Viscoplastic Regularization of Local Damage Models: A Latent Solution

Niazi, Muaz A.; Wisselink, H.H.; Meinders, Vincent T.

doi:10.4028/www.scientific.net/kem.504-506.845

Cited by 8 publications

(5 citation statements)

References 6 publications

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“…The failure predictions were improved significantly and the strain localization length scale were obtained very accurately. Mesh independent damage distribution was obtained for the cross die drawing test without introducing any arbitrary regularization parameter [21]. It is worth mentioning that dual phase steel has a rate dependent hardening characteristics and the cross die drawing is carried out a punch velocity of 1 mm/s, which is normal punch speed in deep drawing process.…”

Section: Discussionmentioning

confidence: 99%

Viscoplastic regularization of local damage models: revisited

2012

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Local damage models are known to produce pathological mesh dependent results. Regularization techniques are therefore mandatory if local damage models are used for academic research or industrial applications. The viscoplastic framework can be used for regularization of local damage models. Despite of the easy implementation of viscoplasticity, this method of regularization did not gain much popularity in comparison to the non-local or gradient damage models. This work is an effort to further explore viscoplastic regularization for quasi-static problems. The focus of this work is on ductile materials. Two different types of strain rate hardening models i.e. the Power law (with a multiplicative strain rate part) and the simplified Bergström van Liempt (with an additive strain rate part) models are used in this study. The modified Lemaitre's anisotropic damage model with a strain rate dependency was used in this study. It was found that the primary viscoplastic length scale is a function of the hardening and softening (damage) parameters and does not depend upon the prescribed strain rate whereas the secondary length scale is a function of the strain rate. As damage grows, the effective regularization length gradually decreases. When the effective regularization length gets shorter than the element length numerical results become mesh dependent again. This loss of objectivity can not be solved but the effect can be minimized by selecting a very fine mesh or by prescribing high deformation velocities.

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Section: Discussionmentioning

confidence: 99%

Viscoplastic regularization of local damage models: revisited

2012

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“…Local continuum damage models are known to cause pathological mesh dependence in finite element simulations due to strain softening. 27 Various approaches were proposed to address mesh dependence. Rabczuk and Belytschko 28,29 proposed a novel approach for modeling discrete cracks in meshfree particle methods by using a local enrichment of the test and trial functions with a sign function to deal with the discontinuities at particles around the crack surface.…”

Section: Constitutive Model Formulationmentioning

confidence: 99%

“…Viscoplastic regularization was employed as an alternative approach by Niazi et al to address the issue of pathological mesh dependence. 27 One method for regularizing the mesh dependency of the local damage model is viscoplasticity, which involves introducing rate effects-a physical phenomenon-into the constitutive model. This technique was successfully used by Niazi et al with a local anisotropic damage model to predict failure in a cross die drawing process with the actual physical process parameters.…”

Section: Constitutive Model Formulationmentioning

confidence: 99%

Microscale and mesoscale modeling for compressive failure in unidirectional carbon fiber reinforced polymer composites with random distribution of fiber misalignments

Xie,

Ning

2024

Polymer Composites

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Compressive strength and failure mode of carbon fiber reinforced polymer (CFRP) composites are affected by the severity of fiber misalignment. In this paper, numerical models based on computational micromechanics are proposed to investigate the correlation between fiber misalignment and compression failure. A single‐fiber micromodel including fiber, matrix, and interface phases is first developed to capture the influence of misalignment severity on the material failure mode. The failure longitudinal stress distribution in the fiber predicted by the micromodel indicates that the failure mode depending on the initial misalignment can be identified as uniform compression failure, compression‐bending combination collapse, and fiber buckle. A mesoscale 2D model with multiple fibers is then constructed to investigate the kink band formation. This model takes into account the distribution of fiber misalignments to capture the key geometric features of fiber misalignment that influent the compression failure in realistic composite materials at the structural scale. The results show that fiber misalignment angle amplitude, misalignment dispersion (characterized by the standard deviation), and misalignment wavelength are the key parameters of fiber misalignment, which have significant effects on compression strength and kink band geometry.Highlights Single‐fiber model to capture the effect of misalignment severity on failure mode. Multi‐fiber model with randomly distributed fiber misalignments. Failure mode depending on the severity of initial misalignment was identified. Key parameters of misalignment on compression strength and kink band geometry.

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“…Several works, such as by Needleman , Sluys and De Borst , and Niazi et al . , showed that by including rate effects, the mesh dependence could be reduced significantly. A disadvantage is that this technique can only be applied to transient loading conditions .…”

Section: Materials Modelingmentioning

confidence: 99%

3D fluid–structure interaction analysis of a typical liquid rocket engine cycle based on a novel viscoplastic damage model

Kowollik

Tini

Reese

et al. 2013

Numerical Meth Engineering

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SUMMARYIn many space missions, expandable or reusable launch systems are used. In this context, the reliable design of liquid rocket engines (LREs) is a key issue. In the present paper, we present a novel combination of numerical schemes. It is applied to model the extreme physical phenomena a typical LRE undergoes during its loading cycles. The numerical scheme includes a partitioned fluid–structure interaction (FSI) algorithm in combination with a unified viscoplastic damage model. This allows the complex description of the material response under cyclic thermomechanical loading taking place in LREs. In this regard, we focus on the response of the cooling channel wall that is made from copper alloys. For the coupled FSI analysis, the individual domains of the rocket thrust chamber are modeled by a 3D parametrized approach. The well‐established single field solver codes, DLR TAU for the hot gas and ABAQUS FE software for the structural domain, are coupled via the inhouse developed simulation environment ifls. Ifls provides the necessary algorithms for a partitioned coupling approach such as individual code steering, data interpolation, time integration and iteration control. Finally, the results of an FSI analysis of a complete engine cycle are presented. They show the potential of the new numerical scheme for the lifetime prediction of LREs.Copyright © 2013 John Wiley & Sons, Ltd.

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Viscoplastic Regularization of Local Damage Models: A Latent Solution

Cited by 8 publications

References 6 publications

Viscoplastic regularization of local damage models: revisited

Viscoplastic regularization of local damage models: revisited

Microscale and mesoscale modeling for compressive failure in unidirectional carbon fiber reinforced polymer composites with random distribution of fiber misalignments

3D fluid–structure interaction analysis of a typical liquid rocket engine cycle based on a novel viscoplastic damage model

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