Method of simulating temperature effect on sensitivity of strain gauge force sensor in non-uniform temperature field

Abstract

A method of simulating temperature effect on sensitivity of strain gauge force sensors is proposed in this paper. The temperature effect on sensitivity, i.e., when the force sensor readings are different for the same load at different temperatures, can be almost fully eliminated by inserting passive compensation elements in the Wheatstone bridge. However, in order for this method to work properly, the temperature distribution in sensor’s elastic element must be uniform. Often times this condition is not fully satisfied in industrial force-measuring systems, i.e., temperature gradients are present. A simulation method is required in order to estimate possible measurement errors stemming from temperature gradients. The proposed method of simulating temperature effect on sensor sensitivity is based on calculating the strain and temperature distribution of the sensor elastic element using Finite Element Analysis (FEA). The analysis results (strain and temperature distributions) are used as input for the developed mathematical model of the Wheatstone bridge which is used for calculating the temperature effect on sensor sensitivity. The method was used to evaluate the temperature effect on sensitivity of a membrane force sensor the steady-state temperatures of the sensor’s bottom and the load introduction point vary. The results of simulation using the proposed method have shown that the temperature effect on sensitivity is greatly influenced by the arrangement of strain gauges on the sensor elastic element. The proposed method can be applied to other types of force sensors for determining the placement of strain gauges so that the temperature effect on sensitivity during uneven heating is minimized.