Thermo‐Hygro‐Mechanical Tensile Strength Modeling of Fiber‐Reinforced Polymer Composites Integrating Energy Equivalence Principle and Micromechanics Framework

ABSTRACT

As aerospace technology continues to advance, fiber‐reinforced polymer (FRP) composites are being used increasingly in environments characterized by elevated temperature and humidity. Because tensile strength represents the maximum stress that a material can withstand under tensile loading, accurately quantifying its variation with temperature and humidity has become an important research focus. However, existing theoretical formulations still have difficulty describing the coupled environmental effects without introducing empirical fitting parameters. To address this issue, a thermo‐hygro‐mechanical temperature‐humidity‐dependent tensile strength (THDTS) model is developed for FRP composites. The model incorporates temperature effects, moisture absorption, and humidity‐induced plasticization to describe their combined influence on tensile strength. Comparisons with previously reported experimental data show satisfactory agreement between the predictions and measurements, supporting the physical validity of the formulation. The analysis further identifies the key parameters governing tensile strength under different hygrothermal conditions. All inputs required by the THDTS model can be obtained directly from material handbooks or published literature, and no fitting parameters are introduced. The proposed formulation therefore provides a theoretical basis for evaluating FRP performance and supporting engineering applications in hygrothermal environments.