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Delamination Growth In Graphite Epoxy Composite Laminates Under Tensile Loading
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Book Synopsis Delamination Growth in Graphite/epoxy Composite Laminates Under Tensile Loading by : Narendra Venugopal Bhat
Download or read book Delamination Growth in Graphite/epoxy Composite Laminates Under Tensile Loading written by Narendra Venugopal Bhat and published by . This book was released on 1993 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growth of triangular-shaped delaminations bordered by matrix cracks, defined herein as "compound delaminations", occurring at the free edges of [±15n]s and [±15n0n]s laminates in static tensile loading was investigated. This triangular compound delamination is the first macroscopic damage observed. Failure of the laminates occurs by unstable growth of these delaminations. The experimental study involved the manufacture of specimens with Teflon implants to create an initial delamination configuration with the delamination oriented at 90° to the matrix crack. The delamination front was monitored using strain gages and X-ray radiographs. Growth was observed to occur at the delamination front near the free edge region with no growth at the matrix crack front resulting in the same configuration as observed in originally unflawed specimens. A three-dimensional displacement-based finite element model of the delaminated region was created and the equivalent domain integral was used to determine the energy release rate at the delamination and matrix crack fronts. The energy release rate was predicted to be highest at the intersection of the delamination and the free edge and was lowest at the intersection of the delamination and the matrix crack. The peak energy release rate predicted at the matrix crack front was smaller than that at the delamination front. Growth was simulated in the model by tilting the delamination front about the matrix crack front. The maximum energy release rate along the delamination dropped and became more uniform as the delamination was tilted. These results indicate that the stable delamination configuration observed is formed by the growth of the delamination front at the free edge region in regions of high energy release rate in preference to the growth of the matrix crack resulting in a curved delamination contour. The overall decrease in energy release rate associated with this delamination growth indicates that the resulting curved delamination is a more stable configuration. The failure process in these specimens involves the formation of these stable delaminations, followed by secondary cracking in the plies adjacent to the delamination, and lastly final failure via unstable growth of the entire triangular region to the ends of the specimen.
Book Synopsis Characterization of Delamination Onset and Growth in a Composite Laminate by : TK. O'Brien
Download or read book Characterization of Delamination Onset and Growth in a Composite Laminate written by TK. O'Brien and published by . This book was released on 1982 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The onset and growth of delaminations in unnotched [±30/±30/90/90 ̄]s graphite-epoxy laminates is described quantitatively. These laminates, designed to delaminate at the edges under tensile loads, were tested and analyzed. Delamination growth and stiffness loss were monitored nondestructively. Laminate stiffness decreased linearly with delamination size. The strain energy release rate, G, associated with delamination growth, was calculated from two analyses. A critical G for delamination onset was determined, and then was used to predict the onset of delaminations in [+45n/-45n/0n/90n]s (n = 1,2,3) laminates. A delamination resistance curve (R-curve) was developed to characterize the observed stable delamination growth under quasi-static loading. A power law correlation between G and delamination growth rates in fatigue was established.
Book Synopsis Hygrothermal Influence on Delamination Behavior of Graphite/epoxy Laminates by :
Download or read book Hygrothermal Influence on Delamination Behavior of Graphite/epoxy Laminates written by and published by . This book was released on 1984 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Sensitivity of Graphite/epoxy to Implanted Delaminations Under Tensile Load by : Thomas F. Grapes
Download or read book Sensitivity of Graphite/epoxy to Implanted Delaminations Under Tensile Load written by Thomas F. Grapes and published by . This book was released on 1985 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation into the effects of implanted delamination on the tensile strength and stress-strain behavior of a graphite/epoxy laminate [45/0/-45]s was performed. No significant effects on the strength were observed and no delamination growth was detected. The tensile strain effects of delamination were somewhat ambiguous, however
Book Synopsis Analysis of Matrix Cracking and Local Delamination in (0/theta/-theta)sub S Graphite Epoxy Laminates Under Tension Load by :
Download or read book Analysis of Matrix Cracking and Local Delamination in (0/theta/-theta)sub S Graphite Epoxy Laminates Under Tension Load written by and published by . This book was released on 1991 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Delamination Growth in a Notched Graphite/Epoxy Laminate Under Compression Fatigue Loading by : AF. Blom
Download or read book Delamination Growth in a Notched Graphite/Epoxy Laminate Under Compression Fatigue Loading written by AF. Blom and published by . This book was released on 1985 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper is concerned with the propagation of delamination in a graphite/epoxy composite laminate with an unloaded circular hole subjected to compression fatigue loading. Experimental and theoretical aspects of the problem are investigated.
Book Synopsis Delamination Growth in Graphite Epoxy Laminates Under Compressive Loads by : Maria Slomiana
Download or read book Delamination Growth in Graphite Epoxy Laminates Under Compressive Loads written by Maria Slomiana and published by . This book was released on 1985 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterizing Delamination Growth in Graphite-Epoxy by : RA. Benson
Download or read book Characterizing Delamination Growth in Graphite-Epoxy written by RA. Benson and published by . This book was released on 1982 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of an overall effort to develop durability and damage tolerance methodology for graphite-epoxy composites, coupon specimens have been developed to measure the fundamental static fracture and subcritical growth behavior of delaminations. Two basic designs, one for the tensile opening mode (Mode I) and one for the forward shear mode (Mode II), are described. These specimens were used to characterize the behavior of two types of interfaces (0/0 and 0/90) for static fracture, constant amplitude fatigue, and spectrum fatigue. Fracture mechanics technology was applied through the principles of strain-energy release rate. Three-dimensional finite-element analyses were employed to interpret the experimental results. A simple growth law was shown to correlate the constant-amplitude and spectrum-growth data. It was found that the applied cyclic load must be nearly equal to the critical static load to obtain observable growth in the tensile opening mode. On the other hand, the graphite-epoxy delamination growth rate in the forward shear mode is comparable to the aluminum growth rate in tension, which suggests that shear is the chief subcritical growth mode for graphite-epoxy.
Book Synopsis Application of a Stochastic Model for Fatigue-Induced Delamination Growth in Graphite/Epoxy Laminates by : RB. Bucineill
Download or read book Application of a Stochastic Model for Fatigue-Induced Delamination Growth in Graphite/Epoxy Laminates written by RB. Bucineill and published by . This book was released on 1998 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: A stochastic model is used to predict the growth of delamination in graphite/epoxy laminates subjected to cyclic loading. The advantage of this model is that both the mean and variance associated with the growth of delamination is predicted. Understanding and predicting the variability associated with the delamination growth process is essential to the estimation of the reliability of composite structures. The empirical nature of the model has been minimized through the introduction of fracture mechanics parameters into the stochastic model. This has been accomplished by assuming that the mean of the stochastic model is represented by a fracture mechanics power law based on strain energy release rate. The applicability of the model is demonstrated through an experimental program that utilizes three laminate geometries. The results of the experimental evaluation illustrate the ability of the model to predict both the mean and variance of the delamination growth process in composite laminates subjected to cyclic loading.
Book Synopsis Studies of Delamination Growth and Final Failure Under Tensile Loading by : Paul A. Lagace
Download or read book Studies of Delamination Growth and Final Failure Under Tensile Loading written by Paul A. Lagace and published by . This book was released on 1987 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments were performed to investigate the mechanisms of delamination initiation, growth, and subsequent final failure. Specimens laminated from both Hercules AS4/3501-6 unidirectional graphite/epoxy tape and Hercules A370-5H/3501-6 woven graphite/epoxy fabric were tested to isolate the influence of interlaminar normal stress ([sigma]zz ) and thermally-induced interlaminar stresses on delamination initiation. The data was successfully correlated using the Quadratic Delamination Criterion and indicated that thermally-induced interlaminar stresses can cause delamination initiation without the application of mechanical load. Graphite/epoxy specimens in a [0n ±15 n]1 (n = 1 to 5) configuration and in a [ ±153]s configuration (specimen widths 10 mm, 20 mm, 30 mm, 50 mm, and 70 mm) were used to evaluate the effects of effective ply thickness and specimen width on delamination growth and final failure. These specimens were loaded beyond delamination initiation in increments of up to 25 MPa until final failure. Delaminated area was determined via dye penetrant-enhanced x-radiography. The results showed that growth of sufficient size to be detected by the x-radiography is delayed until the onset of transverse cracking in the angled plies. These cracks always occur at the tips of the edge delamination. The delamination front then advances with the tip of the transverse crack and extends between the tip of the crack and the free edge. This emphasizes the importance of the interaction of in-plane and out-of-plane damage modes leading to final failure. A thickness effect on growth and final failure similar to that seen for delamination initiation in earlier work was observed. There was no specimen width dependence of the stress at which significant stable growth first appeared or of the final failure stress.
Book Synopsis Tension Fatigue of Glass/epoxy and Graphite/epoxy Tapered Laminates by :
Download or read book Tension Fatigue of Glass/epoxy and Graphite/epoxy Tapered Laminates written by and published by . This book was released on 1990 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Mixed-mode Strain-energy-release Rate Effects on Edge Delamination of Composites by : Kevin T. O'Brien
Download or read book Mixed-mode Strain-energy-release Rate Effects on Edge Delamination of Composites written by Kevin T. O'Brien and published by . This book was released on 1983 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Delamination Behavior of Quasi-isotropic Graphite Epoxy Laminates Subjected to Tension and Torsion Loads by :
Download or read book Delamination Behavior of Quasi-isotropic Graphite Epoxy Laminates Subjected to Tension and Torsion Loads written by and published by . This book was released on 1992 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advanced Fatigue Damage Development in Graphite Epoxy Laminates by : Russell Douglas Jamison
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 238 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.
Book Synopsis The Effect of Ply Thickness on the Initiation and Growth of Delamination in Graphite/epoxy Laminates with Holes Under Compressive Cyclic Loading by : Stephen C. Nolet
Download or read book The Effect of Ply Thickness on the Initiation and Growth of Delamination in Graphite/epoxy Laminates with Holes Under Compressive Cyclic Loading written by Stephen C. Nolet and published by . This book was released on 1984 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of "effective ply thickness" on initiation and growth of damage in [+-45xn/0xn]s (qhwew n=1,2, and 3) graphite/epoxy laminates with 6.35 mm holes under compressive cyclic loading has been investigated. Static and cyclic compressive testing was done on axially loaded sandwich specimens. Out-of-plane Moire interferometry and pulse-echo ultrasonic inspection was used to monitor cyclic test specimens for delamination damage. The compressive static tests on the [+-45xn/Oxns sandwich specimens showed no "effective ply thickness" dependence on the compressive fracture stress of 423 MPa. Cyclic tests on the [+-45/0]s specimens showed three different types of damage development for the same applied peak stress: one, a damage mode that led to immediate transverse failure; two, delamination that initiated at the hole edge and grew radially from the hole; and three, a delamination that initiated at the top and bottom of the hole and grew longitudinally within the width of the hole. However, all the [+-45x2/0x2]s and [+-45x3/0x3]s laminates developed only the longitudinal delamination type of damage. The growth of longitudinal delamination was found to be a linear function of the logarithm of the number of applied load cycles. This damage initiates earlier as the "effective ply thickness" and/or peak cyclic stress increases. Furthermore, the growth rate increases with "effective ply thickness." Longitudinal delamination develops due to splitting in the 0° plies of the laminate and subsequent shear failure of the -45°/0° interface between the 0 splits. This mode of damage was also observed in two tensile cyclic tests. results of residual strength testing showed that laminates with longitudinal delamination had an average residual tensile stress of 640 MPa. This is approximate a 50% increase over the ultimate tensile stress of 455 MPa determined from static tensile tests on six coupons and eight sandwich specimens (uncycled) of the [+-45/0]s laminate.
Book Synopsis Delamination and Debonding of Materials by : W. Steven Johnson
Download or read book Delamination and Debonding of Materials written by W. Steven Johnson and published by ASTM International. This book was released on 1985 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
