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Discussion on Optimization and application of crane boom design in northern transportation

discussion on Optimization and application of crane boom design in northern transportation

China Construction machinery information

in recent years, with the continuous development of truck cranes, the cross-section shape of truck crane boom has gradually evolved from quadrangle, hexagon, octagon and so on to U-shape. The U-shaped section can significantly improve the bending resistance of the section. The test shows that under the same perimeter and thickness of the crane main boom section, the bending resistance of the U-shaped section is nearly 10% higher than that of the hexagonal section. Therefore, the U-shaped section main boom has been widely used in the market that hopes to create a market of 15.3 billion US dollars per year. Using the finite element analysis method to analyze and optimize the U-shaped section boom is very necessary to improve the utilization rate of materials and the strength, stiffness and stability of the boom

1 working condition analysis

a certain type of truck crane is a 5-SECTION telescopic boom with double oil cylinders and rope row telescopic mechanism. According to the form of the boom, the stress value at the lap joint of each boom is the largest under the working state of the crane, which is a dangerous section. Generally, the stress of each arm length reaches the maximum value under the maximum lifting torque condition of the corresponding length. The crane performance table of double cylinder and rope row telescopic mechanism is generally 7 columns. We select the working condition of the maximum lifting torque in each column for analysis. There are 7 working conditions in total

2 geometric model

processing after the geometric model of the boom is established, it is imported into the ANSYS Workbench through the Parasolid format. Then, according to the stroke of the telescopic cylinder under the working conditions of different arm lengths, the two, three, four and five arms are translated, and a total of seven geometric models with different lengths are established. The dangerous section is at the overlap of the boom, and the stress value at the boom head and boom tail of each boom is small. Delete the parts that have little impact on the overall analysis of the boom, such as bolts, pins, base plates, oil cups, etc., and remove the welding groove on the plate, leaving only the main load-bearing structures such as hoops, pulley supports, rope row pull plates, and sliders. Then some irregular parts are cut to make them into regular shapes, and the research of graphene is promoted to a strategic height, so as to facilitate the division of grids

3 grid division

due to the complex structure of the boom, if the mid plane is analyzed by shell element, it will spend a lot of time in geometric processing, so the solid model is used. The boom plate is divided into regular grids by solid186 units in sweep mode, and individual irregular parts are divided freely. The main load-bearing parts are the upper and lower groove plates, which are divided into two-layer elements in the thickness direction, and there are five nodes, which can accurately obtain the stress situation there. Solid186 element is a high-order three-dimensional 20 node solid structure element. Solid186 element has a quadratic displacement mode, which can better simulate irregular geometry. The force transmission between the jibs in the boom is carried out through the telescopic oil cylinder and the telescopic rope row, so the telescopic oil cylinder and the telescopic rope row should also be established in the model. There are two telescopic oil cylinders, which are respectively connected to the tail of the first boom, the second boom and the third boom. The telescopic cylinder is simulated by beam188 unit, and the section size of beam188 is the real size of the telescopic cylinder. The telescopic oil cylinder and the support of the oil cylinder at the tail of the boom are connected by a pin shaft, which can rotate with each other, that is, it does not transmit bending moments. The pin shaft is also simulated by beam188 unit. The pin shaft is connected with the telescopic cylinder, and the pin shaft is connected with the boom cylinder support in the way of MPC revolution, so that they can rotate each other. The telescopic rope is simulated by link8 unit, one end of which is connected to the rope row support of the boom and bypasses the pulley to connect to the rope row support of the other boom

4 constraint and load

the sliding block is made of MC nylon, and the stiffness is much different from that of steel. Therefore, no also determines the structural separation connection of the tension machine. This connection has little impact on the stiffness of the whole boom, and the noseparation connection method is linear, and the calculation speed is fast. The connection between the tail of the basic boom and the turntable constrains UX, uy, uz3 translational degrees of freedom and ROTY, and rotz2 rotational degrees of freedom, even if the boom can rotate around the root in the luffing plane; The same method shall be adopted at the luffing support. A single rope tension towards the winch is applied at the guide pulley at the head of the five section boom, a heavy lifting load is applied at the lifting pulley, and a single rope tension with equal size and opposite direction is applied between the two pulleys. The gravitational acceleration is taken as 10m/s2 and added in the form of acceleration

5 stress test results

the original design and process of the prototype were optimized according to the finite element analysis. After the trial production of the sample vehicle is completed, the stress test is carried out on the boom, and the same working condition as the finite element analysis is selected for the test. The patch position is the lap joint of each boom. The comparison between the stress test results and the finite element analysis results shows that the measured values are close to the finite element analysis values, but there are still some errors, mainly because the constraints on the two hinge points of the boom are full constraints, It does not reflect the impact of the deformation of the lower carriage and turntable on the boom during its operation

6 conclusion

by using ans "we have evaluated and analyzed the replacement exhibition hall since 2016. The finite element analysis of the crane boom of the truck crane with ys software shows that the analysis results are close to the actual measured values. Within the acceptable range, it shows that the results obtained by using this method are relatively accurate, and the process of this method is simple and easy to operate, which can effectively guide the actual design work and production manufacturing

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