scholarly journals Deformation of Al85Y8Ni5Co2 Metallic Glasses under Cyclic Mechanical Load and Uniform Heating

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 908
Author(s):  
Arseniy D. Berezner ◽  
Victor A. Fedorov ◽  
Mikhail Yu. Zadorozhnyy ◽  
Igor S. Golovin ◽  
Dmitri V. Louzguine-Luzgin
Keyword(s):  
Amorphous Alloys ◽  
Mechanical Load ◽  
Reaction Force ◽  
Mechanical Action ◽  
Simultaneous Application ◽  
Wave Effects ◽  
Increasing Temperature ◽  
Temperature Heating ◽  
Two Parameter ◽  
Cyclic Mechanical Load

Modelling of the deformation process of Al85Y8Ni5Co2 amorphous alloys was carried out under simultaneous application of cyclic mechanical load (at 0.3 or 3 Hz frequencies) and continuously increasing temperature (heating rate 5 K/min). It is shown that deformation of the amorphous specimens occurs by the hyperbolic temporal dependence. It is analytically determined and experimentally proved that for non-isothermal cyclic deformation, the wave effects take place as a result of the superposition of thermal-activated and mechanical components. The behaviour of the material under thermo-mechanical action was described qualitatively within the framework of Spaepen’s model. The dependencies for the reaction force of the samples were obtained as two-parameter functions of the frequency and temperature. A reaction force surface of a specimen, as a function of the different forcing frequencies and time, has been plotted.

Thermodynamic Study of Eu3+ /Eu2+ Redox Reaction in Aqueous Solutions at Elevated Temperatures and Pressures by Means of Cyclic Voltammetry

1991 ◽  
Vol 46 (12) ◽  
pp. 1108-1116 ◽  
Author(s):  
B. A. Bilal
Keyword(s):  
Cyclic Voltammetry ◽  
Redox Potential ◽  
Redox Reaction ◽  
Elevated Temperatures ◽  
Saturation Pressure ◽  
Significant Shift ◽  
Positive Direction ◽  
Small Pressure ◽  
Increasing Temperature ◽  
Two Parameter

Abstract The redox potential of the couple Eu3+/Eu2+ in aqueous NaCl, NaClO4 and Na2SO4 solutions of different ionic strength and various pH values has been determined by means of cyclic voltammetry up to 458 K and 1 kbar. In all cases reversible voltammograms were obtained. Compared to the redox potential in C1O4- solutions of pH 2, no significant shift was observed in Cl-solutions of the same pH, whereas a drastic shift to more negative potentials in solutions of SO2-4 and in Cl- solutions of higher pH (pH 3-5) was obtained. This indicates a negligible complexation of Eu3* by means of CP but a strong one by means of OH and SO2-4 . An isothermal pressure increase up to 1 kbar led to a shift of only few mV more negative, indicating a small pressure dependence of the change of the partial molar volume (ΔVe1) accompanying the redox reaction, which results in this case only due to the different degrees of electrostriction. A more drastic shift of the redox potential (in the positive direction) results with increasing temperature. The isobaric temperature dependence of the redox potential is described by a two parameter equation which remains valid up to the saturation pressure at 458 K, due to the small pressure effect. ΔS and ΔH of the redox reaction has been determined

Spark Plasma Synthesis/Sintering of Dense Ceramic, Intermetallic and Composite Materials

2006 ◽  
Vol 45 ◽  
pp. 1411-1416
Author(s):  
Antonio Mario Locci ◽  
Roberta Licheri ◽  
Roberto Orrù ◽  
A. Cincotti ◽  
Giacomo Cao
Keyword(s):  
Mechanical Load ◽  
Plasma Synthesis ◽  
Simultaneous Application ◽  
Plasma Sintering ◽  
Pulsed Dc ◽  
Spark Plasma ◽  
One Step ◽  
Powder Particles ◽  
Dc Current ◽  
Spark Plasma Synthesis

Spark Plasma Sintering (SPS) represents a very attractive technique for the obtainment of dense materials including nanostructured ones. SPS basically consists in the simultaneous application of a pulsed DC current and an uniaxial mechanical load through a powder compact. Other than providing rapid Joule heating and likely enhancing mass transport through electromigration, the imposed pulsed high current is also reported to generate a plasma within the voids surrounding the powder particles, thus facilitating the removal of oxides surface layers that may hinder the sintering process. Selected results obtained through SPS in our laboratory for the preparation of a wide variety of materials, i.e. TiC-TiB2, MgB2, and NbAl3, will be presented in this work. Specifically, all the chosen examples are related to the use of the SPS technique for obtaining the desired material by simultaneously performing synthesis and consolidation stages in one-step.

Investigation of crack repair using piezoelectric material under thermo-mechanical loading

2020 ◽  
Vol 31 (19) ◽  
pp. 2243-2260
Author(s):  
Ritesh Kumar ◽  
Akhilendra Singh ◽  
Mayank Tiwari
Keyword(s):  
Piezoelectric Material ◽  
Mechanical Loading ◽  
Mechanical Load ◽  
Piezoelectric Sensor ◽  
Crack Location ◽  
Piezoelectric Patch ◽  
Optimal Value ◽  
Temperature Environment ◽  
Crack Repair ◽  
Cyclic Mechanical Load

This article presents an experimental investigation of repair of a crack in a structure using piezoelectric material under thermo-mechanical loading environment. The cyclic mechanical load is applied on a plate with a straight and angular crack under uniform temperature environment. Two cases have been considered for the repair of crack under (a) mechanical loading and (b) thermo-mechanical loading environment. A piezoelectric sensor is utilized to measure voltage. The measured voltage is used to calculate the stress intensity factor in passive and active modes. The effect of a single and double piezoelectric patch in the repair of the plate is investigated. The double piezoelectric patch is found to be more effective as compared to single patch when placed symmetrically offset from the crack. An optimal value of voltage and phase difference is evaluated for most effective crack repair. Location of the piezoelectric patch is varied with respect to crack location, and best-suited position for effective crack repair is proposed. The viability of piezoelectric used for repair under thermo-mechanical loading is discussed. The active mode of repair by piezoelectric is found to be effective under thermo-mechanical loading environment.

scholarly journals Effect of Heel-First Strike Gait on Knee and Ankle Mechanics

Medicina ◽  
2021 ◽  
Vol 57 (7) ◽  
pp. 657
Author(s):  
Shirin Aali ◽  
Farhad Rezazadeh ◽  
Georgian Badicu ◽  
Wilhelm Robert Grosz
Keyword(s):  
Mechanical Load ◽  
External Rotation ◽  
Reaction Force ◽  
Gait Pattern ◽  
Heel Strike ◽  
Initial Contact ◽  
Vertical Ground Reaction Force ◽  
Cross Sectional ◽  
Mean Values ◽  
Heel Contact

Background and Objectives: Acquiring knowledge about the magnitude and direction of induced joint forces during modifying gait strategies is critical for proper exercise prescription. The present study aimed to evaluate whether a heel-first strike pattern during gait can affect the biomechanical characteristics of ankle and knee joints among asymptomatic people. Materials and Methods: In this cross-sectional study performed in the biomechanics laboratory, 13 professional healthy male athletes walked on an instrumented walkway under two walking conditions. For the normal condition, subjects were instructed to walk as they normally would. For the heel-first strike condition, subjects were instructed to walk with heel-first strike pattern and increase heel contact duration as much as possible. Then, knee and ankle joint range of motions and moments, as well as vertical ground reaction force was measured by the Kistler force plate and Vicon motion analysis system. Results: Knee flexion angle at the initial contact and during stance phase was significantly lower when increasing the heel strike pattern. In addition, the mean values of the knee external rotation and adductor moments during heel strike condition were lower than those in normal walking. Further, the ankle dorsiflexion range of motion (ROM) during mid-stance increased significantly during heel-first strike pattern compared to the value in normal gait pattern. Conclusions: The modification of gait pattern including heel-first strike pattern can reduce the mechanical load applied to the knee, while improving the extensibility of gastro-soleus muscle complex.

scholarly journals Comparative Study of Plantar Pressure during Step Exercise in Different Floor Conditions

2007 ◽  
Vol 23 (2) ◽  
pp. 162-168 ◽  
Author(s):  
Rita Santos-Rocha ◽  
António Veloso
Keyword(s):  
Physical Activity ◽  
Body Weight ◽  
Plantar Pressure ◽  
Mechanical Load ◽  
Reaction Force ◽  
Force Platform ◽  
Contact Forces ◽  
Impact Forces ◽  
The Impact ◽  
Floor Condition

Mechanical load has been estimated during step exercise based on ground reaction force (GRF) obtained by force platforms. It is not yet accurately known whether these measures reflect foot contact forces once the latter depend on footwear and are potentially modified by the compliant properties of the step bench. The aim of the study was to compare maximal and mean plantar pressure (PP), and maximal GRF obtained by pressure insoles after performing seven movements both over two metal force platforms and over the step bench. Fifteen step-experienced females performed the movements at the cadences of 130 and 140 beats per minute. PP and GRF (estimated from PP) obtained for each floor condition were compared. Maximal PP ranged from 29.27 ± 9.94 to 47.07 ± 12.88 N/cm2 as for metal platforms, and from 28.20 ± 9.32 to 43.00 ± 13.80 N/cm2 as for the step bench. Mean PP ranged from 11.09 ± 1.62 to 14.32 ± 2.06 N/cm2 (platforms) and from 10.71 ± 1.54 to 14.22 ± 1.77 N/cm2 (step bench). GRF (normalized body weight) ranged from 1.43 ± 0.14 to 2.41 ± 0.24 BW (platforms) and from 1.38 ± 0.14 to 2.36 ± 0.19 BW (step bench). No significant statistical differences were obtained for most of the comparisons between the two conditions tested. The results suggest that metal force platform surfaces are suitable to assess mechanical load during this physical activity. The forces applied to the foot are similar to the softer step bench and the hard force platform surface. This may reflect the ability of the performers to adapt their movement patterns to normalize the impact forces in different floor conditions.

scholarly journals Fatigue and Structural Deformation of Aged Engineering Plastics by Cyclic Mechanical Load.

1997 ◽  
Vol 54 (2) ◽  
pp. 61-68 ◽  
Author(s):  
Shigeki TAKAYAMA ◽  
Tomoyuki ISHIKAWA ◽  
Kunihiko TAKEDA
Keyword(s):  
Mechanical Load ◽  
Structural Deformation ◽  
Engineering Plastics ◽  
Cyclic Mechanical Load

Development of a Novel Model System to Study Remodeling of ECM Scaffolds in Response to Cyclic Stretching

2003 ◽  
Author(s):  
Thomas W. Gilbert ◽  
James H.-C. Wang ◽  
Stephen F. Badylak ◽  
Savio L.-Y. Woo
Keyword(s):  
Mechanical Load ◽  
Complex Loading ◽  
Biological Tissues ◽  
In Vitro Models ◽  
Matrix Remodeling ◽  
Cyclic Stretching ◽  
A Cell ◽  
Cyclic Mechanical Load

In an effort to better understand the role of mechanical loading on the healing and remodeling of biological tissues, a number of in vitro models have been developed to apply either static or cyclic mechanical load to cell-seeded scaffolds (Huang 1993, Langelier 1999, Cacou 2000). The current study describes the validation of a new system designed to facilitate the study of matrix remodeling in cell seeded scaffolds, as well as the formation of tissue engineered scaffolds for potential use in repair of healing ligaments and tendons. Our objective was to develop a system that would allow a cell seeded scaffold to remain viable under cyclic loading for long periods of time, with the capability to apply complex loading regimes to the scaffold while monitoring the load in the scaffold.

Critical currents of Nb/sub 3/Sn superconductors for generators under cyclic mechanical load

1994 ◽  
Vol 30 (4) ◽  
pp. 1927-1930 ◽  
Author(s):  
H. Kasahara ◽  
S. Torii ◽  
S. Akita ◽  
K. Uyeda ◽  
T. Ogawa ◽  
...  
Keyword(s):  
Mechanical Load ◽  
Critical Currents ◽  
Cyclic Mechanical Load
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