Considering the coupling of a droplet, keyhole, and molten pool, a three-dimensional transient model for the full penetration laser + metal inert gas (MIG) hybrid welding of thin copper alloy plate was established, which is able to simulate the temperature and velocity fields, keyhole behavior, and generation of the welding defect. Based on the experimental and simulation results, the weld formation mechanism for the hybrid butt welding of a 2 mm-thick copper alloy plate was comparatively studied in terms of the fluid dynamic feature of the melt pool. For single laser welding, the dynamic behavior of liquid metal near the rear keyhole wall is complex, and the keyhole has a relatively drastic fluctuation. An obvious spattering phenomenon occurs at the workpiece backside. Meanwhile, the underfill (or undercut) defect is formed at both the top and bottom surfaces of the final weld bead, and the recoil pressure is identified as the main factor. In hybrid welding, a downward fluid flow is strengthened on the rear keyhole wall, and the stability of the keyhole root is enhanced greatly. There are large and small clockwise vortexes emerging in the upper and lower parts of the molten pool, respectively. A relatively stable metal bulge can be produced at the weld pool backside. The formation defects are suppressed effectively, increasing the reliability of full penetration butt welding of the thin copper alloy plate.

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This study proposes a method of keyword selection in search engine optimization to improve the accuracy of search engine and website rankings. To promote the development of scientific and technological innovation, this paper selects the innovation and entrepreneurship curriculum platform as the experimental object. By comparing different search engine optimization strategies, the keyword search volume data is analyzed based on “comprehensive index evaluation method”, which analyzes and calculates the change of keyword search comparison and the number of related keywords. Therefore, this paper will use the comprehensive index evaluation method for keyword selection, and establish a set of practical keyword selection method combined with the actual situation of innovation and enterprise curriculum platform. The results show that this program can improve search accuracy and website ranking.

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