Download or read book Implementation of Fiber Substructuring Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-15 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to impact loads. Previously, strain rate dependent inelastic constitutive equations developed to model the polymer matrix were incorporated into a mechanics of materials based micromechanics method. In the current work, the micromechanics method is revised such that the composite unit cell is divided into a number of slices. Micromechanics equations are then developed for each slice, with laminate theory applied to determine the elastic properties, effective stresses and effective inelastic strains for the unit cell. Verification studies are conducted using two representative polymer matrix composites with a nonlinear, strain rate dependent deformation response. The computed results compare well to experimentally obtained values.Goldberg, Robert K.Glenn Research CenterDEFORMATION; ELASTIC PROPERTIES; FAILURE ANALYSIS; POLYMER MATRIX COMPOSITES; NUMERICAL ANALYSIS; CONSTITUTIVE EQUATIONS; STRAIN RATE; NONLINEARITY; MICROMECHANICS; LAMINATES; IMPACT LOADS
Download or read book Implementation of Fiber Substructuring Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites written by and published by . This book was released on 2001 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Implementation of Laminate Theory Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites written by Robert K. Goldberg and published by . This book was released on 2000 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rate Dependent Deformation and Strength Analysis of Polymer Matrix Composites written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-16 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: A research program is being undertaken to develop rate dependent deformation and failure models for the analysis of polymer matrix composite materials. In previous work in this program, strain-rate dependent inelastic constitutive equations used to analyze polymers have been implemented into a mechanics of materials based composite micromechanics method. In the current work, modifications to the micromechanics model have been implemented to improve the calculation of the effective inelastic strain. Additionally, modifications to the polymer constitutive model are discussed in which pressure dependence is incorporated into the equations in order to improve the calculation of constituent and composite shear stresses. The Hashin failure criterion is implemented into the analysis method to allow for the calculation of ply level failure stresses. The deformation response and failure stresses for two representative uniaxial polymer matrix composites, IM7/977-2 and AS4-PEEK, are predicted for varying strain rates and fiber orientations. The predicted results compare favorably to experimentally obtained values.Goldberg, Robert K. and Stouffer, Donald C.Glenn Research CenterPOLYMER MATRIX COMPOSITES; DEFORMATION; STRAIN RATE; FAILURE ANALYSIS; MICROMECHANICS; PRESSURE DEPENDENCE; SHEAR STRESS; FIBER ORIENTATION; FAILURE; CONSTITUTIVE EQUATIONS; CRITERIA
Download or read book Strain Rate Dependent Modeling of Polymer Matrix Composites written by Robert K. Goldberg and published by . This book was released on 1999 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Strain Rate Deformation Modeling of a Polymer Matrix Composite Part 2 Composite Micromechanical Model written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-05 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this second paper of a two part report, a three-dimensional composite micromechanical model is described which allows for the analysis of the rate dependent, nonlinear deformation response of a polymer matrix composite. Strain rate dependent inelastic constitutive equations utilized to model the deformation response of a polymer are implemented within the micromechanics method. The deformation response of two representative laminated carbon fiber reinforced composite materials with varying fiber orientation has been predicted using the described technique. The predicted results compare favorably to both experimental values and the response predicted by the Generalized Method of Cells, a well-established micromechanics analysis method. Goldberg, Robert K. and Stouffer, Donald C. Glenn Research Center RTOP 523-24-13...
Download or read book Ls Dyna Implementation of Polymer Matrix Composite Model Under High Strain Rate Impact written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: A recently developed constitutive model is implemented into LS-DYNA as a user defined material model (UMAT) to characterize the nonlinear strain rate dependent behavior of polymers. By utilizing this model within a micromechanics technique based on a laminate analogy, an algorithm to analyze the strain rate dependent, nonlinear deformation of a fiber reinforced polymer matrix composite is then developed as a UMAT to simulate the response of these composites under high strain rate impact. The models are designed for shell elements in order to ensure computational efficiency. Experimental and numerical stress-strain curves are compared for two representative polymers and a representative polymer matrix composite, with the analytical model predicting the experimental response reasonably well. Zheng, Xia-Hua and Goldberg, Robert K. and Binienda, Wieslaw K. and Roberts, Gary D. Glenn Research Center NASA/TM-2003-212583, E-14123, NAS 1.15:212583
Download or read book Experimental and Computational Characterization of the High Strain Rate Tensile Response of Polymer Matrix Composites written by RK. Goldberg and published by . This book was released on 2003 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: A research program is underway to experimentally characterize the strain rate dependent deformation and failure response of polymer matrix composites subject to high strain rate impact loads and to develop strain rate dependent deformation and failure models for the analysis of these types of materials. State variable constitutive equations based on a viscoplasticity approach have been developed to model the deformation of the polymer matrix. The constitutive equations are then combined with a mechanics of materials based micromechanics model which utilizes fiber substructuring to predict the effective mechanical and thermal response of the composite. Tensile stress-strain curves for a representative composite are obtained experimentally for strain rates ranging from quasi-static to several hundred per second. The developed numerical procedure is also used to compute the deformation response. The predictions compare favorably to the experimentally obtained values both qualitatively and quantitatively. Effective elastic and thermal constants are predicted for another composite, and compared to finite element results.
Download or read book Computational Simulation of the High Strain Rate Tensile Response of Polymer Matrix Composites written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: A research program is underway to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. Under these types of loading conditions, the material response can be highly strain rate dependent and nonlinear. State variable constitutive equations based on a viscoplasticity approach have been developed to model the deformation of the polymer matrix. The constitutive equations are then combined with a mechanics of materials based micromechanics model which utilizes fiber substructuring to predict the effective mechanical and thermal response of the composite. To verify the analytical model, tensile stress-strain curves are predicted for a representative composite over strain rates ranging from around 1 x 10(exp -5)/sec to approximately 400/sec. The analytical predictions compare favorably to experimentally obtained values both qualitatively and quantitatively. Effective elastic and thermal constants are predicted for another composite, and compared to finite element results. Goldberg, Robert K. Glenn Research Center NASA/TM-2002-211489, E-13257, NAS 1.15:211489
Download or read book Strain Rate Dependent Deformation and Strength Modeling of a Polymer Matrix Composite Utilizing a Micromechanics Approach written by Robert Keith Goldberg and published by . This book was released on 1999 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Strain Rate Deformation Modeling of a Polymer Matrix Composite written by and published by . This book was released on 1998 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Incorporation of Mean Stress Effects Into the Micromechanical Analysis of the High Strain Rate Response of Polymer Matrix Composites written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results presented here are part of an ongoing research program, to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. A micromechanics approach is employed in this work, in which state variable constitutive equations originally developed for metals have been modified to model the deformation of the polymer matrix, and a strength of materials based micromechanics method is used to predict the effective response of the composite. In the analysis of the inelastic deformation of the polymer matrix, the definitions of the effective stress and effective inelastic strain have been modified in order to account for the effect of hydrostatic stresses, which are significant in polymers. Two representative polymers, a toughened epoxy and a brittle epoxy, are characterized through the use of data from tensile and shear tests across a variety of strain rates. Results computed by using the developed constitutive equations correlate well with data generated via experiments. The procedure used to incorporate the constitutive equations within a micromechanics method is presented, and sample calculations of the deformation response of a composite for various fiber orientations and strain rates are discussed.Goldberg, Robert K. and Roberts, Gary D. and Gilat, AmosGlenn Research CenterCONSTITUTIVE EQUATIONS; DEFORMATION; IMPACT LOADS; MICROMECHANICS; POLYMER MATRIX COMPOSITES; STRAIN RATE; BRITTLENESS; EPOXY RESINS; FAILURE ANALYSIS; FIBER ORIENTATION; HYDROSTATICS; MATRIX MATERIALS; TENSILE TESTS; SHEAR PROPERTIES
Download or read book Incorporation of Mean Stress Effects Into the Micromechanical Analysis of the High Strain Rate Response of Polymer Matrix Composites written by and published by . This book was released on 2002 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book LS DYNA Implementation of Polymer Matrix Composite Model Under High Strain Rate Impact written by and published by . This book was released on 2003 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Strain Rate Deformation Modeling of a Polymer Matrix Composite Part 1 Matrix Constitutive Equations written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-05 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites. Goldberg, Robert K. and Stouffer, Donald C. Glenn Research Center RTOP 523-24-13...
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2005 with total page 960 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structural Health Monitoring 2013 A Roadmap to Intelligent Structures written by Fu-Kuo Chang and published by DEStech Publications, Inc. This book was released on 2013-09-26 with total page 1434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Original research on SHM sensors, quantification strategies, system integration and control for a wide range of engineered materials New applications in robotics, machinery, as well as military aircraft, railroads, highways, bridges, pipelines, stadiums, tunnels, space exploration and energy production Continuing a critical book series on structural health monitoring (SHM), this two-volume set (with full-text searchable CD-ROM) offers, as its subtitle implies, a guide to greater integration and control of SHM systems. Specifically, the volumes contain new research that will enable readers to more efficiently link sensor detection, diagnostics/quantification, overall system functionality, and automated, e.g., robotic, control, thus further closing the loop from inherent signal-based damage detection to responsive real-time maintenance and repair. SHM performance is demonstrated in monitoring the behavior of composites, metals, concrete, polymers and selected nanomaterials in a wide array of surroundings, including harsh environments, under extreme (e.g., seismic) loading and in space. New information on smart sensors and network optimization is enhanced by novel statistical and model-based methods for signal processing and data quantification. A special feature of the book is its explanation of emerging control technologies. Research in these volumes was initially presented in September 2013 at the 9th International Workshop on Structural Health Monitoring (IWSHM), held at Stanford University and sponsored by the Air Force Office of Scientific Research, the Army Research Laboratory, and the Office of Naval Research.
