Orthotropic direction effect on stress-strain state of temperature-perturbed sensing element of micromechanical accelerometer

Abstract

The paper presents research results on effect of the orthotropic axe directions of orthotropic silicon on the stress-strain state of sensing micromechanical accelerometer element within the conditions of thermal agitations. We proposed a mathematical model of orthotropic thin plate for the case of disalignment of the coordinate axes and the material orthotropic direction of sensor sensitive element. We developed and verified software for studying the effect of misalignment of the coordinate axes and the orthotropic direction on the stress-strain state of the sensing element. The software is comparable with ANSYS software package with respect to accuracy of the simulation results. The developed software was used for computer simulation; the displacement field dependences of a uniformly heated sensing element on misalignment angle of coordinate axes and orthotropic direction were obtained. Computer simulation revealed the presence of direction misalignment of orthotropic axes and the coordinate axes, resulting in symmetry disruption in the plate deformation under uniform heating. As part of the study, we have shown a nonlinear character of the stress-strain state dependence of the temperature-perturbed sensor on the misalignment angle of orthotropic axe directions. It was demonstrated that the maximum deflection change for different misalignment angle values does not exceed 3.2% of the nominal value. However, under the conditions of external dynamic, thermal and mechanical exposures, the cumulative effect of the maximum deflection value change can have a significant impact on the characteristics of the micromechanical accelerometer. Therefore, it seems advisable to perform future research of the effect of misalignment of orthotropic axe directions on the parameters of the inertial information sensors.