The Energy Absorption Characteristics of Square Mild Steel Tubes With Multiple Induced Circular Hole Discontinuities—Part II: Numerical Simulations

This paper is Part II of a two-part article and presents the results of numerical simulations conducted to investigate the energy absorption characteristics of square tubes subjected to dynamic axial loading. Part I reports the experimental results of both quasistatic and dynamic tests. The validated model is used to study the crushing characteristics of tubes with multiple induced circular hole discontinuities using the finite element package ABAQUS/EXPLICIT version 6.4-6. Holes of diameter 17 mm are used as crush initiators, which are laterally drilled into the tube wall to form opposing hole pairs. Holes of diameters 12.5 mm and 25 mm are also used to assess the effects of hole diameter on energy absorption. Two hole spacing configurations are investigated, one in which the hole pairs are placed at regular intervals of 50 mm along the tube wall and another in which the hole pairs are spaced symmetrically along the tube length. Holes are also drilled on either two or all four opposing tube walls. The number of holes is varied from 2 to 10. The results indicate that the introduction of the holes decreases the initial peak force. However, an increase in the number of holes, beyond two holes, does not further significantly decrease the initial peak force. A study of the crushing history of the tubes reveals that crushing is initiated at the location of the holes. The results also indicate that the type of hole spacing determines how crushing is initiated at the hole locations. The model satisfactorily predicts the resultant collapse shapes but overpredicts the crushed distance.