Nondestructive testing technology has become important guarantee and technical support for safe and reliable operation of aviation equipments, and played an extremely important role whether in the process of aviation equipment manufacturing, producing and detection in service or daily maintenance, inspection of various models of airplane.
Nondestructive detection of aerospace equipment covers a wide range that includes the detections for aviation materials, manufacturing process of aviation components and detection of equipment (aircraft) in service, etc. Although the detections belong to nondestructive detection, but very big difference is also existed in detection points and cover areas.
1.The detection technology in service for aerospace field
In order to ensure the flight safety of aircraft and spacecraft it is necessary for related components to detect in service regularly. The vortex and ultrasonic testing technology are usually used to detect fatigue cracks of aero-engine turbine blade, turbine disc, labyrinth disc, compressor disc and bolt, screw hole, beam, purlin for fuselage and wing, landing gear, wheel hub and riveting points of multilayer aluminum skins, and corrosion damage of skin and so on.
Nondestructive testing technology has become important guarantee and technical support for safe and reliable operation of aviation equipments, and played an extremely important role whether in the process of aviation equipment manufacturing, producing and detection in service or daily maintenance, inspection of various models of airplane.
2 .In manufacturing process of aerospace industry
Nondestructive testing method is very important for raw material detection (including aluminium alloy, titanium alloy, high strength steel) ,the nondestructive testing methods such as vortex, ultrasonic, etc. are extensively used for the detections of small diameter thin-walled tube for fuel system and control system of aircraft, rocket, small diameter bars, etc for manufacturing various structural parts and fasteners. In the process of manufacturing various parts, nondestructive detection is often used. The vortex inspection or ultrasonic test are also used for finding surface defects of components, testing cracks of bolt hole inner wall, surface cracks and internal defects of turbine disk, testing main part and rim part of wheel hub.
3.Detection of aerospace composites
Composite material and cementing structure have been widely used in the manufacturing areas such as aerospace, vehicles, chemical with the advantages such as light weight, high strength and easily processing forming, excellent flexibility, corrosion resistance or heat-resistant. For instance, the fuselage of modern aerospace aircraft is made of large number of composite material and cementing structure. The nondestructive testing methods used commonly in composite materials and cementing structural are ultrasonic, acoustic impedance, sound frequency sweep, etc. Due to the problems such as material, structural, production technology, there are lot of defects in composite material and bonding structure , therefore only a detection method is difficult to achieve a comprehensive test.
4.Magnetic memory testing
Magnetic memory testing technology is a new technology developed fast in recent years which is mainly based on the magneto-elastic effect of ferromagnetic and the irreversible effect of leakage magnetic field. In the area of stress concentration, the tangential component of the magnetic field Hp (X) has a maximum value, the normal component Hp (Y) changing its symbol (crossing zero point). As a result, the stress concentration line may be judged according to symbol change of the Hp (Y) value, and the stress concentration degree calculated according to the Hp (X) values or rate of change of the Hp (Y). In this way through detection of magnetic field, the stress status of components and the stress concentration area may be judged so as to achieve the early diagnosis for the fatigue cracks such as the wing bolt hole and the landing gear , etc. For new airplane, the metal magnetic memory diagnostic technique can be used for detecting the stress distribution state of inside and outside surface of aircraft’s main load carrying structure to achieve the purpose of early diagnosis, and puts forward guidance for nondestructive testing of the future aircraft.
5.Typical application
1) Aircraft detection in service
2) Wheel hub automatic detection system
3) Vortex ultrasonic testing for precision tubes and bars
4) The manufacturing testing for aircraft components
5) The test for composite material
6) Stress concentration detection (magnetic memory testing)