Bearings are crucial components that decide whether or not a wind turbine can work smoothly and that have a significant impact on the transmission efficiency and stability of the entire wind turbine’s life. However, wind power equipment operates in complex environments and under complex working conditions over long time periods. Thus, it is extremely prone to bearing wear failures, and this can cause the whole generator set to fail to work smoothly. This paper takes wind turbine bearings as the research object and provides an overview and analysis for realizing fault warnings, avoiding bearing failure, and prolonging bearing life. Firstly, a study of the typical failure modes of wind turbine bearings was conducted to provide a comprehensive overview of the tribological problems and the effects of the bearings. Secondly, the failure characteristics and diagnosis procedure for wind power bearings were examined, as well as the mechanism and procedure for failure diagnosis being explored. Finally, we summarize the application of fault diagnosis methods based on spectrum analysis, wavelet analysis, and artificial intelligence in wind turbine bearing fault diagnosis. In addition, the directions and challenges of wind turbine bearing failure analysis and fault diagnosis research are discussed.

Wind power, being a recyclable and renewable resource, makes for a sizable portion of the new energy generation sector. Nonetheless, the wind energy industry is experiencing early failure of important components of wind turbines, with the majority of these issues also involving wind power bearings. Bearing dependability is directly tied to the transmission efficiency and work performance of wind turbines as one of its major components. The majority of wind turbine failures are due to bearings, and the vast majority of bearing failures are due to lubrication. The topic of improving the accuracy and life of wind power bearing motion is becoming increasingly essential as the wind power industry develops rapidly. This study examines the various constructions and types of wind turbines, as well as their bearings. We also examined the most typical causes of friction and lubrication failure. Furthermore, contemporary research on wind turbine bearings has been compiled, which mostly comprises the study and development of lubrication technology and other areas. Finally, a conclusion and outlook on current challenges, as well as future research directions, are offered.

Power generation from wind farms is growing rapidly around the world. In the past decade, wind energy has played an important role in contributing to sustainable development. However, wind turbines are extremely susceptible to component damage under complex environments and over long-term operational cycles, which directly affects their maintenance, reliability, and operating costs. It is crucial to realize efficient early warning of wind turbine failure to avoid equipment breakdown, to prolong the service life of wind turbines, and to maximize the revenue and efficiency of wind power projects. For this purpose, wind turbines are used as the research object. Firstly, this paper outlines the main components and failure mechanisms of wind turbines and analyzes the causes of equipment failure. Secondly, a brief analysis of the cost of wind power projects based on equipment failure is presented. Thirdly, the current key technologies for intelligent operation and maintenance (O&M) in the wind power industry are discussed, and the key research on decision support systems, fault diagnosis models, and life-cycle costs is presented. Finally, current challenges and future development directions are summarized.

The temperature and humidity were found to be the most effective parameters in the behavior of polyurethane flexible adhesive bonded aluminum joints. In order to obtain the effect of environment on bond strength, toughness, failure displacement, joints stiffness and failure model, in this work, aluminum single-lap joints were tested under various temperatures (25, 40, 60 and 80 °C) and relative humidity (RH, 55, 65, 75, 85, 95 and 99%) using an environmental chamber. The results showed that as the humidity increased from 55 to 99%, bond strength decreased as linear function. As the temperature increased from 25 to 80 °C, the bond strength decreased as exponential function. The joints stiffness reduced gradually with the increase of temperature and humidity. The analysis of the failure section of the ageing joints showed that the humidity caused the transition of the failure model, and the increase of the temperature promoted the change of the failure model. Besides, at low humidity (55 and 65%), failure displacement decreased gradually with the increase of temperature, and at high humidity (95 and 99%), failure displacement increased. This study will help engineers design a reliable, safe and effective bonding structure. And it is conducive to solve the problem of joint strength degradation in the hygrothermal environment.

This paper focuses on the effect of cyclic hygrothermal aging on the mechanical behavior of the adhesive bonded aluminum joints. The adhesive joint specimens were immerged in the temperature/relative humidity set at 80 °C/95％ and −40 °C/30％ for cycle experiments for un–aged, 20, 40, and 60 cycles, respectively. Joint bonding angles were set to 0°, 15°, 30°, 45°, 60°, 75° and 90°. The stress modes of the adhesive joints were directly related to the bonding angles. It revealed that the hygrothermal aging significantly decreased the ultimate failure strength and stiffness of adhesive joints. The failure strength decreased with the increase of aging cycles. Besides, for the tensile–shear combined loading, the environmental degradation was much more obvious. The joint failure displacement values increased obviously after hygrothermal aging than that of un–aged. With the increase of aging cycles, the failure displacement of 75° and 90° joints increased more obviously than that of 0°, 15°, 30°, 45° and 60° joints. Moreover, Fourier Transform Infrared (FTIR), Energy Dispersive X-ray Spectrometer (EDS), Scanning electron microscope (SEM) and Differential scanning calorimetry (DSC) was used to analyze the characteristic of adhesive.

Fiber-reinforced polymers (FRPs) have great potential in shipbuilding. As a new type of material, basalt-fiber-reinforced polymer (BFRP) has received increasing attention due to its good economic and environmental performance. In this paper, BFRP single-lap joints (SLJs) bonded by Araldite^®2011 and Araldite^®2014 were selected as sample objects, the joints, aged for 240 h, 480 h, and 720 h, were experimentally analyzed in 3.5% NaCl solution/5% NaCl solution at 80 °C. The sequential dual Fickian (SDF) model was used to fit the water absorption process of the dumbbell specimen material. By comparison, the water absorption of the material occurred mainly on the adhesive and the water absorption of Araldite^®2011 was higher than that of Araldite^®2014. The decrease in the T_g of the aged joint adhesive was characterized by DSC, and the TG test showed that the polymer material in the joint was degraded by the damp–heat effect. The quasi-static tensile test showed that the decrease in joint failure strength was positively correlated with the water content of the solution. The Araldite^®2011 adhesive joint showed better mechanical properties and stability than the Araldite^®2014 adhesive joint, while the secondary crosslinking of the bound water with the polymer chain resulted in a slight increase in the stiffness of the aged joint. From comprehensive observation of the macro-section and SEM-EDX images, it is concluded that the failure mode of the joint changes from fiber tearing to mixed failure of fiber tearing and adhesive layer cohesion, and the plasticizing effect of the epoxy resin in the adhesive and chemical corrosion of salt ions weakens the adhesive layer’s bond strength.