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Author : Erik Saether
Publisher :
ISBN 13 :
Total Pages : 145 pages
Book Rating : 4.:/5 (612 download)
Download or read book RESTRAN: Residual Strength Analysis of Impact Damaged Composite Laminates written by Erik Saether and published by . This book was released on 2001 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 129 pages
Book Rating : 4.:/5 (946 download)
Download or read book RESTRAN: Residual Strength Analysis of Impact Damaged Composite Laminates. Volume I: Theoretical Manual written by and published by . This book was released on 2001 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of composite material systems in structural design has yielded significant improvements in material efficiency by minimizing weight while meeting static and dynamic strength requirements. The complexity of composite materials, however, has presented a spectrum of additional design considerations in the areas of fabrication, strength tailoring, failure mechanisms, and damage tolerance. Laminated composites exhibit a variety of damage and failure modes which include matrix cracking, fiber breakage, delamination propagation, and instability. Of prime concern is the predication of residual strength in composite structures subjected to damage-causing impact threats in the intended service environment. The present effort aims to account for many of the salient damage mechanisms utilizing a numerical, finite element-based approach. Such an approach permits a broad range of failure modes to be accounted for while allowing the modeling of complex geometries, support conditions, and applied loading. This report details the theoretical and algorithmic basis of a developed computer program denoted RESTRAN (REsidual STRength ANalysis), incorporating both material and structural failure modes in the prediction of residual strength in composite structures containing internal damage.
Author :
Publisher :
ISBN 13 : 9781423527664
Total Pages : 159 pages
Book Rating : 4.5/5 (276 download)
Download or read book RESTRAN: Residual Strength Analysis of Impact Damaged Composite Laminates written by and published by . This book was released on 2001-07-01 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 (3-D) geometry, loading and 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 due to 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.
Author : Erik Saether
Publisher :
ISBN 13 : 9781423527657
Total Pages : 129 pages
Book Rating : 4.5/5 (276 download)
Download or read book RESTRAN: Residual Strength Analysis of Impact Damaged Composite Laminates written by Erik Saether and published by . This book was released on 2001-07-01 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of composite material systems in structural design has yielded significant improvements in material efficiency by minimizing weight while meeting static and dynamic strength requirements. The complexity of composite materials, however, has presented a spectrum of additional design considerations in the areas of fabrication, strength tailoring, failure mechanisms, and damage tolerance. Laminated composites exhibit a variety of damage and failure modes which include matrix cracking, fiber breakage, delamination propagation, and instability. Of prime concern is the predication of residual strength in composite structures subjected to damage-causing impact threats in the intended service environment. The present effort aims to account for many of the salient damage mechanisms utilizing a numerical, finite element- based approach. Such an approach permits a broad range of failure modes to be accounted for while allowing the modeling of complex geometries, support conditions, and applied loading. This report details the theoretical and algorithmic basis of a developed computer program denoted RESTRAN (REsidual STRength ANalysis), incorporating both material and structural failure modes in the prediction of residual strength in composite structures containing internal damage.
Author :
Publisher :
ISBN 13 :
Total Pages : 159 pages
Book Rating : 4.:/5 (946 download)
Download or read book RESTRAN: Residual Strength Analysis of Impact Damaged Composite Laminates. Volume II: User's Manual written by and published by . This book was released on 2001 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 (3-D) geometry, loading and 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 due to 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.
Author : D. E. Pettit
Publisher :
ISBN 13 :
Total Pages : 344 pages
Book Rating : 4.:/5 (319 download)
Download or read book Advanced Residual Strength Degradation Rate Modeling for Advanced Composite Structures written by D. E. Pettit and published by . This book was released on 1979 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents the results of the first task of a three task program directed at the study of relationship between damage propagation and residual static strength of composite laminates. In Task 1: Preliminary screening, two laminates a 24-Ply 67% 0 deg. fiber and a 32-Ply quasi-isotropic laminate of T300/5208 graphite epoxy material were selected for study. Two damage types were studied, a low velocity impact condition (i.e., simulated tool drop) and a badly drilled hole. An initial study was conducted for each damage type to determine the detailed damage introduction parameters resulting in the selection of one set of impact and one set of poor drilling conditions. Baseline static tension and static compression tests were conducted on each of the four damage/laminate conditions. Stress vs life (S-N) fatigue data were then generated at range ratio R=-1 for each of the four conditions. The damage growth characteristics were monitored on each fatigue specimen using a modified Holscan ultrasonic unit. A subset of the damaged hole specimens was also evaluated in static compression and fatigue (R = -1) using TBE enhanced X-ray methods to monitor damage growth and to assess any detrimental effect of TBE on subsequent behavior of the damage. The results indicate significant reduction in initial static tension and compression strengths for the damaged hole condition in both laminates.
Author : K. N. Lauraitis
Publisher :
ISBN 13 :
Total Pages : 334 pages
Book Rating : 4.:/5 (319 download)
Download or read book Advanced Residual Strength Degradation Rate Modeling for Advanced Composite Structures written by K. N. Lauraitis and published by . This book was released on 1981 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents the results of the first task of the last two tasks of a three-task program focusing on the study of relationship between damage propagation and residual strength of graphite/epoxy laminates. Specimens of two laminate types, a 32-ply quasi-isotropic and 24-ply 67%-0, containing a centered poorly drilled hole were evaluated in this study. Baseline static tension and compression tests were conducted at high and low strain rates and at elevated temperature.
Author : Erik Saether
Publisher :
ISBN 13 :
Total Pages : 62 pages
Book Rating : 4.:/5 (359 download)
Download or read book Modeling Considerations in the Prediction of Residual Strength in Composite Laminates written by Erik Saether and published by . This book was released on 1994 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Kenneth L. Reifsnider
Publisher :
ISBN 13 :
Total Pages : 58 pages
Book Rating : 4.:/5 (319 download)
Download or read book Fatigue Damage-strength Relationships in Composite Laminates. Volume 1 written by Kenneth L. Reifsnider and published by . This book was released on 1983 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report is Vol. I of a 2-part final report on the activities which were conducted under Contract No. F33615-81-3225. The general objective of this program was to investigate the precise nature of the damage events caused by cyclic (fatigue) loading of composite laminates that are directly related to fracture of those laminates, to develop a conceptual understanding of how those damage events reduce the residual strength of the laminates, and to determine how the collective damage condition following long-term cyclic loading precipitates the final fracture event. The program was conducted in four phases: (1) the development of fatigue damage during long-term cyclic loading was investigated in such a way that the damage events which occur quite late in the fatigue life of the material, just prior to fracture, were identified and characterized; (2) the special contribution and nature of fiber fracture was investigated; (3) the nature of the collective damage condition which precipitates the fracture event under long-term fatigue loading was investigated; (4) a philosophy of fracture in composite laminates following severe damage development due to cyclic loading was developed. A wide variety of destructive and nondestructive experimental evaluation schemes were used in the program, and several analytical efforts were conducted to support the experimental activities.
Author : WB. Avery
Publisher :
ISBN 13 :
Total Pages : 25 pages
Book Rating : 4.:/5 (125 download)
Download or read book Effects of Stacking Sequence on Impact Damage Resistance and Residual Strength for Quasi-Isotropic Laminates written by WB. Avery and published by . This book was released on 1991 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Residual strength of an impacted composite laminate is dependent on details of the damage state. Stacking sequence was varied to judge its effect on damage caused by low-velocity impact. This was done for quasi-isotropic layups of a toughened composite material. Experimental observations on changes in the impact damage state and post-impact compressive performance were presented for seven different laminate stacking sequences. The applicability and limitations of analysis compared to experimental results were also discussed.
Author : CE. Harris
Publisher :
ISBN 13 :
Total Pages : 7 pages
Book Rating : 4.:/5 (125 download)
Download or read book A Progressive Damage Model and Analysis Methodology for Predicting the Residual Strength of Composite Laminates written by CE. Harris and published by . This book was released on 2006 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The durability and damage tolerance of laminated composites are critical design considerations for airframe composite structures. Therefore, the ability to model damage initiation and growth and predict the life of laminated composites is necessary to achieve efficient and economical structural designs. The purpose of the research presented in this paper is to experimentally verify the application of the damage model developed by the authors to predict progressive damage development in a toughened material system. Damage growth, stiffness degradation, and residual strength were experimentally determined for cross-ply and quasi-isotropic IM7/5260 graphite/bismaleimide laminates due to monotonic and tension-tension fatigue. The damage model, which has been implemented into a finite element code, was used to predict the stiffness loss and residual strength of unnotched and notched laminates. The model predictions were in good agreement to experimental results for several different fatigue loading histories and several different laminate stacking sequences.
Author : Douglas Scott Cairns
Publisher :
ISBN 13 :
Total Pages : 30 pages
Book Rating : 4.:/5 (95 download)
Download or read book Residual Tensile Strength of Graphite/epoxy and Kevlar/epoxy Laminates with Impact Damage written by Douglas Scott Cairns and published by . This book was released on 1988 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to examine the damage tolerance of composite laminates with impact damage. A model is presented to predict the residual strength of such laminates. The in-plane strain distribution near the region of damage is determined using Lekhnitskii's solution for an anisotropic inclusion in an anisotropic medium with compromised constitutive properties of the impact region used for the properties of the inclusion. The residual strength is then predicted using an average criterion based on strain. Results from experiments of impacted specimens of [±45/0]s Kevlar/epoxy and [±45/0]2s graphite/epoxy show good correlation with the analytical predictions. The model is applied over a wide range of impactor conditions with equally good results. Although the damage was inflicted with different impactor masses, velocities, and laminate boundary conditions, the data indicates that the residual strength is only a function of the damage present and not the manner in which the damage is introduced. The use of the measured damage in conjunction with the predicted properties of the compromised region thus shows good promise to be applied over a wide range of structures in a practical fashion. An overall analytical philosophy to deal with the problem of impact in composite laminates is discussed.
Author : Kenneth L. Reifsnider
Publisher :
ISBN 13 :
Total Pages : 60 pages
Book Rating : 4.:/5 (319 download)
Download or read book Fatigue Damage-Strength Relationships in Composite Laminates. Volume 2 written by Kenneth L. Reifsnider and published by . This book was released on 1984 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents information and experience generated during the subject investigation which provided support for the major thrust of the effort, but was not the eventual focus of the program. The activities are discussed in the context of the various experimental techniques used (and developed) to investigate the context of the damage development. Whil much of the information discussed is not complete, it is thought that a description of the experimental methods and experiences will be valuable to the technical community. Included are descriptions of virtually every experimental technique used in this program and a variety of findings not discussed elsewhere.
Author : S. Girshovich
Publisher :
ISBN 13 :
Total Pages : 12 pages
Book Rating : 4.:/5 (125 download)
Download or read book Residual Strength of Impacted Composites written by S. Girshovich and published by . This book was released on 1994 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The influence of impact damage on the structural performance of composite laminates was investigated by a joint effort including nondestructive evaluation (NDE), mechanical testing, and analysis. The impacted NASA-Industry Standard Compression After Impact test specimen was chosen. Damage characterization was based on ultrasonic methods. Computerized ultrasonic inspection from both sides of the test panels provided accurate information on the damage area. From the NDE data a simplified damage model was constructed and analyzed for strength and stability. Failure loads and modes were predicted. Compression after impact tests were performed for various materials and applied impact energies. All test results were in very good agreement with the analytical predictions.
Author : Alan T. Nettles
Publisher : BiblioGov
ISBN 13 : 9781289172831
Total Pages : 30 pages
Book Rating : 4.1/5 (728 download)
Download or read book Damage Tolerance of Composite Laminates from an Empirical Perspective written by Alan T. Nettles and published by BiblioGov. This book was released on 2013-07 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Damage tolerance consists of analysis and experimentation working together. Impact damage is usually of most concern for laminated composites. Once impacted, the residual compression strength is usually of most interest. Other properties may be of more interest than compression (application dependent). A damage tolerance program is application specific (not everyone is building aircraft). The "Building Block Approach" is suggested for damage tolerance. Advantage can be taken of the excellent fatigue resistance of damaged laminates to save time and costs.
Author : Muhammad Munir Zanial
Publisher :
ISBN 13 :
Total Pages : 156 pages
Book Rating : 4.:/5 (15 download)
Download or read book Effects of Large Damage on Residual Strength of Carbon Fiber Reinforced Composite Laminates written by Muhammad Munir Zanial and published by . This book was released on 2014 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tension or compression fracture behavior studies are normally initiated with open hole tension or compression tests performed at the laminate level. While these test data serve as an excellent starting point in residual strength studies in small notch sizes, the need to evaluate and verify the residual strength for larger structures and at larger notch sizes region is still there. An experimental study was performed with the focus on large notch sizes of circular hole and narrow slit flaw configurations on laminates fabricated with a carbon/epoxy oven-cure capable prepreg material system. The current part of the study focused on uniaxial tension loading with a constant width and height to flaw dimension ratio. Experimental test data were then combined with lamina and laminate level data for residual strength curves generation and the curves were validated against Whitney-Nuismer and Mar-Lin fracture mechanics models. The effects of flaw sizes and the flaw type towards the residual strength capability of a laminate turn out to be substantial as the notch size gets larger than one inch. Test results showed that a narrow slit or saw cut damage is far more critical than a circular hole cut-out. The notch sensitivity order of a saw cut flaw is also roughly three times more than that of a circular hole. Analytical studies were also performed to evaluate several finite element method variable effects on residual strength prediction and to discover the best practice in stress analyses of notched composite laminates. Point Stress failure criterion was used in the analyses and predicted failure loads were compared to the experimental data. Good agreements and correlations were found between the analytical predictions and the experimental data. It can be concluded that the residual strength of a notched laminated composite can be reasonably predicted from finite element analyses.
Author : Steven Gary Llorente
Publisher :
ISBN 13 :
Total Pages : 522 pages
Book Rating : 4.:/5 (153 download)
Download or read book The Residual Strength of Graphite/epoxy Sandwich Laminates Due to Impact Damage and Environmental Conditioning written by Steven Gary Llorente and published by . This book was released on 1986 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt: The residual strength of graphite/epoxy sandwich laminates due to impact damage and environmental conditioning was investigated. Two specimen configurations and two layups were used to determine the effect of these factors in both tension and compression. The effects of environmental conditioning and physical damage are found to be both layup and load direction dependent. The influence of environmental conditioning on a sandwich structure is examined. The absorption qualities of the filament wound graphite epoxy facesheets is experimentally determined. It is found that moisture plays a larger role in the compressive behavior of graphite/epoxy sandwich laminates than in the tensile behavior, and that degradation is more severe at higher temperatures. Impact damage to the composite, even at barely detectable damage levels, is found to be detrimental to the performance of the structure under load. Low energy level impact is shown by photomicrography to cause delamination between the plies of the composite facesheets. The effect of severe impact damage is investigated via specimens damaged with the crosshead shaped impactor. Finally, the loss of the facesheet-to-core adhesive bond is simulated using compression specimens with implanted circular debonds. It is found that interlaminar stresses resulting in delamination between the facesheet plies is a cause of failure in the virgin specimens. The severe impact damage test results are correlated with a fracture stress analysis. A comparison with the properties of the pre-impregnated graphite/epoxy material system is made.
