In fields such as industrial engineering and healthcare, additive manufacturing technology is a focal point for researchers. Wear represents a significant challenge for additive manufacturing technology, increasingly emerging as a research hotspot in recent years. This review categorizes and summarizes wear issues in additive manufacturing technology, providing a comprehensive overview of wear mechanisms, materials, and the effects of additive manufacturing processes on wear. Research indicates that different wear mechanisms result in varying wear characteristics. The inherent properties of the materials significantly influence wear during the manufacturing process. Modifying material compositions and optimizing microstructures can enhance the wear properties of additive manufacturing products. Additionally, the study of additive manufacturing technology in repair and maintenance is a current and anticipated research hotspot for the coming decades. In the research of additive manufacturing processes, the effective regulation of process parameters and their post-processing play a positive role in enhancing the wear characteristics of products produced via additive manufacturing. Lastly, the challenges and recent advancements concerning wear issues in the field of additive manufacturing technology research are summarized.

A conformal microstrip antenna is highly integrated with the carrier profile, giving it the advantage of reduced carrier space. However, the processing technology for fabricating an antenna with a conformal surface is complicated and expensive owing to its irregular shape. Therefore, it is particularly important to find ways to reduce the difficulty in producing conformal conductive patterns. For the production of conformal microstrip antennas, a five-axes motion printing system is proposed to print conductive patterns on nonexpanded surfaces. The conductive pattern uses a new boundary-alignment-optimization algorithm in the printing process to improve the accuracy of the boundary of the conductive pattern by optimizing the ink-dropping points in the motion command. The short-time and low-temperature sintering of the conductive pattern by using a flash light enables it to exhibit conductive properties. This method is practically implemented to fabricate a conformal array microstrip antenna. The main and side lobes of the electric and magnetic fields in the directional pattern measured in the microwave darkroom have the same trend as in the simulation diagram. Thus, the effectiveness of this method was verified through simulation analysis and experimental results.

Inkjet printing technology is widely used in the manufacture of conformal structures, such as load-bearing antennas or frequency-selective surface radomes. It is particularly promising for preparing conductive patterns on non-developable surfaces. Existing printing technologies employ a single nozzle and a five-axis linkage technique for printing, which is time-consuming. In this study, a conformal plane printing technology based on the arrayed nozzle was developed to prepare conductive patterns on a non-developable surface. The technique actualizes fast printing of passive circuits on a conformal surface, such as a microstrip antenna. Compared to printing techniques employing a single nozzle, the proposed method greatly improves the printing efficiency on conformal surfaces. Specifically, we first developed a model for the driver waveforms and the printing injection parameters via simulation. Subsequently, the accuracy of the computational fluid dynamic simulation results was validated by comparing them with the experimental measurements of droplet trajectory captured using a camera. Next, a droplet spreading model was established, considering energy conservation principles. Finally, a conformal surface printing technology using arrayed nozzles was developed based on the injection parameter and droplet spreading models. The effectiveness and feasibility of the proposed printing method were further validated via simulation and experimental tests of return loss.

This letter proposes a Ka-band highly integrated phased-array antenna (HIPAA) by utilizing the joint design of phased-array antennas and microchannel heat sinks. In the HIPAA, 52-element patch antennas, tile transmitting (Tx) modules, microchannel heat sinks and a stripline feeding network were integrated in a 2.8 mm thin functional block. Moreover, a new microchannel heat sink with a ladder-shaped inlet header was designed to decrease the maximum temperature and temperature non-uniformity. Low-temperature cofired ceramic (LTCC) was applied to fabricate the antenna prototype. The electromagnetic and thermal experiments were conducted, and a satisfactory performance was achieved: a peak gain of 20.9 dBi, a side-lobe level of -12 dB, and the scanning angle range from -44.5° to 45.3°.

With the advent of wearable communication devices, microstrip antennas have developed multiple applications due to their ultra-low-profile properties. Therefore, it is essential to analyze the problem of frequency shift and impedance mismatch when the antenna is bent. For the case of a rectangular patch antenna E-plane bent on the cylindrical surface, (1) this paper introduces the effective dielectric constant into the cavity model, which can accurately predict the resonance frequency of the antenna, and (2) according to the equivalent circuit model of the antenna resonance mode, the lumped element parameters are calculated based on the above effective dielectric constant, so that impedance characteristics and the S-parameter matching the port can be quickly constructed. From the perspective of circuit frequency characteristics, it explains the change in the transmission performance of the curved antenna. The experimental results show that the maximum difference between the experimental and theoretical calculation frequencies is less than 1%. These results verify the validity and applicability of the theory in the analysis of ultra-low-profile patch antennas and wearable electronic communication devices. It provides a theoretical basis for the fast impedance matching of patch antennas under different working conditions.