Dynamic behaviour of aluminium alloy plates with surface cracks subjected to repeated impacts

Abstract

Highlights The dynamic response of aluminum alloy plates repeatedly impacted by a rigid impactor has been investigated experimentally and theoretically. The permanent deformations of an impacted plate increase with each additional impact, and reach the largest values when the surface crack reaches the other side of the plate. The load-carrying capacity of a plate with a surface crack is sensitive to the crack length especially when the crack is shorter than the impactor diameter. The load-carrying capacity of a plate with a surface crack is also sensitive to the depth of the surface crack.  Within the scope of the test program, the surface cracks had rather moderate influences on the permanent deformations. The analytical formulae of Jones was modified with the stresses determined based on the true stresses. Discussions were also given to some assumptions in this refined analytical formula. AbstractThis paper investigates the behavior of aluminum plates with and without initial cracks under repeated impacts. Three series of repeated impact tests were conducted to study the behaviors of circulate plates that do not have any cracks (series B), have surface cracks with varying length (series L), and have cracks varying depths (series D). A hammer was dropped from the same height with a constant initial striking energy 60J for all tests. For each test specimen, the hammer was dropped nine times to simulate the scenario of repeated impacts. It was observed that plates with larger cracks carried smaller impact forces and assumed larger deformations. When the crack length was larger than the diameter of impactor, the responses of aluminum alloy plates became less sensitive to the crack length. With the increase in impact number, the effects of crack lengths and depths on dynamic behavior of aluminum alloy plates became much more significant. Predictions using a rigid-plastic theoretical model were compared with these test results, and discussions were given to the assumptions of this theoretical model. With the stresses determined based on the true strain-stress curve obtained by standard tension test, the refined analytical formula provides better predictions that agree well with the lab tests.

Experimental Research on Dynamic Behavior of Circular Mild Steel Plates with Surface Cracks Subjected to Repeated Impacts in Low Temperature

“…Compared with the intact specimen, the load carrying capacity of the cracked specimen is greatly reduced under impact load [1].…”

“…Such factors may significantly reduce the load carrying capability of the structures and even cause catastrophic damage. Besides, potential minor crack may occur during fabrication and operation or could be caused by corrosion during the life cycle service, and there is a growing interest in understanding the influence of the initial crack on the load carrying capability of the structures [1].…”

Experimental Research on the Repeated Impacts Behavior of Aluminum Corrugated-Core Sandwich Structures

“…Shi [10,11] proposed an ideal elastic-plastic analytical method for predicting the deformation and the structural stiffness of rectangular plates and beams made of metal material under repeatedly uniform pressure loadings. Duan [12] and Zeng [13] investigated the mechanical behavior of aluminum alloy plates and mild steel plates with precast cracks under repeated drop weight impacts. ey showed that the initial crack reduced the energy absorption of thin plates and leaded plates become more sensitive with the increase in impact number.…”