Continuous measurements of load-penetration curves with spherical microindenters and the estimation of mechanical properties

1998 ◽  
Vol 13 (5) ◽  
pp. 1390-1400 ◽  
Author(s):  
J. Alcalá ◽  
A. E. Giannakopoulos ◽  
S. Suresh
Keyword(s):  
Young’S Modulus ◽  
Large Scale ◽  
Young's Modulus ◽  
Accurate Determination ◽  
Elastic Response ◽  
Small Scale ◽  
Depth Of Penetration ◽  
Plastic Properties ◽  
Continuous Measurements ◽  
Contact Response

Elastic and plastic properties of metals and Young's modulus of ceramics are determined in the microindentation regime by continuous measurements of load versus depth of penetration with spherical indenters. Calibration procedures, usually applied in nanoindentation experiments, are not needed in the microregime where spherical indenters (rather than sharp indenters with microscopical spherical tips) can be manufactured. As indenters of larger diameters are used, the elastic response of the specimen can be probed during the loading stage of the indentation tests (and not only during unloading, as is the case with nanoindenters). Hence, an accurate determination of Young's modulus can be achieved without a prior knowledge of possible “piling up” or “sinking in” which may occur at the perimeter of the contact area. The contact response of materials is shown to undergo four distinct regions: (i) pre-Hertzian regime, (ii) Hertzian regime, (iii) small-scale plasticity, and (iv) large-scale plasticity. A general methodology for estimation of yield strength and hardening exponent of metals is proposed in the last regime.

scholarly journals Approximate Dynamic Programming Based Control of Proppant Concentration in Hydraulic Fracturing

Mathematics ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 132 ◽  
Author(s):  
Harwinder Singh Sidhu ◽  
Prashanth Siddhamshetty ◽  
Joseph Kwon
Keyword(s):  
Mechanical Properties ◽  
Dynamic Programming ◽  
Hydraulic Fracturing ◽  
Young’S Modulus ◽  
Large Scale ◽  
Approximate Dynamic Programming ◽  
Young's Modulus ◽  
Computational Cost ◽  
Control Technique ◽  
Rock Mechanical Properties

Hydraulic fracturing has played a crucial role in enhancing the extraction of oil and gas from deep underground sources. The two main objectives of hydraulic fracturing are to produce fractures with a desired fracture geometry and to achieve the target proppant concentration inside the fracture. Recently, some efforts have been made to accomplish these objectives by the model predictive control (MPC) theory based on the assumption that the rock mechanical properties such as the Young’s modulus are known and spatially homogenous. However, this approach may not be optimal if there is an uncertainty in the rock mechanical properties. Furthermore, the computational requirements associated with the MPC approach to calculate the control moves at each sampling time can be significantly high when the underlying process dynamics is described by a nonlinear large-scale system. To address these issues, the current work proposes an approximate dynamic programming (ADP) based approach for the closed-loop control of hydraulic fracturing to achieve the target proppant concentration at the end of pumping. ADP is a model-based control technique which combines a high-fidelity simulation and function approximator to alleviate the “curse-of-dimensionality” associated with the traditional dynamic programming (DP) approach. A series of simulations results is provided to demonstrate the performance of the ADP-based controller in achieving the target proppant concentration at the end of pumping at a fraction of the computational cost required by MPC while handling the uncertainty in the Young’s modulus of the rock formation.

scholarly journals Dynamic Radiation Effects Induced by Short-Pulsed GeV U-Ion Beams in Graphite and h-BN Targets

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Philipp Bolz ◽  
Philipp Drechsel ◽  
Alexey Prosvetov ◽  
Pascal Simon ◽  
Christina Trautmann ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Young’S Modulus ◽  
Radiation Effects ◽  
Large Scale ◽  
Hexagonal Boron Nitride ◽  
Young's Modulus ◽  
Target Surface ◽  
High Dose ◽  
Velocity Signal ◽  
Isotropic Graphite

Targets of isotropic graphite and hexagonal boron nitride were exposed to short pulses of uranium ions with ∼1 GeV kinetic energy. The deposited power density of ∼3 MW/cm³ generates thermal stress in the samples leading to pressure waves. The velocity of the respective motion of the target surface was measured by laser Doppler vibrometry. The bending modes are identified as the dominant components in the velocity signal recorded as a function of time. With accumulated radiation damage, the bending mode frequency shifts towards higher values. Based on this shift, Young’s modulus of irradiated isotropic graphite is determined by comparison with ANSYS simulations. The increase of Young’s modulus up to 3 times the pristine value for the highest accumulated fluence of 3 × 1013 ions/cm2 is attributed to the beam-induced microstructural evolution into a disordered structure similar to glassy carbon. Young’s modulus values deduced from microindentation measurements are similar, confirming the validity of the method. Beam-induced stress waves remain in the elastic regime, and no large-scale damage can be observed in graphite. Hexagonal boron nitride shows lower radiation resistance. Circular cracks are generated already at low fluences, risking material failure when applied in high-dose environment.

scholarly journals Integrated dynamic wet spinning of core-sheath hydrogel fibers for optical-to-brain/tissue communications

2020 ◽  
Author(s):  
Guoyin Chen ◽  
Gang Wang ◽  
Xinrong Tan ◽  
Kai Hou ◽  
Qingshuo Meng ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Optical Fibers ◽  
Rational Design ◽  
Large Scale ◽  
Young's Modulus ◽  
Solution Viscosity ◽  
Wet Spinning ◽  
Deep Tissue ◽  
Optogenetic Stimulation ◽  
Tissue Therapy

Abstract Hydrogel optical light-guides have received substantial interest for applications such as deep-tissue biosensors, optogenetic stimulation and photomedicine due to their biocompatibility, (micro)structure control and tissue-like Young's modulus. However, despite recent developments, large-scale fabrication with a continuous synthetic methodology, which could produce core-sheath hydrogel fibers with the desired optical and mechanical properties suitable for deep-tissue applications, has yet to be achieved. In this study, we report a versatile concept of integrated light-triggered dynamic wet spinning capable of continuously producing core-sheath hydrogel optical fibers with tunable fiber diameters, and mechanical and optical propagation properties. Furthermore, this concept also exhibited versatility for various kinds of core-sheath functional fibers. The wet spinning synthetic procedure and fabrication process were optimized with the rational design of the core/sheath material interface compatibility [core = poly(ethylene glycol diacrylate-co-acrylamide); sheath = Ca-alginate], optical transparency, refractive index and spinning solution viscosity. The resulting hydrogel optical fibers exhibited desirable low optical attenuation (0.18 ± 0.01 dB cm−1 with 650 nm laser light), excellent biocompatibility and tissue-like Young's modulus (<2.60 MPa). The optical waveguide hydrogel fibers were successfully employed for deep-tissue cancer therapy and brain optogenetic stimulation, confirming that they could serve as an efficient versatile tool for diverse deep-tissue therapy and brain optogenetic applications.

Determination of the hardness and young's modulus from the depth of penetration of a pyramidal indentor

1983 ◽  
Vol 15 (11) ◽  
pp. 1624-1628 ◽  
Author(s):  
B. A. Galanov ◽  
O. N. Grigor'ev ◽  
Yu. V. Mil'man ◽  
I. P. Ragozin
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Depth Of Penetration

Advanced Optimization of Industrial Large-Scale Roll-to-Roll Systems Under Parametric Uncertainties

2012 ◽  
Author(s):  
J. Frechard ◽  
D. Knittel
Keyword(s):  
Young’S Modulus ◽  
Large Scale ◽  
Young's Modulus ◽  
Robust Design Optimization ◽  
Parametric Uncertainties ◽  
Optimization Approach ◽  
Roll To Roll ◽  
Polymer Metal ◽  
The Web ◽  
Web Tension

In industrial plants some parameters can not be evaluated properly or they are varying with time. These parametric uncertainties has to be taken into account during the design process of industrial systems. In this work, the developped optimization approach is applied on an industrial roll-to-roll sytem. Such systems are commonly used to handle materials as polymer, metal, paper and textile. The key challenge is to move the web at the expected speed while maintaining the web tension in an acceptable range around its reference. Moreover, the Young’s modulus of the web is difficult to evaluate and it is varying with time due to temperature and moisture variations. This paper deals with the web tension controller synthesis on a large-scale roll-to-roll system with uncertain Young’s modulus. To synthesize web tension controllers, an H∞ approach is applied and adapted to the system with parametric uncertainties using multi-objective robust design optimization.

Development of Porous Material with High Young’s Modulus and Low Thermal Expansion Coefficient in SiC-Vitrified Bonding Material-LiAlSiO4 System

2009 ◽  
Vol 620-622 ◽  
pp. 715-718 ◽  
Author(s):  
Tatsuya Ono ◽  
Koji Matsumaru ◽  
Isaías Juárez-Ramírez ◽  
Leticia M. Torres-Martínez ◽  
Kozo Ishizaki
Keyword(s):  
Thermal Expansion ◽  
Porous Material ◽  
Porous Materials ◽  
Young’S Modulus ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Large Scale ◽  
Young's Modulus ◽  
Negative Thermal Expansion ◽  
Low Thermal Expansion

Machines for manufacturing large scale flat displays are enlarging as the size of glasses increases. This work develops porous materials with a low thermal expansion coefficient and a high Young’s modulus. SiC and LiAlSiO4 were used for a positive and a negative thermal expansion materials, respectively. Compositions of powders for porous materials were determined to obtain a desirable Young’s modulus and thermal expansion coefficient by using SiC-VBM-LiAlSiO4 phase diagram at 20 % of porosity. The empirical values of Young’s modulus and a thermal expansion coefficient are close to the theoretical values by using the diagram. Fabricated porous material had high enough Young’s modulus of 87 GPa, and low enough thermal expansion coefficient of 2 x 10-6 K-1 at temperatures ranging from -17 °C to 190 °C with 22 % of porosity.

Mechanical Properties Of Cu-Based Composites with in Situ Formed Ultrafine Filaments

1981 ◽  
Vol 12 ◽  
Author(s):  
J. Bevk ◽  
W. A. Sunder ◽  
G. Dublon ◽  
David E. Cohen
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Young’S Modulus ◽  
Size Dependence ◽  
Young's Modulus ◽  
Plastic Properties ◽  
Young’S Moduli ◽  
Lattice Softening

ABSTRACTElastic and plastic properties of in situ Cu-based composites with Nb, V, and Fe filaments are reviewed. The evidence is presented for a pronounced size dependence of both the ultimate tensile strength and the Young's moduli. In composites with the smallest filaments (d∼50–200Å) and filament densities as high as 1010/cm2 dislocation density reaches values of 1013 cm/cm3. The yield stress of these samples increases dramatically over the predictions based on the “rule of mixtures” and their ultimate tensile strength approaches the estimated theoretical strength of the material (∼2.7GPa). The observed decrease of Young's modulus as a function of inverse wire diameter in the as-drawn composites is attributed to lattice softening due to high density of extended lattice defects. Upon annealing, Young's modulus increases by as much as 100% and exceeds the maximum values calculated from bulk elastic constants. Possible mechanisms leading to modulus enhancement and to related changes in magnetic and superconducting behavior of in situ composites are discussed.

Investigation into the Dynamic Fracture Properties of Large Scale Functionally Graded Materials

2006 ◽  
Vol 324-325 ◽  
pp. 239-242 ◽  
Author(s):  
Xiao Bin Yang ◽  
Zhuo Zhuang ◽  
Xue Feng Yao
Keyword(s):  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Large Scale ◽  
Young's Modulus ◽  
Mass Density ◽  
Poisson's Ratio ◽  
Constant Mass ◽  
Functionally Gradient Materials ◽  
Gradient Materials ◽  
Functionally Gradient

A crack propagation perpendicular to gradient in a large scale functionally gradient materials, which has (1) a linear variation of Young’s modulus with a constant mass density and Poisson’s ratio, and (2) a exponential variation of Young’s modulus with a constant mass density and Poisson’s ratio, is modelled by finite element methods. Based on the experimental result of large scale functionally gradient materials, the dynamic propagation process of the FGMs is modelled and the dynamic parameters, like the energy release rate and crack tip opening angle, are calculated through a generation phase.

scholarly journals Arctic Sea Ice of Various Ages: II. Elastic Properties

1964 ◽  
Vol 5 (37) ◽  
pp. 99-105
Author(s):  
E. R. Pounder ◽  
M. P. Langleben
Keyword(s):  
Sea Ice ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Arctic Sea Ice ◽  
P Wave ◽  
Small Samples ◽  
Small Scale ◽  
S Wave ◽  
Seismic Method ◽  
P Wave Velocity

AbstractYoung’s modulus E and Poisson’s ratio σ0 were calculated for biennial and polar ice from measurements of the P-wave velocity in small samples and from a study of the resonant frequencies of the saure samples. P- and S-wave velocities in the biennial ice cover were also found by a seismic method. The small-scale tests showed no significant differences between the two types of ice tested. Young’s modulus averaged 3.6 per cent lower than the comparable figure for annual sea ice. The seismic method gave values of E and σ0 about 20 per cent lower than the small-scale tests.

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