Characterization of deformation behaviour and fracture mode of recycled aluminium alloys (AA6061) subjected to high-velocity impact

2020 ◽  
Vol 14 (3) ◽  
pp. 7222-7234
Author(s):  
Choon Sin Ho ◽  
Mohd Khir Mohd Nor
Keyword(s):  
Impact Velocity ◽  
Aluminium Alloys ◽  
Deformation Behaviour ◽  
Economic Benefits ◽  
Fracture Modes ◽  
Impact Surface ◽  
Impact Area ◽  
Footprint Analysis ◽  
Dynamic Loading Conditions ◽  
The Impact

Recycling aluminium alloys have been shown to provide great environmental and economic benefits. The global demands placed upon recycled aluminium and its product has further increased the need for better understanding and prediction of the deformation behaviour of such materials subjected to various dynamic loading conditions. It is also a topic of high interest for both the designer and the user of metal structures, specifically in the automotive industry. Even though numerous efforts have been made to improve recycling processes of aluminium alloys, very little attention is given on the fracture behaviour related damage and anisotropy during impact. In this study, therefore, the anisotropic-damage behaviour of the recycled aluminium alloys (AA6061) is examined via Taylor Cylinder Impact test. A gas gun was used to fire the projectiles towards a target at impact velocity ranging from 170m/s to 370 m/s. The deformation behaviour, including the fracture modes, digitized footprint and side profile of the deformed specimens, are observed and analysed. Scanning Electron Microscope (SEM) is further used to observe the damage behaviour, including microstructural changes of the impact surface. The damage progression is also analysed by observing the microstructural behaviour of location 0.5 cm from the impact area. General speaking, there are three different types of ductile fracture modes (mushrooming, tensile splitting and petalling) can be observed in this study within the impact velocity range of 170m/s to 370m/s. The critical impact velocity is defined at 212 m/s. The digitized footprint analysis exhibited a non-symmetrical (ellipse-shaped) footprint where the footprints showed plastic anisotropic behaviour and localized plastic strain in such recycled material. The damage evolution of the material is increasing with the increase in impact velocity.

An experimental study on the deformation behaviour and fracture mode of recycled aluminium alloy AA6061-reinforced alumina oxide undergoing high-velocity impact

2020 ◽  
Vol 234 (23) ◽  
pp. 4659-4670
Author(s):  
MK Mohd Nor ◽  
CS Ho ◽  
FNA Janudin
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Aluminium Alloy ◽  
Impact Velocity ◽  
Damage Evolution ◽  
Deformation Behaviour ◽  
Alumina Oxide ◽  
Impact Area ◽  
The Impact ◽  
Scanning Electron

The anisotropic behaviour and the damage evolution of recycled aluminium alloy-reinforced alumina oxide are investigated in this paper using Taylor impact test. The test is performed at various impact velocity ranging from 190 to 360 m/s by firing a cylindrical projectile towards anvil target. The deformation behaviour and the fracture modes are analysed using the digitized footprint of the deformed specimens. The damage initiation and the progression are observed around the impact surface and the surface 0.5 cm from the impact area using the scanning electron microscope. The deformed specimens showed several ductile fracture modes of mushrooming, tensile splitting and petalling. The critical impact velocity is defined below 280 m/s. The specimens showed a strong strain-rate dependency due to the damage evolution that is driven by severe localized plastic-strain deformation. The scanning electron microscope analysis showed the damage mechanism progress via voids initiation, growth and coalescence in the material. The micrograph within the footprint surface shows the presence of alumina oxide particles within the specimen. The microstructure analysis shows a significant refinement of the specimen particle at the surface located 0.5 cm above the impact area. ImageJ software is adopted in this work to measure the average size of voids within this surface. Non-symmetrical (ellipse-shaped) footprint around the footprints showed plastic anisotropic behaviour. The results in this paper provide a better understanding of the deformation behaviour of recycled materials subjected to dynamic loading. This information on mechanical response is crucial before any potential application can be established to substitute the primary sources.

Microstructural level response of HMX–Estane polymer-bonded explosive under effects of transient stress waves

2012 ◽  
Vol 468 (2147) ◽  
pp. 3725-3744 ◽  
Author(s):  
A. Barua ◽  
Y. Horie ◽  
M. Zhou
Keyword(s):  
Impact Velocity ◽  
Bonding Strength ◽  
Scaling Laws ◽  
Volume Fraction ◽  
Stress Waves ◽  
Transient Wave ◽  
Transient Stress ◽  
Impact Surface ◽  
The Impact ◽  
Interface Bonding Strength

The effect of transient stress waves on the microstructure of HMX–Estane, a polymer-bonded explosive (PBX), is studied. Calculations carried out concern microstructures with HMX grain sizes on the order of 200 μm and grain volume fractions in the range of 0.50–0.82. The microstructural samples analysed have an aspect ratio of 5:1 (15×3 mm), allowing the transient wave propagation process resulting from normal impact to be resolved. Boundary loading is effected by the imposition of impact face velocities of 50–200 m s −1 . Different levels of grain–binder interface strength are considered. The analysis uses a recently developed cohesive finite element framework that accounts for coupled thermal–mechanical processes involving deformation, heat generation and conduction, failure in the forms of microcracks in both bulk constituents and along grain/matrix interfaces, and frictional heating along crack faces. Results show that the overall wave speed through the microstructures depends on both the grain volume fraction and interface bonding strength between the constituents and that the distance traversed by the stress wave before the initiation of frictional dissipation is independent of the grain volume fraction but increases with impact velocity. Energy dissipated per unit volume owing to fracture is highest near the impact surface and deceases to zero at the stress wavefront. On the other hand, the peak temperature rises are noted to occur approximately 2–3 mm from the impact surface. Scaling laws are developed for the maximum dissipation rate and the highest temperature rise as functions of impact velocity, grain volume fraction and grain–binder interfacial bonding strength.

Effect of Random Defects on Dynamic Response of Honeycomb Structures

2012 ◽  
Vol 706-709 ◽  
pp. 805-810 ◽  
Author(s):  
Zhi Jun Zheng ◽  
Ji Lin Yu
Keyword(s):  
Impact Velocity ◽  
Cell Walls ◽  
Plateau Stress ◽  
Impact Surface ◽  
Critical Impact Velocity ◽  
Crushing Behavior ◽  
The Impact ◽  
Stress Uniformity ◽  
Random Defects ◽  
Deformation Modes

The dynamic crushing behavior of cellular metals is closely related to their microstructure. Two types of random defects by randomly thickening/removing cell walls are investigated in this paper. Their influences on the deformation modes and plateau stresses of honeycombs are studied by finite element simulation using ABAQUS/Explicit code. Three deformation modes, i.e. the Homogeneous Mode, the Transitional Mode and the Shock Mode, are used to distinguish the deformation patterns of honeycombs under different impact velocities. The critical impact velocity for mode transition between the Homogeneous and Transitional modes is quantitatively determined by evaluating a stress uniformity index, defined as the ratio between the plateau stresses on the support and impact surfaces. It is found that the critical impact velocity decreases with increasing thickening ratio but increases with increasing removing ratio. The plateau stress on the impact surface heavily depends on the impact velocity due to the inertia effect. The random defects lead to a weakening effect on the plateau stress. For the honeycombs with randomly removing cell walls, the weakening effect is especially obvious at a moderate impact velocity. For the honeycombs with randomly thickening cell walls, the weakening effect is particularly severe at a low impact velocity, but this effect almost disappears when the impact velocity is high enough.

Plastic anisotropic and damage evolution analysis of recycled aluminium alloy AA6061 at high rate of strain

2020 ◽  
Vol 14 (4) ◽  
pp. 7589-7599
Author(s):  
C. S. Ho ◽  
M. K. Mohd Nor ◽  
M. A. Ab Rani ◽  
N. Ma'at ◽  
M. T. Hameed Sultan ◽  
...  
Keyword(s):  
Aluminium Alloy ◽  
High Velocity ◽  
Aluminium Alloys ◽  
Damage Evolution ◽  
Deformation Behaviour ◽  
High Energy ◽  
High Rate ◽  
Primary Sources ◽  
Rate Dependency ◽  
The Impact

Aluminium alloys have been widely used in many applications, and its usage is increasing yearly due to its distinctive properties. Nevertheless, it required high energy consumption and pollution during the production of primary sources. This leads to the attention in producing secondary sources to substitute the primary aluminium. Recycling of aluminium alloys adopted in automotive structures is a great option to save thousands of energy and prevent tons of CO2 from being released to the atmosphere. Numerous investigations must be conducted to establish the mechanical behaviour before the specific applications can be identified. However, there is a challenge for such recycled aluminium to achieve the same application as the primary sources due to material properties degradation related to damage. It is still an open study area to be explored for a better understanding of the behaviours of recycled aluminium. Thus, in this work, the Taylor Cylinder Impact test is used to investigate anisotropic-damage behaviour of recycled aluminium alloy AA6061 undergoing high-velocity impact from 190m/s to 300 m/s using two length-to-diameter (L/D) ratios. The recovered samples are observed under an optical microscope (OM) and scanning electron microscope (SEM). A strong strain rate dependency can be seen as the damage evolution is increasing as the impact velocity increase. Further, the corresponding digitized footprints analysis exhibit plastic anisotropic and localized plastic strain in such recycled material. This can be clearly observed from the development of a non-symmetrical footprint within the impact surface. This test is the first to explore the deformation behaviour of recycled materials using high-velocity cylinder impact in a high rate of strain deformation regime.

Investigation on Deformation in ZK60 at High Strain Rate

2005 ◽  
Vol 488-489 ◽  
pp. 527-530
Author(s):  
Xing Zhang ◽  
Bao Cheng Li ◽  
Zhi Min Zhang ◽  
Zhi Wen Wang
Keyword(s):  
Magnesium Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
Impact Velocity ◽  
High Strain ◽  
Dynamic Properties ◽  
Deformation Behaviour ◽  
Fine Grain ◽  
Zk60 Alloy ◽  
The Impact

Split Hopkinson Pressure Bars (SHPB) was applied to investigate shock resistance of magnesium alloy. The deformation behaviour was reported of ZK60 magnesium alloy at high strain rate, and the relationship was established between the dynamic properties and the impact velocity. Results indicate: with impact velocity improvement, much twinned crystal and fine grain can be obtianed, this made dynamic properties enhancement of ZK60 alloy.

Shear Wave Attenuation and its Micro-Mechanism of Polymers

2013 ◽  
Vol 446-447 ◽  
pp. 249-253
Author(s):  
Zhi Ping Tang ◽  
Ting Li
Keyword(s):  
Shear Wave ◽  
Impact Velocity ◽  
Shear Failure ◽  
Wave Attenuation ◽  
Optical Microscope ◽  
Shear Loading ◽  
Impact Surface ◽  
Gas Gun ◽  
Electro Magnetic ◽  
The Impact

The impact shear response of crystallized polypropylene under combined compression and shear loading was studied by using an inclined gas gun and electro-magnetic particle velocity gauges. The experimental results show that the transverse wave velocity increases nonlinearly with the impact velocity, indicating its shear behavior is strongly related to the hydrostatic pressure. Remarkable shear wave attenuation occurs near the impact surface when the impact velocity and inclination angle reach the critical value. The micro-observation of recovered samples with a polarized optical microscope reveals that there exists a melting layer of about 2-3μm thick, i.e. adiabatic shear failure layer, very near the impact surface (about 5μm) which causes the shear wave attenuation.

The Impact of a Potential Public/Private Initiative on a Defined Region of the South Suburban Chicago Metropolitan Area

2019 ◽  
pp. 14-32
Keyword(s):  
Supply Chain ◽  
Economic Impact ◽  
Impact Analysis ◽  
Census Data ◽  
Economic Benefits ◽  
Local Economy ◽  
Market Area ◽  
State And Local ◽  
The University ◽  
The Impact

The university is considered one of the engines of growth in a local economy or its market area, since its direct contributions consist of 1) employment of faculty and staff, 2) services to students, and supply chain links vendors, all of which define the University’s Market area. Indirect contributions consist of those agents associated with the university in terms of community and civic events. Each of these activities represent economic benefits to their host communities and can be classified as the economic impact a university has on its local economy and whose spatial market area includes each of the above agents. In addition are the critical links to the University, which can be considered part of its Demand and Supply chain. This paper contributes to the field of Public/Private Impact Analysis, which is used to substantiate the social and economic benefits of cooperating for economic resources. We use Census data on Output of Goods and Services, Labor Income on Salaries, Wages and Benefits, Indirect State and Local Taxes, Property Tax Revenue, Population, and Inter-Industry to measure economic impact (Implan, 2016).

Model estimates of the results of diabetes patients using modern glucometers with tri-color technology for displaying test results

2019 ◽  
pp. 81-89
Author(s):  
Larisa Dmitrievna Popovich ◽  
Svetlana Valentinovna Svetlichnaya ◽  
Aleksandr Alekseevich Moiseev
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 1 Diabetes ◽  
Economic Benefits ◽  
Test Results ◽  
Self Monitoring ◽  
Patients With Diabetes ◽  
The Impact

Diabetes – a disease in which the effect of the treatment substantially depends on the patient. Known a study showed that the use of glucometers with the technology of three-color display of test results facilitates self-monitoring of blood sugar and leads to a decrease in glycated hemoglobin (HbAlc). Purpose of the study: to modeling the impact of using of a glucometer with a color-coded display on the clinical outcomes of diabetes mellitus and calculating, the potential economic benefits of reducing the hospitalization rate of patients with diabetes. Material and methods. Based on data from two studies (O. Schnell et al. and M. Baxter et al.) simulation of the reduction in the number of complications with the use of a glucometer with a color indication. In a study by O. Schnell et al. a decrease of HbA1c by 0.69 percent is shown when using the considered type of glucometers, which was the basis of the model. Results. In the model, the use of a glucometer with a color-coded display for type 1 diabetes led to a decrease in the total number of complications by 9.2 thousand over 5 years per a cohort of 40 thousand patients with different initial levels of HbA1c. In a cohort of 40 thousand patients with type 2 diabetes, the simulated number of prevented complications was 1.7 thousand over 5 years. When extrapolating these data to all patients with diabetes included in the federal register of diabetes mellitus (FRD), the number of prevented complications was 55.4 thousand cases for type 1 diabetes and 67.1 thousand cases for type 2 diabetes. The possible economic effect from the use of the device by all patients with a diagnosis of diabetes, which are included in the FRD, estimated at 1.5 billion rubles for a cohort of patients with type 1 diabetes and 5.3 billion rubles for patients with type 2 diabetes. Conclusion. Improving the effectiveness of self-monitoring, which is the result of the use of glucometers with color indicators, can potentially significantly reduce the incidence of complications in diabetes and thereby provide significant economic benefits to society.

Global challenges to functioning of precious gemstones market

2019 ◽  
pp. 15-19
Author(s):  
Maryna Khmara
Keyword(s):  
Social Impact ◽  
Negative Impact ◽  
Economic Benefits ◽  
Small Enterprises ◽  
Ecological Responsibility ◽  
Global Challenges ◽  
Production And Consumption ◽  
Managerial Strategies ◽  
The Impact ◽  
Complicated Nature

The peculiarities of gemstone market functioning under the impact of globalization are examined. Modern condition of financial stabilization in world is defined and main features of gemstones are outlined. Negative impact of illegal market on socio-economic development of countries, namely on revenues to the country’s budget from the business, is revealed. The importance of the problem of transferring most of gemstones processing operations beyond the countries of production is emphasized. Poor public control over the circulation of precious stones is proven. The challenges are substantiated to be aggravating under the impact of globalization. The diamonds market, which has peculiar high demand, is analyzed: diamonds and derivatives account for 85% of global turnover. Application of managerial strategies for gemstones market to efficiently use resources is defined to be complicated by the fact that managerial strategies impact the high cost of product items and its variability; unique features; intangible qualities; complicated processing. More environmentally friendly production and social responsibility are confirmed to have impact on forming of demand on gemstones. Investment attractiveness of gemstones, except for diamonds, is proven to be low. Condition of production and consumption of diamonds is analyzed. Development condition of the market segment – non-diamonds gemstones – is shown. The activity of small enterprises and households engaged in gemstones production is confirmed to be characterized by chaotic and complicated nature of broker networks, leading to aggravated global challenges. The paper defines that expansion of spectrum and emergence of new opportunities for illegal activity, reduced income and loss of other types of economic benefits, growing negative ecological and social impact, growing exploitation of workers at illegal enterprises remain to be the global challenges of gemstones market functioning. The author suggests increasing of social and ecological responsibility of business, strengthening of the state regulating functions and promotion of gemstones market legalization in order to reduce the challenges.

scholarly journals The Economic Effects of Electromobility in Sustainable Urban Public Transport

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 878 ◽  
Author(s):  
Oliwia Pietrzak ◽  
Krystian Pietrzak
Keyword(s):  
Public Transport ◽  
Research Study ◽  
Renewable Energy Sources ◽  
Economic Benefits ◽  
Economic Effects ◽  
Urban Transport ◽  
Energy Mix ◽  
Zero Emission ◽  
The Impact ◽  
The Given

This paper focuses on effects of implementing zero-emission buses in public transport fleets in urban areas in the context of electromobility assumptions. It fills the literature gap in the area of research on the impact of the energy mix of a given country on the issues raised in this article. The main purpose of this paper is to identify and analyse economic effects of implementing zero-emission buses in public transport in cities. The research area was the city of Szczecin, Poland. The research study was completed using the following research methods: literature review, document analysis (legal acts and internal documents), case study, ratio analysis, and comparative analysis of selected variants (investment variant and base variant). The conducted research study has shown that economic benefits resulting from implementing zero-emission buses in an urban transport fleet are limited by the current energy mix structure of the given country. An unfavourable energy mix may lead to increased emissions of SO2 and CO2 resulting from operation of this kind of vehicle. Therefore, achieving full effects in the field of electromobility in the given country depends on taking concurrent actions in order to diversify the power generation sources, and in particular on increasing the share of Renewable Energy Sources (RES).

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