NAL successfully tests LCA O/B Elevon Box at hot wet conditions

Test setup of static strength test of Elevon box

It was a great day on friday the 17 April 2009, for the SIG group of STTD division, NAL Bangalore for successfully completed the static strength tests of LCA O/B Elevon Box at hot wet conditions
The test article tested was an Outboard Elevon box of LCA which was tested at hot wet conditions to ascertain its static strength ,before which the test box was aged for several months for moisture absorption . The Elevon box was tested for a few critical loadcases upto design limit load and finally tested for the design ultimate load for one of the most critical loadcases.
A robust test rig was designed for the testing of the elevon box which is shown in the above figure . An environmental chamber was built around the test box using high temperature polythene sheet for the circulation of steam around the box for maintaining the required temperature and humidity. The test rig and the fixtures was designed in- house in the division.
"The test article was loaded for100% DLL and was further continued to go to 150% DLL which is the design ultimate load and the test box survived that load level without any failure or amage and it was a success"said the Scientist in charge of the test Mr. M Mohan kumar .
It was observed that the strains at the critical locations monitored were well below the limits
and was not of any concern. The good thing that came out from this test was that the elevon box was able to take the ultimate loads at the aged conditions without even a small snag as the earlier experiences in testing the same elevon box at room temperature had some design issues
As an implication of these tests ,the LCA design team are assured of theLCA wing component elevon box strength capability in the worst operating conditions involving high temperatutre and humidity conditions.