Crack layer model for semi-elliptical surface cracks in HDPE pipes and application in buried pipes with complicated loading conditions

Crack layer model provides a comprehensive foundation for modeling of fracture growth, failure analysis, and lifetime prediction. During the past two decades, it has been widely applied for modeling various aspects of brittle fracture in general. This paper illustrates in details the procedure of implementation by an example of slow crack growth in a commercialized high-density polyethylene undergoing creep conditions. Firstly, we determine experimentally the basic parameters employed in constitutive equations of crack layer model such as draw ratio λ, the specific energy of transformation γtr, and drawing stress σdr, etc.. Secondly, we implement crack layer model numerically in lab-developed “Simulator”. The paper provides a paradigm for implementation of crack layer model in slow crack growth, and a blueprint for potential software development that can be used in ranking and the lifetime assessment of a large set of engineering polymers.

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Fracture capacity of girth welded pipelines with 3D surface cracks subjected to biaxial loading conditions

International Journal of Pressure Vessels and Piping ◽

10.1016/j.ijpvp.2011.10.019 ◽

2012 ◽

Vol 92 ◽

pp. 115-126 ◽

Cited By ~ 25

Author(s):

Yi Dake ◽

Idapalapati Sridhar ◽

Xiao Zhongmin ◽

Shashi Bhushan Kumar

Keyword(s):

Biaxial Loading ◽

Surface Cracks ◽

Loading Conditions ◽

3D Surface

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Development and Application of Slow Crack Propagation of Polyethylene Based on Crack Layer Theory

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.345-346.489 ◽

2007 ◽

Vol 345-346 ◽

pp. 489-492 ◽

Cited By ~ 1

Author(s):

Byoung Ho Choi ◽

Alexander Chudnovsky

Keyword(s):

Numerical Simulation ◽

Crack Propagation ◽

Crack Growth ◽

Driving Forces ◽

Slow Crack Growth ◽

Layer Model ◽

Elapsed Time ◽

Simulation Based ◽

Crack Layer

For explaining the SCG behavior of polyethylene, the crack layer theory is applied based on the description of two driving forces: crack and PZ. The relations between the speed of SCG, crack length and elapsed time are the most important characteristics of polyethylene resistance to crack propagation, or long-term brittle fracture. The crack layer model of slow crack growth in polyethylene is designed in such a way that it qualitatively reproduces the main features of the process indicated above and makes it possible to quantitatively match any pattern of step-wise crack growth. In this paper, the behavior of SCG of polyethylene is developed for numerical simulation based on the crack layer theory. Some parametric study and applications are addressed based on the developed simulation program.

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Local Approach of Ductile Rupture Under Cyclic Loading Conditions

Journal of Pressure Vessel Technology ◽

10.1115/1.4053162 ◽

2021 ◽

Author(s):

Remmal Almahdi ◽

Stephane Marie

Keyword(s):

Cyclic Loading ◽

Limit Analysis ◽

Classical Model ◽

Ductile Failure ◽

Loading Conditions ◽

Layer Model ◽

Local Approach ◽

Number Of Cycles ◽

Definition Of ◽

Ductile Behavior

Abstract Experiments have shown that ductile failure occurs sooner under cyclic loading conditions than under monotone ones. This reduction of ductility probably arises from an effect called "ratcheting of the porosity" that consists of a continued increase of the mean porosity during each cycle with the number of cycles. Improved micromechanical simulations confirmed this interpretation. The same work also contained a proof that Gurson's classical model for porous ductile materials does not predict any ratcheting of the porosity. In a recent work [6], the authors proposed a Gurson-type "layer model" better fit than Gurson's original one for the description of the ductile behavior under cyclic loading conditions, using the theory of sequential limit analysis. A very good agreement was obtained between the model predictions and the results of the micromechanical simulations for a rigid-hardenable material. However, the ratcheting of the porosity is a consequence of both hardening and elasticity, and sequential limit analysis [14, 15] is strictly applicable in the absence of elasticity. In this work, a proposal is made to take into account elasticity in the layer model through the definition of a new objective stress rate leading to an accurate expression of the porosity rate accounting for both elasticity and plasticity. This proposal is assessed through comparison of its predictions with the results of some new micromechanical simulations performed for matrices exhibiting both elasticity and all types of hardening. Finally, a comparison of the predictions regarding finite element modeling of pipes loaded cyclically is proposed.

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Experimental Determination of the Ratcheting of the Porosity for the Study of Ductile Rupture Under Cyclic Loading Conditions

Volume 5: High-Pressure Technology; Rudy Scavuzzo Student Paper Symposium and 27th Annual Student Paper Competition; ASME Nondestructive Evaluation, Diagnosis and Prognosis Division (NDPD) ◽

10.1115/pvp2019-93831 ◽

2019 ◽

Author(s):

Al Mahdi Remmal ◽

Stéphane Marie ◽

Jean-Baptiste Leblond

Keyword(s):

Cyclic Loading ◽

Theoretical Work ◽

Model Material ◽

Experimental Program ◽

Loading Conditions ◽

Layer Model ◽

New Model ◽

Number Of Cycles ◽

Ductile Behavior ◽

Center Section

Abstract It is known that for ductile porous materials, cyclic loadings lead to lower fracture strains than monotone ones. This reduction of ductility probably arises from an effect called “ratcheting of the porosity” that consists of a continued increase of the mean porosity during each cycle with the number of cycles. Finite element based micromechanical simulations confirmed this interpretation. Recently the authors proposed a Gurson-type “layer model” better fit that Gurson’s original one which does not predict the ratcheting of the porosity, for the description of the ductile behavior under cyclic loading conditions. A very good agreement was obtained between the results of the micromechanical simulations and the model predictions for a rigid-hardenable material. Yet, the ratcheting of the porosity is a consequence of both hardening and elasticity; and the theory of sequential limit analysis used in order to get the “layer model” is strictly applicable in the absence of elasticity. Based on an expression of the porosity rate accounting for elasticity, a proposal was made to improve the new model with regard to elasticity. Simultaneously to this theoretical work, an experimental program was conducted on a model material in order to assess experimentally this new model. The material is a HIPed 316L stainless steel, with Al2O3 almost spherical inclusions acting like porosities, complying with the hypothesis made to derive the theoretical model. Notched tensile specimens, with a center section of 4mm, were cyclically loaded. Several tomographies were performed at ESRF, using a 120 keV beamline and 3x3 microns detector, in order to prove experimentally the ratcheting effect of the porosity. The void growth through the cycles is precisely described and the experimental results could then be processed and compared to the numerical porosities predictions of the model. This paper presents the experimental activity of this PhD program.

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The Anisotropic Homogenized Model for Pouch Type Lithium-ion Battery under Various Abuse Loadings

Journal of Electrochemical Energy Conversion and Storage ◽

10.1115/1.4049239 ◽

2020 ◽

pp. 1-19

Author(s):

Huacui Wang ◽

Xudong Duan ◽

Binghe Liu

Keyword(s):

Lithium Ion Battery ◽

Lithium Ion ◽

Loading Conditions ◽

Layer Model ◽

Calibration Methods ◽

Safety Design ◽

Width Direction ◽

Out Of Plane ◽

Length Direction ◽

Plane Compression

Abstract Pouch type lithium-ion battery (LIB) has now been widely used in electric vehicles, smartphones, computers and et al. Mechanical abuse is one of the main reasons to cause the safety issues for lithium-ion battery. The highly accurate and efficient computational model is helpful for the safety design, application and analysis of LIB. The previous homogenized mechanical models of the pouch LIB use different material parameters for various loading conditions. Herein, we establish an anisotropic homogenized method to predict the mechanical behavior in in-plane and out-of-plane directions simultaneously. Engineering constants and Hill's 48 criteria are used for the anisotropic properties, and bilinear plastic model is used as the hardening curve under large deformation. Based on this method, we established two homogenized models i.e. one-layer model and multi-layer model. Experiments in various loading conditions including 3-point bending (length direction and width direction), out-of-plane compression, and in-plane compression (length direction and width direction) are conducted for parameters calibration. The calibration methods are then discussed and confirmed through these experiments. The computational models show good correlation with experiments both in in-plane and out-of-plane directions. The difference is that the global buckling behavior can be predicted by both of the two models, while the local buckling can only be predicted by the multi-layer model. The results may shield light on the safety design, application and analysis for pouch LIB.

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New Model for Ductile Rupture Under Cyclic Loading Conditions

Volume 3: Design and Analysis ◽

10.1115/pvp2019-93836 ◽

2019 ◽

Author(s):

Al Mahdi Remmal ◽

Stéphane Marie ◽

Jean-Baptiste Leblond

Keyword(s):

Cyclic Loading ◽

Limit Analysis ◽

Classical Model ◽

Ductile Failure ◽

Loading Conditions ◽

Layer Model ◽

Accurate Expression ◽

Number Of Cycles ◽

Definition Of ◽

Ductile Behavior

Abstract Experiments have shown that ductile failure occurs sooner under cyclic loading conditions than under monotone ones. This reduction of ductility probably arises from an effect called “ratcheting of the porosity” that consists of a continued increase of the mean porosity during each cycle with the number of cycles. Improved micromechanical simulations confirmed this interpretation. The same work also contained a proof that Gurson’s classical model for porous ductile materials does not predict any ratcheting of the porosity. In a recent work [6], the authors proposed a Gurson-type “layer model” better fit than Gurson’s original one for the description of the ductile behavior under cyclic loading conditions, using the theory of sequential limit analysis. A very good agreement was obtained between the model predictions and the results of the micromechanical simulations for a rigid-hardenable material. However, the ratcheting of the porosity is a consequence of both hardening and elasticity, and sequential limit analysis is strictly applicable in the absence of elasticity. In this work, we make a proposal to take into account elasticity in the layer model through the definition of a new objective stress rate leading to an accurate expression of the porosity rate accounting for both elasticity and plasticity. This proposal is assessed through comparison of its predictions with the results of some new micromechanical simulations performed for matrices exhibiting both elasticity and all types of hardening: isotropic, kinematic and mixed, to better comply with the hypothesis made to derive the model.

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