Metal Nanostructures: Size Effect on the Impact Responses of Metal Nanostructures

2016 ◽  
pp. 521-530
Keyword(s):  
Size Effect ◽  
Metal Nanostructures ◽  
Impact Responses ◽  
The Impact

scholarly journals Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2323
Author(s):  
Yubing Du ◽  
Zhiqing Zhao ◽  
Qiang Xiao ◽  
Feiting Shi ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Compressive Stress ◽  
Failure Modes ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Substitution Ratio ◽  
The Impact

To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.

Numerical Study on Impact Response of Aircraft Sandwich Wing Made of Fiber-Metal Laminate Face-Sheets Subjected to Bird Strike

2012 ◽  
Vol 488-489 ◽  
pp. 8-13 ◽  
Author(s):  
S.M.R. Khalili ◽  
M. Assar ◽  
R. Eslami Farsani ◽  
I. Hajiyousefi
Keyword(s):  
Energy Absorption ◽  
Numerical Study ◽  
Metal Layer ◽  
Element Model ◽  
Fiber Types ◽  
Bird Strike ◽  
Impact Phenomena ◽  
Impact Responses ◽  
Fiber Metal ◽  
The Impact

Aircraft structures are frequently subjected to impacts from objects such as runway debris and birds. In new aircraft structural design, Fiber Metal Laminates (FMLs) play a significant role due to their excellent mechanical properties, particularly the impact properties. In this study, the aircraft sandwich wing with FML face-sheets are analyzed by finite element model for simulating the bird strike. The numerical simulations of bird strike impact are performed adopting a lagrangian approach to design the wing by MSC/PATRAN FE code. The numerical obtained results are compared with the results in the literature for validation of the model. The effect of fiber orientations, fiber types, metal types in FML face sheets in sandwich wing on impact responses are investigated. The impact responses are illustrated by displacement history, contact force history and energy absorption. According to these results, the sandwich panel with FML skin is suitable structure for energy absorption (that is the most important factor in impact phenomena). The lay-ups with titanium metal layer with aramid fibers are the best.

A Study on the Ricochet of Concrete Debris Against Soil

2015 ◽  
Vol 12 (04) ◽  
pp. 1540009 ◽  
Author(s):  
J. Xu ◽  
C. K. Lee ◽  
S. C. Fan
Keyword(s):  
Numerical Modeling ◽  
Kinetic Energy ◽  
Incident Angle ◽  
Experimental Results ◽  
Impact Process ◽  
Impact Responses ◽  
The Impact

In this study, the impact responses of concrete debris against soil are investigated. Three types of concrete debris are shot at soil with different incident conditions in experiments. A numerical modeling for the impact process is established and calibrated by the experimental results. A further study on the effect of debris size is then carried out based on the calibrated numerical modeling. A set of formulation is presented to predict the outgoing velocity and the outgoing angle in terms of the incident velocity and the incident angle. Critical lethality curves are derived based on the assumption of a critical kinetic energy of 79 J.

Molecular Dynamics Simulations of Cluster-size Effect on Sputtering Process with Reactive Gas Cluster Ions

2005 ◽  
Vol 908 ◽  
Author(s):  
Takaaki Aoki ◽  
Jiro Matsuo
Keyword(s):  
Molecular Dynamics ◽  
Size Effect ◽  
Cluster Size ◽  
Incident Energy ◽  
Md Simulations ◽  
Cluster Ions ◽  
Experimental Conditions ◽  
Near Surface ◽  
The Impact ◽  
Reactive Cluster

AbstractTo investigate the size-effect of reactive clusters on sputtering processes, we performed molecular dynamics (MD) simulations of reactive cluster ions with various sizes impacting on solid targets. Various sizes of fluorine clusters, (F2)30, (F2)300 and (F2)3000, were irradiated on a Si(100) target at the same total incident energy of 6 keV. These clusters were irradiated on the same target one after another in order to reproduce real experimental conditions such as the accumulation of fluorine atoms in the target. The MD simulations of sequential cluster impacts enabled to perform various statistical analyses regarding the sputtered particles. The study of cluster size distributions showed that the sputtering process by reactive cluster ion impact has similarity with the emission from quasi-liquid materials excited to hyper-thermal conditions by ion bombardment. However, the major sputtered particles were different with each other; Si for (F2)30 (100 eV/atom), SiF2 for (F2)300 (10 eV/atom), and SiF3 for (F2)3000 (1 eV/atom). At the impact of a large size cluster with low incident energy, a large number of Si-F bondings were generated at the cluster-target interface surface, which enhances formation of volatile SiFx compounds with many fluorine atoms. In contrast, a small cluster with high kinetic energy-per-atom could cause the formation of numerous energetic surface atoms at the near surface region, which could be sputtered without being well fluoridated.

The Influence of Size on the Brittle Strength of Steel

1947 ◽  
Vol 14 (1) ◽  
pp. A63-A67
Author(s):  
N. Davidenkov ◽  
E. Shevandin ◽  
F. Wittmann
Keyword(s):  
Size Effect ◽  
Stress Gradient ◽  
Special Role ◽  
Static Tension ◽  
Statistical Nature ◽  
Brittle Strength ◽  
Notched Specimens ◽  
Tension Tests ◽  
The Impact

Abstract In this paper the influence of size effect on the impact cold brittleness of carbon steel is discussed. Static bending of notched specimens shows the same size effect, so that an assumption of the special role played by high velocity must be rejected. The experiments on the determination of the critical temperature of brittleness for impact-tension tests also display the size effect and therefore exclude any possible influence of the stress gradient. Experiments on static tension and bending of cylindrical specimens of brittle phosphorous steel in liquid air reveal the statistical nature of the size effect and give a good qualitative verification of Weibull’s theory. Weibull’s homogeneity exponent m calculated from experiments with tension and bending is found to have nearly identical values (namely 23.5 and 25.4). The theoretical values of the brittle strength of small specimens calculated with this value of m differ from the experimental ones by about 3 per cent; the ratio of the strengths in the case of bending and tension is found experimentally to be 1.40 against 1.39, according to the theory. The “scatter” in particular values for large specimens, as predicted by theory, is smaller than for small ones.

scholarly journals Estimation of the impact stress gradient in the range of size effect

2017 ◽  
Vol 5 ◽  
pp. 840-847 ◽  
Author(s):  
Tomasz Tomaszewski ◽  
Przemysław Strzelecki
Keyword(s):  
Size Effect ◽  
Stress Gradient ◽  
Impact Stress ◽  
The Impact

Santa Claus Rally and firm size

2016 ◽  
Vol 42 (8) ◽  
pp. 817-829 ◽  
Author(s):  
Kenneth M Washer ◽  
Srinivas Nippani ◽  
Robert R Johnson
Keyword(s):  
Stock Market ◽  
Size Effect ◽  
Firm Size ◽  
Convincing Evidence ◽  
Market Returns ◽  
Stock Market Returns ◽  
Content Type ◽  
Santa Claus ◽  
The Usa ◽  
The Impact

Purpose – Several articles in the popular press have detailed an end-of-year anomaly known as the Santa Claus Rally, a period best defined as the last five trading days of December and the first two trading days of January. The purpose of this paper is to examine US stock market returns over this period from 1926 to 2014. Design/methodology/approach – The authors examine the Santa Claus Rally by relating it to firm size in the stock markets of the USA. The Santa Claus Rally consists of the last five trading days in December and the first two in January. The authors use t-tests, non-parametric test and regression analysis to determine if investors in small firms get superior returns over the period 1926-2014. Findings – The authors find that returns are generally higher during the period and that the effect is considerably stronger for small-firm portfolios relative to large capitalization portfolios. The authors also provide convincing evidence that the three most important trading days (especially for small stock portfolios) are the last trading day in December and the first two trading days in January. Research limitations/implications – The authors only check the markets in the USA. Market makers can use this to get significantly high returns during the Christmas-New Year period. The study shows for the first time that there is a size effect as part of the Santa Claus Rally. Practical implications – This is the first study to show that Santa Claus Rally exists for a long time in the USA. It is the first study to show that there is a size effect in Santa Claus Rally. Market participants could get significantly higher returns by investing or being invested in the stock market during this period. Social implications – The impact of the holiday season on stock market returns. Originality/value – This is the first major academic study to examine Santa Claus Rally in this much detail. The authors not only show that the rally exists, the authors show that it is based on firm size and has been in existence for nearly 90 years in the USA.

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