Dynamic Performance And Experimental Study Of Fiber Composite Flexible Protective System Under Impact Load

Because of the complexity of topography and climate,debris flow has become one of the main natural disasters.In terms of debris flow prevention measures,flexible protection system has been widely used in practical projects because of its good energy dissipation capacity.Throughout the research history of flexible protection system in China,wire rope net is widely used,while the research on the other protective materials is not very sufficient.Based on the research status of the flexible protection system at home and abroad,this paper introduces a new flexible protection system which is mainly composed of fiber composite materials and fixed system on the basis of inheriting the traditional passive flexible protection form.The shape of the protective net in this paper is mainly rectangle,because of its flexibility,it is easy to operate.The rectangle used in the protective net can be connected into multi span system,which can adapt to various terrain.In this paper,the dynamic response analysis of the basic component of the flexible protection system of fiber composite is carried out by the method of ANSYS/LS-DYNA finite element analysis software and impact test.The main research contents include the following aspects:(1)The research status of debris flow prevention and control project at home and abroad is understood,and its own direction is determined on the basis of inheriting the previous research results.At the same time,the dynamic balance equation,the energy and impact calculation formula,the main setting of ANSYS/LS-DYNA finite element analysis software and the motion equation of flexible structure in rope dynamics are deduced and sorted out.(2)The basic mechanical properties of different fiber composites were studied by uniaxial tensile test of four groups of fiber composite specimens,and the differences between the materials were compared.The results show that the tensile strength of the composites is carbon fiber,aramid fiber and glass fiber in turn,while the tensile strength of the carbonaramid co-braided hybrid composites is negative hybrid effect.(3)From the boundary conditions,the length-width ration of system,material category and structure form,the impact force,energy,displacement and acceleration of the model are analyzed by ANSYS/LS-DYNA finite element software.The main conclusions are as follows: reducing constraints,enlarging the length-width ration of system and size of grid are beneficial to the optimization of energy dissipation capacity of flexible protective network;the peak value of impact force of high elastic modulus materials is larger,and the contact time between impact objects and structures is accelerated;the impact cross structure,3 × 3 and 5 × 5 systems are faster when the impact force reaches the peak value and the time of energy conversion,while the peak displacement decreases gradually.(4)Based on the results of finite element simulation,some numerical simulation conditions are selected as the test scheme for impact test.The strain,displacement and acceleration data of the key points of the model are recorded in the test,and compared with the corresponding numerical simulation results.The results show that the longer the path of stress wave,the strain peak and acceleration response of the structure gradually weaken;the peak displacement of glass fiber composite is the largest when the impact mass is increased;compared with the two joint connection modes,the buckle connection will affect the dynamic response value of the component,and the knot mode can strengthen the structure integrity and avoid the former's shortcomings.