Effect of deformer geometry on mechanical responsiveness of cylindrical silicone rubber housing for macrobending optical fiber load sensor

Macrobending‑based fiber‑optic load sensors convert mechanical deformation into changes in optical intensity. This study investigated how four different deformer shapes—double‑flat (DFL), double‑cylindrical protrusion (DCP), cylindrical protrusion–concave bowl (CP–CB), and double concave bowl (DCB)—affect the mechanical and optical behavior of a cylindrical silicone‑rubber housing. Finite element analysis (FEA) with a two‑parameter Mooney–Rivlin hyperelastic model was performed and confirmed by experiments under quasi‑static compression up to 35 kg. The deformer shape strongly influences both the overall deformation and fiber curvature. The DCP had the highest global deflection sensitivity (0.37 mm/kg), while the DCB had the highest optical sensitivity (21.06 mV/kg) and excellent linearity (R2 = 0.999), low hysteresis (0.23 %), and low repeatability error (0.125 %). These results show that optical performance is influenced not only by the housing’s overall deformation or the smallest curvature radius but also by the fiber’s curvature extent and location. This study presents a quantitative foundation for selecting deformer geometry in macrobending‑based fiber‑optic load sensors.