The vertical distribution characteristics of Monochamus alternatus on the trucks of infested Pinus yunnanensis were investigated both in field and laboratory.The results showed that the quantity distribution of ovipos...The vertical distribution characteristics of Monochamus alternatus on the trucks of infested Pinus yunnanensis were investigated both in field and laboratory.The results showed that the quantity distribution of oviposition scar in trunk was lower part > middle part > upper part;and the density distribution of oviposition scar had not significant difference(P>0.05).The quantity distribution of entrance hole in trunk was middle part > lower part > upper part;and the density distribution of entrance hole was upper part > middle part > lower part.The quantity distribution of exit hole in trunk was middle part > upper part > lower part;and the density distribution of exit hole was upper part > middle part > lower part.There were positive correlations between the quantities of oviposition scar or entrance hole in lower part of trunk and the entrance hole or exit hole in whole trunk,respectively.The linear regression equations of the quantity of oviposition scar in lower part(x1),the entrance hole in lower part(x2) and the quantity of oviposition scar in whole trunk(y1),the entrance hole in whole trunk(y2),the exit hole in whole trunk(y3) are y1=7.117+2.283 x1,y2=24.220+0.701 x1,y3=8.794+0.434 x1,y2=28.805+2.211 x2,y3=20.367+0.778 x2.All partial correlations had reached the very signiticant level.展开更多
The exit-hole in friction stir spot welded(FSSWed) 2024-T4 aluminum alloy joints was successfully repaired by using a three-phase secondary rectification resistance spot welding machine, which is termed as filling exi...The exit-hole in friction stir spot welded(FSSWed) 2024-T4 aluminum alloy joints was successfully repaired by using a three-phase secondary rectification resistance spot welding machine, which is termed as filling exit-hole based on resistance welding(FEBRW). The filling dynamic behavior of force was recorded by a device monitoring. Optical microscope(OM), electron backscatter diffraction(EBSD), and tensile shear tests and finite element modelling were conducted to investigate the repairing stages and bonding mechanisms of the repaired joints in detail. Results showed that exit-hole was completely filled and repaired experiencing three stages. Metallurgical bonding was achieved between plug and exit-hole wall in two forms, including melting bonding in the middle of the joints and partial diffusion bonding on both the upper and bottom of the joints. The highest tensile shear strength of the repaired joints was 7.43 kN, which was 36.3% higher than that of the as welded joints. Resistance welding paves an efficient way to repair the exit-hole in FSSWed joints.展开更多
文摘The vertical distribution characteristics of Monochamus alternatus on the trucks of infested Pinus yunnanensis were investigated both in field and laboratory.The results showed that the quantity distribution of oviposition scar in trunk was lower part > middle part > upper part;and the density distribution of oviposition scar had not significant difference(P>0.05).The quantity distribution of entrance hole in trunk was middle part > lower part > upper part;and the density distribution of entrance hole was upper part > middle part > lower part.The quantity distribution of exit hole in trunk was middle part > upper part > lower part;and the density distribution of exit hole was upper part > middle part > lower part.There were positive correlations between the quantities of oviposition scar or entrance hole in lower part of trunk and the entrance hole or exit hole in whole trunk,respectively.The linear regression equations of the quantity of oviposition scar in lower part(x1),the entrance hole in lower part(x2) and the quantity of oviposition scar in whole trunk(y1),the entrance hole in whole trunk(y2),the exit hole in whole trunk(y3) are y1=7.117+2.283 x1,y2=24.220+0.701 x1,y3=8.794+0.434 x1,y2=28.805+2.211 x2,y3=20.367+0.778 x2.All partial correlations had reached the very signiticant level.
基金financially supported by the National Natural Science Foundation of China (No. 51874179)。
文摘The exit-hole in friction stir spot welded(FSSWed) 2024-T4 aluminum alloy joints was successfully repaired by using a three-phase secondary rectification resistance spot welding machine, which is termed as filling exit-hole based on resistance welding(FEBRW). The filling dynamic behavior of force was recorded by a device monitoring. Optical microscope(OM), electron backscatter diffraction(EBSD), and tensile shear tests and finite element modelling were conducted to investigate the repairing stages and bonding mechanisms of the repaired joints in detail. Results showed that exit-hole was completely filled and repaired experiencing three stages. Metallurgical bonding was achieved between plug and exit-hole wall in two forms, including melting bonding in the middle of the joints and partial diffusion bonding on both the upper and bottom of the joints. The highest tensile shear strength of the repaired joints was 7.43 kN, which was 36.3% higher than that of the as welded joints. Resistance welding paves an efficient way to repair the exit-hole in FSSWed joints.
