Study On The Mechanical Properties Of The Energy Dissipator In The Passive Flexible Protection

As an advanced rockfall protective structure,passive flexible protection net,which was introduced into china in the 1990s,is widely used in the protection engineering along the railway and highway route.As the energy consumption device,the energy dissipator can absorb rockfall impact kinetic energy and reduce the peak load of the whole structure,which is one of the key energy consumption components in the passive flexible protection net structure.Therefore,the study and optimization of the mechanical properties of energy dissipation can effectively improve the energy consumption properties of passive flexible protective net structure.In this paper,the mechanical properties of two passive flexible fence structures are studied.Ⅰ.The finite element method is used to study the deformation characteristics and energy consumption principle of GS8000 energy brake ring.The results show that the stress in the inner ring of the steel pipe is greater than that of the outer ring during the stretching process of the energy brake-ring.The maximum stress of the steel pipe occurs near the end of the inner ring.The aluminum tube stress is relatively small but it has a high strain rate.The first energy dissipation path of the energy brake ring is friction energy consumption,and the second is plastic deformation energy consumption.In the total friction energy consumption of the energy brake ring,the friction energy consumption between the steel pipe and the aluminum pipe is the largest,followed by the friction energy consumption between the steel pipe and the steel pipe.The stress of the energy brake ring in the process of interference assembly is analyzed,and the calculation formula of the PR tensioning force of the energy brake ring and the assembly stress of the steel pipe and aluminum tube are given.Ⅱ.Taking U-150 energy dissipation as an example,the finite element model of U-type energy dissipator is established,and the force characteristics and energy dissipation principle of U-type energy dissipator are analyzed.The results show that the stress state of the U-type energy dissipator is not changed during the stretching process.The tensile stress is large on the load part.The maximum stress occurs at the position where the steel plate is in contact with the roller.the energy consumption of U-type energy dissipator are mainly from the plastic deformation of steel plate and the friction between the steel plate and roller.Reducing the roller diameter can increase the energy consumption of the U-type energy dissipator,but it could also increase its starting load.Increasing the thickness,width and length of the steel plate can increase the energy consumption of the U-type energy dissipator.The most effective way to increase the energy consunmption of U-type energy dissipator is increasing the width of steel plate.