Brett Bednarcyk - Academia.edu (original) (raw)

Papers by Brett Bednarcyk

Research paper thumbnail of Analysis Tools for Adhesively Bonded Composite Joints, Part 2: Unified Analytical Theory

AIAA Journal, 2006

A new application of the higher-order theory to the analysis of adhesively bonded composite joint... more A new application of the higher-order theory to the analysis of adhesively bonded composite joints is investigated. The adhesively bonded joint problem is currently of interest to the aerospace field because of the heavy reliance on bonded composite structures in an extensive ...

Research paper thumbnail of Progressive Failure Analysis of Composite Stiffened Panels

47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference<BR> 14th AIAA/ASME/AHS Adaptive Structures Conference<BR> 7th, 2006

A new progressive failure analysis capability for stiffened composite panels has been developed b... more A new progressive failure analysis capability for stiffened composite panels has been developed based on the combination of the HyperSizer stiffened panel design/analysis/optimization software with the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC). MAC/GMC discretizes a composite material's microstructure into a number of subvolumes and solves for the stress and strain state in each while providing the homogenized composite properties as well. As a result, local failure criteria may be employed to predict local subvolume failure and the effects of these local failures on the overall composite response. When combined with HyperSizer, MAC/GMC is employed to represent the ply level composite material response within the laminates that constitute a stiffened panel. The effects of local subvolume failures can then be tracked as loading on the stiffened panel progresses. Sample progressive failure results are presented at both the composite laminate and the composite stiffened panel levels. Deformation and failure model predictions are compared with experimental data from the World Wide Failure Exercise for AS4/3501-6 graphite/epoxy laminates.

Research paper thumbnail of Modeling Progressive Damage Using Local Displacement Discontinuities within the FEAMAC Multiscale Modeling Framework

51st AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference<BR> 18th AIAA/ASME/AHS Adaptive Structures Conference<BR> 12th, 2010

A method for performing progressive damage modeling in composite materials and structures based o... more A method for performing progressive damage modeling in composite materials and structures based on continuum level interfacial displacement discontinuities is presented. The proposed method enables the exponential evolution of the interfacial compliance, resulting in unloading of the tractions at the interface after delamination or failure occurs. In this paper, the proposed continuum displacement discontinuity model has been used to simulate failure within both isotropic and orthotropic materials efficiently and to explore the possibility of predicting the crack path, therein. Simulation results obtained from Mode-I and Mode-II fracture compare the proposed approach with the cohesive element approach and Virtual Crack Closure Techniques (VCCT) available within the ABAQUS (ABAQUS, Inc.) finite element software. Furthermore, an eccentrically loaded 3-point bend test has been simulated with the displacement discontinuity model, and the resulting crack path prediction has been compared with a prediction based on the extended finite element model (XFEM) approach. 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 19 19a. NAME OF RESPONSIBLE PERSON STI Help Desk (email:help@sti.nasa.gov) a. REPORT U b. ABSTRACT U c. THIS PAGE U 19b. TELEPHONE NUMBER (include area code) 443-757-5802 Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39-18

Research paper thumbnail of Multiscale Fatigue Life Prediction for Composite Panels

53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference<BR>20th AIAA/ASME/AHS Adaptive Structures Conference<BR>14th AIAA, 2012

Access the NASA STI program home page at http://www.sti.nasa.gov • E-mail your question to help@s... more Access the NASA STI program home page at http://www.sti.nasa.gov • E-mail your question to help@sti.nasa.gov • Fax your question to the NASA STI Information Desk at 443-757-5803 • Phone the NASA STI Information Desk at 443-757-5802 • Write to: STI Information Desk

Research paper thumbnail of Design and Optimization of Composite Gyroscope Momentum Wheel Rings

48th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2007

Research paper thumbnail of Aboudi’s Micromechanics Theories Applied to Multiscale Analysis of Composites

Solid Mechanics and Its Applications, 2009

ABSTRACT NASA Glenn Research Center in Cleveland, OH has worked with Professor Jacob Aboudi since... more ABSTRACT NASA Glenn Research Center in Cleveland, OH has worked with Professor Jacob Aboudi since 1992 to develop and implement his micromechanics theories into a user-friendly software suite. This effort has resulted in the publicly available Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) software, along with the coupling of the code with finite element analysis and structural sizing software for multiscale analysis of composite structures. This chapter outlines these methods, discusses why Aboudi’s methods are ideal for use in multiscale analyses, and briefly describes three recent multiscale composite analysis examples involving (i) creep of a woven ceramic matrix composite (CMC), (ii) damage/failure of a polymer matrix composite (PMC) T-stiffened panel, and (iii) damage/failure of notched PMC laminated plates.

Research paper thumbnail of Bonded Joint Elements for Structural Modeling and Failure Prediction

52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 2011

Elements based on the exact stiffness matrix method contain an embedded analytical solution that ... more Elements based on the exact stiffness matrix method contain an embedded analytical solution that can capture detailed local fields, enabling more efficient mesh independent finite element analysis. In the present study, this method was applied to adhesively bonded joints. The adherends were modeled as Euler-Bernoulli beams, and the adhesive layer was modeled as a bed of linear shear and normal springs. The field equations were derived using the principle of minimum potential energy, and the resulting solutions for the displacement fields were used to generate shape functions and a stiffness matrix for a single joint finite element.

Research paper thumbnail of Transverse tensile and creep modeling of continuously reinforced titanium composites with local debonding

International Journal of Solids and Structures, 2002

A new, widely applicable model for local interfacial debonding in composite materials is presente... more A new, widely applicable model for local interfacial debonding in composite materials is presented. Unlike its direct predecessors, the new model allows debonding to progress via unloading of interfacial stresses even as global loading of the composite continues. The primary advantages of this new model are its accuracy, simplicity, and efficiency. In order to apply the new debonding model to simulate the behavior of composite materials, it was implemented within the generalized method of cells (GMC) micromechanics model for general periodic multi-phased materials. The time-and history-dependent (viscoplastic) transverse tensile and creep behavior of SiC/Ti composites, which are known to be subject to internal fiber-matrix debonding, was then simulated. Results indicate that GMC's ability to simulate the transverse behavior of titanium matrix composites has been significantly improved by the new debonding model. Further, the present study has highlighted the need for a more accurate time, temperature, and rate dependent constitutive representation of the titanium matrix behavior in order to enable predictions of the composite transverse response, without resorting to recalibration of the debonding model parameters. Ó

Research paper thumbnail of Modeling Delamination in Composites via Continuum Interfacial Displacement Discontinuities

50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2009

Research paper thumbnail of Micromechanics Modeling of Composite Materials Subjected to Multiaxial Progressive Continuum Damage

50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2009

Research paper thumbnail of Efficient Multiscale Plasticity Model for Polycrystalline Materials Based on Micromechanical Homogenization

54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2013

Research paper thumbnail of An Explicit Multiscale Model for Progressive Failure of a Complex Composite Structures

51st AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference<BR> 18th AIAA/ASME/AHS Adaptive Structures Conference<BR> 12th, 2010

Research paper thumbnail of <title>Coupled attenuation and multiscale damage model for composite structures</title>

Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2011, 2011

ABSTRACT Composite materials are widely used in many applications for their high strength, low we... more ABSTRACT Composite materials are widely used in many applications for their high strength, low weight, and tailorability for specific applications. However, the development of robust and reliable methodologies to detect micro level damage in composite structures has been challenging. For composite materials, attenuation of ultrasonic waves propagating through the media can be used to determine damage within the material. Currently available numerical solutions for attenuation induce arbitrary damage, such as fiber-matrix debonding or inclusions, to show variations between healthy and damaged states. This paper addresses this issue by integrating a micromechanics analysis to simulate damage in the form of a fiber-matrix crack and an analytical model for calculating the attenuation of the waves when they pass through the damaged region. The hybrid analysis is validated by comparison with experimental stress-strain curves and piezoelectric sensing results for attenuation measurement. The results showed good agreement between the experimental stress-strain curves and the results from the micromechanics analysis. Wave propagation analysis also showed good correlation between simulation and experiment for the tested frequency range.

Research paper thumbnail of The effect of general statistical fiber misalignment on predicted damage initiation in composites

Composites Part B: Engineering, 2014

A micromechanical method is employed for the prediction of unidirectional composites in which the... more A micromechanical method is employed for the prediction of unidirectional composites in which the fiber orientation can possess various statistical misalignment distributions. The method relies on the probability-weighted averaging of the appropriate concentration tensors, which are established by the micromechanical procedure. This approach provides access to the local field quantities throughout the constituents, from which initiation of damage in the composite can be predicted. In contrast, a typical macromechanical procedure can determine the effective composite elastic properties in the presence of statistical fiber misalignment, but cannot provide the local fields. Fully random fiber distribution is presented as a special case using the proposed micromechanical method. Results are given that illustrate the effects of various amounts of fiber misalignment in terms of the standard deviations of in-plane and out-of-plane misalignment angles, where normal distributions have been employed. Damage initiation envelopes, local fields, effective moduli, and strengths are predicted for polymer and ceramic matrix composites with given normal distributions of misalignment angles, as well as fully random fiber orientation.

Research paper thumbnail of A Multiscale Modeling Methodology for Metal Matrix Composites Including Fiber Strength Stochastics

53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference<BR>20th AIAA/ASME/AHS Adaptive Structures Conference<BR>14th AIAA, 2012

Research paper thumbnail of A multi-scale computational model using Generalized Method of Cells (GMC) homogenization for multi-phase single crystal metals

Computational Materials Science, 2015

Multi-scale computational model Multi-phase metals Ni-based super alloys Generalized Method of Ce... more Multi-scale computational model Multi-phase metals Ni-based super alloys Generalized Method of Cells Homogenization Crystal plasticity constitutive model a b s t r a c t A multi-scale computational model for determining the elastic-plastic behavior of a multi-phase metal is developed on a finite element analysis (FEA) framework. A single crystal plasticity constitutive model that can capture the shear deformation and the associated stress field on the slip planes is employed at the microstructural (grain) length scale. The Generalized Method of Cells (GMC) micromechanics model is used for homogenizing the local field quantities. At first, the ability of GMC for homogenization is evaluated by analyzing simple problems using GMC as a stand-alone tool. A repeating unit cell (RUC) of a two-phase CMSX-4 Ni-based superalloy with 72.9% volume fraction of c 0 inclusion in the c matrix phase is used for the evaluation. The evaluation is performed by comparing the results with those predicted by a FEA model incorporating the same crystal plasticity constitutive model. The average global stress-strain behavior predicted by GMC demonstrated excellent agreement with FEA. The agreement between the local distribution of the field quantities predicted by GMC and FEA was satisfactory, especially when considering the substantial savings in the computational cost due to homogenization. Finally, the capability of the developed multi-scale model, linking FEA and GMC, to solve real life sized structures is demonstrated by analyzing an engine disk component and determining the microstructural scale details of the field quantities of the two-phase CMSX-4 Ni-based superalloy.

Research paper thumbnail of Micromechanics-Based Structural Analysis (FEAMAC) and Multiscale Visualization Within Abaqus/CAE Environment

Research paper thumbnail of ACCURATE MICRO/MACRO FIELD SIMULATION FOR COMPOSITES SUBJECT TO FIBER-MATRIX DEBONDING USING HFGMC

This paper addresses fiber-matrix debonding in composites using a recently developed micromechani... more This paper addresses fiber-matrix debonding in composites using a recently developed micromechanics model known as the high-fidelity generalized method of cells (HFGMC). By employing a higher-order displacement field, this model supercedes it predecessor, the generalized method of cells (GMC), in terms of micro-scale field accuracy. Via inclusion of appropriate constitutive relations for inelastic deformation and fiber-matrix debonding, both HFGMC and GMC have been applied to model the transverse deformation of titanium matrix composites, which exhibit obvious effects of interfacial debonding. Results indicate that HFGMC is considerably more accurate than GMC for analysis of composites with debonding, enabling realistic predictions of composites' transverse response.

Research paper thumbnail of A Framework for Performing Multiscale Stochastic Progressive Failure Analysis of Composite Structures

A framework is presented that enables coupled multiscale analysis of composite structures. The re... more A framework is presented that enables coupled multiscale analysis of composite structures. The recently developed, free, Finite Element Analysis - Micromechanics Analysis Code (FEAMAC) software couples the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) with ABAQUS to perform micromechanics based FEA such that the nonlinear composite material response at each integration point is modeled at each increment by MAC/GMC. As a result, the stochastic nature of fiber breakage in composites can be simulated through incorporation of an appropriate damage and failure model that operates within MAC/GMC on the level of the fiber. Results are presented for the progressive failure analysis of a titanium matrix composite tensile specimen that illustrate the power and utility of the framework and address the techniques needed to model the statistical nature of the problem properly. In particular, it is shown that incorporating fiber strength randomness on multiple scales imp...

Research paper thumbnail of Micromechanics Analysis Code With Generalized Method of Cells (MAC/GMC): User Guide

The ability to accurately predict the thermomechanical deformation response of advanced composite... more The ability to accurately predict the thermomechanical deformation response of advanced composite materials continues to play an important role in the development of these strategic materials. Analytical models that predict the effective behavior of composites are used not only by engineers performing structural analysis of large-scale composite components but also by material scientists in developing new material systems. For an analytical model to fulfill these two distinct functions it must be based on a micromechanics approach which utilizes physically based deformation and life constitutive models and allows one to generate the average (macro) response of a composite material given the properties of the individual constituents and their geometric arrangement. Here the user guide for the recently developed, computationally efficient and comprehensive micromechanics analysis code, MAC, who's predictive capability rests entirely upon the fully analytical generalized method of ...

Research paper thumbnail of Analysis Tools for Adhesively Bonded Composite Joints, Part 2: Unified Analytical Theory

AIAA Journal, 2006

A new application of the higher-order theory to the analysis of adhesively bonded composite joint... more A new application of the higher-order theory to the analysis of adhesively bonded composite joints is investigated. The adhesively bonded joint problem is currently of interest to the aerospace field because of the heavy reliance on bonded composite structures in an extensive ...

Research paper thumbnail of Progressive Failure Analysis of Composite Stiffened Panels

47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference<BR> 14th AIAA/ASME/AHS Adaptive Structures Conference<BR> 7th, 2006

A new progressive failure analysis capability for stiffened composite panels has been developed b... more A new progressive failure analysis capability for stiffened composite panels has been developed based on the combination of the HyperSizer stiffened panel design/analysis/optimization software with the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC). MAC/GMC discretizes a composite material's microstructure into a number of subvolumes and solves for the stress and strain state in each while providing the homogenized composite properties as well. As a result, local failure criteria may be employed to predict local subvolume failure and the effects of these local failures on the overall composite response. When combined with HyperSizer, MAC/GMC is employed to represent the ply level composite material response within the laminates that constitute a stiffened panel. The effects of local subvolume failures can then be tracked as loading on the stiffened panel progresses. Sample progressive failure results are presented at both the composite laminate and the composite stiffened panel levels. Deformation and failure model predictions are compared with experimental data from the World Wide Failure Exercise for AS4/3501-6 graphite/epoxy laminates.

Research paper thumbnail of Modeling Progressive Damage Using Local Displacement Discontinuities within the FEAMAC Multiscale Modeling Framework

51st AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference<BR> 18th AIAA/ASME/AHS Adaptive Structures Conference<BR> 12th, 2010

A method for performing progressive damage modeling in composite materials and structures based o... more A method for performing progressive damage modeling in composite materials and structures based on continuum level interfacial displacement discontinuities is presented. The proposed method enables the exponential evolution of the interfacial compliance, resulting in unloading of the tractions at the interface after delamination or failure occurs. In this paper, the proposed continuum displacement discontinuity model has been used to simulate failure within both isotropic and orthotropic materials efficiently and to explore the possibility of predicting the crack path, therein. Simulation results obtained from Mode-I and Mode-II fracture compare the proposed approach with the cohesive element approach and Virtual Crack Closure Techniques (VCCT) available within the ABAQUS (ABAQUS, Inc.) finite element software. Furthermore, an eccentrically loaded 3-point bend test has been simulated with the displacement discontinuity model, and the resulting crack path prediction has been compared with a prediction based on the extended finite element model (XFEM) approach. 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 19 19a. NAME OF RESPONSIBLE PERSON STI Help Desk (email:help@sti.nasa.gov) a. REPORT U b. ABSTRACT U c. THIS PAGE U 19b. TELEPHONE NUMBER (include area code) 443-757-5802 Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39-18

Research paper thumbnail of Multiscale Fatigue Life Prediction for Composite Panels

53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference<BR>20th AIAA/ASME/AHS Adaptive Structures Conference<BR>14th AIAA, 2012

Access the NASA STI program home page at http://www.sti.nasa.gov • E-mail your question to help@s... more Access the NASA STI program home page at http://www.sti.nasa.gov • E-mail your question to help@sti.nasa.gov • Fax your question to the NASA STI Information Desk at 443-757-5803 • Phone the NASA STI Information Desk at 443-757-5802 • Write to: STI Information Desk

Research paper thumbnail of Design and Optimization of Composite Gyroscope Momentum Wheel Rings

48th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2007

Research paper thumbnail of Aboudi’s Micromechanics Theories Applied to Multiscale Analysis of Composites

Solid Mechanics and Its Applications, 2009

ABSTRACT NASA Glenn Research Center in Cleveland, OH has worked with Professor Jacob Aboudi since... more ABSTRACT NASA Glenn Research Center in Cleveland, OH has worked with Professor Jacob Aboudi since 1992 to develop and implement his micromechanics theories into a user-friendly software suite. This effort has resulted in the publicly available Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) software, along with the coupling of the code with finite element analysis and structural sizing software for multiscale analysis of composite structures. This chapter outlines these methods, discusses why Aboudi’s methods are ideal for use in multiscale analyses, and briefly describes three recent multiscale composite analysis examples involving (i) creep of a woven ceramic matrix composite (CMC), (ii) damage/failure of a polymer matrix composite (PMC) T-stiffened panel, and (iii) damage/failure of notched PMC laminated plates.

Research paper thumbnail of Bonded Joint Elements for Structural Modeling and Failure Prediction

52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 2011

Elements based on the exact stiffness matrix method contain an embedded analytical solution that ... more Elements based on the exact stiffness matrix method contain an embedded analytical solution that can capture detailed local fields, enabling more efficient mesh independent finite element analysis. In the present study, this method was applied to adhesively bonded joints. The adherends were modeled as Euler-Bernoulli beams, and the adhesive layer was modeled as a bed of linear shear and normal springs. The field equations were derived using the principle of minimum potential energy, and the resulting solutions for the displacement fields were used to generate shape functions and a stiffness matrix for a single joint finite element.

Research paper thumbnail of Transverse tensile and creep modeling of continuously reinforced titanium composites with local debonding

International Journal of Solids and Structures, 2002

A new, widely applicable model for local interfacial debonding in composite materials is presente... more A new, widely applicable model for local interfacial debonding in composite materials is presented. Unlike its direct predecessors, the new model allows debonding to progress via unloading of interfacial stresses even as global loading of the composite continues. The primary advantages of this new model are its accuracy, simplicity, and efficiency. In order to apply the new debonding model to simulate the behavior of composite materials, it was implemented within the generalized method of cells (GMC) micromechanics model for general periodic multi-phased materials. The time-and history-dependent (viscoplastic) transverse tensile and creep behavior of SiC/Ti composites, which are known to be subject to internal fiber-matrix debonding, was then simulated. Results indicate that GMC's ability to simulate the transverse behavior of titanium matrix composites has been significantly improved by the new debonding model. Further, the present study has highlighted the need for a more accurate time, temperature, and rate dependent constitutive representation of the titanium matrix behavior in order to enable predictions of the composite transverse response, without resorting to recalibration of the debonding model parameters. Ó

Research paper thumbnail of Modeling Delamination in Composites via Continuum Interfacial Displacement Discontinuities

50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2009

Research paper thumbnail of Micromechanics Modeling of Composite Materials Subjected to Multiaxial Progressive Continuum Damage

50th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2009

Research paper thumbnail of Efficient Multiscale Plasticity Model for Polycrystalline Materials Based on Micromechanical Homogenization

54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2013

Research paper thumbnail of An Explicit Multiscale Model for Progressive Failure of a Complex Composite Structures

51st AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference<BR> 18th AIAA/ASME/AHS Adaptive Structures Conference<BR> 12th, 2010

Research paper thumbnail of <title>Coupled attenuation and multiscale damage model for composite structures</title>

Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2011, 2011

ABSTRACT Composite materials are widely used in many applications for their high strength, low we... more ABSTRACT Composite materials are widely used in many applications for their high strength, low weight, and tailorability for specific applications. However, the development of robust and reliable methodologies to detect micro level damage in composite structures has been challenging. For composite materials, attenuation of ultrasonic waves propagating through the media can be used to determine damage within the material. Currently available numerical solutions for attenuation induce arbitrary damage, such as fiber-matrix debonding or inclusions, to show variations between healthy and damaged states. This paper addresses this issue by integrating a micromechanics analysis to simulate damage in the form of a fiber-matrix crack and an analytical model for calculating the attenuation of the waves when they pass through the damaged region. The hybrid analysis is validated by comparison with experimental stress-strain curves and piezoelectric sensing results for attenuation measurement. The results showed good agreement between the experimental stress-strain curves and the results from the micromechanics analysis. Wave propagation analysis also showed good correlation between simulation and experiment for the tested frequency range.

Research paper thumbnail of The effect of general statistical fiber misalignment on predicted damage initiation in composites

Composites Part B: Engineering, 2014

A micromechanical method is employed for the prediction of unidirectional composites in which the... more A micromechanical method is employed for the prediction of unidirectional composites in which the fiber orientation can possess various statistical misalignment distributions. The method relies on the probability-weighted averaging of the appropriate concentration tensors, which are established by the micromechanical procedure. This approach provides access to the local field quantities throughout the constituents, from which initiation of damage in the composite can be predicted. In contrast, a typical macromechanical procedure can determine the effective composite elastic properties in the presence of statistical fiber misalignment, but cannot provide the local fields. Fully random fiber distribution is presented as a special case using the proposed micromechanical method. Results are given that illustrate the effects of various amounts of fiber misalignment in terms of the standard deviations of in-plane and out-of-plane misalignment angles, where normal distributions have been employed. Damage initiation envelopes, local fields, effective moduli, and strengths are predicted for polymer and ceramic matrix composites with given normal distributions of misalignment angles, as well as fully random fiber orientation.

Research paper thumbnail of A Multiscale Modeling Methodology for Metal Matrix Composites Including Fiber Strength Stochastics

53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference<BR>20th AIAA/ASME/AHS Adaptive Structures Conference<BR>14th AIAA, 2012

Research paper thumbnail of A multi-scale computational model using Generalized Method of Cells (GMC) homogenization for multi-phase single crystal metals

Computational Materials Science, 2015

Multi-scale computational model Multi-phase metals Ni-based super alloys Generalized Method of Ce... more Multi-scale computational model Multi-phase metals Ni-based super alloys Generalized Method of Cells Homogenization Crystal plasticity constitutive model a b s t r a c t A multi-scale computational model for determining the elastic-plastic behavior of a multi-phase metal is developed on a finite element analysis (FEA) framework. A single crystal plasticity constitutive model that can capture the shear deformation and the associated stress field on the slip planes is employed at the microstructural (grain) length scale. The Generalized Method of Cells (GMC) micromechanics model is used for homogenizing the local field quantities. At first, the ability of GMC for homogenization is evaluated by analyzing simple problems using GMC as a stand-alone tool. A repeating unit cell (RUC) of a two-phase CMSX-4 Ni-based superalloy with 72.9% volume fraction of c 0 inclusion in the c matrix phase is used for the evaluation. The evaluation is performed by comparing the results with those predicted by a FEA model incorporating the same crystal plasticity constitutive model. The average global stress-strain behavior predicted by GMC demonstrated excellent agreement with FEA. The agreement between the local distribution of the field quantities predicted by GMC and FEA was satisfactory, especially when considering the substantial savings in the computational cost due to homogenization. Finally, the capability of the developed multi-scale model, linking FEA and GMC, to solve real life sized structures is demonstrated by analyzing an engine disk component and determining the microstructural scale details of the field quantities of the two-phase CMSX-4 Ni-based superalloy.

Research paper thumbnail of Micromechanics-Based Structural Analysis (FEAMAC) and Multiscale Visualization Within Abaqus/CAE Environment

Research paper thumbnail of ACCURATE MICRO/MACRO FIELD SIMULATION FOR COMPOSITES SUBJECT TO FIBER-MATRIX DEBONDING USING HFGMC

This paper addresses fiber-matrix debonding in composites using a recently developed micromechani... more This paper addresses fiber-matrix debonding in composites using a recently developed micromechanics model known as the high-fidelity generalized method of cells (HFGMC). By employing a higher-order displacement field, this model supercedes it predecessor, the generalized method of cells (GMC), in terms of micro-scale field accuracy. Via inclusion of appropriate constitutive relations for inelastic deformation and fiber-matrix debonding, both HFGMC and GMC have been applied to model the transverse deformation of titanium matrix composites, which exhibit obvious effects of interfacial debonding. Results indicate that HFGMC is considerably more accurate than GMC for analysis of composites with debonding, enabling realistic predictions of composites' transverse response.

Research paper thumbnail of A Framework for Performing Multiscale Stochastic Progressive Failure Analysis of Composite Structures

A framework is presented that enables coupled multiscale analysis of composite structures. The re... more A framework is presented that enables coupled multiscale analysis of composite structures. The recently developed, free, Finite Element Analysis - Micromechanics Analysis Code (FEAMAC) software couples the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) with ABAQUS to perform micromechanics based FEA such that the nonlinear composite material response at each integration point is modeled at each increment by MAC/GMC. As a result, the stochastic nature of fiber breakage in composites can be simulated through incorporation of an appropriate damage and failure model that operates within MAC/GMC on the level of the fiber. Results are presented for the progressive failure analysis of a titanium matrix composite tensile specimen that illustrate the power and utility of the framework and address the techniques needed to model the statistical nature of the problem properly. In particular, it is shown that incorporating fiber strength randomness on multiple scales imp...

Research paper thumbnail of Micromechanics Analysis Code With Generalized Method of Cells (MAC/GMC): User Guide

The ability to accurately predict the thermomechanical deformation response of advanced composite... more The ability to accurately predict the thermomechanical deformation response of advanced composite materials continues to play an important role in the development of these strategic materials. Analytical models that predict the effective behavior of composites are used not only by engineers performing structural analysis of large-scale composite components but also by material scientists in developing new material systems. For an analytical model to fulfill these two distinct functions it must be based on a micromechanics approach which utilizes physically based deformation and life constitutive models and allows one to generate the average (macro) response of a composite material given the properties of the individual constituents and their geometric arrangement. Here the user guide for the recently developed, computationally efficient and comprehensive micromechanics analysis code, MAC, who's predictive capability rests entirely upon the fully analytical generalized method of ...