Dear Researchers,
I would like to know the logical margin between the strain of a polymer in the tensile test determined through the traverse (the value from the machine itself) or using a video extensometer. I have obtained a value with a high difference, around 2 (it means that a value of the strain determined using the machine's traverse is twice greater than the value determined using a video extensometer)
How we could explain this difference and what is the reason behind this difference?
Sincerely
Hi,
Such a difference is usual. It comes from slight slidding of the sample in the grips which causes an overestimation of the real strain of the material when using the traverse displacement to measure the deformation. So, avoid using the machine displacement to measure the strain of the material.
The correct/accurate way to measure the strain/deformation is definitely using a strain gauge or an extensometer fixed on the sampe (if rigid sample), or using a video extensometer (contactless method, can be used with thin samples such as plastic films)
Hi.
My assumptions.
1) Different measurement base.
2) Not a perfect fixing of the sample.
Hi,
Such a difference is usual. It comes from slight slidding of the sample in the grips which causes an overestimation of the real strain of the material when using the traverse displacement to measure the deformation. So, avoid using the machine displacement to measure the strain of the material.
The correct/accurate way to measure the strain/deformation is definitely using a strain gauge or an extensometer fixed on the sampe (if rigid sample), or using a video extensometer (contactless method, can be used with thin samples such as plastic films)
- Badges
- Science topic