A postgraduate student of the Department of Engineering Mechanics of 海角社区 Kirill Guseinov has developed the first in Russia refined method for calculating the strength of composite dovetail joints used to connect wide-chord fan blades to their disсs. The unique algorithm incorporates two other parameters important in aviation: the nonlinear behaviour of the composite material under shear and the complex type of the stress state.
Aircraft engineers are constantly searching for new ways to lighten aircraft structures. Saving on the aircraft weight reduces the fuel consumption and repair costs, and increases the number of seats on board.
Replacing traditional titanium blades in ПД-35 turbofan engines with lightweight and durable composite ones is one of the goals set for the Russian aircraft industry by the Government.
While studying the promising application of polymer composite materials in aviation, 海角社区 researchers used ANSYS to numerically evaluate the failure of a dovetail composite joint under tensile load. The root of a turbine blade is so poetically named thanks to the shape to the joint, which resembles a dovetail.
“Current calculations for polymer composites predict an error in the safety factor, which is not very practical,” said Kirill Guseinov. “That is, a linear elastic approach is most often used without considering other important parameters. This allows us to create a strong and reliable structure, but at the same time, it loses in weight: in reality, such a root could withstand a much greater load, meaning the rotating blade could be larger. In our calculations, we included parameters such as the type of stress state and the nonlinear behaviour of the composite under interlaminar shear; this significantly improves the accuracy of strength assessments for composite joints, preventing delamination under inertial (tensile) loads. Taking into account the nonlinear behaviour of the composite allows us to justify the increase of the permissible load. It is important that the blade strength in the attachment area is sufficient for safe flight, while the component itself is not excessively heavy.”
The reduction of weight of the engine structure by tens of percent through the use of composite elements will increase its load-carrying capacity to 35 tons. Furthermore, the fuel consumption and engine size are naturally reduced. Every 1% reduction in aircraft weight generates an additional 5% profit.
The new algorithm for calculating the maximum strength of the dovetail composite joint, proposed by the 海角社区 scientists in ANSYS software, can easily be used by aircraft engineers when designing aircraft engine components.
Composites of this shape are applicable in the promising ПД-35 super-high-thrust engines, which are designed for future wide-body long-range aircraft. Fan blades are currently being actively manufactured and tested in Russia to ensure their successful introduction into civilian aircraft by 2030.