Reseahch On Lightweighting And Properties Of Trackless Telescopic Gantry Crane

As a new type of hoisting crane machine,the trackless telescopic gantry crane adopts the tire type running mechanism,which can change the span in different working conditions to meet the construction requirements in the different tunnel sections with different spans,it plays an indispensible role in the process of laying the ballastless track.However,the current domestic research on trackless telescopic gantry crane mainly focuses on the structure design and maintain,the mechanical properties research involving less,therefore,this paper will analyze the mechanical properties of the trackless telescopic gantry crane,and further research on its lightweight.Regarded the structure of the trackless telescopic gantry crane with 12 t lifting capacity as the research object,and established the parametric model by finite element software ANSYS,then,finished the static analysis to check its strength and stiffness of the structure.The results showed that the strength and stiffness of trackless telescopic gantry crane system meet the design requirements,and a large amount of surplus.The telescopic legs’ sliders(plates)are the key components for gantry crane,which suffer complex force.In order to explore the actual force of each slider(plate)of the telescopic legs,the nonlinear contact analysis and the nodal coupling linear analysis were carried out of each slider(plate),then,by exploring the differences between the two models to study the feasibility of using the nodal coupling linear analysis instead of the nonlinear contact analysis.The results showed that,when there is relative sliding in the contact area,the larger friction coefficient can make the two models have similar results;When there is small relative sliding in the contact area,the two models have little difference.When dealing with contact problems,since the complicated contact parameter setup and low computation efficiency,for models with no high precision calculation requirements,a simplified approach based on node coupling analysis can be used to replace contact analysis to improve computational efficiency.The static analysis results of the gantry crane showed that the structure of the gantry crane has great redundancy in the strength and stiffness.In order to take full advantage of the bearing performance of material and reduce the manufacturing cost,it is necessary to do the structure optimization design.Regarded the self-weight,stress,displacement of trackless telescopic gantry crane as the output response,invoked the design method of optimal latin hypercube in the ISIGHT platform to do the design variables analysis and selected the variables which have a great influence on the output response,on this basis,used the selected design variables to construct the response surface approximation model and optimized the response surface model to improve its mechanical properties and reduce the structural weight.the results of optimization indicated that the structure weight of trackless telescopic gantry crane reduced 23.4%,and the lightweight effect was obvious.The optimal solution of each design parameter of the gantry crane after the deterministic optimization is almost the lower limit of the constraint boundary,but there is still a great redundancy in the strength and stiffness of gantry crane system,therefore,proposed a new method which is used Q235 to replace Q345 as the gantry crane material.Since deterministic optimization ignore the influence of uncertainty factors,which cause the deterministic optimization results tend to have lower reliability.In order to verify the reliability of using the Q235 as the gantry crane material,robust analysis technique and 6Sigma quality optimization have been combined with to analyze the robustness of the gantry crane deterministic optimization result and further research on its design the robust optimization.The 6σ optimization results indicated that the structure weight of gantry crane reduced 20.1% compared with the initial trackless telescopic gantry crane model,and reduced the sensitivity of the structure to the fluctuation of uncertainty factors,which greatly improved the reliability and robustness;Compared with the result of deterministic optimization model using the Q345 as the gantry crane material,when both the reliability are 1,the structure weight of Q235 is higher than that of Q345 gantry crane by 295 kg.Considering the factors such as reliability and economic benefit,Q235 can be used to replace Q345 as the gantry crane material,and take the value of the design parameters after the robust optimization as the gantry crane structure size.