The Effect of the Impulse IR Laser Radiation Upon the Mechanical Properties of Thick Films of C60

2003 ◽  
Vol 17 (10n12) ◽  
pp. 697-700
Author(s):  
V. Rahvalov ◽  
D. Spoiala ◽  
V. Prilepov
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Acoustic Emission ◽  
Quartz Substrate ◽  
Thick Films ◽  
Light Filter ◽  
The Body ◽  
Mechanical Parameters ◽  
Dislocation Mechanism ◽  
Plastic Properties

The study of mechanical properties of crystals under exterior factors gives important information on the structure in the body of a crystal. So, for example, exterior magnetic field ~ 1–10 T brings about change in the plastic properties in dielectric crystals and polymers. The influence of pulsing magnetic field more than 10 ΔH on the change of a microhardness monocrystal C60 is also revealed. In the present work the influence of another type of exterior effect in the form of pulsing laser irradiation upon mechanical parameters is studied. The mechanical parameters, the microhardness and acoustic emission, are studied under microindentation. The study is done on thick films C60 on a quartz substrate; the thickness of the film C60 ~ 3 μm. In order to prevent photoboosted oxidizing, the measuring of a microhardness was performed in darkness with a red light filter on the PMT-3 device. The experiments for the study of the acoustic emission (Å) were also carried out with microindentation C60 and the dependences Å from the energy of laser bundle are received. An explanation is offered of a similar dependence of microhardness bound with the dislocation mechanism of plastic deformation.

Isotropic polyconvex electromagnetoelastic bodies

2018 ◽  
Vol 24 (3) ◽  
pp. 738-747
Author(s):  
M Šilhavý
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Electromagnetic Field ◽  
Smart Materials ◽  
Equilibrium Solution ◽  
Deformation Gradient ◽  
Electric Displacement ◽  
The Body ◽  
Sufficient Condition ◽  
Energy Functions

The recent renewal of interest in nonlinear electromagnetoelastic interactions comes from the technological importance of electro- or magnetosensitive elastomers, smart materials whose mechanical properties change instantly on the application of an electric or magnetic field. We consider materials with free energy functions of the form [Formula: see text], where F is the deformation gradient, d is the electric displacement, and b is the magnetic induction. It was recently shown by the author that such an energy function is polyconvex if and only if it is of the form [Formula: see text] where [Formula: see text] is a convex function (of 31 scalar variables). Moreover, an existence theorem was proved for the equilibrium solution for a system consisting of a polyconvex electromagnetoelastic solid plus the vacuum electromagnetic field outside the body. The condition (8), is not just the combination of Ball’s polyconvexity of elastomers [Formula: see text] with the convexity in the electromagnetic variables. The differential constraints div [Formula: see text], div [Formula: see text] allow for the cross mechanical–electric and mechanical–magnetic terms Fd and Fb which substantially enlarge the class of energies covered by the theory. The result (*), applies to a material of any symmetry; this paper analyzes the condition in the case of isotropic materials. A broad sufficient condition for the polyconvexity is given in that case. Further, it is shown that the commonly used isotropic electroelastic or magnetoelastic invariants are polyconvex except for the biquadratic ones; the paper explicitly determines their quasiconvex envelopes and shows that they are polyconvex.

scholarly journals A dynamical model of a crystal structure. II

1949 ◽  
Vol 196 (1045) ◽  
pp. 171-181 ◽  
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Shear Strain ◽  
Reasonable Agreement ◽  
The Body ◽  
Two Dimensional ◽  
Main Subject ◽  
Plastic Properties ◽  
Shear Strains ◽  
Low Shear

A quantitative study of the mechanical properties of two-dimensional bubble rafts has been made. The elastic properties have been used to check the theory of the interaction of the bubbles, and reasonable agreement is obtained. The plastic properties are the main subject of this paper. Plastic deformation proceeds by the motion of dislocations, and we have taken advantage of the possibility of making absolutely perfect crystalline rafts to study the production of dislocations. They are produced either in pairs in the body of the rafts, or singly from the edges. The shear strain required to produce them varies from 7° for bubbles of 2 mm. diameter to a fraction of a degree for bubbles of less than 0.5 mm. diameter. The analogy with metals is best for bubbles of about 1.2 mm. diameter; for these the critical shear strain is about 3°. The observed shear strains can be explained in terms of the forces between the bubbles, and so it seems that the very low shear strengths of metallic single crystals cannot be explained in terms of dislocation creation, but must be a consequence of the initial presence of faults of some kind.

Fully Biodegradable Magnetic Micro-Nanoparticles: A New Platform for Tissue Regeneration and Theranostic

2013 ◽  
Author(s):  
Monica Sandri ◽  
Michele Iafisco ◽  
Silvia Panseri ◽  
Elisa Savini ◽  
Anna Tampieri
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field ◽  
Magnetic Materials ◽  
Tissue Regeneration ◽  
Biomedical Applications ◽  
The Body ◽  
Nano Particles ◽  
Delivery Vehicles

Nowadays, magnetic materials are receiving special attention due to their potential applications in different fields and in particular in medicine. Magnetic micro-nano-particles have been progressively employed as support materials for enzyme immobilization, and have been used as drug-delivery vehicles, contrast agents for magnetic resonance imaging as well as heat mediators for hyperthermia-based anti-cancer treatments and many other exciting biomedical applications. Magnetic materials have also attracted a big interest in the field of bone tissue regeneration because it has been demonstrated that magnetic nanoparticles have effect of osteoinduction even without external magnetic force. Therefore, one of the most big challenge in this field is the production of magnetic materials with good biocompatibility and biodegradability. In fact, the long-term effects in the human body of iron oxide (maghemite or magnetite), the most popular magnetic phase used in medicine and biotechnology, are not yet completely assessed. To this aim, in this work we developed an innovative biocompatible and bioresorbable superparamagnetic-like phase by doping nano-hydroxyapatite with Fe2+/Fe3+ ions (FeHA). Moreover the same magnetic nanoparticles were used as nano-particulate emulsifier for the preparation of hollow hybrid Fe-HA-poly(L-lactic) acid (PLLA) micro-nano-spheres. PLLA has been used because poly(α-hydroxy-esters) are the most frequently used synthetic polymers for biomedical applications owing to their biocompatibility, hydrolytic degradation process and proper mechanical properties. These micro-nanospheres could be used as new type of scaffold for hard tissue regeneration. In fact, spherical scaffold display several advantages respect to the monolithic counterpart e.g., (i) improving control over sustained delivery of therapeutic agents, signalling biomolecules and even pluripotent stem cells, (ii) serving as stimulus-sensitive delivery vehicles for triggered release, (iii) introducing porosity and/or improve the mechanical properties of bulk scaffolds by acting as porogen or reinforcement phase, (iv) supplying compartmentalized micro-reactors for dedicated biochemical processes, (v) functioning as cell delivery vehicle, and, finally, (vi) giving possibility of preparing injectable and/or mouldable formulations to be applied by using minimally invasive surgery. Moreover, the same magnetic materials could find applications in nanomedicine as a multifunctional carrier. Their magnetic functionality could be utilized to move them into the body towards target organs by an external magnetic field. Furthermore, the superparamagnetic feature of the nanoparticles could allow to tailor the release of the therapeutic agent by switching (on-off) the external magnetic field and/or to treat cancer cells by hyperthermia.

Development of Combined Machining Modes, Investigation of Mechanical Properties and Structure of Deformed Semi-Finished Products from Alloy 01417

2020 ◽  
Vol 992 ◽  
pp. 498-503
Author(s):  
S. Sidelnikov ◽  
D. Voroshilov ◽  
M. Motkov ◽  
M. Voroshilova ◽  
V. Bespalov
Keyword(s):  
Mechanical Properties ◽  
Rare Earth Metals ◽  
Electrophysical Properties ◽  
Intermediate Annealing ◽  
Plastic Properties ◽  
Bar Rolling ◽  
Annealing Temperatures ◽  
Continuous Ingot ◽  
The Wire ◽  
Deformation Modes

The article presents the results of studies on the production of wire with a diameter of 0.5 mm from aluminum alloy 01417 with a content of rare-earth metals (REM) in the amount of 7-9% for aircraft construction needs. The deformation modes, the experimental technique and equipment for the implementation of the proposed technology described. The wire was obtained by drawing and bar rolling with subsequent drawing from a rod with a diameter of 5 mm, obtained previously using the process of combined rolling-extruding (CRE) from a continuous ingot with a diameter of 12 mm, cast in an electromagnetic mold (EMM). The wire obtained by the presented technology was subjected to 4 different heat treatment modes with annealing temperatures from 350 to 500 °C and holding time of 1 h in the furnace to achieve mechanical and electrophysical properties corresponding to TS 1-809-1038-2018. The level of strength and plastic properties obtained in the course of research required only one intermediate annealing. The microstructure of the wire was investigated and the modes were revealed that made it possible to obtain the required level of mechanical properties and electrical resistivity, satisfying TS 1-809-1038-2018.

scholarly journals Novel Hydrogels of Chitosan and Poly (vinyl alcohol) Reinforced with Inorganic Particles of Bioactive Glass

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 691
Author(s):  
O. Sánchez-Aguinagalde ◽  
Ainhoa Lejardi ◽  
Emilio Meaurio ◽  
Rebeca Hernández ◽  
Carmen Mijangos ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Drug Release ◽  
Bioactive Glass ◽  
Vinyl Alcohol ◽  
Release Kinetics ◽  
The Body ◽  
Poly Vinyl Alcohol ◽  
X Ray Diffraction ◽  
Inorganic Particles ◽  
Release Studies

Chitosan (CS) and poly (vinyl alcohol) (PVA) hydrogels, a polymeric system that shows a broad potential in biomedical applications, were developed. Despite the advantages they present, their mechanical properties are insufficient to support the loads that appear on the body. Thus, it was proposed to reinforce these gels with inorganic glass particles (BG) in order to improve mechanical properties and bioactivity and to see how this reinforcement affects levofloxacin drug release kinetics. Scanning electron microscopy (SEM), X-ray diffraction (XRD), swelling tests, rheology and drug release studies characterized the resulting hydrogels. The experimental results verified the bioactivity of these gels, showed an improvement of the mechanical properties and proved that the added bioactive glass does affect the release kinetics.

scholarly journals Preparation of Electric- and Magnetic-Activated Water and Its Influence on the Workability and Mechanical Properties of Cement Mortar

2021 ◽  
Vol 13 (8) ◽  
pp. 4546
Author(s):  
Kaiyue Zhao ◽  
Peng Zhang ◽  
Bing Wang ◽  
Yupeng Tian ◽  
Shanbin Xue ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Cement Paste ◽  
Cement Mortar ◽  
Environmental Issues ◽  
Chemical Admixtures ◽  
Untreated Water ◽  
Alternating Voltage

Cement-based materials prepared with activated water induced by a magnetic field or electric field represent a possible solution to environmental issues caused by the worldwide utilization of chemical admixtures. In this contribution, electric- and magnetic-activated water have been produced. The workability and mechanical properties of cement mortar prepared with this activated water have been investigated. The results indicate that the pH and absorbance (Abs) values of the water varied as the electric and magnetic field changed, and their values increased significantly, exhibiting improved activity compared with that of the untreated water. In addition, activated water still retains activity within 30 min of the resting time. The fluidity of the cement paste prepared with electric-activated water was significantly larger than that of the untreated paste. However, the level of improvement differed with the worst performance resulting from cement paste prepared with alternating voltage activated water. In terms of mechanical properties, both compressive strength and flexural strength obtained its maximum values at 280 mT with two processing cycles. The compressive strength increased 26% as the curing time increased from 7 days to 28 days and flexural strength increased by 31%. In addition, through the introduction of magnetic-activated water into cement mortar, the mechanical strength can be maintained without losing its workability when the amount of cement is reduced.

Study on mechanical properties and damage evolution of carbonaceous shale under triaxial compression with acoustic emission

2021 ◽  
pp. 105678952199119
Author(s):  
Kai Yang ◽  
Qixiang Yan ◽  
Chuan Zhang ◽  
Wang Wu ◽  
Fei Wan
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Water Content ◽  
Damage Evolution ◽  
Damage Assessment ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Damage Variable ◽  
Natural State ◽  
Carbonaceous Shale

To explore the mechanical properties and damage evolution characteristics of carbonaceous shale with different confining pressures and water-bearing conditions, triaxial compression tests accompanied by simultaneous acoustic emission (AE) monitoring were conducted on carbonaceous shale rock specimens. The AE characteristics of carbonaceous shale were investigated, a damage assessment method based on Shannon entropy of AE was further proposed. The results suggest that the mechanical properties of carbonaceous shale intensify with increasing confining pressure and degrade with increasing water content. Moisture in rocks does not only weaken the cohesion but also reduce the internal friction angle of carbonaceous shale. It is observed that AE activities mainly occur in the post-peak stage and the strong AE activities of saturated carbonaceous shale specimens appear at a lower normalized stress level than that of natural-state specimens. The maximum AE counts and AE energy increase with water content while decrease with confining pressure. Both confining pressure and water content induce changes in the proportions of AE dominant frequency bands, but the changes caused by confining pressure are more significant than those caused by water content. The results also indicate that AE entropy can serve as an applicable index for rock damage assessment. The damage evolution process of carbonaceous shale can be divided into two main stages, including the stable damage development stage and the damage acceleration stage. The damage variable increases slowly accompanied by a few AE activities at the first stage, which is followed by a rapid growth along with intense acoustic emission activities at the damage acceleration stage. Moreover, there is a sharp rise in the damage evolution curve for the natural-state specimen at the damage acceleration stage, while the damage variable develops slowly for the saturated-state specimen.

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