疲劳断裂失效讲义.pptVIP

飞机失效问题 世界上每年都有若干飞机发生灾难性事故，80％是由于各种部件的疲劳断裂。飞机失事造成巨大的经济损失和人员伤亡。世界上有众多的航空公司，从未发生事故的很少。以华航为例，它在2002年发生事故时统计：20年里，700余名乘客丧生。 Mystery failures - de Havilland Comet G-ALYY was leased from B.O.A.C. to South African Airways. Flight SA201 was on its way from London to Johannesburg. After a fuel stop in Rome the plane took-off, but only 36 minutes later the radio-contact was interrupted in the area of Stromboli. January 1954. The next morning remains were found in the sea. Since the sea was at this place as deep as 1000 meters, no parts of the aircraft could be inspected. Only four days after the crash the Comet flights were again suspended, one of the reasons being the similarities to the YP crash. G-ALYY had only performed 2704 flighthours. A very intensive flight test program was performed in order to find out the reason of the YY and YP crashes, with no special conclusion. Only after a very long expensive investigations, which included the assembly of the remains of the crashed YP and the underwater stress test of the YU Comet which came from B.O.A.C. Finally the fuselage of YU broke up on a sharp edge of the forward escape-hatch. After that this rupture was repaired the tests were restarted, but only shortly afterwards the fuselage broke up. This time the rupture started at the upper edge of a window and was three meters long. The YP and YY crashes were due to metal fatigue, which took place because of the crystalline changes in the fuselage skin. They were amplified by the high speed and altitude the Comets were operated. The metal fatigue resulted in ruptures of the fuselage, this had as a consequence a terrible decompression at 33Kft, tearing up the plane with all known consequences. The Aloha Boeing 737 Accident Buckfuge fatigue crack propagation 发电机组轴的疲劳破坏 人体骨骼的疲劳 Complex muscle models offer deeper understanding of hip joint loading compared to Pauwel‘s model Model valida