Prediction and Experimental Validation of an Impact Energy Threshold for Mechanical Surface Smoothing

Buckling Thresholds for Pre-Loaded Spherical Shells Subject to Localized Blasts

Journal of Applied Mechanics ◽

10.1115/1.4045588 ◽

2019 ◽

Vol 87 (3) ◽

Cited By ~ 1

Author(s):

Jan Sieber ◽

John W. Hutchinson ◽

J. Michael T. Thompson

Keyword(s):

Impact Energy ◽

Energy Barrier ◽

Threshold Energy ◽

External Pressure ◽

Extensive Study ◽

Energy Threshold ◽

Integration Scheme ◽

Spherical Shells ◽

Buckling Mode ◽

The Impact

Abstract This paper investigates the robustness against localized impacts of elastic spherical shells pre-loaded under uniform external pressure. We subjected a pre-loaded spherical shell that is clamped at its equator to axisymmetric blast-like impacts applied to its polar region. The resulting axisymmetric dynamic response is computed for increasing amplitudes of the blast. Both perfect shells and shells with axisymmetric geometric imperfections are analyzed. The impact energy threshold causing buckling is identified and compared with the energy barrier that exists between the buckled and unbuckled static equilibrium states of the energy landscape associated with the pre-loaded pressure. The extent to which the impact energy of the threshold blast exceeds the energy barrier depends on the details of its shape and width. Targeted blasts that approximately replicate the size and shape of the energy barrier buckling mode defined in the paper have an energy threshold that is only modestly larger than the energy barrier. An extensive study is carried out for more realistic Gaussian-shaped blasts revealing that the buckling threshold energy for these blasts is typically in the range of at least 10–40% above the energy barrier, depending on the pressure pre-load and the blast width. The energy discrepancy between the buckling threshold and energy barrier is due to elastic waves spreading outward from the impact and dissipation associated with the numerical integration scheme. Buckling is confined to the vicinity of the pole such that, if the shell is not shallow, the buckling thresholds are not strongly dependent on the location of the clamping boundary, as illustrated for a shell clamped halfway between the pole and the equator.

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Planetesimal fragmentation and giant planet formation

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834168 ◽

2019 ◽

Vol 625 ◽

pp. A138 ◽

Cited By ~ 3

Author(s):

I. L. San Sebastián ◽

O. M. Guilera ◽

M. G. Parisi

Keyword(s):

Impact Energy ◽

Planet Formation ◽

Giant Planet ◽

Realistic Model ◽

Giant Planets ◽

Energy Threshold ◽

Accretion Rates ◽

The Cross ◽

Catastrophic Impact ◽

Massive Cores

Context. Most planet formation models that incorporate planetesimal fragmentation consider a catastrophic impact energy threshold for basalts at a constant velocity of 3 km s−1 throughout the process of the formation of the planets. However, as planets grow, the relative velocities of the surrounding planetesimals increase from velocities of the order of meters per second to a few kilometers per second. In addition, beyond the ice line where giant planets are formed, planetesimals are expected to be composed roughly of 50% ices. Aims. We aim to study the role of planetesimal fragmentation on giant planet formation considering the planetesimal catastrophic impact energy threshold as a function of the planetesimal relative velocities and compositions. Methods. We improved our model of planetesimal fragmentation incorporating a functional form of the catastrophic impact energy threshold with the planetesimal relative velocities and compositions. We also improved in our model the accretion of small fragments produced by the fragmentation of planetesimals during the collisional cascade considering specific pebble accretion rates. Results. We find that a more accurate and realistic model for the calculation of the catastrophic impact energy threshold tends to slow down the formation of massive cores. Only for reduced grain opacity values at the envelope of the planet is the cross-over mass achieved before the disk timescale dissipation. Conclusions. While planetesimal fragmentation favors the quick formation of massive cores of 5–10 M⊕ the cross-over mass could be inhibited by planetesimal fragmentation. However, grain opacity reduction or pollution by the accreted planetesimals together with planetesimal fragmentation could explain the formation of giant planets with low-mass cores.

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Experimental validation of impact energy model for the rub–impact assessment in a rotor system

Mechanical Systems and Signal Processing ◽

10.1016/j.ymssp.2011.04.004 ◽

2011 ◽

Vol 25 (7) ◽

pp. 2549-2558 ◽

Cited By ~ 23

Author(s):

Feiyun Cong ◽

Jin Chen ◽

Guangming Dong ◽

Kun Huang

Keyword(s):

Impact Assessment ◽

Impact Energy ◽

Experimental Validation ◽

Energy Model ◽

Rotor System

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Effect of Impact Energy in ESSO Test (Part 3: Experimental Validation for New Validity Criteria of Impact Condition Giving Constant Evaluation in ESSO Test)

Journal of Testing and Evaluation ◽

10.1520/jte20170150 ◽

2018 ◽

Vol 47 (1) ◽

pp. 20170150 ◽

Cited By ~ 2

Author(s):

Masahito Kaneko ◽

Tomoya Kawabata ◽

Shuji Aihara

Keyword(s):

Impact Energy ◽

Experimental Validation ◽

Test Part ◽

Impact Condition ◽

Validity Criteria

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Mechanical surface smoothing of micron-sized iron powder for improved silica coating performance as soft magnetic composites

Applied Surface Science ◽

10.1016/j.apsusc.2020.147340 ◽

2020 ◽

Vol 531 ◽

pp. 147340 ◽

Cited By ~ 1

Author(s):

Peter Slovenský ◽

Peter Kollár ◽

Nanxuan Mei ◽

Miloš Jakubčin ◽

Adriana Zeleňáková ◽

...

Keyword(s):

Iron Powder ◽

Silica Coating ◽

Surface Smoothing ◽

Soft Magnetic ◽

Magnetic Composites ◽

Coating Performance ◽

Soft Magnetic Composites ◽

Mechanical Surface

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Comparing fast inductive tempering and conventional tempering: Effects on microstructure and mechanical properties

Metallurgical Research & Technology ◽

10.1051/metal/2018015 ◽

2018 ◽

Vol 115 (4) ◽

pp. 407 ◽

Cited By ~ 4

Author(s):

Annika Eggbauer Vieweg ◽

Gerald Ressel ◽

Peter Raninger ◽

Petri Prevedel ◽

Stefan Marsoner ◽

...

Keyword(s):

Mechanical Properties ◽

Impact Energy ◽

Charpy Impact ◽

Heat Treating ◽

Processing Route ◽

High Heating Rate ◽

Heating Rates ◽

High Heating ◽

Tempering Treatment ◽

Carbide Distribution

Induction heating processes are of rising interest within the heat treating industry. Using inductive tempering, a lot of production time can be saved compared to a conventional tempering treatment. However, it is not completely understood how fast inductive processes influence the quenched and tempered microstructure and the corresponding mechanical properties. The aim of this work is to highlight differences between inductive and conventional tempering processes and to suggest a possible processing route which results in optimized microstructures, as well as desirable mechanical properties. Therefore, the present work evaluates the influencing factors of high heating rates to tempering temperatures on the microstructure as well as hardness and Charpy impact energy. To this end, after quenching a 50CrMo4 steel three different induction tempering processes are carried out and the resulting properties are subsequently compared to a conventional tempering process. The results indicate that notch impact energy raises with increasing heating rates to tempering when realizing the same hardness of the samples. The positive effect of high heating rate on toughness is traced back to smaller carbide sizes, as well as smaller carbide spacing and more uniform carbide distribution over the sample.

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