Evaluation of a Modified Cyclic Neuber Relation

1991 ◽  
Vol 113 (3) ◽  
pp. 350-353 ◽  
Author(s):  
K. C. Wang ◽  
W. N. Sharpe
Keyword(s):  
Close Agreement ◽  
Notch Root ◽  
Preceding Paper ◽  
Cyclic Form ◽  
Biaxial Strain ◽  
Predictive Capability ◽  
Strain Measurements ◽  
Aluminum Specimen ◽  
Reversed Cyclic ◽  
Tension Loading

A preceding paper reported the results of biaxial strain measurements at the roots of notched aluminum specimen subjected to monotonic tension loading. The specimens had different amounts of constraints at the notch root, and it was shown that a modified version of the Neuber relation gave some improvement in its predictive capability. Several of those specimens were also subjected to fully reversed cyclic loading until microcracks formed at the notch roots, and the results of those biaxial strain measurements are reported here. The modified Neuber relation in the cyclic form was used to predict the strains at the notch roots. Reasonably close agreement between the predicted and the measured load-strain loops was found for all three levels of constraint.

Evaluation of a Modified Monotonic Neuber Relation

1991 ◽  
Vol 113 (1) ◽  
pp. 1-8 ◽  
Author(s):  
W. N. Sharpe ◽  
K. C. Wang
Keyword(s):  
Plane Strain ◽  
Notch Root ◽  
Strain Curve ◽  
Uniaxial Stress ◽  
Predictive Capability ◽  
Stress Strain Curve ◽  
Interferometric Technique ◽  
Strain Stress ◽  
Concentration Factors ◽  
Elastoplastic Strains

It has been proposed in the literature that the Neuber relation be modified to read Kε/Kt×(Kσ/Kt)m=1 in order to improve its predictive capability when plane strain loading conditions exist. Kε, Kσ, and Kt are respectively the strain, stress, and elastic concentration factors. The exponent m is proposed to be 1 for plane stress and 0 for plane strain. This paper reports the results of biaxial notch root strain measurements on three sets of double-notched aluminum specimens that have different thicknesses and root radiuses. Elastoplastic strains are measured over gage lengths as short as 150 micrometers with a laser-based in-plane interferometric technique. The measured strains are used to compute Kε directly and Kσ using the uniaxial stress-strain curve. The exponent m can then be determined for each amount of constraint. The amount of constraint is defined as the negative ratio of lateral to longitudinal strain at the notch root and determined from elastic finite element analyses. As this ratio decreases for the three cases, the values of m are found to be 0.65, 0.48, and 0.36. The modified Neuber relation is an improvement, but discrepancies still exist when plastic yielding begins at the notch root.

An asymptotic model of two-dimensional convection in the limit of low Prandtl number

1981 ◽  
Vol 102 ◽  
pp. 75-83 ◽  
Author(s):  
F. H. Busse ◽  
R. M. Clever
Keyword(s):  
Nusselt Number ◽  
Prandtl Number ◽  
Buoyancy Force ◽  
Close Agreement ◽  
Preceding Paper ◽  
Critical Value ◽  
Temperature Fields ◽  
Asymptotic Model ◽  
Two Dimensional ◽  
Velocity And Temperature Fields

An approximate solution of two-dimensional convection in the limit of low Prandtl number is presented in which the buoyancy force is balanced by the inertial terms. The results indicate that inertial convection becomes possible when the Rayleigh number exceeds a critical value of about 7 × 103. Beyond this value the velocity and temperature fields become independent of the Prandtl number except in thin boundary layers. The convective heat transport approaches the law Nu = 0·175 R¼ for the Nusselt number Nu. These results are in reasonably close agreement with the numerical results described in the preceding paper by Clever & Busse (1980).

Benchmark Cyclic Plastic Notch Strain Measurements

1983 ◽  
Vol 105 (4) ◽  
pp. 235-241 ◽  
Author(s):  
William N. Sharpe ◽  
Michael Ward
Keyword(s):  
Test Section ◽  
Notch Root ◽  
Axial Loading ◽  
Plastic Strains ◽  
Computational Approaches ◽  
Strain Measurements ◽  
Notched Specimens ◽  
Benchmark Data ◽  
Load Spectra ◽  
Further Development

Plastic strains at the roots of notched specimens of Inconel 718 subjected to tension-compression cycling at 650°C are reported. These strains were measured with a laser-based technique over a gage length of 0.1 mm and are intended to serve as “benchmark” data for further development of experimental, analytical, and computational approaches. The specimens were 250 mm by 2.5 mm in the test section with double notches of 4.9 mm radius subjected to axial loading sufficient to cause yielding at the notch root on the tensile portion of the first cycle. The tests were run for 1000 cycles at 10 cpm or until cracks initiated at the notch root. The experimental techniques are described, and then representative data for the various load spectra are presented. All the data for each cycle of every test are available on floppy disks from NASA.

scholarly journals Biaxial Strain Measurements of JC on a (RE)BCO Coated Conductor

2018 ◽  
Vol 28 (4) ◽  
pp. 1-5
Author(s):  
Jack R. Greenwood ◽  
Elizabeth Surrey ◽  
Damian P. Hampshire
Keyword(s):  
Coated Conductor ◽  
Biaxial Strain ◽  
Strain Measurements

Air-to-Air Missile Airframe Captive Flight Vibro-Acoustic Environment

1990 ◽  
Vol 33 (4) ◽  
pp. 44-52
Author(s):  
Stanley Poynor
Keyword(s):  
Close Agreement ◽  
Flight Tests ◽  
Acoustic Environment ◽  
Strain Measurements ◽  
Test Article

Ground simulation and captive flight tests were conducted on an air-to-air missile airframe. Both internal carriage, at subsonic and transonic speeds (0.7 <M≪1.0), and conformal carriage, at supersonic speeds (M≪1.8), were tested for the missile/FB-111 combination. Twenty-three vibro-acoustic and 27 strain measurements were made at six locations on the test article. The tests were performed to demonstrate flight worthiness of the airframe technology and compatibility of the missile with the aircraft. Comparison of responses measured in flight with predicted captive environments showed close agreement.

Poly(Dimethylsiloxane) Elastomers from Aqueous Emulsions: II. Mechanical Properties

1998 ◽  
Vol 71 (5) ◽  
pp. 928-940 ◽  
Author(s):  
J. E. Mark ◽  
D. W. McCarthy
Keyword(s):  
Mechanical Properties ◽  
Uniaxial Extension ◽  
Preceding Paper ◽  
Aqueous Environment ◽  
Strain Measurements ◽  
Tin Catalyst ◽  
Equilibrium Swelling ◽  
Crosslinker Concentration ◽  
Reinforcing Effects ◽  
State Increase

Abstract Stress—strain measurements in simple uniaxial extension were used to characterize the mechanical properties of the elastomers prepared from poly(dimethylsilxoxane) emulsions as described in the preceding paper. The studies were carried out on the materials in the unswollen state, after they had received different treatments, specifically no aging, aging in the dry state, or aging in the wet (emulsion) state. Increase in silane crosslinker concentration was found to increase nominal stresses and moduli but to decrease extensibility, two changes that parallel the observed decreases in soluble polymer fractions and extents of equilibrium swelling reported earlier. The energy for rupture (“toughness”) frequently stays roughly constant because the decreased extensibility at least partially offsets the increased stresses. The changes in mechanical properties are due both to increased crosslinking and to reinforcing effects from silica generated from the silane, with the latter effect generally being the more important. The mechanical properties are much more affected by aging in the wet state, as opposed to aging in the dry state. For example, wet-aged elastomers generally had values of the nominal stress and modulus that were consistently lower than those for the unaged elastomers. Wet aging appears to be the result of the continual breaking and reforming of siloxane bonds in the aqueous environment of the emulsion, as probably accelerated by the presence of the tin catalyst.

scholarly journals Intra-Operative Video-Based Measurement of Biaxial Strains of the Ascending Thoracic Aorta

Biomedicines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 670
Author(s):  
Shaiv Parikh ◽  
Berta Ganizada ◽  
Gijs Debeij ◽  
Ehsan Natour ◽  
Jos Maessen ◽  
...  
Keyword(s):  
Thoracic Aorta ◽  
Longitudinal Strain ◽  
Circumferential Strain ◽  
Biaxial Strain ◽  
Mechanistic Studies ◽  
Tissue Properties ◽  
Strain Measurements ◽  
Biaxial Deformation ◽  
Coefficients Of Variation ◽  
Deformation Measurements

Local biaxial deformation measurements are essential for the in-depth investigation of tissue properties and remodeling of the ascending thoracic aorta, particularly in aneurysm formation. Current clinical imaging modalities pose limitations around the resolution and tracking of anatomical markers. We evaluated a new intra-operative video-based method to assess local biaxial strains of the ascending thoracic aorta. In 30 patients undergoing open-chest surgery, we obtained repeated biaxial strain measurements, at low- and high-pressure conditions. Precision was very acceptable, with coefficients of variation for biaxial strains remaining below 20%. With our four-marker arrangement, we were able to detect significant local differences in the longitudinal strain as well as in circumferential strain. Overall, the magnitude of strains we obtained (range: 0.02–0.05) was in line with previous reports using other modalities. The proposed method enables the assessment of local aortic biaxial strains and may enable new, clinically informed mechanistic studies using biomechanical modeling as well as mechanobiological profiling.

New Dimensions in Freeze-Etching

1969 ◽  
Vol 27 ◽  
pp. 202-203 ◽  
Author(s):  
Russell L. Steere ◽  
Michael Moseley
Keyword(s):  
Fracture Surfaces ◽  
Aluminum Specimen ◽  
Specimen Holder ◽  
Freeze Etching ◽  
The Right

A redesigned specimen holder and cap have made possible the freeze-etching of both fracture surfaces of a frozen fractured specimen. In principal, the procedure involves freezing a specimen between two specimen holders (as shown in A, Fig. 1, and the left side of Fig. 2). The aluminum specimen holders and brass cap are constructed so that the upper specimen holder can be forced loose, turned over, and pressed down firmly against the specimen stage to a position represented by B, Fig. 1, and the right side of Fig. 2.

The quantitative comparison of experimental and simulated diffraction contrast images

1995 ◽  
Vol 53 ◽  
pp. 102-103
Author(s):  
Stuart McKernan
Keyword(s):  
Image Processing ◽  
Personal Computer ◽  
Close Agreement ◽  
Quantitative Comparison ◽  
Image Simulation ◽  
Computing Power ◽  
Diffraction Contrast ◽  
Simulated Images ◽  
Made In

For many years the concept of quantitative diffraction contrast experiments might have consisted of the determination of dislocation Burgers vectors using a g.b = 0 criterion from several different 2-beam images. Since the advent of the personal computer revolution, the available computing power for performing image-processing and image-simulation calculations is enormous and ubiquitous. Several programs now exist to perform simulations of diffraction contrast images using various approximations. The most common approximations are the use of only 2-beams or a single systematic row to calculate the image contrast, or calculating the image using a column approximation. The increasing amount of literature showing comparisons of experimental and simulated images shows that it is possible to obtain very close agreement between the two images; although the choice of parameters used, and the assumptions made, in performing the calculation must be properly dealt with. The simulation of the images of defects in materials has, in many cases, therefore become a tractable problem.

A Simple Method for the Evaluation of Internal Doses in Nuclear Medicine

1974 ◽  
Vol 13 (02) ◽  
pp. 193-206
Author(s):  
L. Conte ◽  
L. Mombelli ◽  
A. Vanoli
Keyword(s):  
Nuclear Medicine ◽  
Close Agreement ◽  
Whole Body ◽  
Simple Method ◽  
Rapid Estimation ◽  
Absorbed Doses ◽  
The Mean ◽  
The Individual ◽  
Estimation Of Risk

SummaryWe have put forward a method to be used in the field of nuclear medicine, for calculating internally absorbed doses in patients. The simplicity and flexibility of this method allow one to make a rapid estimation of risk both to the individual and to the population. In order to calculate the absorbed doses we based our procedure on the concept of the mean absorbed fraction, taking into account anatomical and functional variability which is highly important in the calculation of internal doses in children. With this aim in mind we prepared tables which take into consideration anatomical differences and which permit the calculation of the mean absorbed doses in the whole body, in the organs accumulating radioactivity, in the gonads and in the marrow; all this for those radionuclides most widely used in nuclear medicine. By comparing our results with dose obtained from the use of M.I.R.D.'s method it can be seen that when the errors inherent in these types of calculation are taken into account, the results of both methods are in close agreement.

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