Effect of Pre-strain, Processing Conditions, and Impact Velocity on Energy Dissipation in Silicone Foams and Rubber

The analysis of energy dissipation characteristics is a basic way to elucidate the mechanism of coal rock fragmentation. In order to study the energy dissipation patterns during dynamic tensile deformation damage of coal samples, the Brazilian disc (BD) splitting test under impact conditions was conducted on burst-prone coal samples using a split Hopkinson pressure bar (SHPB) loading system. The effects of impact velocity, bedding angle, and water saturated on the total absorbed energy density, total dissipated energy density, and damage variables of coal samples were investigated. In addition, the coal samples were collected after crushing to produce debris with particle sizes of 0-0.2 mm and 0.2-5 mm, and the distribution characteristics of different size debris were compared and analyzed. The results show that the damage variables of natural dry coal samples increase approximately linearly with the increase of impact velocity; however, the overall damage variables of saturated coal samples increase exponentially as a function of impact velocity. Compared with air-dry samples, the number of fragments with the particle size of 0-0.2 mm of saturated samples decreases by 14.1%-31.3%, and the number of fragments with the particle size of 0.2-5 mm decreases by 33.7%-53.0%. However, when the bedding angle is 45°, the percentage of fragment mass of saturated samples is larger than that of air-dry samples. The conclusions provide a theoretical basis for understanding the deterioration mechanism of coal after water saturation and the implementation of water injection dust prevention technology in coal mines.

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Elasto-Plastic Impact on Auxetic/Metal Foams

Journal of Applied Mechanics ◽

10.1115/1.4048198 ◽

2020 ◽

Vol 87 (12) ◽

Author(s):

N. Kumar ◽

S. N. Khaderi ◽

K. Tirumala Rao

Keyword(s):

Energy Dissipation ◽

Impact Velocity ◽

Poisson’S Ratio ◽

Metal Foam ◽

Coefficient Of Restitution ◽

Peak Force ◽

Poisson's Ratio ◽

Rigid Sphere ◽

Yield Strain ◽

Maximum Displacement

Abstract We investigate the normal impact of a rigid sphere on a half-space of elasto-plastic auxetic/metal foam using the finite element method. The dependence of the coefficient of restitution, peak force, maximum displacement, and contact duration on the yield strain, impact velocity, and elastic and plastic Poisson’s ratio is analyzed. For a given elastic Poisson’s ratio, the coefficient of restitution generally decreases with an increase in the plastic Poisson’s ratio and impact velocity. When the plastic Poisson’s is maintained constant, the coefficient of restitution increases with an increase of the elastic Poisson’s ratio. These trends are explained using plastic energy dissipation. The energy dissipation trends are further investigated by decomposing it into deviatoric and hydrostatic parts. For a given impact velocity, the peak force is relatively insensitive to most of the elastic and plastic Poisson’s ratio combinations. We also show that for the cases where the elastic and plastic Poisson’s ratios are equal, the coefficient of restitution is relatively insensitive to their actual values. These findings can guide researchers to identify the right elastic and plastic Poisson’s ratio combinations so that lattice materials with exceptional energy absorbing capacity can be designed using topology optimization.

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Advanced Pipeline Impact Design

Volume 5: Pipelines, Risers, and Subsea Systems ◽

10.1115/omae2016-54855 ◽

2016 ◽

Author(s):

Ragnar T. Igland ◽

Hagbart S. Alsos ◽

Stig Olav Kvarme

Keyword(s):

Energy Dissipation ◽

Kinetic Energy ◽

Impact Velocity ◽

Large Diameter ◽

Small Diameter ◽

Energy Estimates ◽

Dissipated Energy ◽

Accurate Information ◽

Cross Sectional ◽

The Impact

The safety of pipelines and subsea structures are key elements in subsea field developments. As part of the safety engineering, protection from dropped objects and third party impact actions is required. This article addresses this aspect. Dropped object from a platform or a vessel is one of the design scenarios. The fall-pattern of the object is essential for the impact velocity and corresponding energy, model of the path and the effects of hydrodynamic behavior is outlined. In lieu of accurate information, the design code use energy band for energy estimates and may give extremely conservative impact energy. The falling objects structural flexibility and properties are discussed and evaluated regarding the energy dissipation and possible damage of the pipeline. The pipeline combined response from global deflection and denting regarding impacts are investigated. Analysis and testing methods applied in pipeline design are presented. Focus is placed on the overall interaction between the impacting object, the deformed pipeline and energy dissipation by coating and soil. Typically, pipeline damage from design codes provides conservative cross sectional damage estimates. This is confirmed from both simplified and detailed FE analyses, as well as fullscale impact experiments performed by REINERTSEN AS. One of the main objectives promoted by the authors is the importance of both impact velocity and mass during impact, and not only the kinetic energy of the impact. The kinetic energy from a dropped object is unlikely to be fully dissipated as cross sectional deformation of the pipeline. Global deformations will be triggered, which implies that the dissipated energy going into local denting is reduced to a fractional value. The effect is more pronounced for small diameter pipelines than for pipelines with large diameter. This paper discusses the impact mechanics and seeks to estimate the fractional value by using simplified element analysis.

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Design Mixers to Minimize Effects of Erosion and Corrosion Erosion

International Journal of Chemical Engineering ◽

10.1155/2012/171838 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8

Author(s):

Julian Fasano ◽

Eric E. Janz ◽

Kevin Myers

Keyword(s):

Energy Dissipation ◽

Kinetic Energy ◽

Impact Velocity ◽

Surface Coating ◽

Hydraulic Efficiency ◽

Impact Frequency ◽

Fluid Regime ◽

Life Improvement ◽

Liquid Slurry ◽

Solid Liquid

A thorough review of the major parameters that affect solid-liquid slurry wear on impellers and techniques for minimizing wear is presented. These major parameters include (i) chemical environment, (ii) hardness of solids, (iii) density of solids, (iv) percent solids, (v) shape of solids, (vi) fluid regime (turbulent, transitional, or laminar), (vii) hardness of the mixer's wetted parts, (viii) hydraulic efficiency of the impeller (kinetic energy dissipation rates near the impeller blades), (ix) impact velocity, and (x) impact frequency. Techniques for minimizing the wear on impellers cover the choice of impeller, size and speed of the impeller, alloy selection, and surface coating or coverings. An example is provided as well as an assessment of the approximate life improvement.

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Research on the Fractal Characteristics and Energy Dissipation of Basalt Fiber Reinforced Concrete after Exposure to Elevated Temperatures under Impact Loading

Materials ◽

10.3390/ma13081902 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1902

Author(s):

Wenbiao Liang ◽

Junhai Zhao ◽

Yan Li ◽

Yue Zhai

Keyword(s):

Fractal Dimension ◽

Energy Consumption ◽

Reinforced Concrete ◽

Energy Dissipation ◽

Impact Velocity ◽

Impact Loading ◽

Basalt Fiber ◽

Fiber Content ◽

Fiber Reinforced Concrete ◽

Fractal Characteristics

The fractal characteristics and energy dissipation of basalt fiber reinforced concrete (BFRC) with five kinds of fiber volume contents (0.0%, 0.1%, 0.2%, 0.3%, 0.4%) after exposure to different temperatures (20 °C, 200 °C, 400 °C, 600 °C, 800 °C) under impact loading were investigated by using a 50 mm diameter split Hopkinson pressure bar (SHPB) apparatus. Scale-mass distribution rules and fractal dimension characteristics of fragments were studied based on the screening statistical method and the fractal theory. Furthermore, the relationship between the energy consumption density and the fractal dimension of fragments was established, and the effects of fiber content, temperature and impact velocity on fractal dimension and absorption energy were analyzed. The results show that the crushing severity of fragments and fractal dimension increase with the impact velocity under the same fiber content. The energy consumption density increases first and then decreases with increasing fiber content, and also decreases with increasing temperature. When the temperature and fiber content remain unchanged, the energy consumption density increases linearly with the increasing fractal dimension, and under the same impact velocity and temperature, there is no obvious linear relationship between energy consumption density and fractal dimension.

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Formation of defects in implanted hipox-structures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131668 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1406-1407

Author(s):

Peter Pegler ◽

N. David Theodore ◽

Ming Pan

Keyword(s):

High Pressure ◽

Cross Section ◽

Semiconductor Devices ◽

Silicon Substrates ◽

Processing Conditions ◽

Pressure Oxidation ◽

Deep Trench ◽

Local Oxidation ◽

Trench Isolation ◽

And Behavior

High-pressure oxidation of silicon (HIPOX) is one of various techniques used for electrical-isolation of semiconductor-devices on silicon substrates. Other techniques have included local-oxidation of silicon (LOCOS), poly-buffered LOCOS, deep-trench isolation and separation of silicon by implanted oxygen (SIMOX). Reliable use of HIPOX for device-isolation requires an understanding of the behavior of the materials and structures being used and their interactions under different processing conditions. The effect of HIPOX-related stresses in the structures is of interest because structuraldefects, if formed, could electrically degrade devices.This investigation was performed to study the origin and behavior of defects in recessed HIPOX (RHIPOX) structures. The structures were exposed to a boron implant. Samples consisted of (i) RHlPOX'ed strip exposed to a boron implant, (ii) recessed strip prior to HIPOX, but exposed to a boron implant, (iii) test-pad prior to HIPOX, (iv) HIPOX'ed region away from R-HIPOX edge. Cross-section TEM specimens were prepared in the <110> substrate-geometry.

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Energy dissipation across the front of shock wave in rheological materials filled with second phase inclusions

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:2006134135 ◽

2006 ◽

Vol 134 ◽

pp. 883-887

Author(s):

Jian-kang Chen ◽

Jue Zhu

Keyword(s):

Shock Wave ◽

Energy Dissipation ◽

Second Phase

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Progressive Debonding of Multilayer Interconnect Structures

MRS Proceedings ◽

10.1557/proc-473-21 ◽

1997 ◽

Vol 473 ◽

Cited By ~ 9

Author(s):

Michael Lane ◽

Robert Ware ◽

Steven Voss ◽

Qing Ma ◽

Harry Fujimoto ◽

...

Keyword(s):

Thin Films ◽

Crack Growth ◽

Driving Force ◽

Adhesion Energy ◽

Time Dependent ◽

Multilayer Thin Films ◽

Processing Conditions ◽

Interface Morphology ◽

Entire Sample ◽

Crack Growth Velocity

ABSTRACTProgressive (or time dependent) debonding of interfaces poses serious problems in interconnect structures involving multilayer thin films stacks. The existence of such subcriticai debonding associated with environmentally assisted crack-growth processes is examined for a TiN/SiO2 interface commonly encountered in interconnect structures. The rate of debond extension is found to be sensitive to the mechanical driving force as well as the interface morphology, chemistry, and yielding of adjacent ductile layers. In order to investigate the effect of interconnect structure, particularly the effect of an adjacent ductile Al-Cu layer, on subcriticai debonding along the TiN/SiO2 interface, a set of samples was prepared with Al-Cu layer thicknesses varying from 0.2–4.0 μm. All other processing conditions remained the same over the entire sample run. Results showed that for a given crack growth velocity, the debond driving force scaled with Al-Cu layer thickness. Normalizing the data by the critical adhesion energy allowed a universal subcriticai debond rate curve to be derived.

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