Analysis and Experimental Verification of the Strength of Telescopic Booms for Construction Machinery

Telescopic booms are key elements for payload lifting in construction machineries. They usually consist of thin-walled hollow segments that can retract, extend or elevate during operation. The mechanical properties of the telescopic booms directly determine the lifting capacity of these machines. The overlapping contact regions between the adjacent booms are critical locations where high stresses occur, thus the stress level in these regions is the key factor representing the strength of the telescopic boom structures. According to the principle of superposition, a mathematical model has been proposed for analysis of stresses in the contact zones of telescopic boom structure. The proposed model calculates the global bending stress according to the beam bending theory, then uses a partial telescopic boom geometry isolated from the contact zones to establish a local analytical model to determine the local stresses according to the plate bending theory, and finally superimposes the two states of stresses to obtain the final stress state which represents the strength of the telescopic booms. The proposed analytical model has been validated by both finite element analysis and experimental test conducted on a telescopic aerial platform.