article · Materials & Design
Metal and ceramic bonded materials combine structural toughness with heat resistance, but differences in thermal expansion and stiffness generate residual stresses that often trigger cracking. To address this vulnerability, a three-dimensional computational model examined the thermomechanical response of a cracked copper and alumina joint containing functionally graded material interlayers. The investigation evaluated property transitions following linear, logarithmic, and exponential profiles. Thermal loads were found to drive stress generation, with elevated temperatures increasing residual stresses and mode-I stress intensity factors. Cracks located near the joint experienced the greatest stress amplification. Introducing a functionally graded transition smoothed stress patterns and lowered stress concentrations. Across the tested configurations, a logarithmic variation achieved the most effective reduction of von Mises stress, though the ideal gradation profile for minimising crack propagation risk depended on crack dimensions and distance from the joint.
Combining metals with ceramics is crucial for components exposed to extreme heat and heavy loads, such as those in energy and industrial systems. By showing how gradual material transitions lessen internal stress and prevent cracking, this research guides the design of more durable hybrid components that resist structural failure during thermal cycling.
This work informs the design of high-temperature structural components joining ceramics to metals, which are relevant to aerospace, energy, and advanced manufacturing sectors. The findings can help engineering teams select optimal material gradation profiles to prevent interface cracking. Based solely on finite element simulations, this is early-stage research that requires physical manufacturing and experimental fracture testing before industrial deployment.
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Metal–ceramic bimaterials are widely used in high-temperature and structural applications because they combine the toughness of metals with the thermal resistance of ceramics. However, differences in elastic modulus and coefficient of thermal expansion (CTE) create significant residual stresses at the interface, which can lead to cracking and failure. This study investigates the thermomechanical behavior of a cracked copper/alumina (Cu/Al 2 O 3 ) system using a three-dimensional finite element model. Functionally graded material (FGM) interlayers with linear, logarithmic, and exponential property variations are analyzed. Results show that thermal loading plays a dominant role in stress development, significantly increasing stress concentrations near the interface due to material mismatch. As temperature rises, both residual stresses and the mode-I stress intensity factor (K I ) increase, indicating a higher risk of crack propagation. Cracks located close to the interface experience the greatest amplification in K I , highlighting strong interaction effects. The inclusion of an FGM interlayer effectively reduces stress concentration and smooths stress distribution across the interface. Among the investigated gradation profiles, the logarithmic variation provides the most favorable overall redistribution of von Mises stress, whereas the gradation law producing the lowest mode-I stress intensity factor depends on crack length and crack–interface distance.
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DOI: 10.1016/j.matdes.2026.116844
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