Carbon fiber reinforced polymer (CFRP) composites have gained widespread application in aerospace, automotive manufacturing, wind turbine blades, and other fields due to their high specific strength, high specific stiffness, excellent fatigue resistance, and superior corrosion resistance. However, characteristics such as anisotropy and low interlaminar strength render them highly susceptible to various forms of damage during the drilling process, significantly affecting the service performance of the components. This paper presents a systematic review of the formation mechanisms of drilling damage in CFRP, its influence on the mechanical performance of laminates, and recent advances in damage suppression strategies. Typical damage, including fiber burrs, fiber tearing, hole-wall damage, and internal delamination, are first summarized in terms of their characteristics and underlying formation mechanisms, together with the application of acoustic emission techniques for damage identification and monitoring. The effects of drilling damage on the tensile, compressive, flexural, bearing, and fatigue properties of CFRP laminates are then critically discussed, with particular emphasis on the intrinsic correlations between damage evolution and mechanical property degradation. Damage suppression strategies are systematically reviewed from the perspectives of process parameter optimization, dedicated tool development, advanced drilling technologies, and intelligent process control. Followed by a discussion of future research directions, future studies should focus on further elucidating the quantitative relationship between drilling damage and mechanical performance, while advancing multiscale simulation methods, intelligent in-process monitoring, and adaptive control technologies, thereby promoting high-quality and high-efficiency drilling of CFRP components.

To enhance the adhesion of ceramic coatings in turbine blade Thermal Barrier Coatings (TBCs) systems, Laser Surface Texturing (LST) was employed to create microstructures on the metal bond coat. The bonding conditions and failure mechanisms of the ceramic coatings within these microstructures were thoroughly investigated. Femtosecond laser technology was used to fabricate three types of high-quality microstructure grooves: linear, sine wave, and grid patterns. These grooves exhibit uniform morphology, well-defined edges, and smooth inner walls. After ceramic coating deposition, columnar crystal structures grew perpendicularly along the groove walls, completely filling the microstructures and forming an arched support structure that significantly enhances mechanical interlocking and adhesion. Among the different microstructures, grid patterns demonstrated the best adhesion performance. In scratch tests, grid-patterned microstructures exhibited only localized small block spalling under high load conditions, avoiding large-scale delamination. This superior performance is attributed to the ability of grid pattern to effectively distribute stress in multiple directions and prevent crack propagation. By reducing stress concentration and enhancing mechanical interlocking points, grid-patterned microstructures also showed excellent resistance to spallation during thermal cycling, markedly improving the thermal resistance and adhesion of coating.

To establish the mechanism of millisecond laser processing of SiC_f/SiC ceramic matrix composites, and to support the design and optimization of millisecond laser processing techniques, this paper conducted experimental and simulation studies. The research focused on the ablation threshold of millisecond laser processing of SiC_f/SiC ceramic matrix composites and laser scribing experiments, investigating the removal mechanism of these materials. By measuring scribing width, depth, and thermally affected zone thickness, the study revealed the removal mechanism of millisecond laser processing of SiC_f/SiC ceramic matrix composites and the influence of different laser process parameters on processing outcomes. The results indicate that effective ablation processing of SiC_f/SiC ceramic matrix composites can be achieved at a laser processing speed of 1 mm/s; the ablation threshold for SiC_f/SiC ceramic matrix composites is approximately Φ_th = 0.013 J/cm². The increasing laser energy density results in higher processing depth, width, and thermal affected zone thickness, with depth showing the most significant increase, approximately 1870.07 μm. Increasing the equivalent pulse number enhances processing depth and width, but reduces the thermal affected zone thickness by approximately 6.0 μm.

The deviation in wall thickness caused by core shift during the investment casting process significantly impacts the strength and service life of hollow turbine blades. To address this issue, a core shift limitation method is developed in this study. Firstly, a shift model is established based on computational fluid dynamics and motion simulation to predict the movement of the ceramic core in investment casting process. Subsequently, utilizing this model, an optimization method for fixturing layout inside the refractory ceramic shell is devised for the ceramic core. The casting experiment demonstrates that by utilizing the optimized fixture layout, not only can core shift during the investment casting pouring process be effectively controlled, but also the maximum wall thickness error of the blade can be reduced by 42.02%. In addition, the core shift prediction is also validated, with a prediction error of less than 26.9%.

Ultrasonic vibration-assisted drilling (UVAD) has recently been successfully applied in the drilling of carbon fiber reinforced polymer/plastic (CFRP) due to its high reliability. Multiple defects have been observed in the CFRP drilling process which negatively affects the quality of the hole. The carbon fiber/bismaleimide (BMI) composites is an advanced kind of CFRPs with greater strength and heat resistance, having been rapidly applied in lightweight and high temperature resistant structures in the aerospace field. To suppress the defect during the drilling of carbon fiber/BMI composites, it is necessary to comprehensively understand the defect formation and suppression mechanism at different positions. In this study, the defects formation in both conventional drilling (CD) and UVAD were observed and analyzed. The variation trend in the defect factor and thrust force with the spindle speed and feed rate were acquired. The results revealed that the UVAD could significantly enhance the hole's quality with no delamination and burr. Meanwhile, the defect suppression mechanism and thrust force in UVAD were analyzed and verified, where the method of rod chip removal affected the exit defect formation. In summary, UVAD can be considered a promising and competitive technique for drilling carbon fiber/BMI composites.

Interference fit has advantages in improving fatigue behaviors of composite bolted joints; however, interference fit bolt insertion tends to cause damages in laminates weakening joint mechanical properties. Therefore, an experimental study was conducted to investigate bolt insertion damages of Carbon Fiber Reinforced Polymer (CFRP)/CFRP interference fit bolted joints. Mechanical behaviors of joints were also evaluated experimentally under both quasi-static loads and cyclic loads. Scanning Electron Microscope (SEM) and high-resolution X-ray micro-CT scan were used to examine micro damages in laminates. Damage and failure behaviors of joints were characterized. The results demonstrated that the hole entrance in upper laminate and the laminate boundary near the hole wall were the most critical regions for damages during bolt insertions. However, the influence of those damages on quasi-static failure loads and fatigue failure modes of joints was minimal. Delamination and matrix cracking occurred first in laminates following fiber and matrix fracture in quasi-static tensile tests. Interference fit could improve the fatigue resistance of the laminate hole; however, the bolt seemed to suffer a more critical local fatigue loading condition. This paper can contribute to composite structure designs, especially in understanding damage and failure behaviors of composite bolted joints.

The in-situ TiB₂ particle reinforced Al-based metal matrix composites have become a series of promising aeronautical materials due to the advanced properties such as finer evenly-distributed grains, cleaner particle-matrix interface, improved mechanical performance and strength when compared with ex-situ SiC particle reinforced Al-based metal matrix composites. However, over the last 50 years, a significant body of research has been carried out on ex-situ SiC particle reinforced Al-based metal matrix composites from material fabrication process, material property improvement, material mechanical test to machining performance such as machined surface integrity, cutting process simulation and modeling, parameter optimization and fatigue characteristics. For in-situ TiB₂ particle reinforced Al-based metal matrix composites, studies in recent years were mainly focused on the material preparation process and property development and few published works was found on the machining performance of this new kind material. Hence, this article aims to provide a general overview of recent achievement on machining performance of in-situ TiB₂ particle reinforced Al-based metal matrix composites.