Finite element analysis of the special support of

2022-10-20
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SGA3723 mining dump truck special support finite element analysis and structural improvement

preface

sga3723 mining truck is a heavy mining transport truck jointly developed by Beijing Shougang heavy truck manufacturing plant and Beijing University of science and technology on the basis of SGA3722, which is suitable for transporting bulk materials in open-air mines, coal, water conservancy, electric power and construction sites. The cab support, water tank support and water tank cover support of SGA3722 mining truck, which has been produced for many years, are arranged independently; Complex structure. There are many defects such as high quality, high cost, poor welding technology, long production cycle and so on in the complex box components made of steel plates and steel beams with different thicknesses and shapes. In order to reduce the consumption of raw materials, improve the processability of product structure, shorten the production cycle and improve production efficiency, the manufacturer plans to improve the structure of the original vehicle

1 new support structure design

in view of the above problems, the following improvements are made in the new car design:

(1) the cab support, water tank support, water tank cover and walking platform support are integrated. Under the condition of meeting the use requirements, simplify the structural design scheme, reduce the weight of the assembly and save the layout space

(2) reasonably arrange the position of ribs. In the design, because the right side of this support interferes with the water outlet pipe of the water tank, considering the convenient disassembly and assembly of the pipeline, a notch is made on the front panel. Therefore, the back rib plate should also be shifted accordingly

(3) reserve the installation position of the lamp. On the premise of not weakening the structural strength too much, work with the lighting designer to determine the mounting hole of the headlamp to achieve aesthetic coordination

all plates are welded with Q235

the improved structure is welded from panel, rib, side decorative plate, bottom plate and ladder assembly. This structure is designed by experience, and it must also be quantitatively analyzed to verify the feasibility of the structure and determine the final design parameters

2 finite element modeling

2.1 model simplification

in automotive cad/cae technology, finite element analysis method and software technology occupy an extremely important position. For complex structures, the finite element method has been proved to be the most successful and widely used approximate analysis method for the study of mechanical properties and optimal design. There are two commonly used modeling methods in ANSYS: (1) modeling in general CAD software, importing in IGES, step and other formats, or directly converting the built model with the special interface program specially configured for UG, pro/e and CATIA; (2) Use ANSYS pre-processing module to model directly

use ANSYS finite element analysis software to carry out the solid modeling of the new support, assuming that the strength of welding is enough to jointly build an aluminum based new material aircraft carrier is large enough, and regard the finite element model of the support as a whole piece of rigid connection, regardless of the influence of the assembly lap of parts' welds, bolt holes and chamfers on the structure, and regardless of the influence of the ladder assembly. This simplified treatment is conducive to finite element analysis and calculation

2.2 unit selection

because this structural part is composed of plate and wall parts, especially the economic structure of our country, the dimension in the thickness direction of this kind of plate is much smaller than that in the length and width direction. In addition to the tension and compression in the plane, it also bears the bending and torsion. Therefore, shell element shell63 is used to simulate it. It is a four node three-dimensional elastic shell element, and each node has 6 degrees of freedom. This type of element is suitable for the comprehensive analysis of pure membrane stress, pure bending stress and two kinds of stresses of thin-walled or thin-walled structures. In addition, it can also be used for the analysis of composite layers

2.3 partition lattice

for different plates, different real constants need to be defined. Before dividing the grid, manually define the cell size, and divide the places requiring high precision separately

2.4 apply load

in the process of establishing the finite element model according to the actual situation of load application, define the loading plane at the corresponding position on the top of the panel respectively, and connect the loading surface with the model as a whole through the lapping command

2.5 constraints and boundary conditions

in the design, the support itself is assembled by welding, and then the bottom plate is fixedly connected with the frame through bolt connection, and its top end face is connected with each support assembly by bolts. Therefore, it is necessary to constrain all degrees of freedom of the base plate. According to the above finite principles, the finite element model of the support structure is established

3 calculation results

after the above finite element model is established, the finite element analysis software ANSYS is used for analysis and calculation

because the working conditions of mining truck are very bad, its support has to bear the load under different working conditions, such as the dead weight of the upper cab and water tank, the dead weight of the walking platform, the inertial impact force, the turning side tilt force, etc. Considering the actual working environment of mining truck, when carrying out static analysis. The dynamic load factor is 2.0 and the safety factor is 1.5 Therefore, the actual stress of the material should meet

it is found from the stress nephogram that in order to make the rib avoid the water tank pipeline, the rib under the water tank support is offset, causing serious local stress, reaching 94.4mpa, which is beyond the allowable stress range, and must be improved

4 structural improvement

(1) in order to improve the strength of the support, add a reinforcing rib of appropriate length at the lower part of the water tank support, so as not to interfere with the water pipe

(2) to improve the stiffness, add a full-length rib plate on the opposite side of the new rib

the finite element analysis is carried out again after the model is modified. The analysis results show that the maximum stress of the plate is reduced to 31.2mpa, which is because the newly added ribbed plate bears the load transmitted by the free upgrade of the experimental software and the water tank seat. The ribbed plate is located directly below the water tank support, effectively reducing the stress concentration caused by offset. Table 1 lists the strength and stiffness comparison of the support structure before and after the improvement. It can be seen that the improved structure not only reduces the structural stress and makes all parts bear the force evenly, but also improves the stiffness of the structure and reduces the deformation in all directions

5 conclusion

(1) this paper uses shell element to analyze the finite element strength and stiffness of SGA3723 mining truck special support, and improves the design of the support structure according to the analysis results, so that the welding process and stress distribution of the whole frame are more reasonable

(2) using the fast calculation function of ANSYS finite element analysis software, the strength of the modified frame is analyzed at any time, which shortens the design cycle of SGA3723 mining truck frame modification

(3) the finite element comparative analysis results of the support before and after the modification of the mining truck provide a theoretical basis for the design of the new support. At present, the new frame is being produced and processed. After processing, experiments and on-site running in verification are still needed. (end)

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