3D printing technology has been used for sand molding and core printing, but they simply substitute the traditional molding and core making method without changing the shape or size of the sand mold(core) and their de...3D printing technology has been used for sand molding and core printing, but they simply substitute the traditional molding and core making method without changing the shape or size of the sand mold(core) and their dense structure. In this study, a new type of hollow mold based on 3D printing is presented. The new type of mold is a rib reinforced thickness-varying shell mold. This mold design can realize the controlled cooling of castings, i.e., different cooling rates at different areas, and improve the temperature uniformity of a casting after its solidifi cation. Therefore, the performance of castings can be improved and their residual stress and deformation can be reduced. This kind of new mold was applied to a stress frame of A356 aluminum alloy. The 3D printed rib reinforced thickness-varying shell mold was compared with the traditional dense mold, and the castings obtained by these two kinds of molds were also compared. The experimental results showed that the rib reinforced shell mold increased the cooling rate of the casting by 30%, tensile strength by 17%, yield strength by 11%, elongation by 67%, and decreased its deformation by 43%, while sand consumption was greatly reduced by 90%.展开更多
Stiffening-ribbed-hollow-pipe cast-in place reinforced concrete girderless floor is a new-style hollow girderless floor system. Model experimental researches of simply-supported floor and four-corners bearing floor ha...Stiffening-ribbed-hollow-pipe cast-in place reinforced concrete girderless floor is a new-style hollow girderless floor system. Model experimental researches of simply-supported floor and four-corners bearing floor have been done on this new kind of floor system in this paper. The experiment results show that the floor system has good mechanical property such as high bearing capacity, big rigidity and good tensility. A theoretical method is presented in this paper that the stiffening-ribbed-hollow-pipe girderless floor can be analyzed by being converted equivalently to orthotropic solid slab. It is indicated that the method is correct and reasonable according to the contrast between theoretical calculated results and experimental measured results. The theoretical results coincide with the measured results well.展开更多
The jacket offshore platform structures working in the environment are subjected to various external conditions,such as wave loads,wind loads and corrosion of sea water.Therefore,the research on reinforcement of tubul...The jacket offshore platform structures working in the environment are subjected to various external conditions,such as wave loads,wind loads and corrosion of sea water.Therefore,the research on reinforcement of tubular joints has great practical value for the safety of offshore platforms.In this article,the finite element(FE)models of T-type tubular joint(T-joint)and K-type tubular joint(K-joint)are established by ANSYS software.Triangular rib reinforcement and collar plate reinforcement are used to reinforce the tubular joints.The reinforcement effects are assessed through the ultimate bearing capacity,and the influences of parameters of the rib and the collar plate on the ultimate capacity are analyzed.Besides,the effects of the two reinforcement methods are compared under the combined loads,and the results show that the reinforcement of the ribbed plate is more effective in resisting the deformation caused by bending moment,while the reinforcement of the collar plate is more effective to avoid the plastic damage caused by the axial pressure.展开更多
基金funded by the National Science and Technology Major Project of the Ministry of Science and Technology of China under Project No.2016YFB1100703
文摘3D printing technology has been used for sand molding and core printing, but they simply substitute the traditional molding and core making method without changing the shape or size of the sand mold(core) and their dense structure. In this study, a new type of hollow mold based on 3D printing is presented. The new type of mold is a rib reinforced thickness-varying shell mold. This mold design can realize the controlled cooling of castings, i.e., different cooling rates at different areas, and improve the temperature uniformity of a casting after its solidifi cation. Therefore, the performance of castings can be improved and their residual stress and deformation can be reduced. This kind of new mold was applied to a stress frame of A356 aluminum alloy. The 3D printed rib reinforced thickness-varying shell mold was compared with the traditional dense mold, and the castings obtained by these two kinds of molds were also compared. The experimental results showed that the rib reinforced shell mold increased the cooling rate of the casting by 30%, tensile strength by 17%, yield strength by 11%, elongation by 67%, and decreased its deformation by 43%, while sand consumption was greatly reduced by 90%.
文摘Stiffening-ribbed-hollow-pipe cast-in place reinforced concrete girderless floor is a new-style hollow girderless floor system. Model experimental researches of simply-supported floor and four-corners bearing floor have been done on this new kind of floor system in this paper. The experiment results show that the floor system has good mechanical property such as high bearing capacity, big rigidity and good tensility. A theoretical method is presented in this paper that the stiffening-ribbed-hollow-pipe girderless floor can be analyzed by being converted equivalently to orthotropic solid slab. It is indicated that the method is correct and reasonable according to the contrast between theoretical calculated results and experimental measured results. The theoretical results coincide with the measured results well.
基金National Natural Science Foundation of China(Nos.51879272,51579246)Fundamental Research Funds for the Central Universities,China(No.18CX02074A)
文摘The jacket offshore platform structures working in the environment are subjected to various external conditions,such as wave loads,wind loads and corrosion of sea water.Therefore,the research on reinforcement of tubular joints has great practical value for the safety of offshore platforms.In this article,the finite element(FE)models of T-type tubular joint(T-joint)and K-type tubular joint(K-joint)are established by ANSYS software.Triangular rib reinforcement and collar plate reinforcement are used to reinforce the tubular joints.The reinforcement effects are assessed through the ultimate bearing capacity,and the influences of parameters of the rib and the collar plate on the ultimate capacity are analyzed.Besides,the effects of the two reinforcement methods are compared under the combined loads,and the results show that the reinforcement of the ribbed plate is more effective in resisting the deformation caused by bending moment,while the reinforcement of the collar plate is more effective to avoid the plastic damage caused by the axial pressure.
