Numerical Simulation And Macroscopic Characterization Of Pinned Connection Tower Body Damage

Tower cranes are an indispensable large-scale lifting equipment in the construction industry.The use of tower cranes has greatly improved the work efficiency of the construction industry.With the continuous increase of high-rise buildings,larger types of tower crane equipment are also increasing,among which the tower cranes connected by pin shafts account for a large proportion.There are countless accidents caused by problems such as fatigue damage that are not detected in time.Therefore,how to effectively carry out safety monitoring is a key link in the safe operation of tower cranes,and the characteristic signals based on safety monitoring are not easy to obtain in practical engineering.This thesis takes the QTZ80 tower crane as the research object,establishes the damage theoretical model of the steel structure of the tower body and the pin-shaft connection,and obtains the characteristic signals of damage under different working conditions in ANSYS.Through finite element simulation,the characteristic signals corresponding to different damage conditions are obtained.Finally,the characteristic signals under damage and non-destructive conditions are compared and analyzed,and the displacement change law of the characteristic points at the top of the tower body under different damage conditions is obtained,and the tower is established.A rapid parametric design system for the finite element model of the crane beam element.The main contents are as follows:(1)Based on the ANSYS APDL command flow method,a variable-section beam element model is established.On this basis,a multi-scale model is established by combining the solid element and the beam-bar element.Different solid modeling methods are adopted for different components of the tower crane.Build a solid model at the damage location to describe the specific details of the damage.(2)Based on the theory of damage mechanics,a theoretical model of corrosion is established to analyze the corrosion rate and time under the conditions of natural corrosion and stress corrosion;for the anti-corrosion layer of the tower crane steel structure will fail from the weak position and cause corrosion In the case of fatigue damage,two different models of beams and rods with variable cross-section and solid bodies are constructed at the bottom of the tower where the stress is large,which are used to simulate different stages of corrosion of the steel structure of the tower crane,and qualitatively judge the different elements in the different stages of the corrosion process.The influence on the displacement difference of feature points.The results show that the natural corrosion stage has little effect on the displacement difference of characteristic points,and there will be an inflection point,but the corrosion degree varies greatly in different regions;in the stage of corrosion pits in stress corrosion,the stress at the location of the damage is the influence of the displacement difference of characteristic points.The main factor of the value,followed by the depth and number of corrosion pits.In the corrosion fracture stage of stress corrosion,the transverse corrosion fracture has a greater influence on the displacement difference of the feature points than the longitudinal corrosion fracture,and with the increase of the depth,the difference between the influence of the two on the displacement difference of the feature points gradually increases.(3)The stress analysis of the pin shaft is carried out,and the stress distribution is obtained.The definition of continuity in damage mechanics is introduced into the damage of the pin-shaft connection.In the actual project,there may be a large gap between the pin-shaft and the inner hole of the ear plate at the pin-shaft connection of the tower crane.A standard section is established.The multi-scale model simulates the damage of the pin at different positions,and qualitatively judges the influence on the macroscopic characterization of the damage of the pin at different positions with different clearances.The results show that: under the maximum hoisting load,when the damage continuity is after 0.25,the displacement difference of a main limb that is greatly affected under different working conditions will change abruptly;,compared with the single-pin shaft connection gap damage,it has a greater impact on the displacement difference of the main limb 2 feature points in the X and Z directions;The pin-shaft connection gap damage on the same side plays a major role in the displacement difference of the damage feature points of the adjacent main-limb connection gap between multiple main limbs and double-pin shafts.(4)For the traditional GUI modeling methods,there are problems such as slow modeling and difficulty in model updating.In the Windows operating system,Delphi is used as a development tool,and Delphi language is used for secondary development of APDL command flow,and a rapid parametric design system for the finite element model of tower crane beam elements is established,in order to establish a tower crane model damage database.In short,this thesis uses ANSYS APDL command flow to establish a variety of finite element models.On the basis of the theoretical model,the corrosion damage of the tower crane tower body steel structure and the damage of the pin-shaft connection are simulated more accurately.Change is macroscopic characterization,which realizes the rapid identification of different damage states of the tower body,and establishes a rapid parametric design system,which lays the foundation for the safety risk assessment and life prediction of the tower crane in the next step.