Impulsive Effect Of U-Brake Energy Dissipator Under Impact Load

China is a place,there are a lot of mountain geological disasters occur frequently,it is very urgent for rockfall protection.The passive flexible protection net system is a kind of widely used protective measures,and the energy dissipator is the core component of the passive flexible protection net system,it affects the protection efficiency and normal work of the passive flexible protection net system.At present,the mechanical behavior of energy dissipator mainly adopts static tensile test,however,based on impact test of passive flexible protection systems show that there is a big difference between the impact dynamics behavior and static mechanical behavior of energy dissipator,but,the corresponding basic research is much not enough at present.Therefore,it is of great engineering significance and theoretical value to study the impulse effect of energy dissipator.For this purpose,this paper aims at the starting pulse effect of U-brake,the control technical measures of pulse effect is proposed,Through integration with protection system,impact protection system dynamics model is established,on the nonlinear dynamic analysis,to verify the effectiveness of the pulse effect control technology,the paper research content are as follows:First,In this paper,the research status and key problems of passive flexible protection system are discussed,and the research contents and technical lines of this paper are clarified(chapter 1).Second,the working tension control equation of the energy dissipator is established,and the design formula of the work force of the energy dissipator is presented.In this paper,the transient motion state of the steel plate with the circumferential motion of the roller is analyzed by elastic-plastic mechanics theory,and the tensile test is designed.Based on the theoretical analysis and tensile test,the results of the engineering design formula are compared with the test value,and the accuracy of the engineering design formula is verified(chapter 2).Third,the correlation between the power and velocity of the U-brake is analyzed,and the related equations of the starting power and the impact velocity is established.Impact dynamic numerical model was built based on tensile test,the simulation parameters of the impact velocity are analyzed.Research has shown that starting force increased with the increase of impact velocity increases,the impact velocity amounting to more than 20 m/s and pulse effect is very obvious,starting force to work force 4 to 5 times(chapter 3).Fourth,A kind of spring is presented and designed.Based on the dynamic characteristics of U-brake,a buffer which can effectively reduce its pulse effect is designed.A reasonable pulse effect control device has been proposed through the analysis of the parameters,and integrating it into the U-brake.The numerical model of impact dynamics of the protection system is established,and the effectiveness of the pulse effect control technique is verified(chapter 4).