Research And Design Of New Straddle Monorail Beam Bearing

In the field of transportation infrastructure in China,straddle monorail,as a new type of rail transit,is the new trend of the future development of urban rail transit.As a load-bearing structure in straddle monorail system,the reliability and stability of track bridge system directly affect the vehicle safety.However,the rail beam body has the characteristics of small size in the direction of the transverse bridge and large vertical height at the cross section.Once the load occurs eccentricity or the vehicle runs to the curved beam,a large overturning moment and centrifugal force will be generated.Therefore,as the main force transfer component of the track bridge system,the bearing must have a large tensile capacity and lateral stiffness in the whole straddle monorail system.The traditional bridge bearing is not suitable for the structural stress requirement of monorail system,on the basis of which,this paper designs a new type of pull-down bearing which is more suitable for straddle monorail system.Through the monorail beam structure,and combined with the design requirements,the main structure of the new monorail bearing is designed and its working principle is determined.The primary design and material selection of the key parts of the bearing are carried out.The design of the parts is based on the knowledge of material mechanics and elasticity,which mainly focuses on the main parts such as the beam body support,the bearing gantry,the tension sub bearing,compression sub bearing,the shear tenon,the base plate and the anchoring unit.After checking the strength,rigidity and stability of the parts,it is found that all parts of the bearing meet the requirements of design and material performance.Based on the finite element analysis method,the main components of the new monorail bearing designed by ABAQUS software were statical studied and analyzed,and the stress distribution of the bearing under extreme working conditions was obtained.According to the finite element calculation,the stress extremum of each part is within the allowable strength range of the material,which further indicates the rationality of the design of the bearing structure.In the static load and rotation tests,there is no obvious change in the appearance of each component of the beam bearing before and after the test,and no cracks are visible,which has a good bearing capacity.There are certain installation gaps in the test tooling during installation.After the initial loading,some gaps will be eliminated and the displacement of each measuring point will increase.According to the results of the maximum displacement of the compression side and the tension measuring point,the compression side will enter the pure compression state after being loaded,which indicates that the bearing has good stiffness.The data analysis shows that the bearing has good rotational performance.Three million fatigue tests on the new monorail bearing show that there is no fatigue stress damage accumulation and the force-displacement curves are linear.In the fatigue process of the main parts,the stress at each measuring point finally tends to be stable after a certain change.And there is no crack in important parts;The wear of outer ball crown liner and artesian bearing during the test does not affect the overall mechanical properties.The test results show that there is no failure after fatigue test for the bearing of the straddle monorail rail beam,and the mechanical properties of the bearing before the test can be maintained.