Theoretical and Numerical Analysis of the Pressure Effect on Electrical Resistance Strain Measurement on a Cylindrical Convex Surface Under Hydrostatic Pressure

Electrical resistance strain measurement is a commonly used method for structural health monitoring (SHM) in marine engineering, particularly for deep-sea vehicles and offshore structures. Under pressure, a strain gauge deforms with the surface of the specimen and also undergoes additional pressure-induced deformation, which depends on both the ambient pressure and the specimen geometry. Based on the mechanical response of a strain gauge under hydrostatic pressure, a theoretical solution for the pressure effect in electrical resistance strain measurement on a cylindrical surface was derived and validated against previously published experimental results. A finite element model incorporating a simplified strain gauge was also developed to simulate the structural response associated with the pressure effect on a convex cylindrical surface. The proposed theoretical solution was verified using finite element analysis (FEA) together with the experimental data, and the effects of pressure loading and the radius of curvature of the specimen surface on measurement accuracy were examined. The mechanism of the pressure effect was investigated using the proposed theoretical and numerical methods. The results demonstrate a pronounced nonlinear dependence of the pressure effect on the specimen radius, while the proposed first-order model is linear in curvature. This study provides a theoretical basis for correcting strain measurements on curved structural surfaces subjected to pressure loading and for accurately monitoring the safety of cylindrical structures in deep-sea engineering.