How to measure shear strain using SCXI 1520

[ilia.art]

I have a problem, measuring Shear strain using half bridge strain gage. I'm using SCXI 1520 + 1314 configuration. As I figured out half bridge type II for 1520 is designed to measure bend, which is avarage value of strains measured in each gages. I need to measure shear strain which is absolute difference between two strain measurements. I tryed to multiply strain by 2, byt the shear modulus, i'm trying to calculate, still appears higher then the known value for this material. 

So does anybody know how to measure a "raw" strain on Half bridge strain gage using SCXI 1520? I also have SCXI 1120 module, can it help?

[SunainaK]

Hi Ilia,

There is a document called Choosing the Right Strain Gauge for your Application:

http://www.ni.com/white-paper/3092/en

Also, as far as calculating the value:

http://www.ecourses.ou.edu/cgi-bin/ebook.cgi?doc=&topic=me&chap_sec=08.3&page=theory

[ilia.art]

Thank you for information. I have read that. As I figured out, The value that gives Half Bridge Type II from SCXI 1520, should be multiplied by 2 to get shear strain. This is acoording to simple Wheatstone bridge theory. But I was not sure what SCXI module was calculating, because my results are slightly lower than material original data, got by same strain gage by the manufacturer. I guess the problem is somewhare else.