KEYWORDS: Aluminum, Absorption, High speed cameras, Cameras, Video processing, Video, Solids, High speed imaging, Signal processing, Electronics engineering
In order to study the possibility of utilizing the in-plane dynamic property of aluminum honeycombs to soft shock
absorbers in a man-to-car impact or a man-to-machine impact environment, dynamic responses of aluminum
honeycombs of various cell size and cell number to the in-plane and uni-directional impact loading were investigated
experimentally. A high-speed video camera and an acceleration pickup were used to investigate the deformation process
and the shock absorption characteristics.
The dynamic behavior of aggregated spherical particles subjected to the impact of a steel spherical projectile was
simultaneously recorded using two high-speed video cameras at different angles. The post-impact effects of a steel
projectile with an impact velocity of 1-20 m/s and an impact angle of 0-65° on the dynamic behavior of aggregated
particles were examined. The movement of the projectile after impact can be classified into four different types. In
addition, the effects of the particle's diameter of aggregated particles and the depth of the container on the four different
types of the projectile's movement were also examined. The use of small particles resulted in clear boundaries
demarcating between the penetration and the horizontal movement or the rebound of the projectile.
Dynamical deformation and collapse process and stress wave mechanism of an aluminum honeycomb with a defective cell subjected to the in-plane impact of a rigid impactor were investigated experimentally. Deformation process was visualized using a high-speed video camera and a CCD camera and wave propagation mechanisms were investigated using a force gauge at the fixed end and strain-gauges glued on the cell walls. Also, numerical simulation was made using a shock code, AUTODYN-2D. The defect introduced in cells greatly affects wave propagation mechanisms and cell deformation process. The present results were compared with our previous results.
The dynamic behavior of particulate aggregation subjected to the impact of a steel spherical projectile was simultaneously recorded using two high-speed video cameras at different angles and analyzed numerically using a discrete element method. The effects of the impact velocity (1-25 m/s), impact angle (0-65 degrees), and size of the steel projectile on the dynamic response of particulate aggregation and projectile were examined. The movement of the projectile after impact can be classified into four types: penetration into particulate aggregation; stopping at the particulate aggregation surface; rebounding from particulate aggregation; and horizontal movement along the particulate aggregation surface. The type of movement depended on impact velocity and impact angle. The defining boundaries between the four types of movements became clearer as the size of the projectile increased. The results of numerical simulation also indicated that the magnitude, direction, and bifurcation of contact forces propagating into particulate aggregation play an important role in the change of the projectile's movement after impact.
Dynamical deformation and collapse process and stress wave mechanism of aluminum honeycombs subjected to the in-plane impact of a rigid impactor were investigated experimentally. Deformation process was visualized using a high-speed video camera and reaction forces were measured using force-gauges at the contact surface between the honeycomb and fixed wall. Also, numerical simulation was made using a shock code. AUTODYN-2D. Since an aluminum honey-comb has an anisotropic nature owing to its cell shape and cell arrangement, the direction of impact greatly affects the deformation characteristics. The present results were compared with our previous results for different impact direction.
The dynamic response of three-dimensional pariculate aggregation subjected to the impact of a spherical projectile is investigated experimentally and also numerically using discrete element method. It becomes clear the effect of the repulsion of spheres and wave propagation on the scattering behavior of particulate aggregation. It is found that the scattering behavior of the particulate aggregation depends on the lateral gap between nylon spheres.
Deformation processes of aluminum honeycombs with hexagonal cells subjected to the in-plane impact of a rigid impactor are investigated experimentally and numerically in relation to the dynamical behavior of cellular materials and complex materials under high-speed loadings. Strain waves are measured using strain gauges glued on the cell walls and reaction forces are measured using a load cell at the contact surface between the honeycomb and a fixed wall. A high-speed camera is used to visualize the deformation process. Numerical simulations are partly made for the same configuration as the experiment. Very distinctive deformation mechanisms of individual cells and propagation mechanisms of strain waves in the honeycomb are found out. Also, characteristic two-dimensional behavior is revealed in spite of one-dimensional and uni-directional impact loading.
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