Compressive Behaviour of Al-Si-Mg/SiCP Foams

2015 ◽  
Vol 830-831 ◽  
pp. 234-237
Author(s):  
N.V. Ravi Kumar ◽  
Amol A. Gokhale
Keyword(s):  
Volume Fraction ◽  
Ceramic Particle ◽  
Unit Weight ◽  
Al Alloy ◽  
Compression Tests ◽  
Compression Properties ◽  
Foam Properties ◽  
Type Size ◽  
Effective Role

Aluminium foams are of interest due to their ultra low density, high structural stiffness per unit weight. Like conventional Al foams having Ca, ceramic particle (e.g. SiC, Al2O3) containing Al alloy metal matrix composite (MMC) foams can be produced. In this approach, parameters such as particle type, size, and volume fraction need to be optimized to get good quality foams with high foam expansions. However, the role of them on the compression properties of MMC foams is seldom reported. With this objective, the present study explores the effect of SiCP size and vol. % on compression behavior of various Al-Si/SiCP foams prepared at DMRL. From the large number of compression tests, it is observed that the reinforcement parameters don’t seem to play any effective role with respect to foam properties, although they are very important in foam manufacture.

Crashworthiness of cardboard panels reinforced with braided glass fiber rods for vehicle side impact protection

2018 ◽  
Vol 37 (23) ◽  
pp. 1387-1401 ◽  
Author(s):  
Gabriel Y Fortin ◽  
Elsayed A Elbadry ◽  
Hiroyuki Hamada
Keyword(s):  
Glass Fiber ◽  
Single Layer ◽  
Side Impact ◽  
Compression Tests ◽  
Static Compression ◽  
Compression Properties ◽  
Layer Orientation ◽  
Fiber Fragmentation ◽  
Crushing Behavior

This paper investigates the quasi-static compression properties of cardboard panels reinforced with braided glass fiber rods manufactured using a tubular braiding method. Compression tests are performed on single- and two-layer panels reinforced with varying number of rods and panel layer orientation. The crushing results of single-layer panels show more progressive crushing behavior than those of two-layer panels for different number of rods. In two-layer panels, certain rods are inclined from the direction of applied load due to deformation of the surrounding cardboard, resulting in reduced specific energy absorption compared with single-layer panels. Moreover, panels consisting of two layers of cardboard oriented in the same direction perform better than when the layers are off-set 90° where cardboard shifting is more pronounced. The role of cardboard is to constrain the rods from excessive splaying, causing greater levels of fiber fragmentation which consumes more energy compared with rods without cardboard.

scholarly journals Mechanical Properties of Fiber Reinforced Lightweight Concrete Containing Surfactant

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Yoo-Jae Kim ◽  
Jiong Hu ◽  
Soon-Jae Lee ◽  
Byung-Hee You
Keyword(s):  
Mechanical Properties ◽  
Lightweight Concrete ◽  
Volume Fraction ◽  
Lightweight Aggregate ◽  
Unit Weight ◽  
Fiber Reinforced ◽  
Compression Tests ◽  
Stress Strain ◽  
Strain Behavior ◽  
Toughness Index

Fiber reinforced aerated lightweight concrete (FALC) was developed to reduce concrete's density and to improve its fire resistance, thermal conductivity, and energy absorption. Compression tests were performed to determine basic properties of FALC. The primary independent variables were the types and volume fraction of fibers, and the amount of air in the concrete. Polypropylene and carbon fibers were investigated at 0, 1, 2, 3, and 4% volume ratios. The lightweight aggregate used was made of expanded clay. A self-compaction agent was used to reduce the water-cement ratio and keep good workability. A surfactant was also added to introduce air into the concrete. This study provides basic information regarding the mechanical properties of FALC and compares FALC with fiber reinforced lightweight concrete. The properties investigated include the unit weight, uniaxial compressive strength, modulus of elasticity, and toughness index. Based on the properties, a stress-strain prediction model was proposed. It was demonstrated that the proposed model accurately predicts the stress-strain behavior of FALC.

scholarly journals The Role of Grain Refiner in the Nucleation of AlFeSi Intermetallic Phases During Solidification of a 6xxx Aluminum Alloy

2019 ◽  
Vol 50 (11) ◽  
pp. 5242-5252 ◽  
Author(s):  
A. Lui ◽  
P. S. Grant ◽  
I. C. Stone ◽  
K. A. Q. O’Reilly
Keyword(s):  
Grain Refinement ◽  
Intermetallic Phase ◽  
Intermetallic Phases ◽  
Primary Phase ◽  
Al Alloy ◽  
Grain Refiner ◽  
Phase Selection ◽  
Type Size ◽  
6Xxx Series

Abstract Primary grain refinement using inoculant additions and intermetallic compound (IMC) phase selection are critical aspects in the solidification of commercial aluminum alloys, controlling the final mechanical properties in service. Although there have been studies which suggest there are explicit interactions between the two phenomena, they have yet to be fully elucidated. Here, through study of intermetallic phase particles extracted from an inoculated casting, key features relating to the nucleation of different intermetallic phases via eutectic reactions are recognized and explained. In particular, rake-like IMCs are identified as initiation points for the deleterious $$\beta $$ β -AlFeSi IMC phase in a model 6xxx series Al alloy. A mechanism is proposed for how $${\text{TiB}}_{2}$$ TiB 2 inoculant particles, which are commonly used for primary phase refinement, play a role in enhancing the nucleation of intermetallic phases during eutectic reactions at the liquid/$$\alpha $$ α -Al interface in the final stages of solidification. The implication of this mechanism is that, after the event of primary grain refinement, any unused $${\text{TiB}}_{2}$$ TiB 2 inoculant particles could be contributing to IMC formation thereby affecting the overall type, size, and distribution of intermetallic phases in the solidified alloy.

ROLE OF THE THYROID GLAND IN DEVELOPMENT AND MAINTENANCE OF RENAL HYPERTENSION IN RATS

1960 ◽  
Vol XXXIV (III) ◽  
pp. 411-429 ◽  
Author(s):  
Melvin J. Fregly ◽  
Kenneth M. Cook
Keyword(s):  
Blood Pressure ◽  
Rate Increase ◽  
Renal Hypertension ◽  
The Other ◽  
Elevated Blood Pressure ◽  
Unit Weight ◽  
Elevated Blood ◽  
Inhibition Of Growth ◽  
Testicular Size

ABSTRACT The anti-thyroid drugs, thiouracil, propylthiouracil, and methimazole, prevented both development of elevated blood pressure and cardiac hypertrophy usually accompanying kidney encapsulation with latex envelopes. These drugs also reduced elevated blood pressure of rats with hypertension of 13 to 40 weeks' duration prior to drug administration. Addition of desiccated thyroid powder to diet containing an anti-thyroid drug overcame the anti-hypertensive effect of the latter. Withdrawal of thyroid powder only was followed by return of blood pressure to previous low level within 3 weeks. The results suggest that the anti-hypertensive effect of these drugs is related directly to the hypothyroidism produced rather than to extrathyroidal effects of the drugs. Comparison of potencies of the 3 drugs in terms of anti-hypertensive effect, inhibition of growth rate, increase in testicular size, and increase in thyroid size suggests that propylthiouracil and methimazole are equally potent per unit weight of drug. Thiouracil has approximately half the potency of the other two.

Reforming the Role of the African Commission on Human and Peoples’ Rights in Advancing Democratic Principles and Human Rights in African Countries: An Examination Using the Lens of Swaziland/ eSwatini

2019 ◽  
Vol 34 (2) ◽  
Author(s):  
Jeremy Sarkin
Keyword(s):  
Human Rights ◽  
African Countries ◽  
Individual Country ◽  
The Status ◽  
Effective Role ◽  
Limited Compliance ◽  
Fact Finding ◽  
Democratic Principles ◽  
African Commission

This article explores the role of the African Commission on Human and Peoples’ Rights and the role it plays regarding human rights in individual country situations in Africa. It specifically examines the extent to which it has been able to advance a human rights agenda in countries with long-standing human rights problems. The article uses Swaziland/ eSwatini as a lens to examine the matter, because of the longstanding problems that exist in that country. This is done to indicate how the institution works over time on a country’s human rights problems. The article examines a range of institutional structural matters to establish how these issues affect the role of the Commission in its work. The article examines the way in which the Commission uses its various tools, including its communications, the state reporting processes, fact-finding visits, and resolutions, to determine whether those tools are being used effectively. The article examines how the Commission’s processes issues also affect it work. Issues examined negatively affecting the Commission are examined, including problems with the status of its resolutions and communications, limited compliance with its outcomes, and inadequate state cooperation. Reforms necessary to enhance to role and functions of the Commission are surveyed to determine how the institution could become more effective. The African Union’s (AU|) Kagame Report on AU reform is briefly reviewed to examine the limited view and focus of AU reform processes and why AU reform ought to focus on enhancing human rights compliance. The article makes various suggestions on necessary institutional reforms but also as far as the African Commission’s procedures and methods of work to allow it to have a far more effective role in the promotion and protection of human rights on the continent. It is noted that political will by the AU and African states is the largest obstacle to giving the Commission the necessary independence, support and assistance that it needs to play the role in Africa that it should.

Modelling the asymmetric tension–compression properties of additively manufactured alloys using continuum damage mechanics

2021 ◽  
pp. 146442072110134
Author(s):  
A Nayebi ◽  
H Rokhgireh ◽  
M Araghi ◽  
M Mohammadi
Keyword(s):  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Element Model ◽  
Continuum Damage ◽  
Compression Tests ◽  
Compression Properties ◽  
Mechanics Model ◽  
Stress Components ◽  
Tension And Compression ◽  
Closure Effect

Additively manufactured parts often comprise internal porosities due to the manufacturing process, which needs to be considered in modelling their mechanical behaviour. It was experimentally shown that additively manufactured parts’ tensile and compressive mechanical properties are different for various metallic alloys. In this study, isotropic continuum damage mechanics is used to model additively manufactured alloys’ tension and compression behaviours. Compressive stress components can shrink discontinuities present in additively manufactured alloys. Therefore, the crack closure effect was employed to describe different behaviours during uniaxial tension and compression tests. A finite element model embedded in an ABAQUS’s UMAT format was developed to account for the isotropic continuum damage mechanics model. The numerical results of tension and compression tests were compared with experimental observations for additively manufactured maraging steel, AlSi10Mg and Ti-6Al-4V. Stress–strain curves in tension and compression of these alloys were obtained using the continuum damage mechanics model and compared well with the experimental results.

scholarly journals A Thermally Conductive Pt/AAO Catalyst for Hydrogen Passive Autocatalytic Recombination

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 491
Author(s):  
Alina E. Kozhukhova ◽  
Stephanus P. du Preez ◽  
Aleksander A. Malakhov ◽  
Dmitri G. Bessarabov
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Combustion Temperature ◽  
Volume Fraction ◽  
Morphological Characteristics ◽  
Al Alloy ◽  
Impregnation Method ◽  
Case Scenario ◽  
Worst Case ◽  
Thermal Distribution

In this study, a Pt/anodized aluminum oxide (AAO) catalyst was prepared by the anodization of an Al alloy (Al6082, 97.5% Al), followed by the incorporation of Pt via an incipient wet impregnation method. Then, the Pt/AAO catalyst was evaluated for autocatalytic hydrogen recombination. The Pt/AAO catalyst’s morphological characteristics were determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average Pt particle size was determined to be 3.0 ± 0.6 nm. This Pt/AAO catalyst was tested for the combustion of lean hydrogen (0.5–4 vol% H2 in the air) in a recombiner section testing station. The thermal distribution throughout the catalytic surface was investigated at 3 vol% hydrogen (H2) using an infrared camera. The Al/AAO system had a high thermal conductivity, which prevents the formation of hotspots (areas where localized surface temperature is higher than an average temperature across the entire catalyst surface). In turn, the Pt stability was enhanced during catalytic hydrogen combustion (CHC). A temperature gradient over 70 mm of the Pt/AAO catalyst was 23 °C and 42 °C for catalysts with uniform and nonuniform (worst-case scenario) Pt distributions. The commercial computational fluid dynamics (CFD) code STAR-CCM+ was used to compare the experimentally observed and numerically simulated thermal distribution of the Pt/AAO catalyst. The effect of the initial H2 volume fraction on the combustion temperature and conversion of H2 was investigated. The activation energy for CHC on the Pt/AAO catalyst was 19.2 kJ/mol. Prolonged CHC was performed to assess the durability (reactive metal stability and catalytic activity) of the Pt/AAO catalyst. A stable combustion temperature of 162.8 ± 8.0 °C was maintained over 530 h of CHC. To confirm that Pt aggregation was avoided, the Pt particle size and distribution were determined by TEM before and after prolonged CHC.

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