Materials research helps boost Helicopter safety

The Materials Engineering Research Laboratory of the United Kingdom has been called in to help with a NASA (National Aeronautics and Space Administration) program to improve helicopter safety and reliability.

The laboratory is investigating delamination failure mechanisms in the type of composite materials used in the construction of United States military and civilian helicopters.

Throughout their life, any composite material components which form part of aircraft main structures can encounter unexpected or unplanned overloads even during normal flight regimes.

While not causing an immediate failure these may accumulate a 'load history effect' that may result in unexpected delamination growth rates, potentially leading to catastrophic failure of that component. It is important to understand the effects of such overloads to prevent failures, said a Materials Engineering Research Laboratory (MERL) spokesman.

The laboratory is engaged on a 12 month study to investigate effects of such overloads and of 'load history' on the delamination behaviour of composite materials used in helicopter airframes. The work involves investigating the effects of overload size and duration, and of the sequence of successive overloads of different severity. This will help determine the safest modes of helicopter operation.

The work is being conducted using a variety of MERL's servo-hydraulic test machines including its new mark-six multi-station fatigue machine which allows variable loading to be applied to multiple specimens simultaneously, reducing fatigue testing costs. The project is being carried out under contract to Analytical Services and Materials Inc of Hampton, Virginia, US.