scholarly journals Phenomenological model for transient deformation based on state variables

1980 ◽  
Author(s):  
M S Jackson ◽  
C W Cho ◽  
P Alexopoulos ◽  
H Mughrabi ◽  
C Y Li
Keyword(s):  
Phenomenological Model ◽  
State Variables ◽  
Transient Deformation

scholarly journals A Phenomenological Model for Transient Deformation Based on State Variables

1981 ◽  
Vol 103 (4) ◽  
pp. 314-325 ◽  
Author(s):  
M. S. Jackson ◽  
C. W. Cho ◽  
P. Alexopoulos ◽  
Che-Yu Li
Keyword(s):  
Phenomenological Model ◽  
General Structure ◽  
Complex Loading ◽  
Dislocation Motion ◽  
Deformation Model ◽  
State Variables ◽  
Transient Effects ◽  
Variable Theory ◽  
Transient Deformation ◽  
Deformation Properties

The state variable theory of Hart, while providing a unified description of plasticity-dominated deformation, exhibits deficiencies when it is applied to transient deformation phenomena at stresses below macroplastic yielding. It appears that the description of stored anelastic strain is oversimplified. Consideration of a simple physical picture based on continuum dislocation pileups suggests that the neglect of weak barriers to dislocation motion is the source of these inadequacies. An appropriately modified description incorporating such barriers allows the construction of a modified phenomenological model including transient effects. The applicability of the modified model to aluminum has been investigated at room temperature. A consistent set of parameters describing the mechanical properties of the material has been determined experimentally. Agreement between experiment and model predictions for fairly complex loading histories is good. Although the constitutive equations for microplastic flow could not be established unambiguously, the results indicate that the general structure of the transient deformation model represents the deformation properties well.

A Phenomenological Model for Shape Memory Alloys With Uniformly Distributed Porosity

2020 ◽  
Author(s):  
Wael Zaki ◽  
N. V. Viet
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Phenomenological Model ◽  
Free Energy Density ◽  
State Variables ◽  
Mapping Algorithm ◽  
Return Mapping ◽  
Return Mapping Algorithm ◽  
Generalized Standard Materials ◽  
Inelastic Strains

Abstract A phenomenological model is proposed for shape memory alloys considering the presence of uniformly distributed voids. The model is developed within a modified generalized standard materials framework, which considers the presence of constraints on the state variables and ensures thermodynamic consistency. Within this framework, a free energy density is first proposed for the porous material, wherein the influence of porosity is accounted for by means of scalar state variables accounting for damage and inelastic dilatation. By choosing key thermodynamic forces, derived from the expression of the energy, as sub-gradients of a pseud-potential of dissipation, loading functions are derived that govern phase transformation and martensite detwinning. Flow rules are also proposed for damage and inelastic dilatation in a way that ensures positive dissipation. The model is discretized and the integration of the time-discrete formulation is carried out using an implicit formulation, whereby a return mapping algorithm is implemented to calculate increments of dissipative variables including inelastic strains. Comparison with data from the literature is finally presented.

Air Solubility Measurements and Modeling of Brake Fluids

2019 ◽  
Author(s):  
Andreas Eisele ◽  
Simon Sagmeister ◽  
Michael Schneider ◽  
Markus Lienkamp
Keyword(s):  
Water Content ◽  
Phenomenological Model ◽  
Extensive Literature ◽  
Test Results ◽  
State Variables ◽  
Test Rig ◽  
Literature Research ◽  
Stationary Test ◽  
The Impact

Abstract This paper investigates the air solubility of hydraulic oils with specific application in polyglycol based brake fluids. An Extensive literature research revealed a lack of data on the thermodynamic solubility properties of brake fluids. A derivation of the searched quantities cannot be obtained from the values given for hydraulic oils because of the deviation in components. Absolute values and relations to state variables, such as temperatures, have not yet been stated. Therefore, this research aims to investigate these unknown correlations using empirical measurements. A test rig was designed for isobar absorption testing. The quasi-stationary test results confirm Henrys Law. Furthermore the solubility is presented as a function of temperature and water content and a phenomenological model of the Bunsen coefficient is derived. It is apparent that the impact of temperature is inverse to that of common fluids such as water or some alcohols.

Plasminogen Depletion during Streptokinase Treatment or Two-Chain Urokinase Incubation Correlates with Decreased Clot Lysability Ex Vivo and In Vitro

1993 ◽  
Vol 70 (06) ◽  
pp. 0998-1004 ◽  
Author(s):  
Páll T Önundarson ◽  
H Magnús Haraldsson ◽  
Lena Bergmann ◽  
Charles W Francis ◽  
Victor J Marder
Keyword(s):  
Myocardial Infarction ◽  
Ex Vivo ◽  
Time Dependent ◽  
State Variables ◽  
Thrombolytic Treatment ◽  
Direct Proportion ◽  
Plasmin Activity ◽  
Plasma Exposure ◽  
The Relationship

SummaryThe relationship between lytic state variables and ex vivo clot lysability was investigated in blood drawn from patients during streptokinase administration for acute myocardial infarction. A lytic state was already evident after 5 min of treatment and after 20 min the plasminogen concentration had decreased to 24%, antiplasmin to 7% and fibrinogen 0.2 g/1. Lysis of radiolabeled retracted clots in the patient plasmas decreased from 37 ± 8% after 5 min to 21 ± 8% at 10 min and was significantly lower (8 ± 9%, p <0.005) in samples drawn at 20, 40 and 80 min. Clot lysability correlated positively with the plasminogen concentration (r = 0.78, p = 0.003), but not with plasmin activity. Suspension of radiolabeled clots in normal plasma pre-exposed to 250 U/ml two-chain urokinase for varying time to induce an in vitro lytic state was also associated with decreasing clot lysability in direct proportion with the duration of prior plasma exposure to urokinase. The decreased lysability correlated with the time-dependent reduction in plasminogen concentration (r = 0.88, p <0.0005). Thus, clot lysability decreases in conjunction with the development of the lytic state and the associated plasminogen depletion. The lytic state may therefore limit reperfusion during thrombolytic treatment.

Phenomenological model of pulsed corona reactor

2007 ◽  
Vol 2 (Supplement 1) ◽  
pp. 19-30
Author(s):  
Miklós Horváth ◽  
Endre Kiss
Keyword(s):  
Phenomenological Model ◽  
Pulsed Corona

Regular perturbations to the motion of a three-wheeled mobile robot with the front-wheel drive under restricted state variables*

2020 ◽  
Author(s):  
Roman Chertovskih ◽  
Anna Daryina ◽  
Askhat Diveev ◽  
Dmitry Karamzin ◽  
Fernando L. Pereira ◽  
...  
Keyword(s):  
Mobile Robot ◽  
Front Wheel ◽  
Wheeled Mobile Robot ◽  
State Variables ◽  
Wheel Drive

Application of the System Nesting Technology for Studying the Invariance of a Complex Electric System Output in Terms of State Variables

2019 ◽  
Vol 2 (2) ◽  
pp. 26-32
Author(s):  
Kakhraman R. ALLAYEV ◽  
◽  
Akram M. MIRZABAYEV ◽  
Takhir F. MAKHMUDOV ◽  
Temur A. MAKHKAMOV ◽  
...  
Keyword(s):  
State Variables ◽  
Electric System ◽  
System Output
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