The Finite Element Analysis And Research For Its Intensity And Toughness Of Lift Arm And Bracket Of Heavy Wrecker

Heavy wrecker is a kind of the multi-function, big tonnage and heavy type equipment that can complete the rescue and cleanup to the vehicles conked out or happened accidents on road. According to the requirement of the domestic market and the development plan of wrecker series, this type of JG5190TQZ wrecker is developed by the engineering vehicle technique center of Jilin University. It is made up of the two parts: one is the underpan (infrastructure), the other is the rescue snag system (top). This type of STERY 1291.260/046/4X2 underpan is chosed and this underpan has the higher ability of running and nice comfort. The rescue snag system is driven by the whole liquid power, It is made up of two telescopiform box lift arm, the left and right winch, bracket, subframe, front and back moveable pedestal and rescue accessories. The lift arm and bracket are the most imporpant working devices. During the work, the bracket can lift the front bridge or back bridge, which makes the vehicles escape from the accident spot in time. The lift arm and the liquid capstans are matched each other, which can support the capsized vehicles and make it easy dragged or towed. The lift arm and the bracket are beared the more complicated work condition of the load during the snag and rescue. However, the desiged and developed products have been found that there are some unreasonable places exited in the local structure in the process of using and some places have more intensity but some places have less intensity. So there are more hidden dangers in the work and sometimes this engenders huge economy lose. Therefore, it is very necessary for the lift arm and the bracket to carry out the more accurate calculation of intensity and toughness and the dynamic analysis. The lift arm and the bracket of wrecker are the complicated loading structure system. If the classic mechanics method is adopted to calculate the intensity and toughness or carry out the dynamic analysis, then this will require a lot of simplifications and assumption. This method needs a great of computation time and sometimes even can't compute. Therefore, the work of design exists certain blindness for a long time, which influences the rationalization and lightweight process of the structure. For the complicated lift arm and bracket, the finite element method (FEM) is adopted to analyse the condition of the stress and displacement deformation of each structures, which redounds to the designers investigating the intensity and toughness of their each structure parts, supervises the design and manufacture, optimizes the whole structure and enhances the mechanics function of the the whole rescue and snag system. For shortening the development period of the product and lowering the development cost of the product, this has the greatly practical value, accelerates the comprehensive application of the product in our country and lays the solid foundation for entering the international market. The finite element analysis software ANSYS is mainly adopted to complete the simplification, the front and back disposal of the finite element, solution and caculation and the structure improvement of structure for the lift arm and bracket of JG5190TQZ wrecker, and then carry out the research and exploration for the parameter program design of slide block and the mode analysis of structure etc. Building the accurate and dependable model of finite element is the base of finite element analysis, and the accuracy of analysis result mainly relys on the model of finite element. However, the practical engeering structure is very complex generally and there are many kinds of shapes, so in the process of building the model of finite element, some necessary simplifications of structure needs to be done. If this simplification doesn't be done, it is unusually difficult for this structure to process the calculation offinite element and sometimes even could not be calculated. Firstly, the technical drawing of wrecker must be digested, absorbed and comprehended, On the basis of this, applying the knowledge of finite element, according to the characteristic of the structure and beared-force of the lift arm and bracket, on the premise of reflecting the mechanics characteristic, simultaneously following the principle that the element which can make the model simple and the decreased cost is chosen possibly, the model of finite element will be built. According to the geometrical size of each structure and the characteristics subjected to force in the work, three kinds of elements are adopted to disperse the lift arm. The variable -amplitude oil cylinder and the telescopiform oil cylinder are simulated LINK8 Element. The fixed and hinged shallow of the lift arm, the install shaft of the variable-amplitude oil cylinder, the install shaft of the telescopiform oil cylinder and the install shaft of the pulley block are simulated BEAM188 element. The basic arm, telescopiform arm and all kinds of strengthened planks, perpendicular planks and ear planks etc which material are 16Mn are simulated SHEEL63 element, the slide block are simulated LINK8 Element. Three kinds of elements are adopted to disperse the bracket too. The fixed-loosened oil cylinder, telescopiform oil cylinder of bracket and the slide block beteen basic arm and telescopiform arm are simulated LINK8 Element. The fixed shaft on the vertical arm, the install shaft of the fixed-loosened oil cylinder, the install shaft of the telescopiform oil cylinder and the install shaft of the basic arm are simulated BEAM188 element.The vertical arm,basic arm, telescopiform arm and all kinds of strengthened planks,ventral planks and ear planks etc which material are 16Mn are simulated SHEEL63 element.After the model is built, making sure some kinds of the work condition, the beared loads and the boundary conditions in the work, and then the computation and the result analysis will be completed.