Analysis, Modeling and Experimental Study of Stretching Stress in the Design of Pressure Sensor

Abstract

The pressure-sensitive diaphragm is very critical component of a pressure sensor. It is well established that its design, for a given range, basically depends upon mechanical properties of diaphragm such as modulus of elasticity, yield strength and Poisson ratio. Other than that, stretching of diaphragm also affects the sensor performance. In this paper, this aspect of a pressure-sensitive diaphragm is studied. An approach of force balance on an infinitesimal element of diaphragm is taken, and radial distribution of peripheral stress is analyzed. It is considered as an initial stress condition in the simulation. This simulation is used for the design of sensor and to demonstrate the effect of stretching stress on the characteristic of designed sensor. The simulation results are also used to predict the stretching stress of experimentally tested sensor. It is shown  by simulation that the diaphragms of same dimensions and same material show different sensitivity in same pressrue range if stretching stress (intial tensile stress) is different. Experimentally four pressure sensors with SS316L diaphragm (diameter 40.0 mm and thickness 0.2 mm) are tested for the range of 0–100 mbar; which showed diaphragm deflections of 39.85, 38.47, 36.73 and 33.85 µm. It is shown by comparing with theoretical results that Stretching Stress at Periphery (SSaP) in all four lies within the limit of 150 MPa to 200 MPa.