US Air Force researchers to identify root cause for crack formations in aircraft

4 September 2016 (Last Updated September 4th, 2016 18:30)

Researchers at the US Air Force Research Laboratory (AFRL) are investigating microscopic crack formations and metal fatigue that hamper aircraft safety.

Researchers at the US Air Force Research Laboratory (AFRL) are investigating microscopic crack formations and metal fatigue that hamper aircraft safety.

Metal fatigue, which is due to repeated loading and unloading, changes in air pressure and exposure to altitude, will in turn result in small, microscopic cracks in engine, wing or tail structures.

The crack formations tend to affect aviation safety, according to the research team at the metals branch of AFRL's Materials and Manufacturing Directorate.

In order to overcome such problems, scientists are studying the earliest stages of crack formation in turbine engine materials.

AFRL metals branch research scientist Dr. Adam Pilchak said: “The Air Force routinely inspects engine components for cracks, but it is possible to miss microscopically small cracks with current inspection methods.

"We want to be confident that an undetectable crack does not grow to failure before the next inspection.

"In order to overcome such problems, scientists are studying the earliest stages of crack formation in turbine engine materials."

“Because crack growth rates can vary considerably depending on how a material is processed, it is important to understand the worst-case scenario that leads to the shortest fatigue lifetime.”

AFRL researchers are using a scanning electron microscope (SEM) to magnify the surfaces of fractured laboratory samples or components taken from aircraft engine surfaces up to 50,000 times to precisely determine where a crack initiated.

The better understanding of crack initiation sites and the material on which cracks form will help in determining the root cause of a failure, therefore improving safety.


Image: An engineer carrying out aircraft research. Photo: courtesy of US Air Force photo / Michele Eaton.