| This paper discusses the rational utilization of abandoned iron ore tailings sand(ITS)particles as a damping resource in the construction field from the perspective of re-resources so that it will no longer damage the ecological environment.Therein,the regular pattern of change with many parameters(Sand-box filling rate,particle size,particle friction coefficient,excitation frequency,excitation amplitude,sand-box movement time,mixing ratio of different particle sizes of different materials,etc)of the frictional energy dissipation of ITS and multivariate mixed particles in sand-box dampers was studied by PFC3 D simulation.Through the finite element software simulation calculation,the influence factors and the change rule of sand box strain energy of different materials were obtained.With the help of 3D printing technology,the testing sand boxes with different thickness of different materials were prepared.At the same time,the sandbox with different materials was selected to carry out the damping test of the empty box and filled ITS and the structure of the sand box was improved repeatedly.The sand box structure for ITS damping test was finally determined and the correctness of the improved sandbox was verified by standard tiny steel balls.The loss factor of gray resin sand-box composite structure and loss factor of grey resin box of the interior ITS were tested by dynamic thermal mechanical analyzer(DMA-Q800).The strain energy of each part can be obtained by finite element analysis.According to the principle of energy dissipation,the damping loss factor of ITS particles was obtained and theoretically converted into the damping ratio of ITS particles,and the method of the damping ratio was obtained based on the combination of theoretical calculation and experimental test.The influence regular pattern of the damping properties of iron tailings was studied in depth with different particle size,filling density of sand box,moisture content,temperature and amplitude,and some specific valuable conclusions was got as follows:1.It was determined that the stiffness,thickness,and elastic modulus of the sand box are the main factors affecting the strain energy of the sand box by analyze the modal natural frequency of ITS sand-box structure,especially the sandbox thickness(section size)was an important factor in selecting sandbox materials.The material(white resin,grey resin and transparent resin etc.)and structure of sand box were optimized by simulation and experiment,and finally obtained a gray resin sandbox with the thickness of upper wall and the lateral wall are 0.5 mm and 0.3 mm respectively wasthe ideal sand box.Repeated experiments also found that it is important to control the manufacturing precision of the sandbox,and it is necessary and effective to select 3D printing.2.The change rules of particle dissipation of ITS in the sand box granule dampers between the sandbox particles excitation frequency,excitation frequency,sand-box movement time,particle size,particle friction coefficient and sand-box filling rate was obtained by numerically simulated of PFC3 D software in the sand box horizontal excitation,as well as the rules of energy dissipation of the damper filled with three different particles.These rules are as follows:(1)The friction energy dissipation of the ITS sand-box dampers decreases gradually with the increase of the excitation frequency,that is,the particle friction dissipation can be inversely proportional to the excitation frequency.(2)The friction energy dissipation of ITS sand-box dampers increases gradually with the increase of the external excitation amplitude,that is,the friction dissipation of the particle damper of the sand box is proportional to the amplitude.(3)The total friction dissipation of ITS particles increases with the increase of movement time of particle damper.(4)With the increase of particle size,the total friction energy of the particle damper is proportional to its proportion.(5)The total friction dissipation of particle damper increases with the increase of particle friction coefficient.(6)The friction dissipation of particles of sand-box is the largest when the filling rate of damper is 70%.(7)According to the analysis of the orthogonal test results of energy influencing factors of the sand box damper,the optimal combination value of frictional energy consumption of sand-box damper particles was obtained as follows: particle friction coefficient of ITS is 0.7,the particle size of ITS is 0.8mm and the movement time of sandbox particle damper is 2.5s.(8)The friction dissipation of ITS particles,steel balls and ceramics by simulating the same diameter shows that the friction energy of sand box is the largest when the filling rate is 70%.(9)It is found that the friction energy dissipation of particles is much larger than that of single particle friction,and the results show that the ITS particles play a key role in simulating the experiment of two-two mixed of three kinds of particles.The optimal combination of three particle sizes was obtained by orthogonal test: the particle size ofthe steel ball is 0.4mm,the ceramic particle size is 0.9mm,and the particle size of ITS is1.4mm.3.The effects of six factors on the damping of ITS were obtained by test experiments with DMA instruments under the condition of cantilever beam excitation,these are,the loss factor of ITS in sand-box increases with the increase of amplitude;The damping is the best when the moisture content of ITS is 13.2%;The damping of ITS particles increases with the increase of particle size;The particle damping increases with the increase of temperature when the sand box particles do not freeze;The damping loss factor of ITS becomes larger with the particle friction coefficient;The loss factor of damping of ITS is the largest when the filling rate of sand box is 100%. |
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