Titanium alloy has been increasingly applied in aviation industry due to its superior performance. However, the titanium alloy structures are less studied. This work investigates the structural behavior of Ti6Al4V tit...Titanium alloy has been increasingly applied in aviation industry due to its superior performance. However, the titanium alloy structures are less studied. This work investigates the structural behavior of Ti6Al4V titanium alloy stiffened panels under in-plane shear load by experiments and numerical analysis. After the shear tests, the buckling instability, the post-buckling process and the failure mechanism of the specimen were obtained. The Finite Element(FE) models were established with the subsequent validation verification. A parametric analysis was implemented to study the influence of stringer thickness and stringer height on the behavior of the stiffened panels. The results show that after the initial local buckling on the skin, the buckling mode jumps several times with the increase of load. The stringers twist when the load reaches a certain level, and finally the structure damages due to the plastic deformation and the global buckling. The shear clip has little effect on the buckling and failure loads. Compared to the relatively large effect on the buckling load, the influence of the stringer thickness and stringer height on the failure load is neglectable.According to the parametric analysis, the stringer thickness influences the final buckling mode and failure mode, while the stringer height affects the buckling mode transformation.展开更多
Steel structures are often painted to protect against corrosion. Repainting is one of the most important factors in maintaining the corrosion protection function of the coating. Various factors affect the life of the ...Steel structures are often painted to protect against corrosion. Repainting is one of the most important factors in maintaining the corrosion protection function of the coating. Various factors affect the life of the coating film, such as the surface preparation, the type of coating, and the number of coats. Surface preparation is important for the life of the coating film. However, appropriate surface treatment is difficult due to the complex shape of perforated panels, and it has been confirmed that corrosion progresses from the machined area. Therefore, appropriate pretreatment of the machined area is important for corrosion prevention. In this study, we investigated the effects of the repainting process on the atmospheric corrosion behavior of perforated panels. To reproduce the repainting process, a number of pretreatments were performed, such as salt spraying, blasting, and zinc phosphate treatment. In the salt spray test after pretreatment and painting, the corrosion progressed in cases with no zinc phosphate treatment and those left untreated for 48 h before painting. In addition, the coating film on the processed area was confirmed to be thin. These results suggested that appropriate pretreatment and sufficient thickness of the coating on the machined area would affect the occurrence of corrosion.展开更多
The influence of fiber orientation,flow yaw angle and length-to-thickness ratio on flutter characteristics of angle-ply laminated plates in supersonic flow is studied by finite element approach.The structural model is...The influence of fiber orientation,flow yaw angle and length-to-thickness ratio on flutter characteristics of angle-ply laminated plates in supersonic flow is studied by finite element approach.The structural model is established using the Reissner-Mindlin theory in which the transverse shear deformation is considered.The aerodynamic pressure is evaluated by the quasi-steady first-order piston theory.The equations of motion are formulated based on the principle of virtual work.With the harmonic motion assumption,the flutter boundary is determined by solving a series of complex eigenvalue problems.Numerical study shows that （1） The flutter dynamic pressure and the coalescence of flutter modes depend on fiber orientation,flow yaw angle and length-to-thickness ratio;（2） The laminated plate with all fibers aligned with the flow direction gives the highest flutter dynamic pressure,but a slight yawing of the flow from the fiber orientation results in a sharp decrease of the flutter dynamic pressure;（3） The angle-ply laminated plate with fiber orientation angle equal to flow yaw angle gives high flutter dynamic pressure,but not the maximum flutter dynamic pressure;（4） With the decrease of length-to-thickness ratio,an adverse effect due to mode transition on the flutter dynamic pressure is found.展开更多
文摘Titanium alloy has been increasingly applied in aviation industry due to its superior performance. However, the titanium alloy structures are less studied. This work investigates the structural behavior of Ti6Al4V titanium alloy stiffened panels under in-plane shear load by experiments and numerical analysis. After the shear tests, the buckling instability, the post-buckling process and the failure mechanism of the specimen were obtained. The Finite Element(FE) models were established with the subsequent validation verification. A parametric analysis was implemented to study the influence of stringer thickness and stringer height on the behavior of the stiffened panels. The results show that after the initial local buckling on the skin, the buckling mode jumps several times with the increase of load. The stringers twist when the load reaches a certain level, and finally the structure damages due to the plastic deformation and the global buckling. The shear clip has little effect on the buckling and failure loads. Compared to the relatively large effect on the buckling load, the influence of the stringer thickness and stringer height on the failure load is neglectable.According to the parametric analysis, the stringer thickness influences the final buckling mode and failure mode, while the stringer height affects the buckling mode transformation.
文摘Steel structures are often painted to protect against corrosion. Repainting is one of the most important factors in maintaining the corrosion protection function of the coating. Various factors affect the life of the coating film, such as the surface preparation, the type of coating, and the number of coats. Surface preparation is important for the life of the coating film. However, appropriate surface treatment is difficult due to the complex shape of perforated panels, and it has been confirmed that corrosion progresses from the machined area. Therefore, appropriate pretreatment of the machined area is important for corrosion prevention. In this study, we investigated the effects of the repainting process on the atmospheric corrosion behavior of perforated panels. To reproduce the repainting process, a number of pretreatments were performed, such as salt spraying, blasting, and zinc phosphate treatment. In the salt spray test after pretreatment and painting, the corrosion progressed in cases with no zinc phosphate treatment and those left untreated for 48 h before painting. In addition, the coating film on the processed area was confirmed to be thin. These results suggested that appropriate pretreatment and sufficient thickness of the coating on the machined area would affect the occurrence of corrosion.
基金supported by China Postdoctoral Science Founda-tion (20090451045)
文摘The influence of fiber orientation,flow yaw angle and length-to-thickness ratio on flutter characteristics of angle-ply laminated plates in supersonic flow is studied by finite element approach.The structural model is established using the Reissner-Mindlin theory in which the transverse shear deformation is considered.The aerodynamic pressure is evaluated by the quasi-steady first-order piston theory.The equations of motion are formulated based on the principle of virtual work.With the harmonic motion assumption,the flutter boundary is determined by solving a series of complex eigenvalue problems.Numerical study shows that （1） The flutter dynamic pressure and the coalescence of flutter modes depend on fiber orientation,flow yaw angle and length-to-thickness ratio;（2） The laminated plate with all fibers aligned with the flow direction gives the highest flutter dynamic pressure,but a slight yawing of the flow from the fiber orientation results in a sharp decrease of the flutter dynamic pressure;（3） The angle-ply laminated plate with fiber orientation angle equal to flow yaw angle gives high flutter dynamic pressure,but not the maximum flutter dynamic pressure;（4） With the decrease of length-to-thickness ratio,an adverse effect due to mode transition on the flutter dynamic pressure is found.
