Lode Dependences for Isotropic Pressure-Sensitive Elastoplastic Materials

1990 ◽  
Vol 57 (3) ◽  
pp. 498-506 ◽  
Author(s):  
J. P. Bardet
Keyword(s):  
Experimental Investigations ◽  
Present Communication ◽  
Modified Model ◽  
True Triaxial ◽  
The Third ◽  
Pressure Sensitive ◽  
Isotropic Pressure ◽  
Elastoplastic Materials ◽  
Lode Angle ◽  
Stress Invariant

Experimental investigations indicate that the third stress invariant; Lode angle α affects significantly the behavior of pressure sensitive materials. The present communication presents a formulation to account for α in isotropic pressure-sensitive elastoplastic materials. Seven Lode dependences are reviewed. A new one, referred to as LMN, in proposed to generalize Lade and Duncan, and Matsuoka and Nakai failure surfaces. The formulation is general enough to introduce α into the isotropic elastoplastic modes which are only developed in terms of first and second-stress invariants. As an illustration, several Lode dependences are introduced into Roscoe and Burland model. The performance of the modified model is estimated by comparing experimental and analytical results in the case of true triaxial loadings on normally consolidated clay.

On the Development and Identification of Phenomenological Damage Models - Application to Industrial Wire Drawing and Rolling Processes

2013 ◽  
Vol 554-557 ◽  
pp. 213-226 ◽  
Author(s):  
Trong Son Cao ◽  
Christian Bobadilla ◽  
Pierre Montmitonnet ◽  
Pierre Olivier Bouchard
Keyword(s):  
Stress Tensor ◽  
Damage Model ◽  
Stress Triaxiality ◽  
Wire Drawing ◽  
Damage Models ◽  
The Third ◽  
Third Stress Invariant ◽  
Lode Angle ◽  
Stress Invariant ◽  
Angle Parameter

The continuum thermodynamics-based Lemaitre damage model is nowadays widely used to deal with coupled damage analyses for various mechanical applications (e.g. forming process simulations). However, such a model, which only accounts for the stress triaxiality (the ratio between the first and the second invariants of stress tensor) has been found to give incorrect results under shear dominated loading (in terms of damage location as well as risk of crack). Several recent studies have demonstrated the importance of the third stress invariant in damage prediction; the Lode angle parameter is generally used to include it. The idea is to describe completely the stress state in damage model’s formulations, which is defined by the equivalent stress, the stress triaxiality ratio and the Lode angle parameter. This later parameter has proved to have an important influence on ductile damage under low stress triaxiality. Xue’s coupled damage model accounts for the third invariant of the deviatoric stress tensor, allowing a better balance between respective effects of shear and elongation on damage. Some extensions of more physically based damage models, such as the Gurson-Tvergaard-Needleman model, have also been presented to account for this influence of the third stress invariant. In the present work, the phenomenological damage models have been implemented in Forge® Finite Element (FE) software to investigate ductile damage occurring during industrial forming processes. This paper presents the comparative study of Xue’s model and Lemaitre’s model. A complete procedure is detailed to identify the material and damage parameters from experimental mechanical tests on high carbon steel. This identification process has been carried out both for Lemaitre’s coupled damage model and Xue’s coupled damage model. Application to wire drawing followed by flat rolling shows that in such shear-inducing processes, these models predict damage at different locations, due to their different emphasis on shear with respect to elongational strain damage.

An Extension of Burzyński Hypothesis of Material Effort Accounting for the Third Invariant of Stress Tensor

2011 ◽  
Vol 56 (2) ◽  
pp. 503-508 ◽  
Author(s):  
R. Pęcherski ◽  
P. Szeptyński ◽  
M. Nowak
Keyword(s):  
Stress Tensor ◽  
Elastic Energy ◽  
Yield Condition ◽  
The Third ◽  
Third Invariant ◽  
Lode Angle

An Extension of Burzyński Hypothesis of Material Effort Accounting for the Third Invariant of Stress Tensor The aim of the paper is to propose an extension of the Burzyński hypothesis of material effort to account for the influence of the third invariant of stress tensor deviator. In the proposed formulation the contribution of the density of elastic energy of distortion in material effort is controlled by Lode angle. The resulted yield condition is analyzed and possible applications and comparison with the results known in the literature are discussed.

Dispersion Flow in Microchannels

2012 ◽  
Author(s):  
Alfir T. Akhmetov ◽  
Marat V. Mavletov ◽  
Sergey P. Sametov ◽  
Artur A. Rakhimov ◽  
Azat A. Valiev ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Effective Viscosity ◽  
Complex Structure ◽  
Experimental Investigations ◽  
Dispersed Phase ◽  
Rheological Characteristics ◽  
Dense Structure ◽  
The Third ◽  
Dynamic Blocking ◽  
Oil Emulsions

The work is devoted to experimental investigations of the features of flow of dispersions in microchannels. The paper consists of three parts. In the first part the flow of emulsions in smooth contracting cylindrical microchannels is investigated. It is received that a significant role at dynamic blocking of channels is played by the inclusions comparable by size to the diameter of a narrowing. This is in spite of the fact that their influence on the change of a flow rate of emulsion before blocking is insignificant. In the second part the generation of emulsion in a complex structure of microchannels (micromodels) when water is displaced by composition of hydrocarbon with surfactants is investigated. The experimental dependences of the rheological characteristics of emulsions based on the composition of SAS and water at different concentrations of the aqueous phase can explain blocking of a porous structure by generated emulsion. In the third part a comparison of flow of water-in-oil emulsions with the suspension which was obtained by freezing the microdroplets of the aqueous phase of emulsions was studied. It was found that the blocking of suspension is not as complete as in the case of emulsion. It is explained by deformation of the droplets and by formation of a dense structure, as opposed to suspension of beads, through which hydrocarbon phase is filtered. A small increase in effective viscosity due to solidification of freezing droplets of the dispersed phase was found.

Effect of Longitudinal Bulkheads on Damage Stability of Model RO/RO Ferries

2003 ◽  
Vol 40 (01) ◽  
pp. 20-24
Author(s):  
Carl T. F. Ross ◽  
Ioannis Mourtos ◽  
George Papanikolaou
Keyword(s):  
Second World War ◽  
Motor Vehicles ◽  
Scale Model ◽  
Experimental Investigations ◽  
Free Enterprise ◽  
Modified Model ◽  
Damage Stability ◽  
History Of ◽  
Transverse Damage ◽  
Second World

The paper reports on experimental investigations which have been made on three model RO/RO ferries. One of these was based on a 1/100th scale model of the Herald of Free Enterprise ferry. The other models were modified versions of the Herald of Free Enterprise which were so modified that they did not decrease the efficient concept of the throughput of a conventional vessel. One modified model had nine longitudinal compartments, while another had six longitudinal compartments; these vessels should meet SOLAS90+50 regulations. The RO/RO ferry models with nine and six compartments had considerably better damage stability characteristics than the conventional model. The experiments were carried out on all models without the consideration of waves and wind. Small weights were placed on the model ferries, to represent motor vehicles, and water was added on the car deck. Measurements of the resulting heel angles were taken. All results were plotted on graphs and they were compared and discussed. The effect of cargo shift on the transverse damage stability of these vessels was found to be significant. The paper also contains a brief history of a few very important RO/RO ferry accidents that have taken place since the end of the Second World War.

Thermoviscoplasticity Theory Incorporating the Third Deviatoric Stress Invariant

2015 ◽  
Vol 51 (1) ◽  
pp. 85-91 ◽  
Author(s):  
M. E. Babeshko ◽  
Yu. N. Shevchenko ◽  
N. N. Tormakhov
Keyword(s):  
Deviatoric Stress ◽  
The Third ◽  
Stress Invariant

scholarly journals The thermal and electrical conductivity of a single crystal of aluminium

1927 ◽  
Vol 115 (770) ◽  
pp. 236-241 ◽  
Keyword(s):  
Electrical Conductivity ◽  
Single Crystals ◽  
Test Specimen ◽  
Average Diameter ◽  
National Physical Laboratory ◽  
Present Communication ◽  
Uniform Size ◽  
The Third ◽  
Physical Laboratory

The recent work of Carpenter and Elam on the growth of single crystals of large dimensions has rendered possible the study of the physical constants of single crystals of the commoner metals, and the present communication describes the determination of the thermal and electrical conductivity of aluminium in the form of an isolated crystal. The form of the crystal investigated is shown in fig. 1. This crystal had been prepared at the National Physical Laboratory employing the technique described by Carpenter in “Nature,” p. 266, August 21, 1926, which briefly is as follows:— The test specimen is machined and subjected to three treatments, thermal, mechanical, and thermal. The first treatment is necessary to soften the metal completely and produce new equiaxed crystals of so far as possible uniform size, the average diameter being 1/150 inch. The second consists in straining these crystals to the required amount, and the third in heating the strained crystals to the requisite temperature, so that the potentiality of growth conferred by strain could be brought fully into operation.

Nonlinear Optics of Linear Conjugated Polymers

1992 ◽  
Vol 247 ◽  
Author(s):  
D. Guo ◽  
S. Mazumdar ◽  
G. I. Stegeman ◽  
M. Cha ◽  
D. Neher ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Dipole Moments ◽  
Harmonic Signal ◽  
Oscillator Strengths ◽  
Experimental Investigations ◽  
Transition Dipole ◽  
Third Harmonic ◽  
The Third ◽  
Transition Dipole Moments ◽  
Spectral Ranges

The third order nonlinear optical properties of conjugated polymers have been considered promising since the 1970s when Sauteret et al reported large non-resonant values in PTS.[1] Although it is well-understood that the physical origin of the nonlinearities is due to the delocalization of the π-electrons, the details, and how best to calculate them have been the focus of a continuing theoretical dialogue. Until recently, experimental investigations of nonlinearities have been limited to only a few wavelengths. Now third harmonic generation (THG), which accesses only the electronic nonlinearities, can be performed over wide spectral ranges, for example from 500 to 2000 nm. The resulting third harmonic wavelength typically spans the electronic molecular transitions associated with the nonlinearities. By measuring the spectral distribution of both the amplitude and phase of the third harmonic signal, the dominant transitions (between the“essential states”) contributing to the nonlinearity can be identified. Such information is most useful for comparing with theories in which the oscillator strengths (transition dipole moments) for the various molecular transitions are calculated.

Etude du parasitisme des simulies (Diptera : Simuliidae) par des Mermithidae (Nematoda) en Afrique de l'ouest. IV : Description de Isomermis lairdi, n.sp., parasite de Simulium damnosum

1977 ◽  
Vol 55 (12) ◽  
pp. 2011-2017 ◽  
Author(s):  
B. Mondet ◽  
G. O. Poinar Jr. ◽  
J. Bernadou
Keyword(s):  
New Species ◽  
West Africa ◽  
Ivory Coast ◽  
Present Communication ◽  
Body Width ◽  
Spicule Length ◽  
The Third ◽  
Simulium Damnosum ◽  
Mermithid Nematode ◽  
A New Species

The present communication describes a new species of mermithid nematode, Isomermis lairdi, found parasitizing blackflies in the Ivory Coast, West Africa. This nematode is the most common mermithid parasite of Simulium damnosum Theobald and occurs in the larval, pupal, and adult stages of this blackfly in streams of various sizes. The diagnostic characters of the adults of I. lairdi are (1) terminal mouth. (2) strongly S-shaped vagina, (3) ratio of spicule length to anal body width (1.7–2.8), and (4) circular amphids and amphidial openings.The postparasitic juveniles of I. lairdi differ from those of I. tansaniensis Rubtsov, 1972, in having three or four rows of cells in the lateral cords and a longer tail appendage in the male.This is the third species of mermithid nematode described from blackflies (including Simulium damnosum) in West Africa, and the first of the genus.

Experimental Investigations Concerning Erosive Aggressiveness of Cavitation at Different Test Configurations

Volume 3 ◽  
2004 ◽  
Author(s):  
B. Bachert ◽  
M. Dular ◽  
S. Baumgarten ◽  
G. Ludwig ◽  
B. Stoffel
Keyword(s):  
Mass Loss ◽  
Cavitation Erosion ◽  
Evaluation Method ◽  
Experimental Investigations ◽  
Cavitating Flows ◽  
Test Rig ◽  
The Third ◽  
Long Duration ◽  
Initial Stage ◽  
Test Objects

The experimental results, which will be presented in this paper, demonstrate the significant influence of the flow velocity, respectively the rotational speed, on the erosive aggressiveness of cavitating flows. On two of the three investigated test objects, cavitation erosion can only be observed in the initial stage by the so-called pit-count evaluation method. Developed erosion with mass loss is impossible to measure because of the very long duration until mass loss appears. The third test rig generates a very aggressive type of cavitation, so that mass loss, depending on the tested material, will appear after relatively short durations. In addition, the initial stage of cavitation erosion can be observed. Three different techniques were applied to investigate cavitation erosion in the initial and developed stage. Thereby, the capability of methods to quantify erosive effects in dependence of influencing operating parameters has been proven.

scholarly journals V.—On Linnarsson's Recent Discoveries in Swedish Geology

1880 ◽  
Vol 7 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Chas. Lapworth
Keyword(s):  
Geological Survey ◽  
Present Communication ◽  
The Third

In the present communication I propose to direct the attention of British Geologists to three most valuable memoirs recently published by Mr. G. Linnarsson, the eminent palæontologist of the Geological Survey of Sweden; and at the same time to point out, as briefly as may be, what appears to me to be their special bearing upon certain tentative or disputed points in British Geology. They treat of subjects of great interest to the student of the palæontogeology of the Lower Palæeozoic or Proterozoic Rocks; but are printed in the Swedish language, with which, unfortunately, few amongst us are familiar. The first two papers deal with the Graptolite-bearing rocks of Sweden; the third treats of the peculiar fauna of a recently-detected horizon in the prolific Paradoxidian or Primordial Zone.

Sign in / Sign up

Export Citation Format

Share Document