Coarse-Grained Modeling and Interpretation of Phenomenological Creep Rate Behavior with Experimental Validation

Creep is one of the main failure mechanisms of materials at elevated temperatures, and the creep rate curve is a key descriptor of creep deformation and damage evolution. However, existing creep models are mainly phenomenological or stage-wise, and the physical origin of the bathtub-shaped creep rate curve over the full creep process has not been systematically clarified. In this study, creep damage is treated as an aging failure process of a material system, and a physically interpretable hierarchical model is established based on statistical physics for disordered complex systems. By linking the evolution and interaction of microscopic material units with macroscopic creep behavior, the proposed model provides a unified description of the primary, secondary, and tertiary creep stages and offers a theoretical explanation for the bathtub-shaped creep rate curve. Validation using representative metallic and composite material cases shows that the model can reasonably reproduce the overall three-stage creep rate evolution, with residual sums of squares of 1.3088 and 0.5369, respectively. These results demonstrate the ability of the model to capture full-process creep behavior in different material systems. The main advantage of the proposed approach is its physical interpretability within a unified framework, while its current limitation is that the validation remains limited in scale and broader benchmark comparisons with conventional methods are still needed. This work provides a statistical perspective for creep behavior modeling and for understanding the microscopic mechanisms and interactions underlying creep degradation in structural materials.