Propeller airlines are gaining popularity especially over short distances such as European regional routes. These craft are faster, use less fuel, release less harmful emissions, and are now just as quiet and vibration-free as jet liners. MT-Propeller Entwicklung GmBh engineers and manufactures patented natural composite propeller blades that consist of a plasticized wood core, a shell of fiber-reinforced plastics, and a bonded metal erosion sheath. The products are lighter than aluminum blades, have excellent vibration damping characteristics, and are impervious to material fatigue.
This is the regional airliner Jetstream 32 of British Aerospace.
The ability to accurately predict interacting material behavior is critical when designing a propeller made of composite materials. For this, MT-Propeller relies on Femap software for FEA and the Nastran software solver. Femap, a CAD and solver-independent pre- and post-processor, helps MT-Propeller identify and eliminate blade weaknesses at an early stage. You perform static, dynamic, linear, and non-linear calculations. Femap simulates all the different materials as well as the different transitions.
Martin Albrecht’s Extra 330SC was the winning aircraft at the German championship in aerobatics in 2010.
The company operates its simulation and validation process with an error probability of less than one percent. For simulation, the designers convert the 3D CAD models into a finite element model version and transfer them into Femap. This is where all the materials and complex boundary conditions are defined. The NX Nastran solver calculates the results in four to five hours.
Shown here are high-tech propellers in composite construction.
Femap demonstrated its usefulness when bonding steel and the composite materials on a newly launched propeller blade model came undone. While the cause was first investigated as a possible manufacturing fault, the FEA verification showed that the adhesive could not withstand the high shear stresses. Thanks to the software, it was possible to determine another composite fiber layup as a solution. “Based on the FEA results, we were able to reduce stress by one-third,” said Martin Albrecht, MT-Propeller CEO.
Using FEA software, Mt-Propeller increases product quality.
This is a structural analysis of a propeller hub.
Using the software products today, MT-Propeller makes just one prototype for each propeller blade – reducing its product development cycle time. The company is 99% confident that the computer-generated model will be feasible. For instance, in only six months, propellers were produced for the BAE Systems Jetstream 41, a 32-seat twin engine turboprop aircraft. It generates 3.2 tons of thrust during take-off at 1,680 HP.
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