Sensitivity analysis of a non‐local, gradient enhanced damage model

PAMM ◽  
2018 ◽  
Vol 18 (1) ◽  
Author(s):  
Fabian Guhr ◽  
Franz‐Joseph Barthold ◽  
Andreas Menzel ◽  
Leon Sprave ◽  
Jan Liedmann
Keyword(s):  
Sensitivity Analysis ◽  
Damage Model ◽  
Non Local ◽  
Local Gradient

A gradient-enhanced damage model coupled to plasticity—multi-surface formulation and algorithmic concepts

2017 ◽  
Vol 27 (2) ◽  
pp. 253-295 ◽  
Author(s):  
Bjoern Kiefer ◽  
Tobias Waffenschmidt ◽  
Leon Sprave ◽  
Andreas Menzel
Keyword(s):  
Damage Model ◽  
Surface Damage ◽  
Field Equations ◽  
Damage State ◽  
Gauss Point ◽  
Internal Damage ◽  
Penalty Term ◽  
Non Local ◽  
Local Gradient ◽  
Gradient Enhancement

A non-local gradient-enhanced damage-plasticity formulation is proposed, which prevents the loss of well-posedness of the governing field equations in the post-critical damage regime. The non-locality of the formulation then manifests itself in terms of a non-local free energy contribution that penalizes the occurrence of damage gradients. A second penalty term is introduced to force the global damage field to coincide with the internal damage state variable at the Gauss point level. An enforcement of Karush–Kuhn–Tucker conditions on the global level can thus be avoided and classical local damage models may directly be incorporated and equipped with a non-local gradient enhancement. An important part of the present work is to investigate the efficiency and robustness of different algorithmic schemes to locally enforce the Karush–Kuhn–Tucker conditions in the multi-surface damage-plasticity setting. Response simulations for representative inhomogeneous boundary value problems are studied to assess the effectiveness of the gradient enhancement regarding stability and mesh objectivity.

Local and non-local damage model with extended stress decomposition for concrete

2021 ◽  
pp. 105678952199872
Author(s):  
Bilal Ahmed ◽  
George Z Voyiadjis ◽  
Taehyo Park
Keyword(s):  
Shear Stress ◽  
Degrees Of Freedom ◽  
Biaxial Loading ◽  
Damage Model ◽  
Local Model ◽  
Uniaxial Tensile ◽  
Gradient Theory ◽  
Principal Stresses ◽  
Stress Decomposition ◽  
Non Local

In this work, a new damage model for concrete is proposed with an extension of the stress decomposition (limited to biaxial cases), to capture shear damage due to the opposite signed principal stresses. To extract the pure shear stress, the assumption is made that one component of the shear stress is a minimum absolute of the two principal stresses. The opposite signed principal stresses are decomposed into shear stress and uniaxial tensile/compressive stress. A local model is implemented in Abaqus UMAT and it is further extended to a non-local model by utilization of the gradient theory. The concept of three length scales (tension, compression, and shear) is kept the same as the recently proposed nonlocal damage model by the authors. The nonlocal model is implemented in the Abaqus UEL-UMAT subroutine with an eight-node quadrilateral user-defined element, having five degrees of freedom at corner nodes (displacement in X/Y direction and tensile/compressive and shear nonlocal equivalent strain) and two degrees of freedom at internal nodes. Some examples of a local model including uniaxial and biaxial loading are addressed. Also, five examples of mixed crack mode and mode-I cracking are presented to comprehensively show the performance of this model.

Uncertainty and sensitivity analysis for natural risk and adaptation appraisal modeling with CLIMADA

2021 ◽  
Author(s):  
Chahan M. Kropf ◽  
Alessio Ciullo ◽  
Simona Meiler ◽  
Laura Otth ◽  
Jamie W. McCaughey ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Green Infrastructure ◽  
Climate Adaptation ◽  
Damage Model ◽  
Adaptation Measures ◽  
Natural Risk ◽  
Impact Function ◽  
Uncertainty And Sensitivity Analysis ◽  
Global Uncertainty ◽  
The Impact

<p>Modelling societal, ecological, and economic costs of natural hazards in the context of climate change is subject to both strong aleatoric and ethical uncertainty. Dealing with these is challenging on several levels – from the identification and the quantification of the sources of uncertainty to their proper inclusion in the modelling, and the communication of these in a tangible way to both experts and non-experts. One particularly useful approach is global uncertainty and sensitivity analysis, which can help to quantify the confidence in the output values and identify the main drivers of the uncertainty while considering potential correlations in the model. Here we present applications of global uncertainty analysis, robustness quantification, and sensitivity analysis in natural hazard modelling using the new uncertainty module of the CLIMADA (CLIMate ADAptation) platform.</p><p>CLIMADA is a fully open-source Python program that implements a probabilistic multi-hazard global natural catastrophe damage model, which also calculates averted damage (benefit) thanks to adaptation measures of any kind (from grey to green infrastructure, behavioral, etc.). With the new uncertainty module, one can directly and comprehensively inspect the uncertainty and sensitivity to input variables of various output metrics, such as the spatial distribution of risk exceedance probabilities, or the benefit-cost ratios of different adaptation measures. This global approach does reveal interesting parameter interplays and might provide valuable input for decision-makers. For instance, a study of the geospatial distribution of sensitivity indices for tropical cyclones damage indicated that the main driver of uncertainty in dense regions (e.g. cities) is the impact function (vulnerability), whereas in sparse regions it is the exposure (asset) layer. </p><p>CLIMADA: https://github.com/CLIMADA-project/climada_python </p><p>(1) Aznar-Siguan, G. et al., GEOSCI MODEL DEV. 12, 7 (2019) 3085–97<br>(2) Bresch, D. N. and Aznar-Siguan., G.,  GEOSCI MODEL DEV. (2020), 1–20.</p>

Strongly non-local gradient-enhanced finite strain elastoplasticity

2003 ◽  
Vol 56 (14) ◽  
pp. 2039-2068 ◽  
Author(s):  
M. G. D. Geers ◽  
R. L. J. M. Ubachs ◽  
R. A. B. Engelen
Keyword(s):  
Finite Strain ◽  
Non Local ◽  
Local Gradient

Interaction-based non-local damage model for failure in quasi-brittle materials

2013 ◽  
Vol 54 ◽  
pp. 56-62 ◽  
Author(s):  
Laura B. Rojas-Solano ◽  
David Grégoire ◽  
Gilles Pijaudier-Cabot
Keyword(s):  
Damage Model ◽  
Brittle Materials ◽  
Local Damage ◽  
Non Local
Sign in / Sign up

Export Citation Format

Share Document