Study Of Mobile Cranes' Boom

The boom is an essential part of the mobile crane, the design of which has a direct impact on the performance and the cost of the whole machine..The boom should possess enough strength, rigidity and stability. Among other things, the deftness of the boom appears to be more important. In the moderu design, the measure of decreasing the height of the side plate is adopted currently in order to avoid failure. And the failure is due largely to local instability. When this measure is adopted, the section shape of the boom transforms from rectangle to pentagon, hexagon, octagon, dodecagon, even oval. But the calculating quantification has not been seen yet. Especially, there is still no exact method to calculate the local stability over the type of hexagon. Critical flexional load can not be predicted exactly before the design, so that the stress of the design is on the low side, though the high strength steel is adopted.According to Crane Design Criterion's calculating method about the load, intensity and local stability of the boom, I calculated every plate's load of hexagon section by Matlab program in my paper. I also calculated the section's moment of inertia, bending modulus, composition stress and critical yield stress when the base plate's size parameter and incline plate's angle parameter altered together. On the premise of reaching the demands of the boom's strength and local stability, I analyzed these two relationships: (1) the relationship between base plate's size and incline plate's angle when the overlap-length was fixed and every plate's surplus was close; (2) the relationship between variation overlap-length and the maximal load which this crane can lift under this overlap-length. The corresponding relation of these two parameters which reached the demand of the target function can be provided reference for the design of the boom of the crane.All in all, the new structure of the QY16 Mobile Crane which was optimized in my paper is obvious more reasonable and less-weighted than the original one.