Effect of High Pressure on Dynamic Compressive Strength of A95 Alumina Ceramics

2012 ◽  
Vol 446-449 ◽  
pp. 3643-3646
Author(s):  
Guo Wen Yao ◽  
Yan Jun Li ◽  
Xiao Wei Feng
Keyword(s):  
Hydrostatic Pressure ◽  
Yield Criterion ◽  
Dynamic Strength ◽  
Ceramic Materials ◽  
Surface Velocity ◽  
Alumina Ceramics ◽  
Open Problems ◽  
Gas Gun ◽  
Impact Experiments

The dynamic strength expressions of materials were reviewed in case of one-dimensional strain shock loadings in this paper, the effects on the strength were suggested to be considered of hydrostatic pressure and high strain rate. A modified form for the Hugoniot Elastic Limits was given associated with the Drucker-Prager yield criterion, the effect of hydrostatic pressure being included. Free surface velocity histories of particle were measured by VISAR system in plate impact experiments on alumina with a Light Gas Gun. The experimental determination of dynamic strengths of alumina was discussed and the open problems were clarified. By comparing the strength expressions of ceramic materials with the experimental results, the evident differences were pointed out. Their analysis and discussion were further given for the experimental phenomenon.

scholarly journals High velocity impact of an Fe/Cr/Mn/Ni high entropy alloy

2019 ◽  
Author(s):  
M. Cameron Hawkins ◽  
Sarah Thomas ◽  
Robert Hixson ◽  
Nan Li ◽  
Saryu Fensin
Keyword(s):  
Dynamic Properties ◽  
Dynamic Compression ◽  
Surface Velocity ◽  
High Entropy Alloy ◽  
Transition Metal Alloy ◽  
High Entropy ◽  
New Class ◽  
Gas Gun ◽  
Data Points ◽  
Impact Experiments

Abstract A series of shock loading experiments were conducted on High Entropy Alloy (HEA) samples consisting of Fe/Cr/Mn/Ni in weight percentages of 25.2/23.5/24.8/26.5. Characterizing this transition metal alloy is a first step in understanding the shock compression response of this relatively new class of alloy. A single stage light gas gun was used to conduct a series of flyer plate symmetric impact experiments to obtain fundamental dynamic properties. Photonic Doppler Velocimetry (PDV) diagnostics were employed to measure the free surface velocity on the back of each target during dynamic compression. These experiments yielded four data points that are in reasonable agreement with an estimated Hugoniot for the material.

Fracture Toughness Testing on Bars Under Opposite Cylinder Loading

2002 ◽  
Author(s):  
Theo Fett ◽  
Dietrich Munz ◽  
Gerhard Thun
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Ceramic Materials ◽  
Resistance Curve ◽  
Alumina Ceramics ◽  
Practical Applications ◽  
T Stress ◽  
Toughness Testing ◽  
Concentrated Forces

Bars loaded by opposite concentrated forces via rollers are appropriate test specimens for the determination of the fracture toughness, KIc, and the crack resistance curve (R-curve) of ceramic materials. In this paper stress solutions for the proposed test specimens are provided, as well as the stress intensity factor and the T-stress solutions. As practical applications, R-curves are determined for a soft PZT ceramic and several alumina ceramics.

Fracture Toughness Testing on Bars Under Opposite Cylinder Loading

2004 ◽  
Vol 126 (1) ◽  
pp. 50-54
Author(s):  
T. Fett ◽  
D. Munz ◽  
G. Thun
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Ceramic Materials ◽  
Resistance Curve ◽  
Alumina Ceramics ◽  
Practical Applications ◽  
T Stress ◽  
Toughness Testing ◽  
Concentrated Forces

Bars loaded by opposite concentrated forces via rollers are appropriate test specimens for the determination of the fracture toughness, KIc, and the crack resistance curve (R-curve) of ceramic materials. In this paper stress solutions for the proposed test specimens are provided, as well as the stress intensity factor and the T-stress solutions. As practical applications, R-curves are determined for a soft PZT ceramic and several alumina ceramics.

scholarly journals Dust and atmospheric influence on plasma properties observed in light gas gun hypervelocity impact experiments

2021 ◽  
Vol 151 ◽  
pp. 103833
Author(s):  
Benjamin Estacio ◽  
Gil Shohet ◽  
Sean A.Q. Young ◽  
Isaac Matthews ◽  
Nicolas Lee ◽  
...  
Keyword(s):  
Hypervelocity Impact ◽  
Plasma Properties ◽  
Gas Gun ◽  
Impact Experiments

Fracture Behavior of Ceramics Used in Multilayer Capacitors

1986 ◽  
Vol 72 ◽  
Author(s):  
Theresa L. Baker ◽  
Stephen W. Freiman
Keyword(s):  
Crack Growth ◽  
Fracture Behavior ◽  
Ceramic Materials ◽  
Fatigue Tests ◽  
Internal Stresses ◽  
Crack Growth Behavior ◽  
Multilayer Capacitors ◽  
Materials Used ◽  
Aging Phenomena

AbstractThis study involved the determination of the effects of composition and microstructure on the fracture toughness and susceptibility to environmentally enhanced crack growth of several ceramic materials used in multilayer capacitors. Indentation-fracture procedures were used to measure KIC as well as to assess the possible effects of internal stresses on the fracture behavior of these materials and to correlate dielectric aging phenomena with strength. The environmentally enhanced crack growth behavior of these materials was determined by conducting dynamic fatigue tests in water.

Free Water Influence on the Dynamic Tensile Behaviour of Concrete

2011 ◽  
Vol 82 ◽  
pp. 45-50 ◽  
Author(s):  
Benjamin Erzar ◽  
Pascal Forquin
Keyword(s):  
Dynamic Behaviour ◽  
Free Water ◽  
Dynamic Strength ◽  
Fragmentation Process ◽  
Tensile Behaviour ◽  
Water Influence ◽  
Micro Cracks ◽  
The World ◽  
The Difference ◽  
Impact Experiments

Concrete is a material used all over the world for civil engineering but the mechanisms governing its dynamic behaviour are still not well understood. In this work, spalling tests and edge-on impact experiments have been used to determine the influence of the free-water contained in pores and micro-cracks on the dynamic strength and on the fragmentation process. Moreover, spalling tests have been also used to identify the main mechanisms leading to the difference of behaviour observed between wet and dry concrete.

scholarly journals Determination Of Snow Facies and Ice Velocity Using Synthetic Aperture Radar Imagery

1990 ◽  
Vol 14 ◽  
pp. 330-330
Author(s):  
R.A. Bindschadler ◽  
P.L. Vornberger
Keyword(s):  
Synthetic Aperture Radar ◽  
Liquid Water ◽  
Snow Accumulation ◽  
Surface Velocity ◽  
Synthetic Aperture ◽  
Stream Network ◽  
Backscatter Signal ◽  
Volume Scattering ◽  
Aperture Radar

The properties of synthetic aperture radar (SAR) imagery are appropriate for its use to map snow facies. These facies, defined by Benson (1962), are subdivisions of the accumulation area of an ice sheet or polar glacier and represent the interaction of the ice mass with the climate through the processes of snow accumulation and melting. Changes in these climatic parameters are expected to cause changes in the extent and character of these facies. The ability of SAR to discriminate these facies is due to the significant amount of sub-surface volume scattering in the measured radar backscatter signal and the strong absorption of radar energy by liquid water. The amount of volume scattering is dependent on the size and distribution of scatterers in the medium. This dependence varies over the size range of snow grains to ice lenses. Specific examples of the ability to detect different scatterer populations in ice sheets with SAR are shown. Other examples are given to demonstrate the reduction of backscatter signal when liquid water is present.Another important application of SAR data is the determination of surface velocity. Coregistration of a SAR and a TM image spanning an eight-year period was completed for an area in south-western Greenland. The composite image shows that, while the network of surface streams is nearly unchanged, their distance from lakes upstream increased over the eight-year interval between images. Because the lakes are likely fixed in space, a result of surface depressions whose positions are determined by the stationary bedrock topography, the displacement of the stream network was used to calculate a surface velocity of 40 ± 10 m per year near the equilibrium line.

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