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Nowadays, many scholars at home and abroad have studied the vibration of agricultural machinery, especially harvesting machinery. However, this research has lacked the analysis of vibration characteristics of harvesters under the condition of multi-vibration excitation in field work. Therefore, by taking the chassis frame and main vibration sources of a 4JZ-1700 crawler pepper harvester as the research object, this paper aims to investigate the vibration characteristics of the pepper harvester under different working conditions, and the impact of the excitation of various working parts on the chassis frame. Firstly, a modal simulation was carried out with the modal module of ANSYS Workbench to study the natural frequency of the chassis frame. The results demonstrated that the natural frequency of the chassis frame was within 23–76 Hz. A DH5902 dynamic signal acquisition instrument was used to collect vibration signals from seven measuring points under different working conditions of the whole machine, and the collected time domain signals were extracted by Fourier transform. According to the time domain signal, the amplitude at the engine support was the largest under the static no-load condition, and the transmission of engine vibration was attenuated to a certain extent, which imposes a significant effect on the vibration isolation and vibration reduction of the harvester frame. Under the field walking condition, the amplitudes of the left front of the chassis frame and the driving shaft of the cleaning separation device were abnormal, which was mainly attributed to the unequal road surface and the high center of gravity of the cleaning separation device. Through frequency domain analysis, it can be found that the main vibration frequency of most measuring points of the harvester was close to the vibration frequency of the engine under the static no-load condition, and the excitation frequency of most measuring points approximated to the working frequency of the picking drum and the cleaning separation device under the field walking condition. In addition, there were plenty of phenomena in which the main frequency of vibration was detected in the high frequency region above 200 Hz, with messy frequency values. This is due to the poor lubrication of the bearing part of the harvester, causing intense friction between the rotating shaft and the bearing, which also drives the high frequency vibration of the chassis frame. In general, this study can provide a method reference for vibration analysis of agricultural machinery and propose effective measures to reduce vibration based on the conclusions.

The effects of laser shock peening (LSP) on the microhardness, residual stress, and microstructure of the Ni60 cladding layer and the combined area of the 20CrNiMo alloy for high-speed rail brake disks are investigated to address the problem of coarse columnar crystals and residual tensile stress, which affect the coating–substrate bonding performance and the application development of the laser cladding repair process. The results indicate that LSP can improve the microhardness, prefabricate residual compressive stress field, and refine the microstructure of the cladding layer and the combined area. The surface hardness of the cladding layer increased by 14.55%, 34.92%, and 40.21% after the energy impact of 6, 9, and 12 J, with an impact depth of about 1.2, 2.2, and 2.5 mm, respectively. The roughness result showed that the effect is more satisfactory under the 9 J energy impact. The grain refinement is significant compared to the Clad specimen, with the average grain area at the molten layer's top, middle, and bottom reduced by 35.5%, 79.6%, and 85.8%, respectively. A residual compressive stress of −538 MPa is introduced on the surface of the clad layer, with a compressive stress value of −30 MPa at a depth of 2 mm. After the LSP, the microstructure and properties of the clad layer and the combined area are significantly improved. Still, no new phases appear and do not significantly affect the diffusion of elements between the dendrites and the dendrites.

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Copper alloys have excellent mechanical properties, high electrical and thermal conductivity, good resistance to wear and corrosion, and a high recycling rate. Certain parts made from copper alloys are extensively used in automobile, aircraft, and ship-building industries. But, their thermal fatigue performance needs to be improved for extending the application fields of the copper alloys to extreme conditions such as high temperature or