Design and optimization of a novel diaphragm-hinge lever FBG sensor for high-pressure measurement

Addressing the challenges of wide measurement range and high sensitivity in pressure testing for high-pressure pipelines, this paper proposes and develops a novel fiber Bragg grating (FBG) high-pressure sensor based on a composite sensitizing structure of a pressure-sensing metallic diaphragm and flexure-hinge levers. First, by establishing a complete and rigorous mechanical transmission analytical model, the quantitative relationship between fluid pressure and optical fiber strain was elucidated. Subsequently, by combining finite element analysis with a global optimization algorithm, a multi-dimensional parametric design was conducted, successfully establishing the optimal geometric configuration that maximizes the axial displacement output while satisfying the material’s safety strength premise. Compared with the initial empirical design, the terminal displacement output of the optimized structure is substantially enhanced by approximately 30.5% . Experimental results demonstrate that the sensor exhibits excellent comprehensive sensing characteristics under the large-range working condition of 0–40 MPa: its actual average pressure sensitivity reaches 39.41 pm/MPa. Furthermore, to address the unavoidable temperature cross-interference in practical applications, the sensor adopts a cascaded dual-grating structure to achieve high-precision temperature decoupling and error compensation. This study provides a high-performance and highly reliable measurement method for the safety monitoring of modern compact industrial pipeline networks.