Compressive Performance and Design Parameter Analysis of RTM Composite Stiffened Panels With Different Stiffener Angles

ABSTRACT The resin transfer molding (RTM) process enables the cost‐effective fabrication of composite stiffened panels and achieves a series of customized mechanical properties by changing the stiffener angle ( θ ), which is difficult to achieve with traditional manufacturing methods. In this study, experiments and the finite element method were used to explain the influence of θ on the compressive performance of RTM‐stiffened panels. A series of specimens with θ values of 45°, 60° and 90° were designed and tested under compression to examine the effects of θ on structural stiffness, strength and damage modes. Then, high‐fidelity numerical models were developed to reveal the damage mechanisms, while further investigating the effects of failure criteria and shear nonlinearity on damage prediction. Based on these results, an equivalent compressive stiffness K _eq was introduced to evaluate the relationship between θ and mechanical performance. Results indicate that under compressive failure conditions, the parameter K _eq directly determines structural compressive strength. However, when design parameters are changed to make the structure exhibit buckling behavior, K _eq loses its guiding significance. In this case, if K _eq is kept constant, the panel with θ = 90° exhibits optimal stability and strength. When θ increases to an obtuse angle, its mechanical properties are lower than those at supplementary angles. These findings provide new insights for optimizing stiffener design in RTM composite stiffened panels.