Research On Reliability Of Hydraulic Support Under Eccentric Load Condition

As the essential equipment of fully mechanized mining face,hydraulic support is vital to achieve total automation and smart mining,with the continuous increase of mining height and working face length,the support load is more severe,and its reliability level directly affects the efficient and safe production of fully mechanized mining face.In the past,most of the research on the reliability of the support was based on the internal loading method,from the perspective of similarity,the external loading analysis of the hydraulic support is closer to its actual working status,therefore,it has important theoretical significance and engineering application value to study the reliability of large mining height supports from the perspective of external loading.Taking ZY29000/45/100 D hydraulic support as engineering object,according to the eccentric load conditions stipulated in "Powered support for coal mine-Part 1:General specification" GB25974.1-2010,integrating Creo,ANSYS and ADAMS software and the50000 KN hydraulic support test bench designed by the project team to establish a rigid-flexible coupling dynamic simulation model of hydraulic support and test bench based on external loading requirements,and conduct structural reliability analysis of the support.Based on orthogonal test,the reliability of the canopy is evaluated,and the influence of different structural parameters of the canopy on its reliability is analyzed,at the same time,three network models of BP,PSO-BP and ameliorated PSO-BP are built to predict the reliability of the canopy,and the prediction consequence was discussed.The upshot demonstrate that: when the support is in a high position,its bearing force is the largest,the pressure at the front of the base is the smallest,and the support performance is better;during the hydraulic support descends from 10 meters to4.8 meters,the beam end distance changes by 262 mm,which is similar to the double twisted line characteristics,the change limit values of the back angle of the caving shield and the posture angle of the rear linkage are all within a reasonable range,ensuring that the hydraulic support can work reliably under the limit posture state;the overall stress of the support is distributed regionally;the stress of the whole support is distributed regionally,and the maximum stress reaches 996 MPa,which appears at the transverse rib plate above the side column socket of the canopy pad,which exceeds the yield limit of the material,after the topical structure is ameliorated,the stress and deformation are dropped by 435 MPa and 0.6mm,respectively,the strength and stiffness has been improved,and the maximum stress of other components is427.12 MPa,mainly concentrated in the pin hole,main rib plate and cover plate,which meets the strength requirements;the deformation mainly occurs near each pin hole,decrease in the order of caving shield,canopy,front and rear linkage,base and pin shaft,and the maximum deformation is 4.04 mm,which appears near the hinge hole at the rear of the caving shield,which meet stiffness requirements;when the structural parameters change within a specified scope,the elements affecting the reliability of the canopy from high to low are the thickness of the outer main ribs,the thickness of the thick transverse ribs above the column socket,the thickness of the upper cover plate of the canopy,the thickness of the thin transverse rib above the column socket and the diameter of the pin hole of the main rib,the reliability is positively correlated with the increase of the thickness of each plate,but the change range decreases in turn,and the change is stable and has a downward trend with the increase of the diameter of the pin hole of the main rib plate;the regression coefficient of the three prediction models of BP,PSO-BP and improved PSO-BP are 0.80667,0.86696 and 0.98525 respectively,the number of iterations are 12,8 and 6,respectively,the maximum absolute errors are 0.0407,0.0307 and 0.0096,the fluctuations are0.0118,0.0141 and 0.0008,respectively;the maximum relative errors are 5.14 %,3.52%,and1.17%,and the fluctuations are 2.13%,1.74%,and 0.0741%,respectively.Therefore,the prediction accuracy of the improved PSO-BP model are remarkably promoted,and the iteration speed and steadiness of the model are simultaneously enhanced,compared with the traditional reliability evaluation form,it is more simple and more productive,it provides certain guidance and application value for the reliability prediction of the essential components of considerable industrial and mining facilities.