Brands
Vishay Measurements Group
Strain Gages
Creep Compensation
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| Commercial transducers regularly achieve a creep
specification of less than ±0.02% of full scale
(FS) for a 20-minute test. To attain this level on a
high production basis, it is usually necessary to
match the strain gage's creep characteristic to
the spring element creep.
Most Transducer-Class gages can be adjusted in design to exhibit either a positive or negative creep under load. Spring element materials exhibit only positive creep under load. 
Since transducer creep depends on several variables such as spring element material, heat treatment, strain field, adhesive type and test temperature, it is not possible to predict the proper gage compensation necessary to achieve the best creep result. Since it is not possible to predetermine the creep characteristics of a particular transducer, it is suggested that the standard creep code be ordered in quantities sufficient to evaluate three or four transducers. Where creep levels are high enough to warrant correction, a different creep compensation, either more negative or more positive, depending on test results, can often be recommended. A complicating factor in creep code selection is that while different gage patterns may list the same creep code, they do not necessarily exhibit the same creep behavior. This is because the gage backing selection, gridline width and gage length also influence creep characteristics. It should also be noted that this type of creep correction is generally limited to transducers exhibiting less than ±0.1 % FS creep. Higher creep levels in the positive direction are often the result of poor spring element material selection. Negative creep values in excess of 0.1% FS generally are the result of a faulty gage installation. |
