Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 56
Going to Extremes: Meeting the Emerging Demand for Durable Polymer Matrix Composites Appendix E Survey of Some Computational Models for Failure, Damage, and Degradation in Composite Materials Code General Survey Detailed Information Note ABAQUS General-purpose finite-element package with wide variety of element types, suitable for analysis of laminate shells and nonlinear behavior of polymeric materials. General-purpose, extensive finite-element package with wide variety of element types suitable for analysis of laminate shells and nonlinear behavior of plastics. Currently, ABAQUS utilizes the virtual crack closure technique (VCCT), which has been used by Boeing and plays an important role in the design of aero structures involving composites. Development of this implementation of the VCCT was sponsored by the Composite Affordability Initiative, of which Boeing is a member. Boeing has filed a patent application for this implementation of the VCCT, and ABAQUS, Inc., will market the technology. Commercial code Algor General-purpose, low-cost finite-element package with composite elements. Extensive information available online, including case studies and tutorials. General-purpose, low-cost, finite-element package with composite elements. Tons of info online, including case studies and tutorials. Use their search engine. Commercial code Analysis of Progressive Failure in Laminated Composites This work was done by David W. Sleight of Langley Research Center. For further information, access the technical support package free online at <http://www.nasatech.com> under materials category L-17660. A computational methodology for predicting the initiation and propagation of failures in laminated matrix/fiber composite material structures has been developed. The Laboratory
OCR for page 57
Going to Extremes: Meeting the Emerging Demand for Durable Polymer Matrix Composites Code General Survey Detailed Information Note methodology follows the progressive-failure approach, in which it is recognized that a laminated composite structure can develop local failures or exhibit such local damage as matrix cracks, fiber breakage, fiber/matrix debonds, and delaminations under normal operating conditions and that such damage can contribute to the eventual failure of the structure. The ability to predict the initiation and growth of such damage is essential for predicting the performances of composite structures and developing reliable, safe designs that exploit the advantages offered by composite materials. ANSYS A general finite-element package comparable in capabilities to NASTRAN. Most online info is in pdf format. A method for incorporating a damage model for composite structures into the ANSYS general-purpose, finite-element program was developed using MRLife, a damage model developed at Virginia Polytechnic Institute and State University. The damage model was incorporated into a subroutine linked to ANSYS, creating a life prediction system in which entire composite structures can be evaluated for damage using realistic geometry and loading. Commercial code bmi3 Buckling analysis of composite shells, including postcritical path, using ABAQUS. Free executable for DEC/Alpha and SGI UNIX. Site includes full text paper, which documents the program. COSMOS/M Mid-range, general-purpose package from SRAC. Information available onsite. Primarily for PCs but available on some workstations. Mid-range, general-purpose package from SRAC. It has included several different modules, such as advanced nonlinear analysis, stress and displacement analysis, buckling and frequency analysis, heat transfer analysis, dynamic response analysis, fatigue analysis, and design optimization. This package has been used for analysis of failure in composite materials. Commercial code
OCR for page 58
Going to Extremes: Meeting the Emerging Demand for Durable Polymer Matrix Composites Code General Survey Detailed Information Note DYNA3D Using user-defined material (UDM), the package can be used for composite/plastic analysis. A finite-element code developed at Lawrence Livermore National Laboratory. The composite damage model used was for progressive damage of polymer matrix composites as developed at the Stanford University composites and structures group. The DYNA3D code used is an explicit three-dimensional finite-element code for the nonlinear dynamic analysis of materials and structures. The composite damage model used is based on the work of Fu-Kuo Chang and the thesis project of Iqbal Shahid (1993). The implementation of the model into DYNA3D was performed by Steven Kirkpatrick as an independent research project with the assistance of Prof. Chang and Dr. Shahid. Laboratory Dynamic Composite Simulator module of LS-DYNA This enhancement to LS-DYNA enables the most effective and accurate dynamic progressive failure modeling of composite structures currently available. The integration of this module, known as MAT 161, into LS-DYNA allows users to account for progressive damage of various fiber, matrix, and interplay delamination failure modes. Implementing this code will result in the ability to optimize the design of composite structures, with significantly improved survivability under various blast and ballistic threats. Commercial code FEMAP General pre- and postprocessor for finite-element analysis. Not a solver itself but interfaces with 20 different programs. Has a good interface for defining laminates. SDRC also offers structural and thermal solver modules based on the I-DEAS engine. GENOA Structural analysis, part manufacturability, virtual testing, micromechanics. Supports braids, weaves, laminates, stitched laminates. GENOA was selected to receive the Software of the Year award from NASA in 1999 for its unique predictive capabilities of aging and failure of structural materials. Dedicated to the high-speed analysis of next-generation materials, the GENOA software Commercial code
OCR for page 59
Going to Extremes: Meeting the Emerging Demand for Durable Polymer Matrix Composites Code General Survey Detailed Information Note package employs cutting-edge technology from the fields of composites, structures, and parallel computing sciences to deliver unequaled performance and analytical capability directly into the hands of today's engineers. This package can calculate the equivalent material properties of metallic, polymer, and ceramic composites. Evaluates the structural and material response, including life cycle, degradation of material properties due to initiation, location of failure, and growth of damage under in-service operations and environments (static, dynamic, thermal, creep, impact, and low/high/random frequency cyclic fatigue). Identifies the percent contribution of various possible composite failure modes. Predicts the inspection interval, incipient damage locations, and margins of safety. I-DEAS Full-featured CAD system from SDRC, including built-in FEA (or use as a pre- and postprocessor for other systems). Powerful laminates module with a sometimes awkward interface. INERTIA Modular finite-element package from Meridian Marketing. Parametric modeler; structural, dynamic, and thermal analyses; and more. LAMPAT Finite element pre- and postprocessor for analyzing thick composite laminates. Integrates with PATRAN. Originally developed by the U.S. Army Research Laboratory. LUSAS A Collection of finite-element programs, including bridge, structural, civil, composite, and analyst (for general FEA). Detailed product descriptions and case studies.
OCR for page 60
Going to Extremes: Meeting the Emerging Demand for Durable Polymer Matrix Composites Code General Survey Detailed Information Note MAC/GMC (Micromechanics Analysis Code with Generalized Method of Cells) This code was authored by NASA Glenn Research Center. MAC/GMC is a comprehensive, user-friendly, efficient computer program that predicts the elastic and inelastic thermomechanical responses of continuous and discontinuous composite materials with arbitrary internal microstructures and reinforcement shapes. It enables the efficient analysis of composite structures subjected to complex thermomechanical load histories. MAC/GMC won second place in the 1997 NASA Software of the Year competition and has been applied in industrial, government, and academic settings to such diverse composite-material structures as turbine parts, tires, and even brain tissue. Laboratory MECANO Software for nonlinear analysis, including structures, mechanisms, and cables. MRLife MRLife calculates the residual or remaining strength during the application of cyclic loading and compares this value to the failure function. As cyclic loading is applied, the remaining strength will decrease as a result of damage to the composite material. The failure function is based on the applied loading and the known strength of the composite. When the remaining strength decreases enough so that it reaches the value of the failure function, failure of the composite occurs. MRLife predicts the residual life at any time in addition to predicting failure. Commercial code MSC. NASTRAN MSC.NASTRAN can be efficiently and effectively used to model laminated composites. MSC.NASTRAN allows the user to specify the material properties, orientation, and thickness for each lamina in the composite layup. The program then calculates the properties of the equivalent plate. This automatic representation of laminated composites is available in all MSC.NASTRAN solution sequences; however, stresses, strains, and failure indices can be recovered at the lamina Commercial code
OCR for page 61
Going to Extremes: Meeting the Emerging Demand for Durable Polymer Matrix Composites Code General Survey Detailed Information Note level for only statics, normal modes, and nonlinear statics. In addition, MSC.NASTRAN can be used for multidisciplinary structural optimization of laminated composite materials. MSC.PATRAN MSC’s pre- and postprocessor, compatible with several codes. Specialized modules include a materials database and a laminate modeler. MSC.PATRAN laminate modeler is an MSC.PATRAN 2003 application module to aid engineers in the design, analysis, and manufacture of laminated composite structures. Commercial code NASTRAN PC NASTRAN compatible with FEMAP. ME/NASTRAN included for full-feature support. PDALC (Progressive Damage Analysis of Laminated Composite) PDALC is a computational model implemented in the NASA COMET finite-element code. The relationship employed in this analysis describes the matrix crack damage and fiber fracture via kinematics-based, volume-averaged variables. Damage accumulation during monotonic and cyclic loads is predicted by damage evolution laws for tensile load conditions. The implementation of this damage model required the development of two testbed processors. The damage accumulation, stress redistribution, and changes to the global response that occur during the load history can be calculated for laminates subjected to monotonic and cyclic loads. Laboratory Pro/ MECHANICA The simulation portion of Pro/ENGINEER. Full analysis can be run within Pro/E, or it can be used with an external solver. It has the capability to solve laminated shells. RESTRAN (Residual Strength Analysis of Impact Damaged Composite Laminates) This code is developed at the Army Research Laboratory at Aberdeen Proving Ground in Maryland. A general predictive methodology for determining residual strength in impact-damaged composite laminates has been developed and incorporated into a computer code designated RESTRAN (REsidual STRength ANalysis). RESTRAN is a finite-element-based design tool that can analyze composite structures with arbitrary three-dimensional geometry, loading and Laboratory
OCR for page 62
Going to Extremes: Meeting the Emerging Demand for Durable Polymer Matrix Composites Code General Survey Detailed Information Note support conditions, material properties, and initial material and delamination damage. Material failure modes are predicted using a robust suite of failure criteria and damage laws. Structural failure as a result of sequential sublaminate buckling of delaminated layers is also accounted for. A progressive failure analysis is performed until ultimate structural failure is predicted, thereby yielding an estimate of the residual strength. This report contains a user's manual for the RESTRAN program with complete descriptions of input statements and program output. Several examples are shown to illustrate the use of the RESTRAN computer code. SOLVIA General-purpose finite-element program with integrated pre- and postprocessor. Laminate and concrete elements. STAGS An open-source finite-element program for general-purpose analysis of shell structures. STAGS 2.0 is a finite-element program for general-purpose analysis of shell structures. STAGS can be applied to linear systems, but its forte is the analysis of complex, nonlinear systems that depend on post-buckling strength and require analysis well into the postbuckled regime. It is routinely used for pre- and post-test verification of complex systems, especially those sensitive to initial geometric imperfections. Analysis capabilities include stress, stability, vibration, and transient analyses, with both material and geometric nonlinearities permissible. Shells may be thin or thick, with or without stiffeners, which may be modeled either as beams or as shells. The availability of numerous wall fabrication and stiffener-cross-section options, combined with a variety of material models, permits tremendous flexibility in modeling a wide spectrum of construction types. Isotropic and orthotropic materials are permitted. Easily defined standard wall types include laminate composite, permitting up to 100 layers of arbitrary orientation, and corrugation-stiffened composite. STAGS has been under
OCR for page 63
Going to Extremes: Meeting the Emerging Demand for Durable Polymer Matrix Composites Code General Survey Detailed Information Note continuous development since the 1960s by Lockheed's Research and Development Division. STRANAL-PMC (Strain Rate Dependent Analysis of Polymer Matrix Composites) This program was written by Robert K. Goldberg of Glenn Research Center and is available free online at <http://www.nasatech.com/tsp> under the Software category. This computer program is for analyzing strain-rate-dependent, nonlinear deformation and failure responses of composite materials in which the matrices are ductile polymers. Modified versions of the Ramaswamy-Stouffer constitutive equations of viscoplasticity, originally developed for metals, are used to represent deformation of a polymeric matrix. The equations are applied in a micromechanical approach, in which each unit cell is divided into several slices. Appropriate uniform stress and uniform strain assumptions, along with the constitutive equations for the fiber and matrix, are used to compute the response of the slice. Laminate theory is then applied to obtain the effective response of a ply and is applied again to obtain the effective response of a multilayered composite laminate. To predict the ultimate strength of each composite ply, the Hashin failure criteria are implemented within the micromechanics. The constitutive equations are integrated in time by a Runge-Kutta technique. The inputs to STRANAL-PMC are the geometry of the composite laminate, the properties of the fiber and matrix materials, and the applied stress or strain versus time. The outputs of STRANAL-PMC are the stress and strain at the slice, ply, and laminate levels at each time step. Laboratory SYSPLY Finite-element program for design and optimization of composite structures. Extensive capabilities include micromechanics, 3D stresses, winding options, and more.
Representative terms from entire chapter: