Abstract: This article presents a comprehensive review on the machining technology of aero-engine casings. The material removal mechanism of mechanical machining and nontraditional machining is introduced in the first part. Then, several mechanical machining technologies of aero-engine casings (e.g. numerical control machining, turn-milling complex machining, machining vibration suppression) are summarized. Subsequently, the research progress and academic achievements are explored in detail in terms of the electrochemical machining, electric discharging machining and ultrasonic machining in the field of nontraditional machining technology of aero-engine casings. Finally, the existing challenges in mechanical machining technology and nontraditional machining technology of aero-engine casings are analyzed, and the developing tendencies to aero-engine casings machining is proposed.
Abstract: Disks (e.g., compressor disk, turbine disk) are key components of aero-engine, which play an important role in flight safety. Over the past several decades, extensive studies have been carried out to study the modeling and detection methods of aero-engine disks with cracks. However, to the best of the authors’ knowledge, no comprehensive review has been reported yet to summarize the existing studies. In this paper, the dynamic models of disks with cracks are summarized firstly. Then, the crack detection methods are reviewed. Finally, the limitations and future trends are discussed, which can provide inspiration for future research.
Abstract: Due to the high energy density, fast welding speed and non-contact welding, laser welding technology can be used to weld key components with complex curved surfaces. However, narrow work-piece gaps and high matching accuracy are required in laser welding, which increases the difficulty of welding. For this reason, the design of high-precision fixture has become a research hotspot. The difference between laser welding fixture and traditional welding fixture is that laser welding fixture is more complex in structure, requires high precision and needs to apply pressure on the weld. This paper discussed the structural characteristics of fixed, rotating and mobile welding fixture, and analyzed the work-piece shape, welding requirements and production mode. Laser welding fixture design engineers can quickly design the fixture according to product requirements, and refer to the structural type and design method of tooling. It not only improves the design efficiency of fixture, but also improves the processing efficiency and accuracy of welding. Finally, the challenges of structural design in laser welding fixture are pointed out. It provides a direction for the development in the structural design of laser welding fixture in the future.
Abstract: The countersunk bolt is widely used in aircraft bolt connection because it can satisfy the requirements of aircraft aerodynamic shape and reduce the radar reflection area. However, the countersunk bolt is affected by the geometric error of countersink and assembly error in the assembly process, which directly affects the joint strength of composite structure. The tensile strength of the composite structure of the countersunk bolt is affected by the countersink depth, angle error and nail pressing method. In this paper, the effects of sink depth, countersink angle error and nail pressing method on the tensile strength of single-bolt single-lap sink interference joint were studied by experiments and numerical methods. Nine experimental specimens are fabricated according to the ASTM-D5961 standard. According to the comparative analysis of experimental and simulation data, the results indicate that the oblique pressure connection should be better than the direct pressure connection; The ultimate strength of the joint increases with the increase of the countersink angle deviation ; the increase of countersink depth error leads to the decrease of tensile ultimate load of joint ; The ultimate tensile strength of the joint decreases with the increase of the angle of the deflection direction of the angle error, and the angle error of the countersink should be controlled within 1°. The empirical formula of the influence of countersink geometric error on the ultimate tensile strength of the interference connection structure of composite countersunk head bolts is established, which provides a reference for improving the connection strength of composite head bolts in engineering applications.