Specialists of Central Aerohydrodynamic Institute named after N.E. Zhukovsky (TsAGI) have completed endurance tests of composite wing box prototype. These tests have been performed at the request of AeroKompozit JSC (a UAC member) within the frame of MC-21 Programme performed by Irkut Corporation (a UAC member).

Residual strength tests were the final stage of 1,5 year endurance test cycle of wing box prototype. Within this time span, the fin box prototype withstanded 120,000 flight cycles, which is twice as much as design service life. 

TsAGI scientists have defined experimentally the strength and endurance of this composite construction.

According to Serguey Kulikov, the chief designer of AeroKompozit JSC, data on normalized damage localization, as the major expected outcome, has been achieved.

“The work on design of MC-21 composite wing has been performed by the company since the end of 2008. Full scope of research activities beginning from structurally similar prototypes, and then full-scale wing box prototypes could only be conducted with the support of a specialized research center, which in Russia is Central Aerohydrodynamic Institute.

The tests made us confident that damages considered in the design cases corresponded to standards of the developers of similar structures, which meant compliance with the safety of flight requirements. This proves that acquired design-and-technology solutions and applied calculated characteristics have been selected correctly”,- Mr. Kulikov said.

“During the residual strength tests, wing box prototype was loaded with crash loads. We will analyse the obtained result and give recommendations to the Customer. Additionally, we will continue the works on separate elements of this wing box prototype.  We will analyse repeated loads versus strength performance”, - Konstantin Scherban, the deputy chief of aircraft structures endurance research department, explained.

Taking into account obtained results, the tests of the next item of MC-21 wing box prototype will be performed. These tests envisage flight and ground mode alternate loads simulation.

The beginning of certification tests of MC-21 wing box prototype are scheduled for 2015.

There are four MC-21 composite wing box prototypes in TsAGI. All these items, manufactured by Diamond and FACC AG Companies at the request of AeroKompozit JSC, have been put through a set of strength tests since summer 2011. Earlier, TsAGI specialists performed stiffness, natural frequency and static ultimate load tests. Tests were conducted making required damages to the structure.

Landing gear and engine mounts were also tested. These tests allowed estimating metal-composite joints endurance.

For the first time, jointing of the composite wing box to the wing center section and sealing have been performed. Research on the influence of climate factors to strength of composite constructions is carried out.
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