First of all, the Y-20 transport aircraft is a large military transport aircraft independently developed by China, with a large load capacity and range, which is widely regarded as a major achievement in the field of aviation in China. According to reports, in 2014, the Y-20 underwent a full-aircraft static destruction test, which is an important test for the structural strength and safety of the aircraft. 
In such tests, the aircraft model is exposed to forces beyond the limits of its design load to assess its carrying capacity and flight safety. Tests may include simulating a variety of different load scenarios to ensure that the aircraft is able to maintain structural integrity and the safety of its occupants in the event of an accident. According to reports, when the Y-20 wing disintegrated and broke in an instant during the test, the audience seemed to applaud and praise, 1This is a psychological release for designers. Because the static failure test of the whole machine is a high-risk test, designers may have gone through months or even years of design, calculation, and optimization before the test. They are likely to feel very relieved when the trial ends successfully and achieves the desired results and expresses their emotions by clapping and shouting. 
2.This is an affirmation of the design and manufacturing process of the Y-20. The static failure test of the whole aircraft is a key link to ensure the strength and reliability of the aircraft structure. If a fracture is found in the test, it means that the designers have achieved accurate results in the design and calculations of the aircraft, and it also proves that the aircraft behaves in accordance with the simulation when exceeding its design limits. As a result, designers continue to take pride in their work and are satisfied with achieving the desired results. 
3.This is a confident demonstration of the best technology in the industry. Pushing the Y-20 wing to the limit and observing its rupture is an act of public display aimed at demonstrating China's strength and progress in the field of military aviation technology. By publishing such test footage and the high sentiments of the designers, China may be trying to demonstrate the level of development of its military industry at home and abroad, and send a message that China is capable of developing and producing high-performance military aircraft indigenously. To sum up, when the Y-20 wing instantly disintegrated and broke in the static failure test of the whole aircraft, the excitement of the designers and the applause of the audience may be an expression of the smooth progress of the test and the achievement of the expected results. At the same time, this is also a confident demonstration and ability test of the technology of the industry. Please note that the above explanations are based only on the information you provide and do not represent complete accuracy of the facts. For more detailed information, please consult the relevant authoritative ** report.