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Streszczenie:
Multilayered aluminum-matrix composites constitute a subclass of functionally graded materials whose mechanical properties can be systematically tailored to meet specific design requirements. In this study, experimental and numerical investigations are performed to characterize Mode I and mixed-mode I/II fracture behavior and crack growth in graded AlSi12–Al2O3 composites containing a notch oriented along the gradient direction. Mode I fracture tests are conducted on four-layer, disk-shaped compact specimens subjected to tensile loading, with Al2O3 volume fractions of 0 (pure matrix), 10, 20, and 30 percent. Crack propagation on both specimen surfaces is monitored in situ, and full-field displacement measurements are obtained using Digital Image Correlation. The experiments reveal a pronounced nonlinear crack-front propagation induced by material composition gradient along the crack front. Fracture consistently initiates in the layer with the highest content of ceramic particles, propagates within this layer, and subsequently extends into adjacent layers. Distinct fracture surface morphologies are observed using scanning electron microscopy, ranging from brittle features in ceramic-rich layers to progressively more ductile characteristics in layers with lower ceramic content. An elastic–plastic phase-field model is employed to examine the influence of stacking sequence on fracture load capacity as well as on crack-front formation and evolution under both Mode I and mixed-mode I/II loading conditions. The phase-field model is calibrated against experimentally measured fracture loads, and the characteristic length-scale parameter is identified accordingly. The simulations successfully reproduce the experimentally observed nonlinear crack-front morphology and demonstrate that the stacking sequence considerably affects the maximum load-bearing capacity and crack front geometry under both pure Mode I and mixed-mode loading.

Słowa kluczowe:
Metal-matrix composite, Multilayered structure, Nonlinear crack front, Fracture load, Stacking sequence, Phase-field modeling