Normal impact of a low-velocity projectile against a taut string-like membrane

2018 ◽  
Vol 426 ◽  
pp. 219-233 ◽  
Author(s):  
Yifei Zhao ◽  
Zhili Sun
Keyword(s):  
Normal Impact ◽  
Low Velocity ◽  
Taut String

Low Velocity Impact Studies on a 4-Ply Knitted Kevlar Fabric Reinforced Epoxy Composite

2002 ◽  
Vol 21 (2) ◽  
pp. 121-138 ◽  
Author(s):  
C. T. Lim ◽  
V. B. C. Tan ◽  
S. Ramakrishna ◽  
J. B. K. Lee
Keyword(s):  
Epoxy Composite ◽  
Impact Resistance ◽  
Matrix Cracking ◽  
Low Velocity Impact ◽  
Normal Impact ◽  
Low Velocity ◽  
Fibre Breakage ◽  
Significant Difference ◽  
Impact Energies ◽  
Fibre Matrix

Four-ply knitted Kevlar fabric reinforced epoxy composites with three different stacking sequences were subjected to normal impact of up to 10 J using a hemispherical steel impactor. Similar modes of damage were observed from impacts on all three different stacking sequences where damage progressed from matrix cracking and fibre/matrix debonding at low impact energies to fibre breakage and eventual through-thickness cracks at higher impact energies. A critical mode of damage occurred at about 4.5 J where there was a sudden deterioration of impact resistance due to fibre breakage at the top and bottom plys. The only significant difference among composites of different stacking sequences subjected to low velocity impacts of similar magnitude was the propagation of through-thickness cracks at impact energy larger than 5 J.

Low Velocity Transverse Normal Impact of Graphite Epoxy Composite Laminates

1976 ◽  
Vol 10 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Edward J. Mcquillen ◽  
Lee W. Gause ◽  
Richard E. Llorens
Keyword(s):  
Composite Laminates ◽  
Epoxy Composite ◽  
Normal Impact ◽  
Low Velocity

Finite-element impact response of debonded composite turbine blades

2014 ◽  
Vol 03 (01) ◽  
pp. 1450001
Author(s):  
Sudip Dey ◽  
Amit Karmakar
Keyword(s):  
Finite Element ◽  
Dynamic Equilibrium ◽  
Turbine Blades ◽  
Hertzian Contact ◽  
Integration Scheme ◽  
Element Formulation ◽  
Normal Impact ◽  
Low Velocity ◽  
Conical Shells ◽  
The Impact

This paper investigates on the transient behavior of debonded composite pretwisted rotating shallow conical shells which could be idealized as turbine blades subjected to low velocity normal impact using finite-element method. Lagrange's equation of motion is used to derive the dynamic equilibrium equation and the moderate rotational speeds are considered neglecting the Coriolis effect. An eight-noded isoparametric plate bending element is employed in the finite element formulation incorporating rotary inertia and effects of transverse shear deformation based on Mindlin's theory. The modified Hertzian contact law which accounts for permanent indentation is utilized to compute the impact parameters. The time-dependent equations are solved by using Newmark's time integration scheme. Parametric studies are performed to investigate the effects of triggering parameters like angle of twist, rotational speed, laminate configuration and location of debonding considering low velocity normal impact at the center of eight-layered graphite-epoxy composite cantilevered conical shells with bending stiff [Formula: see text], torsion stiff ([45°/-45°/-45°/45°]s) and cross-ply ([0°/90°/0°/90°]s) laminate configurations.

Motions of neutral hydrogen at high latitudes

1967 ◽  
Vol 31 ◽  
pp. 265-278 ◽  
Author(s):  
A. Blaauw ◽  
I. Fejes ◽  
C. R. Tolbert ◽  
A. N. M. Hulsbosch ◽  
E. Raimond
Keyword(s):  
Surface Density ◽  
Velocity Dispersion ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
High Latitudes ◽  
Low Velocity

Earlier investigations have shown that there is a preponderance of negative velocities in the hydrogen gas at high latitudes, and that in certain areas very little low-velocity gas occurs. In the region 100° <l< 250°, + 40° <b< + 85°, there appears to be a disturbance, with velocities between - 30 and - 80 km/sec. This ‘streaming’ involves about 3000 (r/100)2solar masses (rin pc). In the same region there is a low surface density at low velocities (|V| < 30 km/sec). About 40% of the gas in the disturbance is in the form of separate concentrations superimposed on a relatively smooth background. The number of these concentrations as a function of velocity remains constant from - 30 to - 60 km/sec but drops rapidly at higher negative velocities. The velocity dispersion in the concentrations varies little about 6·2 km/sec. Concentrations at positive velocities are much less abundant.

Atomic orientation effects in proton stopping at low velocity

1983 ◽  
Vol 41 ◽  
pp. 708-709
Author(s):  
Kin Lam
Keyword(s):  
Polycrystalline Material ◽  
Charged Particles ◽  
Target Material ◽  
Stopping Power ◽  
Low Velocity ◽  
Electronic Density ◽  
Interatomic Distances ◽  
Frame Work ◽  
Image Position ◽  
Atomic Orientation

The energy of moving ions in solid is dependent on the electronic density as well as the atomic structural properties of the target material. These factors contribute to the observable effects in polycrystalline material using the scanning ion microscope. Here we outline a method to investigate the dependence of low velocity proton stopping on interatomic distances and orientations.The interaction of charged particles with atoms in the frame work of the Fermi gas model was proposed by Lindhard. For a system of atoms, the electronic Lindhard stopping power can be generalized to the formwhere the stopping power function is defined as

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