Specialists of Aircraft Strength Department of the Central Aerohydrodynamic Institute named after Professor N.E. Zhukovsky have completed the endurance testing of a test wing box made of a polymer composite. This work is being carried out under an agreement with AeroComposite (part of United Aircraft Corporation) in the network of development of advanced short- and medium-haul MS-21 aircraft, press-service of TsAGI reports.

«At the final stage of this work (the research took 1.5 years) the residual strength tests have been completed. The test program has amassed over 120,000 cycles (twice as much as the jet’s design service life). During the experiments specialists of TsAGI defined the actual strength and endurance of the composite component», - the press-service noted.

According to Chief Designer of AeroComposite, Sergey Kulikov, the most important results have been obtained – data confirming non-proliferation of standardized damage. «I would like to remind you that the company started the development of MS-21 composite wing in late 2008. This work, which includes testing of models and full-scale test wing boxes, would have been impossible without the assistance of TsAGI. The institute not only has the unique test facilities but also the high-skilled specialists. The test results confirmed that damage included in the boundary conditions during calculations meets the standards set by the developers of such components. This fact confirms that technical and technological solutions used will assure the component’s claimed performance and flight safety», - Kulikov said.

«In the course of residual strength testing the wing box has been loaded to destruction. Now we have to analyze the obtained results and provide the customer with necessary guidelines. In addition, we will continue studying some elements of the wing box. We will study the impact of cyclic loads on strength characteristics», - Konstantin Sherban, Deputy Head of Aircraft Endurance scientific research department, said.

«The next MS-21 test wing box will be tested taking into account the obtained results. During the test the alternating loads will be simulated for both flight and ground conditions. The certification testing of MS-21 composite wing box will be started in 2015», - the press-service added.

A total of four MS-21 test wing boxes have been delivered to TsAGI. All these prototypes manufactured by «Diamond» and «FACC AG» under agreement with AeroComposite, have been undergoing strength tests at the institute’s laboratories since summer 2011. TsAGI has already carried out stiffness, frequency and static tests before.

In the network of the test program the standardized damage has been inflicted on the component. Moreover, mounting brackets for engine and landing gear mounting have also been tested in order to assess the strength of metal-composite joints. For the first time the wing box has been joined with the model of the airframe’s center section and pressurized. The studies, aimed at assessing the impact of climatic conditions on the strength of composite components, are underway, the press-service noted.