Mechanical failure of anodized aluminum under three and four-point bending tests

•We study the flexural behavior of anodic oxide layers formed on aluminum.•Three and four-point bending tests were used as techniques.•Changing the beam configuration will change the flexural response.

In this work, three and four-point bending tests were adopted as methods for characterizing anodized aluminum beams in a sulfuric acid bath. The failure behavior of sandwich beams having aluminum oxide face sheets and aluminum core were tested. In so doing, many configurations were adopted by anodizing aluminum beams on one and both sides to investigate faces in place of tension and compression.Bending tests showed different behaviors. When the oxide was only on the top side of the beam (working in compression) a slight sudden decrease of the load was observed. This fact was absent on beams with oxide layers working in tensile. The bending behavior of sandwich beams was similar to those with oxide on top sides but with much higher loads. The mechanical failure of the oxide was mainly caused by its failure when it is placed in compression beneath the loading rollers.Finally, a morphological study of the aluminum oxide layers after bending tests was conducted by optical microscopy.