Study On Strength Calculation Of Pump Boom And Experimental Verification

On the basis of the testing data of the yield strength of various types of plastic metals under biaxial and triaxial tensile-compressive combined with principal stress, the relative errors calculated using strength theory which are commonly applied in pump truck boom strength design and limiting strain energy strength theory (LSEST) are analyzed, respectively. The result shows that the errors according to LSEST are within10%, being the minimum. The errors calculated by Tresca strength theory, Von Mises strength theory and Mohr-Coulomb strength criterion are-36%,-27%and-23%, respectively. The calculating results are on the conservative side compared with the test ones. For materials with equal tensile and compressive yield strength, Tresca strength theory and Von Mises strength theory could not be applied either, and the theoretical shear yield strength is (?)/2times of the tensile yield strength. LSEST could be applied to calculate the strength under biaxial and triaxial tensile-compressive combined principal stress, which is consistent with Rankine strength theory under full tensile and full compressive principal stress state.Three special working conditions are selected with the angle between the boom and the horizontal plane are0°、45°、80°when pump boom are fully extended, then finite element static model of the boom based on ANSYS is established. Comparing the static test results conducted on the boom pump test rig and the calculated ones by ANSYS, it shows that the calculated ones are relatively consistent with the test results, verifying the correctness of the finite element model of the boom.Under three different loading models with all dynamic loads, dynamic loads except for rotary inertia force, and static loads included, the test pump boom system is calculated by finite element model. The results indicate that the equivalent stress according to LSEST is consistent with the total loads that the boom suffered and the variation of the maximum principal stress. The maximum equivalent stress according to Tresca strength theory is inconsistent with the total loads, and the calculated results using Von Mises strength theory are more closer to actual condition, compared with that according to Tresca strength theory, however, the calculated results according to the two theories are on the contrary.For two dynamic loading models, the equivalent stress according to three strength theories is10%greater than that suffering static loads, with maximum value amounts to27.5%, suggesting that the dynamic loads have an great effect on boom strength. With the impact of rotary inertia force, the equivalent stress according to LSEST is increased over8%, while the equivalent stresses according to the other strength theories are almost unchanged.