Measurement of residual stress by load and depth sensing indentation with spherical indenters

2001 ◽  
Vol 16 (7) ◽  
pp. 2091-2102 ◽  
Author(s):  
J. G. Swadener ◽  
B. Taljat ◽  
G.M. Pharr
Keyword(s):  
Residual Stress ◽  
Surface Stress ◽  
The Other ◽  
Spherical Indentation ◽  
Biaxial Bending ◽  
Depth Sensing ◽  
Unstressed State ◽  
Bending Stresses ◽  
Point To Point

A new experimental technique is presented for making measurements of biaxial residual stress using load and depth sensing indentation (nanoindentation). The technique is based on spherical indentation, which, in certain deformation regimes, can be much more sensitive to residual stress than indentation with sharp pyramidal indenters like the Berkovich. Two different methods of analysis were developed: one requiring an independent measure of the material's yield strength and the other a reference specimen in the unstressed state or other known reference condition. Experiments conducted on aluminum alloys to which controlled biaxial bending stresses were applied showed that the methods are capable of measuring the residual stress to within 10–20% of the specimen yield stress. Because the methods do not require imaging of the hardness impressions, they are potentially useful for making localized measurements of residual stress, as in thin films or small volumes, or for characterization of point-to-point spatial variations of the surface stress.

Characterization of nanocrystalline surface layer induced by shot peening and effect on their fatigue strength.

2004 ◽  
Vol 843 ◽  
Author(s):  
Hideo Mano ◽  
Kondo Satoru ◽  
Akihito Matsumuro ◽  
Toru Imura
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Fatigue Strength ◽  
Vickers Hardness ◽  
Shot Peening ◽  
White Layer ◽  
The Other ◽  
Fatigue Properties ◽  
Nanocrystalline Layer

ABSTRACTThe shot peening process is known to produce a hard layer, known as the white layer” on the surface of coil springs. However, little is known about the fatigue properties of this white-layer.In this study, coil springs with a white-layer were manufactured. The surface of these springs was then examined using micro Vickers hardness, FE-SEM etc. to test fatigue strength of the springs.From the results obtained, a microstructure of the white-layer with grain size of 50–100 nm was observed, with a Vickers hardness rating of 8–10 GPa.Tow category springs were manufactured utilizing a double-peening process. These springs had the same residual stress destruction and surface roughness. Only one difference was observed: one spring had a nanocrystalline layer on the surface, while the other did not. The results of the fatigue test realized an increase in the fatigue life of the nanocrystalline surface layer by 9%.

scholarly journals Characterization of MPI Communication Primitives on a Heterogeneous Cluster

2009 ◽  
Vol 6 (2) ◽  
pp. 23
Author(s):  
Siti Arpah Ahmad ◽  
Mohamed Faidz Mohamed Said ◽  
Norazan Mohamed Ramli ◽  
Mohd Nasir Taib
Keyword(s):  
Message Passing ◽  
High Performance ◽  
Data Transfer ◽  
The Other ◽  
Small Cluster ◽  
Heterogeneous Cluster ◽  
Processing Power ◽  
Basic Performance ◽  
Point To Point

This paper focuses on the performance of basic communication primitives, namely the overlap of message transfer with computation in the point-to-point communication within a small cluster of four nodes. The mpptest has been implemented to measure the basic performance of MPI message passing routines with a variety of message sizes. The mpptest is capable of measuring performance with many participating processes thus exposing contention and scalability problems. This enables programmers to select message sizes in order to isolate and evaluate sudden changes in performance. Investigating these matters is interesting in that non-blocking calls have the advantage of allowing the system to schedule communications even when many processes are running simultaneously. On the other hand, understanding the characteristics of computation and communication overlap is significant, because high- performance kernels often strive to achieve this, since it is both advantageous with respect to data transfer and latency hiding. The results indicate that certain overlap sizes utilize greater node processing power either in blocking send and receive operations or non-blocking send and receive operations. The results have elucidated a detailed MPI characterization of the performance regarding the overlap of message transfer with computation in a small cluster system. 

WJP Applicability Study for PWR Components As a PWSCC Mitigation Technique

2017 ◽  
Author(s):  
Ryuji Kimura ◽  
Noboru Saito ◽  
Hisamitsu Hato ◽  
Akihiro Kanno ◽  
Masami Ando ◽  
...  
Keyword(s):  
Residual Stress ◽  
Water Flow ◽  
Pressure Vessel ◽  
Surface Stress ◽  
Reactor Pressure Vessel ◽  
The Other ◽  
Performance Criteria ◽  
Head Penetration ◽  
Water Chamber ◽  
Reactor Pressure

Water Jet Peening (WJP) has been widely applied to nuclear power plants in Japan as one of mitigation techniques against Stress Corrosion Cracking (SCC) initiation [1]. WJP utilizes high pressure water flow including numerous cavitation bubbles and improves surface residual stress of susceptible materials used in reactor internals from tensile stress to compressive stress without significant plastic deformation, hardening, heating and furthermore retrieval of foreign materials. An inspection relief for the Primary Water SCC (PWSCC) concerned components, by means of peening technique application, has been discussed among PWR owners in the US for about last 10 years. The topical report on PWSCC mitigation by surface stress improvement (Material Reliability Program (MRP)-335, revision 3-A) was published through the above activities by Electric Power Research Institute (EPRI) MRP [2]. The target components, where PWSCC is concerned, are listed as Reactor Pressure Vessel Head Penetration Nozzles (RPVHPNs), such as Control Rod Drive Mechanism Nozzle (CRDMN), and dissimilar metal welds (DMWs) of Reactor Coolant System (RCS) nozzles, and performance criteria for peening are defined in the topical report. Moreover, the technical basis for PWSCC mitigation by surface stress improvement (MRP-267, revision 2) was published by EPRI MRP [3].The report details numerous data for each peening technique which show the effectiveness in mitigating the PWSCC initiation and its sustainability, i.e. state of stress. The report also includes the process control; covering nozzle diameter, water flow rate, application time, jet stand-off, impingement angle and stationary nozzle time for WJP [3]. RPVHPNs inner diameter (ID), such as CRDMN ID, is in narrower areas than the other target components of peening techniques. Hence the WJP nozzle should be set appropriate condition, e. g. sufficient stand-off distance or angle of the WJP nozzle, in line with the MRP-267 in order to ensure the stress improvement effect by WJP. Further, the reactor pressure vessel head, which has the RPVHPNs including the CRDMNs, is placed on the refueling floor and under atmosphere condition during outage, and therefore, the CRDMNs have to be filled with water by plugging etc. for WJP application on CRDMN ID. Thus the CRDMN ID becomes a closed narrow chamber. In such a closed narrow chamber, water flow might become complex and disturb the cavitation collapse on the target surface, resulting in decreased stress improvement. Additionally, WJP has been rarely applied in a narrow closed water chamber, and only a few residual stress measurement data are available for such a WJP treated specimen. For the above reason, we has conducted a WJP test utilizing the water chamber and measured the residual stress of the test coupon simulating the CRDMN ID before and after WJP application as our own research. As a result, an improvement in residual stress was ensured even in an application of WJP in a closed narrow water chamber, which assumes CRDMN ID configuration, and created a depth over the performance criteria (0.01” (0.25 mm) in depth) stated in MRP-335 [2]. As an another applicability study, we developed a WJP tool for Bottom Mounted Instrument (BMI) Nozzles and confirmed that the residual stress of BMI ID and Outer Diameter (OD) can be improved . The background of this study is that BMI nozzle is under discussion for inspection relief as one of the components which are concerned about PWSCC. Especially, BMI ID is narrow area for WJP application; on the other hand it does not need to become a closed chamber since the reactor pressure vessel, which has the BMI Nozzles on the bottom head, is filled with water during outage. As a result, it is ensured that the residual stress for BMI ID and OD is improved by WJP to a depth of at least 0.2mm which is deeper than the performance criteria for the depth of compressive residual stress of Austenitic Stainless Steel in Japan (3.9 × 10−3” (0.1mm) in depth).

Measurement of Residual Stresses by Load and Depth Sensing Spherical Indentation

1999 ◽  
Vol 594 ◽  
Author(s):  
B. Taljat ◽  
G. M. Pharr
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Yield Stress ◽  
Critical Examination ◽  
Spherical Indentation ◽  
Depth Sensing ◽  
Elastic Plastic ◽  
Ideal Plastic ◽  
Plastic Materials

AbstractThe finite element method was used to determine whether load and depth sensing indentation with spherical indenters may be useful in the measurement of residual stresses in materials. The spherical indentation process for a wide range of elastic/ideal-plastic materials to which compressive and tensile biaxial stresses were applied was simulated using standard finite element techniques. The elastic moduli and yield stresses of the materials were varied systematically to model the behavior of a wide variety of metals and ceramics. Elastic-ideal-plastic materials were considered in the study with residual stress levels varied from zero up to the yield stress. All three indentation regimes - elastic, elastic-plastic, and plastic - were examined, with emphasis given to the elastic and the early part of the elastic-plastic regimes, where differences in the load-displacement characteristics caused by residual stress were found to have a significant effect. Systematic examination of the relationships among residual stress, contact pressure, and elastic recovery revealed a simple, measurable indentation parameter which correlates well with the residual stress. Using this parameter, an experimental technique is proposed by which residual stresses can be estimated from measurements of the load of an indentation in the elastic-plastic regime, the yield stress, and the elastic modulus of the material, all of which can be determined by load and depth sensing indentation methods. Based on a critical examination of the technique by finite element simulation, the technique appears promising.

A very rapid in situ Kikuchi technique to determine relative crystal misorientation

1988 ◽  
Vol 46 ◽  
pp. 830-831
Author(s):  
J. I. Bennetch
Keyword(s):  
Electron Beam ◽  
Analytical Techniques ◽  
Superplastic Forming ◽  
The Other ◽  
Kikuchi Pattern ◽  
Kikuchi Line ◽  
Line Analysis

In a recent study of the superplastic forming (SPF) behavior of certain Al-Li-X alloys, the relative misorientation between adjacent (sub)grains proved to be an important parameter. It is well established that the most accurate way to determine misorientation across boundaries is by Kikuchi line analysis. However, the SPF study required the characterization of a large number of (sub)grains in each sample to be statistically meaningful, a very time-consuming task even for comparatively rapid Kikuchi analytical techniques.In order to circumvent this problem, an alternate, even more rapid in-situ Kikuchi technique was devised, eliminating the need for the developing of negatives and any subsequent measurements on photographic plates. All that is required is a double tilt low backlash goniometer capable of tilting ± 45° in one axis and ± 30° in the other axis. The procedure is as follows. While viewing the microscope screen, one merely tilts the specimen until a standard recognizable reference Kikuchi pattern is centered, making sure, at the same time, that the focused electron beam remains on the (sub)grain in question.

Characterization of Rh/Si multilayer structure by HREM and HAADF

1992 ◽  
Vol 50 (1) ◽  
pp. 122-123
Author(s):  
Y. Cheng ◽  
J. Liu ◽  
M.B. Stearns ◽  
D.G. Steams
Keyword(s):  
Normal Incidence ◽  
High Resolution Electron Microscopy ◽  
X Rays ◽  
Beam Direction ◽  
Cross Sectional ◽  
Optical Elements ◽  
Resolution Electron ◽  
Point To Point ◽  
Better Than

The Rh/Si multilayer (ML) thin films are promising optical elements for soft x-rays since they have a calculated normal incidence reflectivity of ∼60% at a x-ray wavelength of ∼13 nm. However, a reflectivity of only 28% has been attained to date for ML fabricated by dc magnetron sputtering. In order to determine the cause of this degraded reflectivity the microstructure of this ML was examined on cross-sectional specimens with two high-resolution electron microscopy (HREM and HAADF) techniques.Cross-sectional specimens were made from an as-prepared ML sample and from the same ML annealed at 298 °C for 1 and 100 hours. The specimens were imaged using a JEM-4000EX TEM operating at 400 kV with a point-to-point resolution of better than 0.17 nm. The specimens were viewed along Si [110] projection of the substrate, with the (001) Si surface plane parallel to the beam direction.

Rapid Isolation of High Molecular Weight Urokinase from Native Human Urine

1982 ◽  
Vol 47 (03) ◽  
pp. 197-202 ◽  
Author(s):  
Kurt Huber ◽  
Johannes Kirchheimer ◽  
Bernd R Binder
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Urine ◽  
Gel Filtration ◽  
Chain Structure ◽  
The Other ◽  
Single Chain ◽  
Apparent Homogeneity ◽  
Sequential Adsorption

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.

scholarly journals Analysis of the Mechanism by Which Glucose Inhibits Maltose Induction of MAL Gene Expression in Saccharomyces

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 121-132
Author(s):  
Zhen Hu ◽  
Yingzi Yue ◽  
Hua Jiang ◽  
Bin Zhang ◽  
Peter W Sherwood ◽  
...  
Keyword(s):  
Gene Expression ◽  
Glucose Repression ◽  
Protein A ◽  
The Other ◽  
Maltose Permease ◽  
Inducer Exclusion ◽  
Glucose Inhibition ◽  
Independent Mechanism ◽  
Mal Genes

Abstract Expression of the MAL genes required for maltose fermentation in Saccharomyces cerevisiae is induced by maltose and repressed by glucose. Maltose-inducible regulation requires maltose permease and the MAL-activator protein, a DNA-binding transcription factor encoded by MAL63 and its homologues at the other MAL loci. Previously, we showed that the Mig1 repressor mediates glucose repression of MAL gene expression. Glucose also blocks MAL-activator-mediated maltose induction through a Mig1p-independent mechanism that we refer to as glucose inhibition. Here we report the characterization of this process. Our results indicate that glucose inhibition is also Mig2p independent. Moreover, we show that neither overexpression of the MAL-activator nor elimination of inducer exclusion is sufficient to relieve glucose inhibition, suggesting that glucose acts to inhibit induction by affecting maltose sensing and/or signaling. The glucose inhibition pathway requires HXK2, REG1, and GSF1 and appears to overlap upstream with the glucose repression pathway. The likely target of glucose inhibition is Snf1 protein kinase. Evidence is presented indicating that, in addition to its role in the inactivation of Mig1p, Snf1p is required post-transcriptionally for the synthesis of maltose permease whose function is essential for maltose induction.

scholarly journals On a New Geometric Constant Related to the Euler-Lagrange Type Identity in Banach Spaces

Mathematics ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 116
Author(s):  
Qi Liu ◽  
Yongjin Li
Keyword(s):  
Banach Spaces ◽  
Product Space ◽  
Sufficient Conditions ◽  
Normal Structure ◽  
The Other ◽  
Inner Product ◽  
Equivalent Characterization ◽  
Geometric Constant ◽  
Geometric Constants

In this paper, we will introduce a new geometric constant LYJ(λ,μ,X) based on an equivalent characterization of inner product space, which was proposed by Moslehian and Rassias. We first discuss some equivalent forms of the proposed constant. Next, a characterization of uniformly non-square is given. Moreover, some sufficient conditions which imply weak normal structure are presented. Finally, we obtain some relationship between the other well-known geometric constants and LYJ(λ,μ,X). Also, this new coefficient is computed for X being concrete space.

The development of body and organ shape

BMC Zoology ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Ansa E. Cobham ◽  
Christen K. Mirth
Keyword(s):  
Relative Position ◽  
Body Shape ◽  
Single Cells ◽  
The Other ◽  
Geometric Features ◽  
Main Text ◽  
Size Characterization ◽  
Organ Shape ◽  
The Many

Abstract Background Organisms show an incredibly diverse array of body and organ shapes that are both unique to their taxon and important for adapting to their environment. Achieving these specific shapes involves coordinating the many processes that transform single cells into complex organs, and regulating their growth so that they can function within a fully-formed body. Main text Conceptually, body and organ shape can be separated in two categories, although in practice these categories need not be mutually exclusive. Body shape results from the extent to which organs, or parts of organs, grow relative to each other. The patterns of relative organ size are characterized using allometry. Organ shape, on the other hand, is defined as the geometric features of an organ’s component parts excluding its size. Characterization of organ shape is frequently described by the relative position of homologous features, known as landmarks, distributed throughout the organ. These descriptions fall into the domain of geometric morphometrics. Conclusion In this review, we discuss the methods of characterizing body and organ shape, the developmental programs thought to underlie each, highlight when and how the mechanisms regulating body and organ shape might overlap, and provide our perspective on future avenues of research.

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