Download or read book Advanced Fatigue Damage Development in Graphite Epoxy Laminates written by Russell Douglas Jamison and published by . This book was released on 1982 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of an experimental investigation of damage development in T300/5208 graphite epoxy laminates subjected to tension-tension cyclic loading are reported. The concept of laminate stiffness reduction as a damage analogue is shown to be a valuable means of test control and damage interpretation. The relationship between stiffness and number of cycles is shown to be unique for each laminate type studied, each possessing three distinct stages, but markedly different among the laminate types. By using two complementary nondestructive evaluation (NDE) techniques, edge replication and penetrant-enhanced stereo X- ray radiography along with a method for deploying fatigue-damaged specimens, the stages of stiffness reduction were found to correspond variously to the predominance of matrix cracking or delamination or interactions of these matrix damage modes. A number of subordinate matrix damage modes including interior delamination, microcracking, and longitudinal splitting are identified with the matrix cracks which produce them.
Download or read book Advanced Fatigue Damage Development in Graphite Epoxy Laminates written by Russell Douglas Jamison and published by . This book was released on 1982 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Fatigue Damage Development in Graphite Epoxy Laminates written by Russell Douglas Jamison and published by . This book was released on 1982 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Experimental and Analytical Study of Fatigue Damage in Notched Graphite epoxy Laminates written by and published by . This book was released on 1979 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Damage Development Mechanisms in Notched Graphite Epoxy Composite Laminates During Compressive Fatigue Loading written by Norman Frederick Black and published by . This book was released on 1981 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 336 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.
Download or read book Initiation and growth of fatigue damage in graphite epoxy and graphite peek laminates written by Claes-Göran Gustafson and published by . This book was released on 1988 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Analytical Study of Fatigue Damage in Notched Graphite Epoxy Laminates written by JD. Whitcomb and published by . This book was released on 1981 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue damage development in notched (0/±45/0)s, (45/0/-45/0)s, (90/±45/0)s, and (45/90/-45/0)s graphite/epoxy laminates was investigated. Both tension and compression fatigue behaviors were studied. Most of the tests were conducted at load levels equal to two thirds of the ultimate tensile strength of the notched specimens. After fatigue loading, specimens were examined for damage type and location using light microscopy, scanning electron microscopy, ultrasonic C-scans, and X-radiography. Delamination and ply cracking were found to be the dominant types of fatigue damage. In general, ply cracks did not propagate into adjacent plies of differing fiber orientation. To help understand the varied fatigue observations, the interlaminar stress distribution was calculated with finite element analysis for the regions around the hole and along the straight free edge. Comparison of observed delamination locations with the calculated stresses indicated that both interlaminar shear and peel stresses must be considered when predicting delamination. The effects of the fatigue cycling on residual strength and stiffness were measured for some specimens of each laminate type. Fatigue loading generally caused only small stiffness losses. In all cases, residual strengths were greater than or equal to the virgin strengths.
Download or read book Fracture Mechanics of Matrix Cracking and Delamination in Glass epoxy Laminates written by M. Caslini and published by . This book was released on 1986 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study focused on characterizing matrix cracking and delamination behavior in multidirectional laminates. Static tension and tension-tension fatigue tests were conducted on two different layups. Damage onset, accumulation, and residual properties were measured. Matrix cracking was shown to have a considerable influence on residual stiffness of glass epoxy laminates, and could be predicted reasonably well for cracks in 90 deg plies using a simple shear lag analysis. A fracture mechanics analysis for the strain energy release rate associated with 90 deg ply matrix crack formation was developed and was shown to correlate the onset of 90 deg ply cracks in different laminates. The linear degradation of laminate modulus with delamination area, previously observed for graphite epoxy laminates, was predicted for glass epoxy laminates using a simple rule of mixtures analysis. The strain energy release rate associated with edge delamination formation under static and cyclic loading was difficult to analyze because of the presence of several contemporary damage phenomena. Keywords: Fatigue(Mechanics), and Stiffness loss.
Download or read book The Development of Fatigue Damage Around Fastener Holes in Thick Graphite Epoxy Composite Laminates written by D. S. Saunders and published by . This book was released on 1993 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper discusses the mechanisms by which damage develops and grows around countersunk fastener holes in composite laminates under fatigue loading conditions. Experiments have shown that the erosion of material between ply layers nucleates delaminations which then grow through the laminate under the action of the fatigue loads. The damage at the hole bore surface produces sites for the nucleation of delaminations. The morphology of the delaminations and ply cracking was mapped extensively and from these maps it was found that the volume of material around the fastener hole, .damaged by the fatigue loading, adopted a characteristic shape, the volume of damaged laminate increased towards the faying surface of the laminate and (metal) fixture. This characteristic damage volume was generated by the fastener rocking under the fatigue loads. Growth of the delaminations has been shown to be preceded by intraply cracking and, as fatigue loading proceeded, more delaminations were generated at the hole bore surface. The interfacial region between the composite laminate and the fixture also provided the nucleation site for fatigue cracks in the fasteners. The effects of initial fastener-hole clearances on damage nucleation and growth, . did not appear to follow any clear pattern. However, coupons with excessive initial hole clearances did appear to exhibit greater than expected damage growth after only one sequence block. Composite materials, Mechanically fastened joints, Fatigue loading, Fatigue damage, Damage development, Damage mechanisms, Thick laminates, Graphite/epoxy.
Download or read book Fatigue Damage Mechanics of Notched Graphite Epoxy Laminates written by M. Spearing and published by . This book was released on 1991 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: A modeling approach is presented that recognizes that the residual properties of composite laminates after any form of loading depend on the damage state. Therefore, in the case of cyclic loading, it is necessary to first derive a damage growth law and then relate the residual properties to the accumulated damage.
Download or read book Advanced Aerospace Materials written by Haim Abramovich and published by Walter de Gruyter GmbH & Co KG. This book was released on 2019-08-19 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Aerospace Materials is intended for engineers and students of aerospace, materials, and mechanical engineering. It covers the transition from aluminum to composite materials for aerospace structures and will include essential and advanced analyses used in today’s aerospace industries. Various aspects of design, failure and monitoring of structural components will be derived and presented accompanied by relevant formulas and analyses.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 348 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.
Download or read book Damage Development Mechanisms in Notched Graphite Epoxy Composite Laminates During Compressive Fatigue Loading written by Norman Frederick Black and published by . This book was released on 1981 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
