Sandwich structures have been widely applied in the wing and the horizontal tail of the aircraft,so face sheets of such structure might occur wrinkling deformation in the process of service,which will largely decrease...Sandwich structures have been widely applied in the wing and the horizontal tail of the aircraft,so face sheets of such structure might occur wrinkling deformation in the process of service,which will largely decrease capability of sustaining loads.As a result,this paper aims at proposing a reasonable strategy resisting wrinkling deformation of sandwich structures.To this end,an enhanced higher-order model has been proposed for wrinkling analysis of sandwich structures.Buckling behaviors of a five-layer sandwich plate are firstly analyzed,which is utilized to assess performance of the proposed model.Subsequently,wrinkling behaviors of four sandwich plates are further investigated by utilizing present model,which have been evaluated by using quasi threedimensional(3D)elasticity solutions,3D Finite Element Method(3D-FEM)results and experimental datum.Finally,the present model is utilized to study the buckling and the wrinkling behaviors of sandwich plates reinforced by Carbon Nano Tubes(CNTs).In addition,influence of distribution profile of CNTs on wrinkling behaviors has been analyzed,and a typical distribution profile of CNTs has been chosen to resist wrinkling deformation.Without increase of additional weight,the present strategy can effectively resist wrinkling deformation of sandwich plates,which is rarely reported in published literature.展开更多
This study aimed to investigate a novel slender buckling-restrained knee brace damper (BRKB) for welded and weld-free steel framing systems. The proposed BRKB adopts steel bar cores connected by a central coupler and ...This study aimed to investigate a novel slender buckling-restrained knee brace damper (BRKB) for welded and weld-free steel framing systems. The proposed BRKB adopts steel bar cores connected by a central coupler and restrained by tube buckling restrainers with a cover tube supporter. The advantages of the proposed damper include easy assembly compared to conventional buckling restrained braces, and high architectural flexibility for the retrofitting of large-span weld-free or welded steel moment-resisting systems. Specifically, by increasing the number of contraction allowances, undesirable failure mechanisms that are global instability and local buckling of the restrainer ends can be effectively suppressed because the more uniform plastic deformation of the core bar can be achieved longitudinally. In this study, displacement-controlled compression and cyclic loading tests were carried out to investigate the deformation capacities of the proposed BRKBs. Structural performance metrics associated with both loading tests, such as strength capacities, strains at the cover tubes and buckling restrainers, and hysteretic behaviors of the proposed damper under cyclic loads, were measured and discussed. Test results revealed that the geometrical characteristics of the cover tubes and adopted contraction allowances at the dampers play essential roles in their load-bearing capacities.展开更多
This paper seeks to outline the temperature effect on the buckling properties of ultra-thin-walled lenticular collapsible composite tube（LCCT） subjected to axial compression.The buckling tests of the LCCT specimens ...This paper seeks to outline the temperature effect on the buckling properties of ultra-thin-walled lenticular collapsible composite tube（LCCT） subjected to axial compression.The buckling tests of the LCCT specimens subjected to axial compression were carried out on INSTRON-500 N servo-hydraulic machine in dry state and at the temperatures of 25 C, 100 C and 80 C. The load–displacement curves and buckling initiation loads were measured and the buckling initiation mechanism was discussed from experimental observations. Experiments show that the buckling initiation load, on average, is only about 2.2% greater at the low temperature of 80 C than at the room temperature of 25 C due to the material hardening, demonstrating an insignificant increase in the buckling initiation load, whereas it is about 19.5% lower at the high temperature of 100 C than at the room temperature owing to the material softening, implying a significant decrease in the buckling initiation load. The failure mode of the LCCT in axial compression tests at three different temperatures can be reckoned to be characteristic of the buckling initiation and propagation around the central region until rupture. The finite element（FE） model is presented to simulate the buckling initiation mechanism based on the eigenvalue-based methodology. Good correlation between experimental and numerical results is achieved.展开更多
基金supported by the National Natural Sciences Foundation of China(No.12172295)SKLLIM1902,China.
文摘Sandwich structures have been widely applied in the wing and the horizontal tail of the aircraft,so face sheets of such structure might occur wrinkling deformation in the process of service,which will largely decrease capability of sustaining loads.As a result,this paper aims at proposing a reasonable strategy resisting wrinkling deformation of sandwich structures.To this end,an enhanced higher-order model has been proposed for wrinkling analysis of sandwich structures.Buckling behaviors of a five-layer sandwich plate are firstly analyzed,which is utilized to assess performance of the proposed model.Subsequently,wrinkling behaviors of four sandwich plates are further investigated by utilizing present model,which have been evaluated by using quasi threedimensional(3D)elasticity solutions,3D Finite Element Method(3D-FEM)results and experimental datum.Finally,the present model is utilized to study the buckling and the wrinkling behaviors of sandwich plates reinforced by Carbon Nano Tubes(CNTs).In addition,influence of distribution profile of CNTs on wrinkling behaviors has been analyzed,and a typical distribution profile of CNTs has been chosen to resist wrinkling deformation.Without increase of additional weight,the present strategy can effectively resist wrinkling deformation of sandwich plates,which is rarely reported in published literature.
基金supported in part by JSPS KAKENHI(NO.JP19K04711)the Mongolia−Japan Higher Engineering Education Development Project(MJEED)(Joint Research Code J16D22).
文摘This study aimed to investigate a novel slender buckling-restrained knee brace damper (BRKB) for welded and weld-free steel framing systems. The proposed BRKB adopts steel bar cores connected by a central coupler and restrained by tube buckling restrainers with a cover tube supporter. The advantages of the proposed damper include easy assembly compared to conventional buckling restrained braces, and high architectural flexibility for the retrofitting of large-span weld-free or welded steel moment-resisting systems. Specifically, by increasing the number of contraction allowances, undesirable failure mechanisms that are global instability and local buckling of the restrainer ends can be effectively suppressed because the more uniform plastic deformation of the core bar can be achieved longitudinally. In this study, displacement-controlled compression and cyclic loading tests were carried out to investigate the deformation capacities of the proposed BRKBs. Structural performance metrics associated with both loading tests, such as strength capacities, strains at the cover tubes and buckling restrainers, and hysteretic behaviors of the proposed damper under cyclic loads, were measured and discussed. Test results revealed that the geometrical characteristics of the cover tubes and adopted contraction allowances at the dampers play essential roles in their load-bearing capacities.
基金supported by the National Natural Science Foundation of China (Nos. 51075019 and 51375033)Aeronautical Science Foundation (No. 20095251024) of Chinathe Fundamental Research Funds for the Central Universities (No. YWF-13-T-RSC-121) of China
文摘This paper seeks to outline the temperature effect on the buckling properties of ultra-thin-walled lenticular collapsible composite tube（LCCT） subjected to axial compression.The buckling tests of the LCCT specimens subjected to axial compression were carried out on INSTRON-500 N servo-hydraulic machine in dry state and at the temperatures of 25 C, 100 C and 80 C. The load–displacement curves and buckling initiation loads were measured and the buckling initiation mechanism was discussed from experimental observations. Experiments show that the buckling initiation load, on average, is only about 2.2% greater at the low temperature of 80 C than at the room temperature of 25 C due to the material hardening, demonstrating an insignificant increase in the buckling initiation load, whereas it is about 19.5% lower at the high temperature of 100 C than at the room temperature owing to the material softening, implying a significant decrease in the buckling initiation load. The failure mode of the LCCT in axial compression tests at three different temperatures can be reckoned to be characteristic of the buckling initiation and propagation around the central region until rupture. The finite element（FE） model is presented to simulate the buckling initiation mechanism based on the eigenvalue-based methodology. Good correlation between experimental and numerical results is achieved.
