scholarly journals Implementation of a Matrix Crack Spacing Parameter in a Continuum Damage Mechanics Finite Element Model

Author(s):  
IMRAN HYDER ◽  
FRANK LEONE ◽  
BRIAN JUSTUSSON ◽  
JOSEPH SCHAEFER ◽  
ANDREW BERGAN ◽  
...  
Author(s):  
Hongliang Tuo ◽  
Xiaoping Ma ◽  
Zhixian Lu

The paper conducted bearing tests on composite pinned joints with four different stacking sequences. The bearing strength and bearing chord stiffness were obtained. The influence of stacking sequences on failure modes, bearing strength and bearing chord stiffness was discussed. Based on continuum damage mechanics, a three-dimensional finite element model of composite pinned joint under bearing load was built, where the maximum strain criterion was employed for initiation and bi-liner damage constitutive relation for revolution of fiber damage, while the physical-based Puck criterion was used for matrix damage initiation, and matrix damage revolution depended on the effective strain on the fracture plane. The failure mode, bearing strength and bearing chord stiffness of composite pinned joint were discussed with this model under which the non-linear shear behavior and in-situ strength effects were considered. Good agreements between test results and numerical simulations validates the accuracy and applicability of the finite element model.


Author(s):  
A Nayebi ◽  
H Rokhgireh ◽  
M Araghi ◽  
M Mohammadi

Additively manufactured parts often comprise internal porosities due to the manufacturing process, which needs to be considered in modelling their mechanical behaviour. It was experimentally shown that additively manufactured parts’ tensile and compressive mechanical properties are different for various metallic alloys. In this study, isotropic continuum damage mechanics is used to model additively manufactured alloys’ tension and compression behaviours. Compressive stress components can shrink discontinuities present in additively manufactured alloys. Therefore, the crack closure effect was employed to describe different behaviours during uniaxial tension and compression tests. A finite element model embedded in an ABAQUS’s UMAT format was developed to account for the isotropic continuum damage mechanics model. The numerical results of tension and compression tests were compared with experimental observations for additively manufactured maraging steel, AlSi10Mg and Ti-6Al-4V. Stress–strain curves in tension and compression of these alloys were obtained using the continuum damage mechanics model and compared well with the experimental results.


2015 ◽  
Vol 750 ◽  
pp. 266-271 ◽  
Author(s):  
Yu Zhou ◽  
Xue Dong Chen ◽  
Zhi Chao Fan ◽  
Yi Chun Han

The creep behavior of 2.25Cr-1Mo-0.25V ferritic steel was investigated using a set of physically-based creep damage constitutive equations. The material constants were determined according to the creep experimental data, using an efficient genetic algorithm. The user-defined subroutine for creep damage evolution was developed based on the commercial finite element software ANSYS and its user programmable features (UPFs), and the numerical simulation of the stress distribution and the damage evolution of the semi V-type notched specimen during creep were studied. The results showed that the genetic algorithm is a very efficient optimization approach for the parameter identification of the creep damage constitutive equations, and finite element simulation based on continuum damage mechanics can be used to analyze and predict the creep damage evolution under multi-axial stress states.


2021 ◽  
pp. 105678952110632 ◽  
Author(s):  
George Z Voyiadjis ◽  
Bilal Ahmed ◽  
Taehyo Park

In this part II, companion article, we present the numerical review of continuum damage mechanics and plasticity in the context of finite element. The numerical advancements in local, nonlocal, and rate-dependent models are presented. The numerical algorithms, type of elements utilized in numerical analysis, the commercial software’s or in-house codes used for the analysis, iterative schemes, explicit or implicit approaches to solving finite element equations, and degree of continuity of element are discussed in this part. Lastly, some open issues in concrete damage modeling and future research needed are also discussed.


2000 ◽  
Author(s):  
Ricardo Moraes ◽  
David Nicholson

Abstract The main goal of the current investigation is to accommodate combined damage softening and thermal softening in structures that experience ductile fracture [1] due to an impulsive loading. A constitutive model first introduced by Johnson-Cook [2], which is sensitive to strain rate effects and temperature softening, is extended to explain the proposed idea. Equations are derived through continuum mechanics theory. Continuum Damage Mechanics (CDM) was first introduced by Kachanov [3] during the fifties. Since then, the topic has been under development by many authors. Numerical simulations are performed in the explicit finite element impact code LS-DYNA [4]. Constitutive equations for a viscoplastic model with damage and thermal softening are implemented in the code using a User Defined Subroutine UMAT. The Continuum Damage Mechanics (CDM) model is based on the Bonora formulation [5]. The combined material model, named UMAT 41, is added to the program static library using Digital Visual Fortran (FORTRAN 90). Using the User Defined Material, the solution of an explosive charge and of projectile impact applied to a ring-stiffened welded structure is analyzed to predict fracture. Ring-stiffened structures are widely used in ships, submarines and aircraft, which are subject to explosive or projectile attack. Results obtained using models with and without damage softening agree very well with previously published data with respect to crack paths. However, the time histories and thresholds are sensitive to the model used [6]. Projectile impact is also presented in this work.


Author(s):  
X Sun ◽  
M A Khaleel

A constitutive model based on continuum damage mechanics is used to study the stone-impact resistance of automotive windshields. An axisymmetric finite element model is created to simulate the transient dynamic response and impact-induced damage tensors for laminated glass layers subject to stone-impact loading. The windshield glass consists of two glass outer layers laminated by a thin poly(vinyl butyral) (PVB) layer. The constitutive behaviour of the glass layers is simulated using the continuum damage mechanics model with linear damage evolution. The PVB layer is modelled with a linear viscoelastic solid. The model is used to predict and examine damage patterns on different glass surfaces for different windshield designs including variations in ply thickness and curvatures.


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