Temperature compensated diaphragm based Fiber Bragg Grating (FBG) sensor for high pressure measurement for space applications

A temperature compensated diaphragm-type Fiber Bragg Grating (FBG) sensor for high pressure measurement, with a maximum pressure up to 700 bar, has been developed and packaged for different applications including space. In this device, a pressure sensitive FBG is bonded at the centre of a Martensitic Stainless Steel (APX-4) diaphragm and a temperature compensation FBG is bonded in the strain-free region of the same diaphragm. The experimental results obtained indicate a pressure sensitivity of 3.64 pm/bar and a non-linearity + Hysteresis error of 0.75% of full-scale pressure in the range of 0 to 700 bar, with a correlative coefficient of 99.99%. Structural and thermal stress analyses of the diaphragm and strain transfer analysis from the diaphragm to FBG have been carried out using Comsol Multiphysics software, to validate the experimental results. Shock tube and vibration tests have also been carried out to study the dynamic characteristics and stability of the sensor. The pressure sensor developed, can be used to measure both static/dynamic pressures of cryogenic propellants as well as pneumatic pressure in rockets, missiles and launch vehicles.

Automated summary

The temperature compensated diaphragm-type Fiber Bragg Grating (FBG) sensor has a pressure sensitivity of 3.64 pm/bar and can measure pressures up to 700 bar with a non-linearity + Hysteresis error of 0.75%. It is developed for high pressure measurement applications, including space, and has been validated through structural and thermal stress analyses.