Effect of component layer thickness on the bending behaviors of roll-bonded tri-layered Mg/Al/STS clad composites

The bending and failure behaviors of roll-bonded tri-layered 3.8 mm thick Mg/Al/STS composite plates with different Mg layer thickness were studied under two different testing conditions (Mg layer in tension, or STS in tension). The load–displacement and failure behaviors were found to be influenced by the stacking structure of Mg, Al and STS with various thicknesses. Bending failure resistance was greater under the bending condition of STS layer in tension. 2.3Mg/Al/STS with a thicker Mg layer (2.3 mm) were found to be more susceptible to the failure due to Mg layer fracture under the condition of Mg in tension whereas it exhibited the higher bending load under the condition of STS in tension. The formation of inter-layer crack was found to be influenced by the position of the interface with respect to the neutral axis in bending because the shear stress reaches the maximum at the neutral axis. Since the neutral axis in bending is closer to the Al/Mg interface with intermetallic compounds in 2.3Mg/Al/STS with a thicker Mg layer (2.3 mm), it exhibited the more pronounced interface cracks. The position of the interfaces with respect to the neutral axis is found to be an important clad design parameter as well as stacking structure, thickness of layers and interface properties when designing multi-functional multi-layered composite plate.