Thermodynamically Consistent Anisotropic Plasticity Model

Volume 2: Integrity Management; Poster Session; Student Paper Competition ◽

10.1115/ipc2006-10398 ◽

2006 ◽

Cited By ~ 7

Author(s):

Alexander A. Lukyanov

Keyword(s):

Stress Tensor ◽

Material Properties ◽

Main Role ◽

Plasticity Model ◽

Anisotropic Plasticity ◽

Future Studies ◽

Hill Criterion ◽

Kronecker Delta ◽

Elasto Plasticity ◽

Deviatoric Part

The objective of the work presented in this paper is to consider the thermodynamically consistent anisotropic plasticity model based on full decomposition of stress tensor into generalised deviatoric part and generalised spherical part of stress tensor. Two fundamental tensors αij and βij which represents anisotropic material properties are defined and can be considered as generalisations of the Kronecker delta symbol which plays the main role in the theory of isotropic materials. Using two fundamental tensors, αij and βij, the concept of total generalised “pressure” and pressure corresponding to the volumetric deformation are redefined. It is shown that the formulation of anisotropic plasticity in the case of incompressible plastic flow must be considered independently from the generalised hydrostatic “pressure”. Accordingly, a modification to the anisotropic Hill criterion is introduced. Based on experimental research which has been published, the modified Hill (1948, 1950) criterion for anisotropic elasto-plasticity is validated. The results are presented, discussed and future studies are outlined.

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Anisotropic Materials Behavior Modeling Under Shock Loading

Journal of Applied Mechanics ◽

10.1115/1.3130447 ◽

2009 ◽

Vol 76 (6) ◽

Cited By ~ 4

Author(s):

Alexander A. Lukyanov

Keyword(s):

Equation Of State ◽

Stress Tensor ◽

Shock Loading ◽

Yield Function ◽

Anisotropic Materials ◽

Behavior Modeling ◽

Plasticity Model ◽

Anisotropic Plasticity ◽

Pressure Sensitive ◽

Materials Behavior

In this paper, the thermodynamically and mathematically consistent modeling of anisotropic materials under shock loading is considered. The equation of state used represents the mathematical and physical generalizations of the classical Mie–Grüneisen equation of state for isotropic material and reduces to the Mie–Grüneisen equation of state in the limit of isotropy. Based on the full decomposition of the stress tensor into the generalized deviatoric part and the generalized spherical part of the stress tensor (Lukyanov, A. A., 2006, “Thermodynamically Consistent Anisotropic Plasticity Model,” Proceedings of IPC 2006, ASME, New York; 2008, “Constitutive Behaviour of Anisotropic Materials Under Shock Loading,” Int. J. Plast., 24, pp. 140–167), a nonassociated incompressible anisotropic plasticity model based on a generalized “pressure” sensitive yield function and depending on generalized deviatoric stress tensor is proposed for the anisotropic materials behavior modeling under shock loading. The significance of the proposed model includes also the distortion of the yield function shape in tension, compression, and in different principal directions of anisotropy (e.g., 0 deg and 90 deg), which can be used to describe the anisotropic strength differential effect. The proposed anisotropic elastoplastic model is validated against experimental research, which has been published by Spitzig and Richmond (“The Effect of Pressure on the Flow Stress of Metals,” Acta Metall., 32, pp. 457–463), Lademo et al. (“An Evaluation of Yield Criteria and Flow Rules for Aluminium Alloys,” Int. J. Plast., 15(2), pp. 191–208), and Stoughton and Yoon (“A Pressure-Sensitive Yield Criterion Under a Non-Associated Flow Rule for Sheet Metal Forming,” Int. J. Plast., 20(4–5), pp. 705–731). The behavior of aluminum alloy AA7010 T6 under shock loading conditions is also considered. A comparison of numerical simulations with existing experimental data shows good agreement with the general pulse shape, Hugoniot elastic limits, and Hugoniot stress levels, and suggests that the constitutive equations perform satisfactorily. The results are presented and discussed, and future studies are outlined.

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Mesophyll conductance: the leaf corridors for photosynthesis

Biochemical Society Transactions ◽

10.1042/bst20190312 ◽

2020 ◽

Vol 48 (2) ◽

pp. 429-439 ◽

Cited By ~ 3

Author(s):

Jorge Gago ◽

Danilo M. Daloso ◽

Marc Carriquí ◽

Miquel Nadal ◽

Melanie Morales ◽

...

Keyword(s):

Molecular Mechanisms ◽

Current Knowledge ◽

Main Role ◽

Mesophyll Conductance ◽

Future Studies ◽

Cell Structures ◽

Leaf Tissues ◽

Change Framework ◽

Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

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