With the continuous development of intelligent society, piezoelectric sensors are increasingly used. The types, structures, measurement principles and application scenarios of piezoelectric sensors are described. The research progress on sensitive element materials is reviewed, and the application of high-temperature piezoelectric materials and lead-free piezoelectric materials is summarized. Finally, the future development direction of piezoelectric sensors is prospected.

Research progress on four piezoelectric application materials in the field of energy harvesting, including piezoelectric ceramics, multi-stacked piezoelectric ceramics, piezoelectric polymers and piezoelectric composites, is reviewed. The structural characteristics, preparation methods, and application occasions are highlighted, and the research trends of the piezoelectric materials in future is proposed.

Rubber is an important material in mechanical engineering industries. Rubber sealing materials play a key role in many mechanical instruments, and aging of rubber seals may cause unpredictable failures or even huge losses. Hence, aging research of rubber sealing materials are attracting great attentions. The aging research progress of rubber sealing materials is reviewed, including aging behavior and mechanism, effects of stress and chemical media on aging, lifetime evaluation indexes and prediction, and aging analysis techniques. The existing problems in aging research of rubber sealing materials are discussed. Future research perspectives are proposed, including studies on accelerated aging methods, aging mechanism, correlation between accelerated aging and natural aging of rubber seals, and so on.

Additive manufacturing is an important development direction of advanced manufacturing technique for metal parts, but the metal powder for additive manufacturing has some problems such as insufficient research and development, weak stability and incomplete standards, which seriously restrict its development. The basic principles of common spherical metal powder preparation techniques including centrifugal atomization method, two-stream atomization method and spheroidization method are summarized, and their advantages, disadvantages and development status are introduced. It is proposed that the development of domestic additive manufacturing powder preparation technique can start from two aspects. One is to carry out process and equipment improvement and standardization research on traditional methods, and build automated factories; the other is to strengthen the research on basic theories of powdering and explore new processes.

Fatigue failure analysis processes and fatigue life assessment methods for metal materials are reviewed. The evaluation theories and models which were used widely in engineering, such as the Miner linear cumulative damage theory, the energy method, the elastic-plastic finite element method, the overload retardation model, are mainly introduced. The application conditions, advantages and disadvantages of these methods and models are also analyzed. With the development of the experimental technique and computer simulation technology, the assumptions will be more accuracy. Therefore the combined method of experiment and computer simulation for the fatigue life prediction and assessment of metal materials will be one of the most important development directions in the future.

The wire and arc additive manufacturing (WAAM) has gained more and more attention because of its unique advantages in forming large-scale components, and has become one of the most widely used metal additive manufacturing technology. The development history of WAAM is described. The influence of process parameters on the morphology of deposited layer and the evolution mechanism of microstructure is analyzed from the perspective of “shape and property control”. The numerical simulation methods for residual stress and their advantages and disadvantages are discussed, and it is pointed out that the combination of computational fluid dynamics and finite element method is one future research trend. The common methods for controling the residual stress and deformation, as well as the problems and challenges in wire and arc additive manufacturing, are summarized.

On the basis of active and passive vibration control principles, four piezoelectric smart materials used in vibration control field, including single layer piezoelectric ceramics, multi-stacked piezoelectric ceramics, piezoelectric fiber composite and 0-3 type piezoelectric composite, are reviewed. The research progress of the structural characteristics, preparation process of the materails and their application for vibration attenuation in the fields of machinery manufacturing, aerospace and marine shipping are highlighted. The research direction in future of the piezoelectric materials is proposed.

As a main raw material for metal additive manufacturing, spherical metal powder characteristics play an important role in the performance of additive manufacturing parts. The efficient preparation of high-quality spherical metal powder has become an important development direction to promote the upgrading of additive manufacturing technologies and industrial applications. The main preparation methods of spherical metal powder including gas atomization, plasma rotating electrode atomization and plasma atomization are introduced. The technical principle and the influence of important process parameters on powder characteristics are discussed, and the future development direction of these three types of technologies is prospected.

When the thermal stress caused by sudden temperature change of ceramic materials exceeds its strength, materials will happen to crack, peel and even fracture, and then failure. Therefore, the study of thermal shock resistance of ceramic materials becomes a hot spot. The evaluation theory of thermal shock resistance of ceramic materials and the methods for testing and characterizing are described. The methods of improving thermal shock resistance, including strengthening and toughening, improving thermal conductivity, reducing thermal expansion coefficient, and reducing elastic modulus, are reviewed. The external influencing factors of thermal shock resistance are summarized. The development direction of improving thermal shock resistance of ceramic materia