A stress concentration area of big tilling depth rotary blade with 350 mm turning radius is found by ANSYS, and is strengthened by laser shock peening (LSP). The surface properties of rotary blade for LSP, included residual stress, surface micrograph, microstructure and hardness, are researched in this article. The results show that microstructure density is higher after LSP, and the layer is smoother, then the stress concentration is decreased. Meanwhile, the hardness and residual stress of rotary blade surface layer are significantly increased. The average residual stress reaches 390.7 MPa, and the average Rockwell hardness number achieves 45.1 HRC. Measuring results of residual stress, surface micrograph, microstructure and hardness after LSP indicate that LSP can significantly improve the surface properties of rotary blade, and it provides a new basis for further mending surface quality and fatigue property of big tilling depth rotary blade.
The laser welding system is used to weld vacuum glass,the organizational structure of welding joint and the combining performance of the laser welding in different speeds are studied in this text. Under the same laser output power,welding combining performance and organizational structure are ideal both in the speed of 5mm/s and 10mm/s. It shows that laser welding is an effective method of the edge welding of vacuum glass. By comparison with experimental results, better solder welding joint organizational structure and combining performance can be obtained when the welding speed is 5mm/s than the welding speed is 10mm/s. It explains that appropriate laser welding speed is one of the effective methods of optimizing vacuum glass welding under certain laser output power.
The mathematical model of the braced stress-strain in the vacuum glazing was established with the crunode method by elastic mechanics. The braced stress-strain field of vacuum glazing was received, and the stress-strain distribution was analyzed at the same time. Electric test method was used to validate the stress distribution. The experimental results are shown that the maximal stress of vacuum glazing occurs in the second braced pillar of the four-square side. The maximal stress value by elastic mechanics is 11.057MPa, while the measured value by electric test method is 11.765MPa, and its tolerance is only 6.02%. The positive stress in the cross section of the braced pillar is 179MPa, the longitudinal strains of steel and glazing braced pillar are 0.2686μm and 0.7414μm, respectively. The tolerance of braced pillar height and the glazing level degree are controlled to guarantee force equality, which increases strength, dependability, and service life of vacuum glazing.
Based on the vacuum plate glazing produced in laboratory, the residual stress field of seal edge in vacuum plate glazing caused by heat load was researched by electrometric method, and the distribution of residual stress field were successfully measured. The residual stress field of seal edge in vacuum plate glazing was analyzed by numerical calculation, and then the established mathematical model was solved by finite element method and distribution rule of its residual stress was obtained. The effect of linear expansibility and coupled stress of the solder in seal edge on the residual stress of vacuum plate glazing was discussed. The result showed that calculated and experimental results were similar. The relation between intensity of residual stress and elasticity modulus was obtained. The theoretical principle was provided for analyzing allowable value of the residual stress of seal edge in vacuum plate glazing.
The braced pillars were machined by grinding and spark machining. 3-D topography and surface roughness of two kinds of braced pillars were measured. The effect of two kinds of braced pillars on stress distribution of vacuum plate glass was analyzed by electrometric method, and was in comparison. The stress distribution of their important sides was obtained such as sealing side, supporting side and braced pillar. The experimental result showed that maximal stress of braced pillar for vacuum glass occurred in the end side of each braced pillar. Controlling high precision of the brace height and good flatness of the glass sheet considerably improve vacuum plate glass quality, such as its strength, its dependability and service life.
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