Elimination of membrane compliance in undrained triaxial testing. I. Measurement and evaluation

1993 ◽  
Vol 30 (5) ◽  
pp. 727-738 ◽  
Author(s):  
P.G. Nicholson ◽  
R.B. Seed ◽  
H.A. Anwar
Keyword(s):  
Grain Size ◽  
Test Results ◽  
Factors Affecting ◽  
Grain Sizes ◽  
Wide Range ◽  
Specimen Density ◽  
Thin Membranes ◽  
Alternative Approaches ◽  
Measurement And Evaluation ◽  
Material Grain Size

Several alternative approaches have been suggested for evaluation and correction of the testing errors caused by membrane compliance. The degree to which membrane compliance may affect the results of an undrained test is a function of the soil grain size and overall geometry of the test specimen, as well as specimen density and range of effective confining stresses during a given test. Membrane-compliance effects may be negligible for fine sands and silts tested in conventional 71 mm diameter samples, since even very thin membranes cannot penetrate significantly into the small surficial voids. For medium to coarse sands and gravels, however, membrane-compliance effects may have a significant influence on test results. The scope of this paper is threefold: firstly, to review, examine, and evaluate the variety of methods to measure and characterize membrane compliance; secondly, to develop an improved understanding of the factors affecting membrane compliance; and thirdly, to provide an enhanced, updated, and expanded correlation for estimating membrane compliance characteristics as a function of material grain size for a range of soil types, including a wide range of gradation types and representative grain sizes from silts through gravels. Key words : membrane, penetration, compliance, undrained testing, triaxial, measurement, evaluation.

The Processing of Ultrafine-Grained Materials Using High-Pressure Torsion

2007 ◽  
Vol 558-559 ◽  
pp. 1283-1294 ◽  
Author(s):  
Cheng Xu ◽  
Z. Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Metallic Materials ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Wide Range ◽  
Ultrafine Grained Materials ◽  
Thin Disks

It is now well-established that processing through the application of severe plastic deformation (SPD) leads to a significant reduction in the grain size of a wide range of metallic materials. This paper examines the fabrication of ultrafine-grained materials using high-pressure torsion (HPT) where this process is attractive because it leads to exceptional grain refinement with grain sizes that often lie in the nanometer or submicrometer ranges. Two aspects of HPT are examined. First, processing by HPT is usually confined to samples in the form of very thin disks but recent experiments demonstrate the potential for extending HPT also to bulk samples. Second, since the strains imposed in HPT vary with the distance from the center of the disk, it is important to examine the development of inhomogeneities in disk samples processed by HPT.

Environmental magnetism as a stream sediment tracer: an interpretation of the methodology and some case studies

Soil Research ◽  
1998 ◽  
Vol 36 (1) ◽  
pp. 167 ◽  
Author(s):  
R. H. Crockford ◽  
P. M. Fleming
Keyword(s):  
Grain Size ◽  
Case Studies ◽  
Environmental Magnetism ◽  
Extensive Discussion ◽  
Remanent Magnetisation ◽  
Grain Sizes ◽  
South Wales ◽  
Wide Range ◽  
River Confluences ◽  
The Difference

A comprehensive sediment sampling program was undertaken in the upper Molonglo catchment in south-eastern New South Wales to determine if mineral magnetics could be used to estimate sidestream contribution at river confluences in this environment. Some 12 confluences were examined over 1400 km 2 in 2 major basins and over 2 contrasting geological types. Sediment samples were divided into 7 size classes and the following magnetic properties measured: magnetic susceptibility at 2 frequencies, isothermal remanent magnetisation at 3 flux densities, and anhysteristic remanent magnetisation. The sidestream inputs were calculated for each particle size class from the range of magnetic parameters. Significant discrepancies and differences appeared in the resultant sidestream inputs, and this paper outlines the conclusions as to the reliability of the different analytical procedures. It is shown that both the concentration and magnetic grain size of ferrimagnetic minerals in the sediments must be taken into account. Where the difference in magnetic grain size between the upstream and sidestream sediments is small, the use of parameter crossplots or bulked magnetic ratios is generally not appropriate. The use of mass (concentration) magnetic values may be better. The difference in the demands of the crossplots and mass values methods is that crossplots require a wide range of mass magnetic concentrations in each branch, with the upstream and sidestream sediments having different magnetic grain sizes, whereas the mass values procedure does best with a very limited (but different) range of concentrations at the upstream and sidestream branches, but similar magnetic grain sizes. This paper provides an extensive discussion of the estimation technique using different parameter combinations, and uses 3 contrasting confluences as case studies.

Effect of Low-Temperature Aging on Thermally-Induced Phase Transformation of NiTi Wire with a Wide Range of Grain Sizes

2021 ◽  
Vol 1042 ◽  
pp. 9-16
Author(s):  
Zhi Hao Zhao ◽  
Jian Ping Lin ◽  
Jun Ying Min ◽  
Yong Hou ◽  
Bo Sun
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Low Temperature ◽  
Thermally Induced ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Wide Range ◽  
Low Temperature Aging ◽  
Niti Wires ◽  
Temperature Aging

Thermally-induced phase transformation (PT) is of significance and value to the application of NiTi alloy components. Low-temperature aging (LTA) treatment was used to alter PT characteristics of NiTi alloys avoiding undesirable grain growth. Effect of LTA on PT of NiTi wires with a wide range of grain sizes from 34 nm to 8021 nm was investigated in this study. As the average grain size varies from 34 to 217 nm, the temperature of the B2↔R transformation increase as a result of LTA, and the increasing effect is more obvious at a larger grain size. For NiTi alloys with average grain sizes ranging from 523 to 1106 nm, transformation sequence changes from B2↔B19' to B2↔R due to LTA. For the sample with an average grain size of 2190 nm, the B2↔B19' transformation is replaced by B2↔R←B19' after LTA. When the average grain size is larger than 2190 nm, transformation sequence changes from B2↔B19' to B2↔R↔B19' after LTA. Transmission emission microscope observations reveal that the above-mentioned PT behavior correlates with the coupled effect of grain size and precipitation. The precipitation of Ni4Ti3 in the grains with a size smaller than ~150 nm is inhibited after LTA, the temperature of B2→R of samples with average GS smaller than ~150 nm still is elevated due to the inhomogeneous grain size of NiTi wires.

Influence of Grain Size and Grain Boundary of Workpiece on Micro EDM

2014 ◽  
Vol 941-944 ◽  
pp. 2116-2120 ◽  
Author(s):  
Qing Yu Liu ◽  
Qin He Zhang ◽  
Jian Hua Zhang ◽  
Min Zhang
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Micro Edm ◽  
Test Results ◽  
Machining Performance ◽  
Grain Sizes ◽  
Stainless Steel 304 ◽  
Micro Holes ◽  
The Difference ◽  
Micro Features

Micro EDM is used to machine micro features which are of the same size order as material microstructure of workpiece. Due to the difference of the thermal properties between the crystal grain and grain boundary, the machining performance of micro EDM varies with the crystal grain sizes of workpiece. This paper investigated on the influence of grain size and grain boundary on the machining performance of micro EDM. By drilling micro holes on two pieces of stainless steel 304 (SUS 304) which are different in grain sizes, test results revealed that the characteristics of micro EDM is influenced by grain sizes of workpiece materials significantly.

Summary of major factors affecting mechanical properties of TiZr based alloys

2015 ◽  
Vol 12 (4) ◽  
pp. 319-324 ◽  
Author(s):  
Lixia Yin ◽  
Shunxing Liang ◽  
Liyun Zheng
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Test Results ◽  
Factors Affecting ◽  
Β Phase ◽  
Α Phase ◽  
Tc4 Alloy ◽  
Nanoindentation Hardness ◽  
Major Factors ◽  
Zr Alloy

Effects of major factors, such as alloy composition, crystal structure and grain size, on mechanical properties of TiZr based alloys are investigated and summarized in this work. The microhardness of TC4 alloy obviously increases 15.3% and 17.6% after 30 wt.% and 47 wt.% Zr additions, respectively. Nanoindentation results show that the average nanoindentation hardness of α phase in annealed 30 Zr is approximately 18% higher than that of retained β phase. Tensile test results show that variation in strength of basketweave microstructural 30 Zr alloy with original β grain size from 100 to 203 μm is less than 2%.

Modulated Hall-Effect Techniques for the Study of Transport Properties of Microcrystalline Silicon with Different Grain Sizes

1996 ◽  
Vol 420 ◽  
Author(s):  
P. Hapke ◽  
U. Backhausen ◽  
R. Carius ◽  
F. Finger ◽  
S. Ray
Keyword(s):  
Grain Size ◽  
Hall Effect ◽  
Transport Properties ◽  
Thermal Emission ◽  
Clear Correlation ◽  
Microcrystalline Silicon ◽  
Grain Sizes ◽  
Wide Range ◽  
Set Up ◽  
A Current

AbstractHighly doped μc-Si:H samples with a wide range of crystalline volume fractions and grain sizes have been investigated by Hall-effect experiments. We present an experimental set-up with a current modulation technique and a 6-pole contact geometry which allows the measurement of the Hall-effect on highly doped μc-Si:H down to 10K. The experimental results exhibit a clear correlation between the mobility μ and the grain size δ. Further, the results show that the transport in μc-Si:H can not be described by thermal emission over grain boundaries alone, additional transport paths, e.g. tunneling processes through the barriers have to be taken into account.

Characterization of Grains Size by Ultrasounds

2011 ◽  
Vol 482 ◽  
pp. 49-56 ◽  
Author(s):  
Ali Badidi Bouda ◽  
Mohammed S. Aljohani ◽  
Ahmed Mebtouche ◽  
Rafik Halimi ◽  
Wahiba Djerir
Keyword(s):  
Grain Size ◽  
Frequency Shift ◽  
Ultrasonic Wave ◽  
Heat Treatments ◽  
Ultrasonic Waves ◽  
Wave Frequency ◽  
Shift Measurement ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Material Grain Size

A mechanical or thermal treatment of a material can change, among other things, the average grains size. It depends on temperature, holding time, cooling condition or rolling stress. The average grain size, as well as its influence on the propagation velocity and attenuation coefficient of ultrasonic waves, also affects the wave frequency propagating through the material. Grain size is an indicator of material fatigue. It can therefore be used in monitoring or fatigue damage prevention. In this paper, we study the effect of various heat treatments hence different steel average grain sizes on the ultrasonic wave frequency after crossing the material. We have performed the same experimental study on aluminum samples. The different grain sizes are obtained by rolling. The frequency shift measurement of longitudinal waves is achieved by immersion with two probes of different frequencies 2.25 and 5 MHz. The experimental results are shown as curves giving the frequencies depending on the grain size. Heat treatments on steel and aluminum rolling performed on the samples have yielded a grain sizes gradient. Our results are consistent with the theory because of the important path in the sample and in this case the down shift frequency is paramount. They show a direct relationship between the frequency shift and the average grain size. It is therefore possible to trace quantitatively to an average grains size from the frequency of an ultrasonic wave that has passed through this material and hence its thermal or mechanical fatigue state.

The Effect of Grain Boundaries and Second-Phase Particles on Hydride Precipitation in Zirconium Alloys

MRS Advances ◽  
2018 ◽  
Vol 3 (31) ◽  
pp. 1749-1754 ◽  
Author(s):  
Said El Chamaa ◽  
Mitesh Patel ◽  
Catrin M. Davies ◽  
Mark R. Wenman
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Zirconium Alloys ◽  
Second Phase ◽  
Distribution Profile ◽  
Grain Sizes ◽  
Hydride Precipitation ◽  
Nucleation Sites ◽  
Wide Range ◽  
Pure Zirconium

ABSTRACTUnderstanding the precipitation of brittle hydride phases is crucial in establishing a failure criterion for various zirconium alloy nuclear fuel cladding. Accordingly, it is important to quantify the sensitivity of hydride precipitation to the component microstructure. This experimental investigation focuses on two microstructural characteristics and their role as hydride nucleation sites: The grain size and the alloy chemical composition. Samples of commercially pure zirconium (Zr-702) and Zircaloy-4, each with a wide range of grain sizes, were hydrided to 100 ppm and micrographs of the hydride distribution were optically analyzed for inter-granular and intra-granular precipitate sites. For most grain sizes, it was found that a significantly lower fraction of the precipitated hydrides nucleated at grain boundaries in Zircaloy-4 than in Zr-702, suggesting that a higher SPP content encourages the formation of intra-granular hydrides. Moreover, this effect became more prominent as the grain size increased; large-grain specimens contained a higher fraction of intra-granular hydrides than small-grain specimens of both Zr-702 and Zircaloy-4, highlighting the potency of grain boundaries as nucleation sites and how SPPs can influence the hydride distribution profile.

scholarly journals Modified Johnson-Cook Plasticity Model with Damage Evolution: Application to Turning Simulation of 2XXX Aluminium Alloy

2017 ◽  
Vol 33 (6) ◽  
pp. 777-788 ◽  
Author(s):  
H. Ijaz ◽  
M. Zain-ul-abdein ◽  
W. Saleem ◽  
M. Asad ◽  
T. Mabrouki
Keyword(s):  
Grain Size ◽  
Aluminium Alloy ◽  
Fe Simulation ◽  
Damage Model ◽  
Material Model ◽  
Turning Process ◽  
Size Refinement ◽  
Grain Sizes ◽  
Simulation Results ◽  
Material Grain Size

AbstractMechanical properties of the metals and their alloys are influenced by the material grain size at microscale. In the present study, the Johnson-Cook (JC) material model is modified to incorporate the effect of material's grain size along with the plasticity coupled damage model. 2D finite element (FE) simulations of turning process of an aerospace grade aluminium alloy 2024 (AA2024) were performed with different grain sizes using a commercial FE software, ABAQUS/Explicit. FE simulation results were compared with the published experimental data on turning process of AA2024. The proposed modified JC material model successfully simulated the increase in cutting force as a function of grain size refinement.

Factors Affecting Molecular Self-Assembly and Its Mechanism

2012 ◽  
Vol 9 (1) ◽  
pp. 43 ◽  
Author(s):  
Hueyling Tan
Keyword(s):  
Self Assembly ◽  
Building Blocks ◽  
Molecular Engineering ◽  
Molecular Structures ◽  
Polymer Science ◽  
New Approach ◽  
Factors Affecting ◽  
Dna Structures ◽  
Self Assembling ◽  
Wide Range

Molecular self-assembly is ubiquitous in nature and has emerged as a new approach to produce new materials in chemistry, engineering, nanotechnology, polymer science and materials. Molecular self-assembly has been attracting increasing interest from the scientific community in recent years due to its importance in understanding biology and a variety of diseases at the molecular level. In the last few years, considerable advances have been made in the use ofpeptides as building blocks to produce biological materials for wide range of applications, including fabricating novel supra-molecular structures and scaffolding for tissue repair. The study ofbiological self-assembly systems represents a significant advancement in molecular engineering and is a rapidly growing scientific and engineering field that crosses the boundaries ofexisting disciplines. Many self-assembling systems are rangefrom bi- andtri-block copolymers to DNA structures as well as simple and complex proteins andpeptides. The ultimate goal is to harness molecular self-assembly such that design andcontrol ofbottom-up processes is achieved thereby enabling exploitation of structures developed at the meso- and macro-scopic scale for the purposes oflife and non-life science applications. Such aspirations can be achievedthrough understanding thefundamental principles behind the selforganisation and self-synthesis processes exhibited by biological systems.

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