| The compression shear testing machine is a special testing machine derived from the material testing machine to test the axial and radial compressive,shear,rotation and other mechanical properties of bridge bearings,plate bearings,basin bearings and spherical steel bearings under the composite conditions of vertical,horizontal and rotation loading forces.With the improvement of bridge construction scale and standards,large tonnage and super large tonnage bearings are increasingly used,but the existing testing machines can not fully meet the mechanical property testing requirements of such bearings.Therefore,according to the current situation of domestic testing machines and combined with the equipment requirements in the Central Plains,the research and development of 60 MN Super Large Tonnage Static and dynamic multi-directional loading system and equipment are carried out.This paper mainly studies and analyzes from the following parts:(1)The main structure of the testing machine is designed,and a new closed self reaction system structure scheme composed of upper beam,base(lower beam),column and lateral reaction plate is proposed,which avoids the complex working condition of column under tension and pressure in the traditional structure.The corner system,static double shear system,sample delivery trolley(lower pressing plate)system design and dynamic single shear system scheme are designed to realize the multi-function of the testing machine and meet the requirements of hierarchical dynamic and static detection of a single testing machine.(2)The finite element analysis of the performance of the main frame is carried out by using ANSYS Workbench.The static analysis shows that the static performance of the main frame is relatively good,and the stiffness and strength meet the engineering design requirements and have a large surplus;Modal analysis shows that the minimum frequency of structural vibration is far greater than the maximum frequency of its structure during operation,and is greater than the reserved high-frequency dynamic detection frequency of 2 Hz in the later stage,so the equipment will not resonate.(3)The finite element response surface optimization method is used to optimize the design of the upper beam of the compression shear test machine,and the Latin hypercube sampling method is used to generate the test design sample points.According to the design results,a variety of fitting methods are used to fit and verify the accuracy.Finally,the Kriging method which best matches the test points generated by the Latin hypercube test design method is selected to fit the response surface,and then the multi-objective genetic algorithm is used to optimize to obtain the optimal solution,The optimized results are modified through sensitivity analysis to make it more valuable for engineering application.On the basis of meeting the requirements of stiffness and strength,the optimized and modified structure reduces the weight by 11.8% compared with the original structure,and the optimization effect is obvious,realizing the goal of lightweight.(4)The finite element analysis of the giant thread pair connected by the column nut of the testing machine is carried out in ANSYS,and the load distribution and stress of the thread pair are studied.The effects of thread pitch,nut radial size,number of meshing teeth and friction factor on thread load distribution and equivalent stress peak are analyzed.Finally,the bearing capacity of giant nut under heavy load is verified by experiment. |
