Silicone rubber/polyacrylate sequential interpenetrating polymer networks(IPNs) were prepared by silicone rubber sheet dipped into the solution composed of different acrylate monomers and benzoyl peroxides(BPOs) for d...Silicone rubber/polyacrylate sequential interpenetrating polymer networks(IPNs) were prepared by silicone rubber sheet dipped into the solution composed of different acrylate monomers and benzoyl peroxides(BPOs) for different time at room temperature and then acrylate polymerized at 80℃for 2 h. The molecular structure and damping properties of sequential IPNs were studied by means of FT-IR and dynamic mechanical analysis(DMA), respectively. The FT-IR spectrum shows that polyacrylate distributes unevenly along the thickness direction of IPNs, i.e. the concentration of polyacrylate decreases from the midst to the surface of the IPNs. The DMA shows that cold crystallization of silicone in the temperature range from -47℃to -30℃is reduced and loss factor of IPNs is improved after interpenetrating with polyacrylate. This suggestes that IPNs can be used as damping materials.展开更多
Large amounts of used rubber tires are discarded annually. A long time is needed for them to degrade naturally. This poses two major problems: environmental pollution and wastage of valuable rubber. On the other hand,...Large amounts of used rubber tires are discarded annually. A long time is needed for them to degrade naturally. This poses two major problems: environmental pollution and wastage of valuable rubber. On the other hand, with the harm of vibration and noise widely recognized, desires to control them intensify. As an important means of vibration control, viscoelastic damping technology has advanced greatly. The need for cheap and high quality viscoelastic damping materials increases rapidly. This paper made a trial to use ground rubber tire (GRT) recovered from old tires to make damping materials. The GRT is treated specially first. Then it was pressed into slabs and vulcanized. Finally, the product was cut into test samples. An Oberst beam was used to determine the loss factor βand storage modulus E. Results show that the damping materials exhibit good damping α-bility.展开更多
A dynamic model of a flexible rotor supported by ball bearings with rubber damping rings was proposed by combining the finite element and the mass-centralized method.In the proposed model,the rotor was built with the ...A dynamic model of a flexible rotor supported by ball bearings with rubber damping rings was proposed by combining the finite element and the mass-centralized method.In the proposed model,the rotor was built with the Timoshenko beam element,while the supports and bearing outer rings were modelled by the mass-centralized method.Meanwhile,the influences of the rotor’s gravity,unbalanced force and nonlinear bearing force were considered.The governing equations were solved by precise integration and the Runge-Kutta hybrid numerical algorithm.To verify the correctness of the modelling method,theoretical and experimental analysis is carried out by a rotor-bearing test platform,where the error rate between the theoretical and experimental studies is less than 10%.Besides that,the influence of the rubber damping ring on the dynamic properties of the rotor-bearing coupling system is also analyzed.The conclusions obtained are in agreement with the real-world deployment.On this basis,the bifurcation and chaos behaviors of the coupling system were carried out with rotational speed and rubber damping ring’s stiffness.The results reveal that as rotational speed increases,the system enters into chaos by routes of crisis,quasi-periodic and intermittent bifurcation.However,the paths of crisis,quasi-periodic bifurcation,and Hopf bifurcation to chaos were detected under the parameter of rubber damping ring’s stiffness.Additionally,the bearing gap affects the rotor system’s dynamic characteristics.Moreover,the excessive bearing gap will make the system’s periodic motion change into chaos,and the rubber damping ring’s stiffness has a substantial impact on the system motion.展开更多
基金Project (50473013) supported by the National Natural Science Foundation of China
文摘Silicone rubber/polyacrylate sequential interpenetrating polymer networks(IPNs) were prepared by silicone rubber sheet dipped into the solution composed of different acrylate monomers and benzoyl peroxides(BPOs) for different time at room temperature and then acrylate polymerized at 80℃for 2 h. The molecular structure and damping properties of sequential IPNs were studied by means of FT-IR and dynamic mechanical analysis(DMA), respectively. The FT-IR spectrum shows that polyacrylate distributes unevenly along the thickness direction of IPNs, i.e. the concentration of polyacrylate decreases from the midst to the surface of the IPNs. The DMA shows that cold crystallization of silicone in the temperature range from -47℃to -30℃is reduced and loss factor of IPNs is improved after interpenetrating with polyacrylate. This suggestes that IPNs can be used as damping materials.
文摘Large amounts of used rubber tires are discarded annually. A long time is needed for them to degrade naturally. This poses two major problems: environmental pollution and wastage of valuable rubber. On the other hand, with the harm of vibration and noise widely recognized, desires to control them intensify. As an important means of vibration control, viscoelastic damping technology has advanced greatly. The need for cheap and high quality viscoelastic damping materials increases rapidly. This paper made a trial to use ground rubber tire (GRT) recovered from old tires to make damping materials. The GRT is treated specially first. Then it was pressed into slabs and vulcanized. Finally, the product was cut into test samples. An Oberst beam was used to determine the loss factor βand storage modulus E. Results show that the damping materials exhibit good damping α-bility.
基金Projects(51775277,51775265)supported by the National Natural Science Foundation of ChinaProject(190624DF01)supported by Nanjing University of Aeronautics and Astronautics Short Visiting Program,China。
文摘A dynamic model of a flexible rotor supported by ball bearings with rubber damping rings was proposed by combining the finite element and the mass-centralized method.In the proposed model,the rotor was built with the Timoshenko beam element,while the supports and bearing outer rings were modelled by the mass-centralized method.Meanwhile,the influences of the rotor’s gravity,unbalanced force and nonlinear bearing force were considered.The governing equations were solved by precise integration and the Runge-Kutta hybrid numerical algorithm.To verify the correctness of the modelling method,theoretical and experimental analysis is carried out by a rotor-bearing test platform,where the error rate between the theoretical and experimental studies is less than 10%.Besides that,the influence of the rubber damping ring on the dynamic properties of the rotor-bearing coupling system is also analyzed.The conclusions obtained are in agreement with the real-world deployment.On this basis,the bifurcation and chaos behaviors of the coupling system were carried out with rotational speed and rubber damping ring’s stiffness.The results reveal that as rotational speed increases,the system enters into chaos by routes of crisis,quasi-periodic and intermittent bifurcation.However,the paths of crisis,quasi-periodic bifurcation,and Hopf bifurcation to chaos were detected under the parameter of rubber damping ring’s stiffness.Additionally,the bearing gap affects the rotor system’s dynamic characteristics.Moreover,the excessive bearing gap will make the system’s periodic motion change into chaos,and the rubber damping ring’s stiffness has a substantial impact on the system motion.
