Geometric Deformation
Mechanical deformation where the relationship between displacement and strain is described by higher-order terms rather than a linear approximation. In high-pressure applications, non-linear strain occurs when the deflection of a sensing diaphragm becomes comparable to or exceeds its thickness, causing the material to experience stretching as well as bending. This effect introduces second-order and third-order terms into the mechanical response of the transducer, leading to potential measurement errors.
Piezoresistive Effect
Piezoresistive sensing elements mounted on the diaphragm experience this complex stress state, which changes their electrical resistance in a non-proportional manner. This non-proportionality can obscure the linear output of the sensor, requiring more complex signal processing to extract the true pressure.
Structural Threshold
This regime begins when the center deflection of the diaphragm exceeds approximately thirty percent of its thickness, depending on the boundary conditions.
Compensation Method
Signal conditioning circuits use polynomial correction algorithms to linearize the output from sensors operating in this high-strain regime. During the factory calibration process, the sensor is exposed to multiple pressure points across its full scale to determine the unique polynomial coefficients for each device. These coefficients are stored in non-volatile memory and applied in real time to the digitized sensor signal, reducing the non-linear error to within the specified limits of the instrument.
