Theoretical Analysis of the Effective Properties of Polymer-Based Composites Considering Particle-Size Effects and Damage Evolution

In engineering, the demand for lightweight yet strong materials has led to the widespread use of polymer matrix composites reinforced with particles. These composites offer superior mechanical properties, making them ideal for applications in areas such as the automotive, aerospace, and construction industries. This paper presents a micromechanical model for particle-reinforced polymer matrix composites with interphase layers, enabling the prediction of effective bulk, shear, and Young’s moduli while accounting for damage. Model validation is achieved by comparing the calculated elastic moduli for two composite types. This study highlights that stiffer or smaller particles enhance elasticity, while a robust interphase preserves mechanical properties, despite damage. A statistical criterion describes interphase debonding probability, and the Ramberg–Osgood equation captures the polymer matrix’s elastoplastic behavior. Numerical analyses on polypropylene composites with glass beads demonstrate how particle size, interphase strength, and debonding affect performance, aligning well with experimental data.