A closed loop rheometer

摘要

The invention provides a method for operating a controlled stress rheometer in a controlled strain mode to follow a demand strain X d in a sample having applied thereto a variable demand force T d, inducing an actual strain X including the steps of:
monitoring the actual strain X;
continuously comparing the actual strain X with the demand strain X d and calculating the difference;
calculating in real time, using an appropriate algorithm, the value of T d necessary to adjust the strain from X to X d ; and
adjusting T d to the calculated value so as to effect this strain adjustment. The method may be performed by a computer software algorithm installed in a digital signal processor forming part of the controller system of the rheometer.