AXIAL COMPRESSION FAILURE AND PARAMETER INFLUENCE OF UD-CF/AL COMPOSITES AT ROOM AND ELEVATED TEMPERATURES

This study addresses the longitudinal compression failure behavior of self-fabricated unidirectional carbon fiber-reinforced aluminum matrix (UD-CF/Al) composites at room temperature (RT) and elevated temperatures. Macroscopic mechanical properties and microscopic fracture morphologies were acquired via longitudinal compression tests. A two-dimensional multi-fiber finite element (FE) model was developed based on micromechanics theory, incorporating fiber initial misalignment, bilinear interface damage, and elastic-plastic matrix damage. The compression-induced damage evolution, kink band formation mechanism, and the influence of key material parameters were systematically investigated under both RT and elevated-temperature conditions. Results indicate that the simulated macroscopic mechanical properties and microscopic fracture morphologies are in excellent agreement with experimental observations. The compressive strength and modulus of the composites decrease significantly at elevated temperatures, with experimental values reaching 55.6% and 86.0% of the RT values, respectively. Compression failure at both RT and elevated temperatures exhibits a progressive sequence: interface damage - matrix damage - kink band initiation - kink band propagation. At RT, translaminar matrix cracks form, giving rise to single-layer kink bands (width ≈ 60.2 μm, angle ≈ 15°) and stacked multi-layer kink bands (two layer width ≈ 180 μm, angle ≈ 20°), accompanied by moderate fiber debonding at the structural edges. At elevated temperatures, the matrix develops locally dense small crack bands, leading to wider and more severely kinked single-layer kink bands (width ≈ 128 μm, angle ≈ 31°) and non-stacked multi-layer kink bands (two layer width ≈ 274.3 μm, angle ≈ 45°); notable fiber debonding occurs both internally and at the edges of the structure. Fiber initial misalignment angle is the most sensitive factor affecting compressive strength, with a reduction in misalignment significantly enhancing strength. Increasing interface and matrix strength effectively improves compressive performance and delays instability, whereas fiber strength and matrix modulus exert only minor influences. This work elucidates the damage evolution and kink band formation mechanism of UD-CF/Al composites under longitudinal compression at RT and elevated temperatures, clarifies the regulatory roles of key fiber, interface, and matrix parameters, and provides a micromechanical theoretical basis for optimizing the compressive performance of such composites.