (of reading) between 0.2% and 100% of load cell capacity. Between 0.1% and 0.2% of load cell capacity, the accuracy is +/- 1% of reading. Crosshead movement resolution is tyically 0.001mm and accuracy is typically 0.01mm. For Modulus Measurements we have an extensive range of extensometers and other displacement transducers available. Please refer to the relevant product brochures for further technical information. You may also like to refer to an earlier article on the website concerning why you need an extensometer to measure Modulus.
Sources of inaccuracy are usually:- poor sample preparation, wrong machine, load cell, grips, extensometer, test speed, temperature, humidity, software, interpretation of results or off centre loading.
I hope this answers your questions Ok
David
