A stranded wires helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction of spiral. Compared with the conventional single wire spring, the stranded wires h...A stranded wires helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction of spiral. Compared with the conventional single wire spring, the stranded wires helical spring has the notable predominance in strength, damping and vibration reduction, which is usually used in aircraft engines, automatic weapons, etc. However, due to its complicated structure, the precise computation of its strength and rigidity need be a correct mathematical model, which then will be imported to finite element analysis software for solutions. Equations on solving geometric parameters, such as external diameters of strands and screw pitches of wires, are put forward in the paper. It also proposes a novel methodology on solving geometric parameters and establishing entity models of the stranded wires helical spring, which provides foundation of computing mechanical parameters by FEA. Then mathematical models on the centre line of the strand and the surface curve of each wire, after closing two ends in a spring, are proposed. Finally, geometric parameters are solved in a case study, and a 3D entity model of a spring with 3 layers and 16 wires is established, which has validated the accuracy of the proposed methodology and the 3D entity mathematical model. The method provides a new way to design stranded wire helical spring.展开更多
The dynamic behavior of the stranded wire helical spring is described by a modified Bouc-Wen model while the model parameters must be identified using an identification method and experimental data. Existing identific...The dynamic behavior of the stranded wire helical spring is described by a modified Bouc-Wen model while the model parameters must be identified using an identification method and experimental data. Existing identification methods usually relies either solely nonlinear iterative algorithms or manually trial and error. Therefore, the identification process can be rather time consuming and effort taking. As a result, these methods are not ideal for engineering applications. To come up with a more practical method, a three-stage identification method is proposed. Periodic loading and identification simulations are carried out to verify the effectiveness of the proposed method. Noises are added to the simulated data to test the performance of the proposed method when dealing with noise contaminated data. The simulation results indicate that the proposed method is able to give satisfying results when the noise levels are set to be 0.01, 0.03, 0.05 and 0.07. In addition, the proposed method is also applied to experimental data and compared with an existing method. The experimental data is acquired through a periodic loading test. The experiment results suggest that the proposed method features better accuracy compared with the existing method. An effective approach is proposed for identifying the model parameters of the stranded wire helical spring.展开更多
T Parallel wire strands(PWSs),which are widely used in prestressed steel structures,are typically in highstress states.Under fire conditions,significant creep effects occur,reducing the prestress and influencing the m...T Parallel wire strands(PWSs),which are widely used in prestressed steel structures,are typically in highstress states.Under fire conditions,significant creep effects occur,reducing the prestress and influencing the mechanical behavior of PWSs.As there is no existing approach to analyze their creep behavior,this study experimentally investigated the elevated temperature creep model of PWSs.A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test.It was concluded that the temperature level had a more significant effect on the creep strain than the stress level,and 450℃ was the key segment point where the creep rate varied significantly.By comparing the elevated temperature creep test results for PWSs and steel strands,it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels.The parameters in the general empirical formula,the Bailey–Norton model,and the composite timehardening model were fitted based on the experimental results.By evaluating the accuracy and form of the models,the composite time-hardening model,which can simultaneously consider temperature,stress,and time,is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.展开更多
基金supported by National Natural Science Foundation for Distinguished Young Scholar of China (Grant No. 50925518)National Natural Science Foundation of China (Grant No. 50775226)+1 种基金Key Project of Ministry of Education of China(Grant No. 109129)Chongqing Municipal Key Scientific and Technological Project of China (Grant No. CSTC2009AC3049)
文摘A stranded wires helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction of spiral. Compared with the conventional single wire spring, the stranded wires helical spring has the notable predominance in strength, damping and vibration reduction, which is usually used in aircraft engines, automatic weapons, etc. However, due to its complicated structure, the precise computation of its strength and rigidity need be a correct mathematical model, which then will be imported to finite element analysis software for solutions. Equations on solving geometric parameters, such as external diameters of strands and screw pitches of wires, are put forward in the paper. It also proposes a novel methodology on solving geometric parameters and establishing entity models of the stranded wires helical spring, which provides foundation of computing mechanical parameters by FEA. Then mathematical models on the centre line of the strand and the surface curve of each wire, after closing two ends in a spring, are proposed. Finally, geometric parameters are solved in a case study, and a 3D entity model of a spring with 3 layers and 16 wires is established, which has validated the accuracy of the proposed methodology and the 3D entity mathematical model. The method provides a new way to design stranded wire helical spring.
基金Supported by National Natural Science Foundation of China(Grant Nos.51375508,51375517)the Key Technologies R&D Program of China(Grant No.2012BAF12B09)the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(Grant No.IRT1196)
文摘The dynamic behavior of the stranded wire helical spring is described by a modified Bouc-Wen model while the model parameters must be identified using an identification method and experimental data. Existing identification methods usually relies either solely nonlinear iterative algorithms or manually trial and error. Therefore, the identification process can be rather time consuming and effort taking. As a result, these methods are not ideal for engineering applications. To come up with a more practical method, a three-stage identification method is proposed. Periodic loading and identification simulations are carried out to verify the effectiveness of the proposed method. Noises are added to the simulated data to test the performance of the proposed method when dealing with noise contaminated data. The simulation results indicate that the proposed method is able to give satisfying results when the noise levels are set to be 0.01, 0.03, 0.05 and 0.07. In addition, the proposed method is also applied to experimental data and compared with an existing method. The experimental data is acquired through a periodic loading test. The experiment results suggest that the proposed method features better accuracy compared with the existing method. An effective approach is proposed for identifying the model parameters of the stranded wire helical spring.
基金support provided by the National Natural Science Foundation of China(Grant No.51878348)the Shanghai Pujiang Program(No.22PJ1414000).
文摘T Parallel wire strands(PWSs),which are widely used in prestressed steel structures,are typically in highstress states.Under fire conditions,significant creep effects occur,reducing the prestress and influencing the mechanical behavior of PWSs.As there is no existing approach to analyze their creep behavior,this study experimentally investigated the elevated temperature creep model of PWSs.A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test.It was concluded that the temperature level had a more significant effect on the creep strain than the stress level,and 450℃ was the key segment point where the creep rate varied significantly.By comparing the elevated temperature creep test results for PWSs and steel strands,it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels.The parameters in the general empirical formula,the Bailey–Norton model,and the composite timehardening model were fitted based on the experimental results.By evaluating the accuracy and form of the models,the composite time-hardening model,which can simultaneously consider temperature,stress,and time,is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.
