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Effect Of Cylinder Diameter On The Damage Tolerance Of Graphite Epoxy Cylinders With Axial Notches
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Book Synopsis Effect of Cylinder Diameter on the Damage Tolerance of Graphite/epoxy Cylinders with Axial Notches by : Claudia Ute Ranniger
Download or read book Effect of Cylinder Diameter on the Damage Tolerance of Graphite/epoxy Cylinders with Axial Notches written by Claudia Ute Ranniger and published by . This book was released on 1991 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of the damage tolerance of quasi-isotropic composite cylinders with axial notches was conducted to determine the applicability of a previously-developed failure prediction methodology. Previous work has demonstrated the applicability of the prediction methodology for 152 mm radius cylinders, but no variations in cylinder radius have been examined. The goal of this investigation was to expand the prediction methodology to include cylinders with a radius of 76 mm. The material system utilized was AW370/3501-6S, a five-harness graphite/epoxy weave. Coupons of [0f]4, [90f]4, and [±45f]s orientations were tested in tension to determine the material properties. Unnotched and notched [Of/4 5f]s laminate properties were determined experimentally as well. The Mar-Lin equation was used to correlate the failure stresses of the transversely slit coupons. Cylinders 76 mm in radius and 400 mm long were fabricated in a [Of/45f]s layup. Axial slits were precut in the cylinders, and cylinders were monotonically pressurized to failure. Failure pressure predictions were formulated from a quasi-isotropic shell correction to the flat plate failure stress correlation. Experimental cylinder data correlated well with predicted failure pressures. It may be concluded that the curvature correction to the experimentally-determined plate failure stresses properly captures variations of effective cylinder radius for quasi-isotropic fabric cylinders.
Book Synopsis Damage Tolerance and Arrest Characteristics of Pressurized Graphite/epoxy Tape Cylinders by : Claudia Ute Ranniger
Download or read book Damage Tolerance and Arrest Characteristics of Pressurized Graphite/epoxy Tape Cylinders written by Claudia Ute Ranniger and published by . This book was released on 1991 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of the damage tolerance and arrest characteristics of internally-pressurized graphite/epoxy tape cylinders with axial notches was conducted. The extension of an existing failure prediction methodology, developed for quasi-isotropic graphite/epoxy fabric cylinders, to quasi-isotropic and structurally anisotropic tape cylinders was investigated. The effect of external circumferential stiffening bands on the direction of fracture path propagation in structurally anisotropic tape cylinders was also examined. Quasi-isotropic [90/0/±45]s and structurally anisotropic [±45/0]s and [±45/90]s coupons and cylinders were constructed from AS4/3501-6 graphite/epoxy tape. Notched and unnotched coupons were tested in tension to determine the laminate properties. The Mar-Lin equation was used to correlate the fracture stresses of the transversely-slit coupons. Isotropic and specially orthotropic cylinder failure pressure predictions were formulated by applying geometry-dependent stress intensification factors to the coupon stress correlations. Graphite/epoxy cylinders 305 mm in diameter were slit axially and pressurized to failure under two-to-one biaxial loading. Experimental failure pressures of the [90/0/±45]s cylinders agreed with predicted values for all but the specimen with the smallest slit. However, the fracture mode of the cylinder with the 12.7 mm slit indicates that delamination and axial splitting of the 0° ply around the slit may mitigate stresses at the notch tip, resulting in a higher than expected failure load. Failure pressures of structurally anisotropic cylinders were above the values found by isotropic and specially orthotropic shell predictions, and failure pressures for cylinders with 12.7 mm slits were higher than comparable coupon data as well. Possible factors neglected by the predictive methodology include structural coupling in the laminates and axial loading of the cylindrical specimens. Furthermore, applicability of the predictive methodology depends on similarity of initial fracture modes in coupons and cylinders of the same laminate type. Examination of specimen damage indicates that cylinder fracture modes are different from coupon fracture modes in all structurally anisotropic specimens and in the quasiisotropic tape cylinder with the 12.7 mm slit. Comparison of [±45/0]s and [±45/90]s cylinders with and without stiffening bands shows that stiffeners redirect fracture propagation to the circumferential direction, and can contain damage in the center section of the cylinder away from the endcaps. A quantitative assessment of stiffener effectiveness in containing fracture, based on cylinder radius, slit size, and bending stiffnesses of the laminates is proposed.
Book Synopsis Damage Tolerance and Arrest Characteristics of Pressurized Graphite/Epoxy Tape Cylinders by : MJ. Graves
Download or read book Damage Tolerance and Arrest Characteristics of Pressurized Graphite/Epoxy Tape Cylinders written by MJ. Graves and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of the damage tolerance and damage arrest characteristics of internally pressurized graphite/epoxy tape cylinders with axial notches was conducted. An existing failure prediction methodology, developed and verified for quasi-isotropic graphite/epoxy fabric cylinders, was investigated for applicability to general tape layups. In addition, the effect of external circumferential stiffening bands on the direction of fracture path propagation and possible damage arrest was examined. Quasi-isotropic [90/0/±45]s and structurally anisotropic [±45/0]s and [±45/90]s coupons and cylinders were constructed from AS4/3501-6 graphite/epoxy tape. Notched and unnotched coupons were tested in tension and the data correlated using the equation of Mar and Lin. Cylinders with through-thickness axial slits were pressurized to failure achieving a far-field two-to-one biaxial stress state. Experimental failure pressures of the [90/0/±45]s cylinders agreed with predicted values for all cases but the specimen with the smallest slit. However, the failure pressures of the structurally anisotropic cylinders, [±45/0]s and [±45/90]s, were above the values predicted utilizing the predictive methodology in all cases. Possible factors neglected by the predictive methodology include structural coupling in the laminates and axial loading of the cylindrical specimens. Furthermore, applicability of the predictive methodology depends on the similarity of initial fracture modes in the coupon specimens and the cylinder specimens of the same laminate type. The existence of splitting, which may be exacerbated by the axial loading in the cylinders, shows that this condition is not always met. The circumferential stiffeners were generally able to redirect fracture propagation from longitudinal to circumferential. A quantitative assessment for stiffener effectiveness in containing the fracture, based on cylinder radius, slit size, and bending stiffnesses of the laminates, is proposed. Suggestions for further work in these areas to better understand the mechanisms at work, and thus provide a better predictive methodology, are offered.
Book Synopsis Damage Tolerance and Arrest Characteristics of Pressurized Graphite/epoxy Tape Cylinders by : Claudia Ute Ranniger
Download or read book Damage Tolerance and Arrest Characteristics of Pressurized Graphite/epoxy Tape Cylinders written by Claudia Ute Ranniger and published by . This book was released on 1991 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation of the damage tolerance and arrest characteristics of internally-pressurized graphite/epoxy tape cylinders with axial notches was conducted. The extension of an existing failure prediction methodology, developed for quasi-isotropic graphite/epoxy fabric cylinders, to quasi-isotropic and structurally anisotropic tape cylinders was investigated. The effect of external circumferential stiffening bands on the direction of fracture path propagation in structurally anisotropic tape cylinders was also examined. Quasi-isotropic [90/0/±45]s and structurally anisotropic [±45/0]s and [±45/90]s coupons and cylinders were constructed from AS4/3501-6 graphite/epoxy tape. Notched and unnotched coupons were tested in tension to determine the laminate properties. The Mar-Lin equation was used to correlate the fracture stresses of the transversely-slit coupons. Isotropic and specially orthotropic cylinder failure pressure predictions were formulated by applying geometry-dependent stress intensification factors to the coupon stress correlations. Graphite/epoxy cylinders 305 mm in diameter were slit axially and pressurized to failure under two-to-one biaxial loading. Experimental failure pressures of the [90/0/±45]s cylinders agreed with predicted values for all but the specimen with the smallest slit. However, the fracture mode of the cylinder with the 12.7 mm slit indicates that delamination and axial splitting of the 0° ply around the slit may mitigate stresses at the notch tip, resulting in a higher than expected failure load. Failure pressures of structurally anisotropic cylinders were above the values found by isotropic and specially orthotropic shell predictions, and failure pressures for cylinders with 12.7 mm slits were higher than comparable coupon data as well. Possible factors neglected by the predictive methodology include structural coupling in the laminates and axial loading of the cylindrical specimens. Furthermore, applicability of the predictive methodology depends on similarity of initial fracture modes in coupons and cylinders of the same laminate type. Examination of specimen damage indicates that cylinder fracture modes are different from coupon fracture modes in all structurally anisotropic specimens and in the quasiisotropic tape cylinder with the 12.7 mm slit. Comparison of [±45/0]s and [±45/90]s cylinders with and without stiffening bands shows that stiffeners redirect fracture propagation to the circumferential direction, and can contain damage in the center section of the cylinder away from the endcaps. A quantitative assessment of stiffener effectiveness in containing fracture, based on cylinder radius, slit size, and bending stiffnesses of the laminates is proposed.
Book Synopsis Damage Tolerance of Pressurized Graphite/epoxy Tape Cylinders Under Uniaxial and Biaxial Loading by : Stacy Marie Priest
Download or read book Damage Tolerance of Pressurized Graphite/epoxy Tape Cylinders Under Uniaxial and Biaxial Loading written by Stacy Marie Priest and published by . This book was released on 1993 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: The damage tolerance behavior of internally pressurized, axially slit, graphite/epoxy tape cylinders was investigated. Specifically, the effects of axial stress, structural anisotropy, and subcritical damage were considered. In addition, the limitations of a methodology which uses coupon fracture data to predict cylinder failure were explored. This predictive methodology was previously shown to be valid for quasi-isotropic fabric and tape cylinders but invalid for structurally anisotropic [±45/90]s and [±45/0}s cylinders. The effects of axial stress and structural anisotropy were assessed by testing tape cylinders with [90/0/±45]s, [±45/90]s, and [±45/0]s layups in a uniaxial test apparatus, specially designed and built for this work, and comparing the results to previous tests conducted in biaxial loading. Structural anisotropy effects were also investigated by testing cylinders with the quasi-isotropic [0/±45/90]s layup which is a stacking sequence variation of the previously tested [90/0/±45]s layup with higher D16 and D26 terms but comparable D16 and D26 to D 11 ratios. All cylinders tested and used for comparison are made from AS4/3501-6 graphite/epoxy tape and have a diameter of 305 mm. Cylinder slit lengths range from 12.7 to 50.8 mm. Failure pressures are lower for the uniaxially loaded cylinders in all cases. The smallest percent failure pressure decreases are observed for the [ 45/90]8 cylinders, while the greatest such decreases are observed for the [±45/0]s cylinders. The relative effects of the axial stress on the cylinder failure pressures do not correlate with the degree of structural coupling. The predictive methodology is not applicable for uniaxially loaded [ 45/90]s and [ 45/0]. cylinders, may be applicable for uniaxially loaded [90/0/ 45]. cylinders, and is applicable for the biaxially loaded [90/0/±45]s and [0/±45/90]s cylinders. This indicates that the ratios of D16 and D26 to D11, as opposed to the absolute magnitudes of D16 and D26 , may be important in the failure of these cylinders and in the applicability of the methodology. Discontinuities observed in the slit tip hoop strains for all the cylinders tested indicate that subcritical damage can play an important role in the failure of tape cylinders. This role varies with layup and loading condition and is likely coupled to the effects of structural anisotropy. Biaxial failure pressures may exceed the uniaxial values because the axial stress contributes to the formation of 00 ply splitting (accompanied by delamination) or similar stress-mitigating subcritical damage. The failure behavior of similar cylinders can also vary as a result of differences in the role of subcritical damage as observed for the case of a biaxially loaded [90/0/±45]s cylinder with a 12.7 mm slit. For this case, the methodology is valid when the initial coupon and cylinder fracture modes agree. However, the methodology underpredicts the failure pressure of the cylinder when a circumferential fracture path, suggestive of a 0° ply split, occurs at one slit tip. Thus, the failure behavior of some tape cylinders may be highly sensitive to the initial subcritical damage mechanism. Finite element analyses are recommended to determine how structural anisotropy and axial stress modify the slit tip stress states in cylinders from those found in flat plates since similarity of these stress states is a fundamental assumption of the current predictive methodology.
Book Synopsis Damage Tolerance Characteristics of Pressurized Graphite/epoxy Cylinders by : Paul A. Lagace
Download or read book Damage Tolerance Characteristics of Pressurized Graphite/epoxy Cylinders written by Paul A. Lagace and published by . This book was released on 1987 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The various investigations conducted at the Technology Laboratory for Advanced Composites in the Department of Aeronautics and Astronautics at the Massachusetts Institute of Technology on the damage tolerance characteristics of graphite/epoxy cylinders are discussed herein. The basic analytical methodology involves the use of data from flat notched coupons with the use of an appropriate correction factor to account for structural effects in order to predict the failure of damaged pressurized cylinders. The earliest work was performed on ASl/3501-6 unidirectional tape in a [ 45/01 configuration. A subsequent investigator using as-quasi-isotropic layup of -370-5H/3501-6 graphite/epoxy fabric, utilized a curvature correction term to take into account local stress intensification due to bending at the notch tip and was able to obtain a reasonable correlation of the fracture of pressurized cylinders using data from coupons. In further work, the effects of notch geometry on the failure pressures of notched cylinders were investigated. Curvature corrections were developed for the various notch shapes considered and the failure predictions obtained using these corrections correlated adequately with the observed data. Recently, the effect of a high strain-to-failure matrix system on the failure pressures of notched cylinders has also been investigated. Work is currently being done to determine the effects of impact on the residual strength of composite cylinders. To date, implanted delaminations have been used to model the effects of impact.
Book Synopsis Composite Materials by : Roderick H. Martin
Download or read book Composite Materials written by Roderick H. Martin and published by ASTM International. This book was released on 1986 with total page 517 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Collection of Technical Papers by :
Download or read book A Collection of Technical Papers written by and published by . This book was released on 1996 with total page 874 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Damage Tolerance of Internally Pressurized Sandwich Walled Graphite/epoxy Cylinders by : David Wesley Trop
Download or read book Damage Tolerance of Internally Pressurized Sandwich Walled Graphite/epoxy Cylinders written by David Wesley Trop and published by . This book was released on 1985 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytical and experimental investigation was undertaken to determine the elastic and fracture behavior of internally pressurized sandwich walled graphite/epoxy cylinders. The membrane stress-strain state was predicted by treating the two face sheets as separate shells connected by the honeycomb core. Failure pressures were predicted using relative stress intensity factors to extrapolate flat plate data to the configuration of the cylinders. Eight flat plate specimens and eight cylinders were tested. The layup was [90/ ±30/core]s (quasi-isotropic), with 90 degrees being their circumferential direction for the cylinders and the testing direction for the flat specimens. The core was 0.75 inch (19 mm) thick Nomex honeycomb, and the face sheets were 0.030 inches (0.76 mm) thick. The flat specimens were 2 inches (50 mm) wide, were flawed with 1/4 and 1/2 inch (6.3 and 12.7 mm) holes, and were loaded to failure under uniaxial tension. The cylinders had a 24 inch (610 mm) inner diameter, and the wall was of the same construction as the flat specimens except that the face sheets were 0.027 inches (0.69 mm) thick. All cylinders were instrumented with far field strain gages to measure circumferential and longitudinal strains on the inside and outside face sheets. Six cylinders had axial slits ranging from 3.5 to 9 inches (89 to 229 mm) in length. One had a 7 inch (178 mm) long axial slit and a 5 inch (127 mm) long circumferential slit. The remaining one had a slit oriented at a 45 degree angle to the axis, 8.5 inches (216 mm) long. All slits were through-the-wall. The cylinders were sealed with endcaps and pressurized to failure. The elastic solution agreed well with the far field (i.e. membrane) strains measured on the cylinders. The failure pressures of the cylinders correlated well with the prediction extrapolated from the flat plate failure data.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Comparison of the Damage Tolerance of Pressurized Graphite/epoxy and Aluminum Cylinders by : Kevin Jay Saeger
Download or read book A Comparison of the Damage Tolerance of Pressurized Graphite/epoxy and Aluminum Cylinders written by Kevin Jay Saeger and published by . This book was released on 1985 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report details the comparison of the damage tolerance of graphite/epoxy cylinders with similar cylinders made of an aluminum alloy, each with a thickness of approximately 1.3 mm. The test procedures used for the graphite/epoxy tubes have been repeated for the aluminum alloy tubes, and these results have been compared with existing literature. Two 2024-T3 aluminum tubes were pressurized to catastrophic failure and the failure pressures were then compared to the predicted theoretical values. The deviation of the test data from the predicted value is 6.7%. The strength values found for 2024-T3 aluminum indicate that over a range of slit lengths from 25.4 mm to 203.2 mm, the quasi-isotropic graphite/epoxy layup considered has approximately the same strength. However on a strength to weight basis corresponding to this slit range, the graphite/epoxy is approximately 80% better.
Book Synopsis A Collection of Technical Papers: Structures by :
Download or read book A Collection of Technical Papers: Structures written by and published by . This book was released on 1990 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Impact Behaviour of Fibre-Reinforced Composite Materials and Structures by : S. R. Reid
Download or read book Impact Behaviour of Fibre-Reinforced Composite Materials and Structures written by S. R. Reid and published by Elsevier. This book was released on 2000-10-12 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study covers impact response, damage tolerance and failure of fibre-reinforced composite materials and structures. Materials development, analysis and prediction of structural behaviour and cost-effective design all have a bearing on the impact response of composites and this book brings together for the first time the most comprehensive and up-to-date research work from leading international experts. State of the art analysis of impact response, damage tolerance and failure of FRC materials Distinguished contributors provide expert analysis of the most recent materials and structures Valuable tool for R&D engineers, materials scientists and designers
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1997 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fibrous Composites in Structural Design by : Edward M. Lenoe
Download or read book Fibrous Composites in Structural Design written by Edward M. Lenoe and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fourth Conference on Fibrous Composites in Structural Design was a successor to the First-to-Third Conferences on Fibrous Composites in Flight Vehicle Design sponsored by the Air Force (First and Second Conferences, September 1973 and May 1974) and by NASA (Third Conference, November 1975) which were aimed at focusing national attention on flight vehicle applications of a new class of fiber reinforced materials, the advanced com posites, which afforded weight savings and other advantages which had not been previously available. The Fourth Conference, held at San Diego, California, 14-17 November 1978, was the fi rst of these conferences to be jointly sponsored by the Army, Navy and Ai r Force together with NASA, as well as being the first to give attention to non-aerospace applications of fiber reinforced composites. While the design technology for aerospace applications has reached a state of relative maturity, other areas of application such as mi litary bridging, flywheel energy storage systems, ship and surface vessel components and ground vehicle components are in an early stage of development, and it was an important objective to pinpoint where careful attention to structural design was needed in such applications to achfeve maximum structural performance payoff together with a high level of reliability and attractive economics.
Book Synopsis Government Reports Announcements & Index by :
Download or read book Government Reports Announcements & Index written by and published by . This book was released on 1993 with total page 1168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Notch Effects in Fatigue and Fracture by : G. Pluvinage
Download or read book Notch Effects in Fatigue and Fracture written by G. Pluvinage and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: As Directors of this NATO Workshop, we welcome this opportunity to record formally our thanks to the NATO Scientific Affairs Division for making our meeting possible through generous financial support and encouragement. This meeting has two purposes: the first obvious one because we have collected scientists from East, far East and west to discuss new development in the field of fracture mechanics: the notch fracture mechanics. The second is less obvious but perhaps in longer term more important that is the building of bridges between scientists in the frame of a network called Without Walls Institute on Notch Effects in Fatigue and Fracture". Physical perception of notch effects is not so easy to understand as the presence of a geometrical discontinuity as a worst effect than the simple reduction of cross section. Notch effects in fatigue and fracture is characterised by the following fundamental fact: it is not the maximum local stress or stress which governs the phenomena of fatigue and fracture. The physic shows that a process volume is needed probably to store the necessary energy for starting and propagating the phenomenon. This is a rupture of the traditional "strength of material" school which always give the prior importance of the local maximum stress. This concept of process volume was strongly affirmed during this workshop.
