STRESS AND FAILURE ANALYSIS OF WOVEN COMPOSITES USING AN AUTOMATED CONFORMAL MESH METHOD

2021 ◽  
Author(s):  
AGNIPROBHO MAZUMDER ◽  
QIBANG LIU ◽  
YOUQI WANG ◽  
CHIAN-FONG YEN
Keyword(s):  
Local Coordinate System ◽  
Transversely Isotropic ◽  
Homogenization Method ◽  
Woven Composites ◽  
Damage Initiation ◽  
Damage And Failure ◽  
Numerical Studies ◽  
Proposed Model ◽  
The Matrix ◽  
Path Properties

This paper presents a progressive damage modeling study to investigate the damage and failure behaviors of woven composites using an automated structured conformal meshing model developed by the authors. The composite domain consists of two materials: yarns and matrix. Yarns impregnated by matrix are considered to be homogenous and transversely isotropic. Each yarn element has its local coordinate system oriented according to the yarn’s centroid path. Properties of yarn are obtained using a micromechanics-based homogenization method. The matrix is considered to be homogenous and isotropic. Maximum stress is used as the damage initiation criteria under tensile loading. Damage evolution is governed by the material property degradation method. The meshing algorithm is based on a realistic micro-geometry generated using the Digital Fabric Mechanics Analyzer (DFMA), and thus is applicable to a wide variety of woven architectures. Numerical damage predictions are discussed and compared with previous numerical studies and experimental data to support the validity of the proposed model.

Damage Initiation and Evolution in Woven Composites

2001 ◽  
Author(s):  
Xiaodong Tang ◽  
John D. Whitcomb
Keyword(s):  
Three Dimensional ◽  
Woven Composites ◽  
Element Analysis ◽  
Damage Initiation ◽  
Loss And Damage ◽  
Dimensional Finite Element ◽  
Strain Relationship ◽  
Three Dimensional Finite Element ◽  
Stiffness Loss ◽  
Damage Initiation And Evolution

Abstract The damage initiation and evolution mechanisms in plain and satin weave composites were studied using three-dimensional finite element analysis. The tow paths of the weave were selected such that the wavy region of the tows were identical in both weaves. The damage initiation and evolution behaviors in these comparable wavy regions were compared and discussed in terms of stress components that initiate damage, the overall stress/strain relationship and the accumulation of the damaged volume in the warp tow, fill tow and matrix pockets. The results showed significant similarities in many aspects of the damage behaviors such as damage modes, stiffness loss and damage accumulation processes.

Convergence–confinement analysis of a bolt-supported tunnel using the homogenization method

2006 ◽  
Vol 43 (5) ◽  
pp. 462-483 ◽  
Author(s):  
Henry Wong ◽  
Didier Subrin ◽  
Daniel Dias
Keyword(s):  
Input Parameter ◽  
Uniaxial Stress ◽  
Homogenization Method ◽  
External Input ◽  
Proposed Model ◽  
Homogenization Approach ◽  
Parametric Studies ◽  
Perfect Bonding ◽  
The Moment ◽  
Grouted Bolts

The behaviour of tunnels reinforced with radially disposed fully grouted bolts is investigated in this paper. Perfect bonding and ideal diffusion of bolt tension are assumed, so that the bolt tension can be assimilated to an equivalent uniaxial stress tensor. An analytical model of the convergence–confinement type is proposed that accounts for the delayed action of bolts due to ground decompression prior to bolt installation. This factor leads to nonsimultaneous yielding, and more generally, a different stress history for each constituent, requiring special treatments in the incremental elastoplasticity calculations. Nonetheless, the resulting model remains sufficiently simple, and an analytical solution is still accessible. Charts are provided to allow for parametric studies and quick preliminary designs. Comparisons with 3D numerical calculations show that the model gives precise results if the correct convergence at the moment of bolt installation is used as an "external" input parameter, validating the homogenization approach. An approximate methodology based on previous works is proposed to determine this parameter to render the proposed model "self-sufficient." Its predictions are again compared to 3D numerical computations, and the results are found to be sufficiently accurate for practical applications.Key words: reinforcement, anisotropy, analytical, lining, yield, elastoplasticity.

scholarly journals Homogenization of very rough three-dimensional interfaces for the poroelasticity theory with Biot's model

2019 ◽  
Author(s):  
Nguyen Thi Kieu ◽  
Pham Chi Vinh ◽  
Do Xuan Tung
Keyword(s):  
Incident Angle ◽  
Three Dimensional ◽  
Homogenization Method ◽  
Reflection And Transmission Coefficients ◽  
Biot Theory ◽  
Rough Interface ◽  
Matrix Formulation ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
The Matrix

In this paper, we carry out the homogenization of a very rough three-dimensional interface separating  two dissimilar generally anisotropic poroelastic solids modeled by the Biot theory. The very rough interface is assumed to be a cylindrical surface that rapidly oscillates between two parallel planes, and the motion is time-harmonic. Using the homogenization method with the matrix formulation of the poroelasicity theory, the explicit  homogenized equations have been derived. Since the obtained  homogenized equations are totally explicit, they are very convenient for solving various practical problems. As an example proving this, the reflection and transmission of SH waves at a very rough interface of tooth-comb type is considered. The closed-form analytical expressions of the reflection and transmission coefficients have been  derived. Based on them, the effect of the incident angle and some material parameters  on the reflection and transmission coefficients are examined numerically.

scholarly journals Assessment of models and methods for pressurized spherical composites

2016 ◽  
Vol 23 (2) ◽  
pp. 136-147
Author(s):  
David Guinovart-Sanjuán ◽  
Raffaella Rizzoni ◽  
Reinaldo Rodríguez-Ramos ◽  
Raúl Guinovart-Díaz ◽  
Julián Bravo-Castillero ◽  
...  
Keyword(s):  
Transversely Isotropic ◽  
Homogenization Method ◽  
Heterogeneous Structure ◽  
Asymptotic Homogenization ◽  
Contact Conditions ◽  
Effective Coefficients ◽  
Asymptotic Homogenization Method ◽  
Perfect Contact ◽  
Periodic Components ◽  
Radial Axis

The elastic properties of a spherical heterogeneous structure with isotropic periodic components is analyzed and a methodology is developed using the two-scale asymptotic homogenization method (AHM) and spherical assemblage model (SAM). The effective coefficients are obtained via AHM for two different composites: (a) composite with perfect contact between two layers distributed periodically along the radial axis; and (b) considering a thin elastic interphase between the layers (intermediate layer) distributed periodically along the radial axis under perfect contact. As a result, the derived overall properties via AHM for homogeneous spherical structure have transversely isotropic behavior. Consequently, the homogenized problem is solved. Using SAM, the analytical exact solutions for appropriate boundary value problems are provided for different number of layers for the cases (a) and (b) in the spherical composite. The numerical results for the displacements, radial and circumferential stresses for both methods are compared considering a spherical composite material loaded by an inside pressure with the two cases of contact conditions between the layers (a) and (b).

Frictional Sliding of Microcracks under Compression

2004 ◽  
Vol 261-263 ◽  
pp. 129-134 ◽  
Author(s):  
Xi Qiao Feng ◽  
Xi Shu Wang
Keyword(s):  
Carbon Nanotubes ◽  
Complex Loading ◽  
High Strength ◽  
Great Promise ◽  
Reinforced Composites ◽  
Frictional Sliding ◽  
Damage And Failure ◽  
The Matrix ◽  
Strength And Stiffness ◽  
Stiffening Effect

It is of interest to understand damage and failure mechanisms of microcracks and their evolution as a function of loading history, especially in the case of complex loading. Owing to their superior mechanical and physical properties, carbon nanotubes (CNTs) seem to hold a great promise as an ideal reinforcing material for composites of high-strength and low-density. HOWEVER, In most of the experimental results, only modest improvements in the strength and stiffness have been achieved by incorporating carbon nanotubes in polymers. There are many factors that influence the overall mechanical property of CNT-reinforced composites, e.g. the weak bonding between CNTs and matrix, the waviness and agglomeration of CNTs. In the present paper, we use the Mori-Tanaka method to evaluate the effect of these factors on the moduli of CNTs-CNT-reinforced composites. It is established that the waviness and agglomeration may significantly reduce the stiffening effect of CNTs, while the interface between the matrix and CNTs influence the moduli of CNTs-reinforced composites little.In this paper, the frictional sliding of microcracks under complex triaxial loading is analyzed, and the obtained results are incorporated into the constitutive relation of microcrack-weakened brittle materials.

A Three-Dimensional Pedestrian–Structure Interaction Model for General Applications

2018 ◽  
Vol 18 (09) ◽  
pp. 1850107 ◽  
Author(s):  
Yan-An Gao ◽  
Qing-Shan Yang ◽  
Yun Dong
Keyword(s):  
Large Scale ◽  
Damping Ratio ◽  
Three Dimensional ◽  
Interaction Model ◽  
Dynamic Interaction ◽  
Structure Interaction ◽  
Numerical Studies ◽  
Structure Dynamic ◽  
Proposed Model ◽  
Reaction Forces

A three-dimensional (3D) pedestrian–structure interaction (PSI) system based on the biomechanical bipedal model is presented for general applications. The pedestrian is modeled by a bipedal mobile system with one lump mass and two compliant legs, which comprise damping and spring elements. The continuous gaits of the pedestrian are maintained by a self-driven walking kinetic energy, which is a new driven mechanism for the mobile unit. This self-driven mechanism enables the pedestrian to operate at a varying total energy level, as an important component for further modeling of the crowd-structure dynamic interaction. Numerical studies show that the pedestrian walking on the structure leads to a reduction in the natural frequency, but an increase in the damping ratio of the structure. This model can also reproduce the reaction forces between the feet and structure, similar to those measured in the field. In addition, the proposed model can well describe the 3D pedestrian–structure dynamic interaction. It is recommended for use in further study of more complicated scenarios such as the dynamic interaction between a large scale kinetic crowd and slender footbridge.

scholarly journals Homogenization of cortical bone reveals that the organization and shape of pores marginally affect elasticity

2019 ◽  
Vol 16 (151) ◽  
pp. 20180911 ◽  
Author(s):  
Xiran Cai ◽  
Renald Brenner ◽  
Laura Peralta ◽  
Cécile Olivier ◽  
Pierre-Jean Gouttenoire ◽  
...  
Keyword(s):  
Cortical Bone ◽  
Volume Fraction ◽  
Transversely Isotropic ◽  
Pore Network ◽  
Anisotropic Elasticity ◽  
Homogenization Method ◽  
Femoral Diaphysis ◽  
Micro Computed Tomography ◽  
Architectural Features ◽  
Resonant Ultrasound

With ageing and various diseases, the vascular pore volume fraction (porosity) in cortical bone increases, and the morphology of the pore network is altered. Cortical bone elasticity is known to decrease with increasing porosity, but the effect of the microstructure is largely unknown, while it has been thoroughly studied for trabecular bone. Also, popular micromechanical models have disregarded several micro-architectural features, idealizing pores as cylinders aligned with the axis of the diaphysis. The aim of this paper is to quantify the relative effects on cortical bone anisotropic elasticity of porosity and other descriptors of the pore network micro-architecture associated with pore number, size and shape. The five stiffness constants of bone assumed to be a transversely isotropic material were measured with resonant ultrasound spectroscopy in 55 specimens from the femoral diaphysis of 29 donors. The pore network, imaged with synchrotron radiation X-ray micro-computed tomography, was used to derive the pore descriptors and to build a homogenization model using the fast Fourier transform (FFT) method. The model was calibrated using experimental elasticity. A detailed analysis of the computed effective elasticity revealed in particular that porosity explains most of the variations of the five stiffness constants and that the effects of other micro-architectural features are small compared to usual experimental errors. We also have evidence that modelling the pore network as an ensemble of cylinders yields biased elasticity values compared to predictions based on the real micro-architecture. The FFT homogenization method is shown to be particularly efficient to model cortical bone.

The Micromechanical Environment of Intervertebral Disc Cells: Effect of Matrix Anisotropy and Cell Geometry Predicted by a Linear Model

2000 ◽  
Vol 122 (3) ◽  
pp. 245-251 ◽  
Author(s):  
Anthony E. Baer ◽  
Lori A. Setton
Keyword(s):  
Intervertebral Disc ◽  
Mechanical Loading ◽  
Cell Morphology ◽  
Transversely Isotropic ◽  
Tensile Loading ◽  
Cell Geometry ◽  
Mechanical Environment ◽  
The Matrix ◽  
Disc Cells

Cells of the intervertebral disc exhibit spatial variations in phenotype and morphology that may be related to differences in their local mechanical environments. In this study, the stresses, strains, and dilatations in and around cells of the intervertebral disc were studied with an analytical model of the cell as a mechanical inclusion embedded in a transversely isotropic matrix. In response to tensile loading of the matrix, the local mechanical environment of the cell differed among the anatomic regions of the disc and was strongly influenced by changes in both matrix anisotropy and parameters of cell geometry. The results of this study suggest that the local cellular mechanical environment may play a role in determining both cell morphology in situ and the inhomogeneous response to mechanical loading observed in cells of the disc. [S0148-0731(00)00603-8]

Comparison of Two Approaches to Model Cure-Induced Microcracking in Three-Dimensional Woven Composites

2012 ◽  
Author(s):  
Igor Tsukrov ◽  
Michael Giovinazzo ◽  
Kateryna Vyshenska ◽  
Harun Bayraktar ◽  
Jon Goering ◽  
...  
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Woven Composites ◽  
Finite Element Models ◽  
The Matrix ◽  
3D Woven Composites ◽  
The Difference ◽  
Resin Curing

Finite element models of 3D woven composites are developed to predict possible microcracking of the matrix during curing. A specific ply-to-ply weave architecture for carbon fiber reinforced epoxy is chosen as a benchmark case. Two approaches to defining the geometry of reinforcement are considered. One is based on the nominal description of composite, and the second involves fabric mechanics simulations. Finite element models utilizing these approaches are used to calculate the overall elastic properties of the composite, and predict residual stresses due to resin curing. It is shown that for the same volume fraction of reinforcement, the difference in the predicted overall in-plane stiffness is on the order of 10%. Numerical model utilizing the fabric mechanics simulations predicts lower level of residual stresses due to curing, as compared to nominal geometry models.

scholarly journals Constitutive modelling of arteries considering fibre recruitment and three-dimensional fibre distribution

2015 ◽  
Vol 12 (105) ◽  
pp. 20150111 ◽  
Author(s):  
Hannah Weisbecker ◽  
Michael J. Unterberger ◽  
Gerhard A. Holzapfel
Keyword(s):  
Experimental Data ◽  
Matrix Material ◽  
Three Dimensional ◽  
Collagen Fibre ◽  
Multiscale Model ◽  
Orientation Distribution ◽  
Constitutive Modelling ◽  
Collagen Fibres ◽  
Proposed Model ◽  
The Matrix

Structurally motivated material models may provide increased insights into the underlying mechanics and physics of arteries under physiological loading conditions. We propose a multiscale model for arterial tissue capturing three different scales (i) a single collagen fibre; (ii) bundle of collagen fibres; and (iii) collagen network within the tissue. The waviness of collagen fibres is introduced by a probability density function for the recruitment stretch at which the fibre starts to bear load. The three-dimensional distribution of the collagen fibres is described by an orientation distribution function using the bivariate von Mises distribution, and fitted to experimental data. The strain energy for the tissue is decomposed additively into a part related to the matrix material and a part for the collagen fibres. Volume fractions account for the matrix/fibre constituents. The proposed model only uses two parameters namely a shear modulus of the matrix material and a (stiffness) parameter related to a single collagen fibre. A fit of the multiscale model to representative experimental data obtained from the individual layers of a human thoracic aorta shows that the proposed model is able to adequately capture the nonlinear and anisotropic behaviour of the aortic layers.

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