Comparison of Three Calculation Models on Overall Stability Analysis of Telescopic Boom with Built-in Cylinder

Telescopic boom of crane is made up of many tapered box sections which can axially slip relatively. The boom is subjected to the whole bending moment, while the axial force is shared by the built-in cylinder and the friction of lap joint, so its mechanical model can not be equivalent to the multi-stepped column, or the tapered box boom with built-in cylinder subjected to the overall axial force. It´s important to analyze the buckling of telescopic boom with cylinder supporting and lapped friction simultaneously. Based on the deflection differential equilibrium equation, the analysis of the three different models to obtain telescopic boom´s Euler critical load are presented, and the model considering the effects of cylinder supporting and the lapped friction simultaneously is addressed. The result shows that the Euler´s critical load of telescopic boom which considering the effects of built-in cylinder and lapped friction is between that of the tapered box boom with built-in cylinder subjected to the overall axial force and that of multi-stepped column.