scholarly journals Rebound mechanics of micrometre-scale, spherical particles in high-velocity impacts

2017 ◽  
Vol 473 (2204) ◽  
pp. 20160936 ◽  
Author(s):  
Baran Yildirim ◽  
Hankang Yang ◽  
Andrew Gouldstone ◽  
Sinan Müftü
Keyword(s):  
Plastic Deformation ◽  
High Velocity ◽  
Time Lag ◽  
Spherical Particles ◽  
Spring Back ◽  
Elastic Plastic ◽  
Impact Mechanics ◽  
High Velocity Impacts ◽  
The Impact ◽  
Elastic Spring

The impact mechanics of micrometre-scale metal particles with flat metal surfaces is investigated for high-velocity impacts ranging from 50 m s −1 to more than 1 km s −1 , where impact causes predominantly plastic deformation. A material model that includes high strain rate and temperature effects on the yield stress, heat generation due to plasticity, material damage due to excessive plastic strain and heat transfer is used in the numerical analysis. The coefficient of restitution e is predicted by the classical work using elastic–plastic deformation analysis with quasi-static impact mechanics to be proportional to V i − 1 / 4 and V i − 1 / 2 for the low and moderate impact velocities that span the ranges of 0–10 and 10–100 m s −1 , respectively. In the elastic–plastic and fully plastic deformation regimes the particle rebound is attributed to the elastic spring-back that initiates at the particle–substrate interface. At higher impact velocities (0.1–1 km s −1 ) e is shown to be proportional to approximately V i − 1 . In this deeply plastic deformation regime various deformation modes that depend on plastic flow of the material including the time lag between the rebound instances of the top and bottom points of particle and the lateral spreading of the particle are identified. In this deformation regime, the elastic spring-back initiates subsurface, in the substrate.

Improving the Quality of Parts Produced by Bending in a Die with an Elastic Element

2019 ◽  
Vol 822 ◽  
pp. 144-149
Author(s):  
Elena Nesterenko ◽  
Anton Volgushev ◽  
Katharina Frese
Keyword(s):  
Plastic Deformation ◽  
Elastic Element ◽  
Spring Back ◽  
Elastic Plastic ◽  
A Value ◽  
The Press ◽  
Elastic Spring

The process of less than 90 degrees angle bending is presented in this article. Elastic-plastic deformation took place in the sample. After removing the force, the effect of elastic spring-back occurs – the angle of the part is increased by a value that depends on many parameters. The usage of an elastic element in the stamp allows us to change the angle of spring-back. This is happened doe to adjusting the height of the press stroke. This allows us to produce parts with accurate dimensions.

scholarly journals Experimental analysis of high velocity impacts of composite fragments on aluminium plates

2021 ◽  
Vol 250 ◽  
pp. 01011
Author(s):  
Jorge López-Puente ◽  
Jesús Pernas-Sánchez ◽  
José Alfonso Artero-Guerrero ◽  
David Varas ◽  
Joseba Múgica ◽  
...  
Keyword(s):  
High Velocity ◽  
High Speed ◽  
Woven Composites ◽  
Residual Velocity ◽  
Video Cameras ◽  
High Speed Video ◽  
High Velocity Impacts ◽  
Deformable Structure ◽  
The Impact ◽  
Composite Blades

The improvement of engines is one of the ways to diminish the fuel consumption in civil aircrafts, and Open Rotors engines are one of the best promises in order to achieve a sensible efficiency increment. These engines have large composite blades that could, in the event of failure, impact against the fuselage, totally or partially. In this case, composite fragments could behave as impactors. In order to design fuselages for this event and adopt these new engines in the future, it is necessary to understand the impact behaviour of a composite fragment against a deformable structure. To this end, unidirectional and woven composites fragments were impacted at high velocity (up to 150 m/s) against aluminium panels at different impact velocities. The composite fragments were made using AS4/8552 (UD) and AGP-193PW (woven) prepregs manufactured by Hexcel Composites, both using AS4 fibres and 8552 epoxy matrix. High speed video cameras were used to record the impact process and to measure both the impact and the residual velocity and hence the energy absorbed.

Study on Rebound Characteristics of Fine Spherical Particles Impacting an AISI 403 Steel With High Velocity

2015 ◽  
Author(s):  
Juan Di ◽  
Shun-sen Wang ◽  
Liu-xi Cai ◽  
Shang-fang Cheng ◽  
Chuang Wu
Keyword(s):  
Particle Size ◽  
High Velocity ◽  
Particle Diameter ◽  
Impact Angle ◽  
Spherical Particles ◽  
Dissipated Energy ◽  
Normal Velocity ◽  
Relative Impact ◽  
Restitution Coefficient ◽  
The Impact

Impingement on blade surface by fine particles with high velocity is commonly seen in steam turbines, gas turbines and compressors, which affect the service life and reliability of the equipment. Study on particles’ rebound characteristics is of great significance to reduce the blade erosion and to control particle trajectory. Based on the nonlinear explicit dynamics analysis software ANSYS/LS-DYNA, the impacts of fine spherical particles with different diameters (20 to 500μm) on a typical martensitic stainless steel (AISI 403) target with high velocity (50 to 250m/s) have been systematically studied. The influences of incident velocities, impact angles, particles sizes on its rebound characteristics, relative impact depth, and relative dissipated energy have been analyzed. Results show that velocity restitution coefficient e decreased with the impact angle β1, the incident velocity V1, and the particle size dp. However, the role of particle size on the velocity restitution coefficient seemed to be far less than that of the other two factors. Both of particle’s tangential and normal velocity coefficient of restitution declined with the increasing impact angle in most cases. However, when the incident velocity V1 = 200m / s and the impact angle β1 > 45°, the tangential velocity restitution coefficient et of 100 μm and 200 μm particles increased with the increase in the impact angle β1. The reason might be that the relative impact depth drel was located a zone ranged from 0.1515 to 0.1677, where the tangential rebound behavior could be enhanced. Most of the variation of the tangential and normal velocity restitution coefficient along β1 decreased with the increase in the particle diameter. However, when V1 = 200m/s and β1 > 15°, the tangential reflected velocity of the larger particles was enhanced gradually. In addition, the values of the relative impact depth drel increased with the increasing impact angle and incident velocity, and it increased with the increasing particle diameter in most cases. The relative dissipated energy of particles steadily increased with the impact angle and incident velocity, respectively. Particle diameter had little effect on energy dissipation in comparison with the impact angle and incident velocity.

Improvement of Energy Absorption of Circular Tubes Subjected to High Velocity Impact

2014 ◽  
Vol 566 ◽  
pp. 575-580
Author(s):  
Masahiro Higuchi ◽  
Shun Suzuki ◽  
Tadaharu Adachi ◽  
Hiroshi Tachiya
Keyword(s):  
Dynamic Behavior ◽  
High Velocity ◽  
Peak Load ◽  
Compressive Deformation ◽  
Straight Tube ◽  
Absorbed Energy ◽  
Velocity Impact ◽  
High Velocity Impacts ◽  
Fixed End ◽  
The Impact

The dynamic behavior of circular straight and stepped tubes made of aluminum alloy under high-velocity impacts was investigated by performing finite element analyses (FEA) and an experiment. The FEA and experiment on the straight tubes suggested that while an increase in the impact velocity enhanced the absorbed energy through compressive deformation just after impact, the peak load at the fixed end was not affected by the velocity. A stepped tube that was thicker near the impacted end was designed on the basis of the results for the straight tubes, and its dynamic behavior was investigated through FEA. The stepped tube absorbed a large amount of impact energy through compressive deformation at the thicker portion during the higher-velocity impact, without increasing the maximum fixed-end load from that of the straight tube.

A New Incremental Formulation of Elastic–Plastic Deformation of Two-Phase Particulate Composite Materials

2014 ◽  
Vol 81 (6) ◽  
Author(s):  
Hong Teng
Keyword(s):  
Plastic Deformation ◽  
Composite Materials ◽  
Spherical Particles ◽  
Particulate Composites ◽  
Plastic Response ◽  
Two Phase ◽  
Elastic Plastic ◽  
Inclusion Model ◽  
The Matrix ◽  
Incremental Formulation

In this study the double-inclusion model, originally developed to determine the effective linear elastic properties of composite materials, is reformulated in incremental form and extended to predict the effective nonlinear elastic–plastic response of two-phase particulate composites reinforced with spherical particles. The study is limited to composites consisting of purely elastic particles and elastic–plastic matrix of von Mises yield criterion with isotropic strain hardening. The resulting nonlinear problem of elastic–plastic deformation of a double inclusion embedded in an infinite reference medium (that has the elastic–plastic properties of the matrix) subjected to an incrementally applied far-field strain is linearized at each load increment through the use of the matrix tangent moduli. The proposed incremental double-inclusion model is evaluated by comparison of the model predictions to the exact results of the direct approach using representative volume elements containing many particles, and to the available experimental results. It is shown that the incremental double-inclusion formulation gives accurate prediction of the effective elastic–plastic response of two-phase particulate composites at moderate particle volume fractions. In particular, the incremental double-inclusion model is capable of capturing the Bauschinger effect often exhibited by heterogeneous materials. A unique feature of the proposed incremental formulation is that the composite matrix is treated as a two-phase material consisting of both an elastic and a plastic region.

On the flow through plastically deformed surfaces under unloading: A spectral approach

2017 ◽  
Vol 232 (5) ◽  
pp. 908-918 ◽  
Author(s):  
Francesc Pérez-Ràfols ◽  
Roland Larsson ◽  
Egbert J van Riet ◽  
Andreas Almqvist
Keyword(s):  
Plastic Deformation ◽  
Applied Load ◽  
Substantial Reduction ◽  
Spectral Approach ◽  
Spring Back ◽  
Flow Through ◽  
Elastic Spring

This study considers flow through the gap left between two surfaces during unloading, in other words, when an applied load is gradually reduced after loading to a state where plastic deformation occurs. In particular, the permeability of the gap is studied. It was found that a substantial reduction of the applied load is required before the permeability starts to increase significantly. The explanation for this phenomenon is given by the combination of components with different wavelengths present in the surface. Components with long wavelengths deform elastically and those with shorter wavelengths may also deform plastically. We found that plastic deformation acts to keep the permeability nearly constant at the beginning of the unloading and elastic spring-back is responsible for the rapid increase at lower loads. This principle constitutes a basis for the strategy that was developed in order to predict the load at which the rapid increase of permeability starts.

Elastic-Plastic Contact Analysis of a Deformable Sphere and a Rigid Flat with Friction Effect

2013 ◽  
Vol 644 ◽  
pp. 151-156 ◽  
Author(s):  
Li Wang ◽  
Yang Xiang
Keyword(s):  
Plastic Deformation ◽  
Contact Area ◽  
Contact Load ◽  
Deformation Analysis ◽  
Elastic Plastic ◽  
Friction Effect ◽  
Finite Element Software ◽  
Plastic Deformation Process ◽  
Rigid Plane ◽  
The Impact

Elastic-plastic deformation analysis of the deformable sphere and the rigid plane was studied using the finite element software,this paper was focused on the impact of the friction effects on the deformation of the elastic-plastic deformation under considering the material strain stiffening properties,studies have shown that，the strain stiffening feature increases the contact load while reducing the contact area，the friction effect reduce both the contact load and contact area during elastic-plastic deformation process of the deformable sphere with increasing contact interference.

scholarly journals High-Velocity Impacts of Pyrophoric Alloy Fragments on Thin Armour Steel Plates

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4649
Author(s):  
Evaristo Santamaria Ferraro ◽  
Marina Seidl ◽  
Tom De Vuyst ◽  
Norbert Faderl
Keyword(s):  
High Velocity ◽  
High Speed ◽  
Failure Modes ◽  
Threshold Value ◽  
Steel Plates ◽  
Terminal Ballistics ◽  
High Velocity Impacts ◽  
Modern Warfare ◽  
The Impact ◽  
Armour Steel

The terminal ballistics effects of Intermetallic Reactive Materials (IRM) fragments have been the object of intense research in recent years. IRM fragments flying at velocities up to 2000 m/s represent a realistic threat in modern warfare scenarios as these materials are substituting conventional solutions in defense applications. The IRM add Impact Induced Energy Release (IIER) to the mechanical interaction with a target. Therefore, the necessity of investigations on IIER to quantify potential threats to existing protection systems. In this study, Mixed Rare Earths (MRE) fragments were used due to the mechanical and pyrophoric affinity with IRM, the commercial availability and cost-effectiveness. High-Velocity Impacts (HVI) of MRE were performed at velocities ranging from 800 to 1600 m/s and recorded using a high-speed camera. 70 MREs cylindrical fragments and 24 steel fragments were shot on armour steel plates with thicknesses ranging from 2 mm to 3 mm. The influence of the impact pitch angle (α) on HVI outcomes was assessed, defining a threshold value at α of 20°. The influence of the failure modes of MRE and steel fragments on the critical impact velocities (CIV) and critical kinetic energy (Ekin crit) was evaluated. An energy-based model was developed and fitted with sufficient accuracy the Normalised EKin crit (E˜kincrit) determined from the experiments. IIER was observed in all the experiments involving MRE. From the analyses, it was observed that the IIER spreads behind the targets with velocities comparable to the residual velocities of plugs and shattered fragment.

REBOUND BEHAVIOUR OF SPHERES DURING ELASTIC-PLASTIC OBLIQUE IMPACTS

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1095-1102 ◽  
Author(s):  
CHUAN-YU WU ◽  
COLIN THORNTON ◽  
LONG-YUAN LI
Keyword(s):  
Plastic Deformation ◽  
Permanent Deformation ◽  
Impact Angle ◽  
Plastic Substrate ◽  
Normal Impact ◽  
Elastic Substrate ◽  
Elastic Plastic ◽  
Oblique Impacts ◽  
Impact Angles ◽  
The Impact

In this paper, the influence of plastic deformation on the rebound behaviour of spheres during oblique impacts with a substrate at various impact angles is analysed using Finite Element Methods (FEM). Both oblique impacts of the elastic spheres with an elastic-plastic substrate and those of an elastic-plastic sphere with an elastic substrate are considered. For each impact case, impact angles ranging from 0° to 85° are specified by either keeping the impact speed constant, i.e, changing impact angle will vary both the normal impact velocities and tangential velocities, or keeping the normal impact velocity constant, i.e., only the tangential velocities are changed for different impact angles. It has been found that, during oblique impacts, the plastic deformation not only dissipates the initial impact kinetic energy but also leads to permanent deformation of the impacting bodies that significantly affect the rebound behaviour of the spheres, especially at relatively high impact angles. Consequently, the rebound behaviour of spheres during oblique impacts depends upon which of contacting bodies (the sphere or the substrate) deforms plastically and different rebound behaviours were observed between the impacts of an elastic sphere with an elastic-plastic substrate and those of an elastic-plastic spheres with an elastic substrate.

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