The working character of the strain gauge

This type of strain gauge is one sense organ which transform the non-coulomb to coulomb,it has different configuration and made of different materials,which are for different use. So diffenent strain gauge, diffenent character and diffenent performance.. It can be tested by checking and testing equipments, and denoted by data or curve, all of these are called the working character of the strain gauge. The brief introduction of every working character as below:

一、The resistance:

When the strain gauge has not been installed, has not force and test in room temperature, this resistance is the strain gauge resistance. The usual resistance of our products are 120Ω、350Ω、500Ω、1000Ω、2000Ω,we also can design and produce strain gauge in other resistance according to our clients demands.

二、The sensitivity coefficient:

When the strain gauge installed on the tested goods, the ratio which between the resistance Relative changes (AR/R) and the tested goods surface strain (Σ) is the sensitivity coefficient, viz：

△R/R

K = ————

       Σ

The sensitivity coefficient K is reflect the Rate output which strain gauge transform the strain to the resistance changing, it usually accroding to the strain precision demand,then it won’t over ±（1~3）%.

三、Zero Excursion and Creep.

Zero Excursion (P) is that when the strain gauge fixed, no force,and constant temperature,then the denoted strain will change by time.

Creep (θ)  is that when the strain gauge fixed, has constant force, and i constant temperature,then then the denoted strain will change by time. actually,the Creep usually includes the Zero Excursion which brings at the same time. 

四、Hysteresis（Zj）.

The strain gauge is fixed, constant temperature,increase or decrease tested goods, then will have different values in the same strain condition,the margin between these values is Hysteresis. It is a speciality that affect the strain gauge’s working Repeatability,but its value come from the degee between strain gauge and the distortion of the adhesive.

五、Ultimate strain（Σlim）.

Σlim is the biggest value between the relative error which about the real strain and ideal strain and regulation value. It is a speciality that to show the transfer-strain ability of strain gauge.

六、Fag life（N）.

The strain gauge under constant force condition, it will be fag damaged circularly after work continuously, that Cyc. time is N . It is a speciality that denote the dynamic strain capability of the strain gauge. Its value relates with not only the strain gauge material and straining, but also the quality of the sensitive grids,lines seal and gauge install etc..

七、Insulation resistance（Rm）.

R is the margin resistance that between the sensitive grids as well as the down-lead of the strain gauge and the tested goods.

八、Heat output（Σt）.

Σt is a speciality that denote the Temp.effect of the strain gauge,it is brought from the Temp. changing in which the proportional Temp.that up and down slowly.

九、The sensitivity coefficient will change along with the Temp..

The sensitivity coefficient is a constant in Normal Temp..but it will change when the Temp. up or down. Different sensitive grids,different change direction. For example, CuNi alloy,its sensitivity coefficient will change linearly and in positive direction during -100~+250℃. But the NnCrAlCu alloy,it change linearly and in negative direction. 

The materials of Sensitive Grids (which its sensitivity coefficient is negative value when the Temp. change) can be made with the materials of Elastomer (which its Elastic Modulus is positive value when the Temp. change) to be Elastic Modulus Self-Compensation strain gauge which used in high precision load cell.  

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