Download or read book Impact and Quasi static Response of Cylindrical Composite Shells written by Brian Lee Wardle and published by . This book was released on 1995 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Work was conducted to explore and begin to understand the impact response of composite shells over a range of impact events considered in the large-mass, low-velocity regime. Both impact and quasi-static experiments were conducted on various structural configurations including convex shells, concave shells, plates, and cylinders with boundary conditions of pinned/no in-plane sliding on the axial edges and free on the circumferential edges. Specimens with a planar aspect ratio of 1 were constructed in [±45n/On]s (n = 1, 2, 3) layups from Hercules AS4/3501-6 graphite epoxy prepreg. Basic structural parameters (radius, span, and thickness) were varied via scaling to determine the effects of these parameters and ratios of these parameters on the response. Damage states were characterized visually and with the dye-penetrant x-ray photography method and compared by defining damage metrics such as the average damage extent and damage extent ratio. An instability phenomenon was noted in the response of many convex shells which has a strong influence on the response. The Hertzian type contact relation does not capture the local response of indented shells and initial stiffness does not characterize the overall shell response. Relative contributions of membrane stiffness and bending stiffness are noted to be key in the overall convex shell response. Boundary conditions were also noted to have a strong influence on the response. Quasi-static and impact response are found to be nearly identical in all respects, including compelling evidence from the damage state comparisons. Two noted differences are that backface spalling was observed for a small number of specimens in impact tests only and that some showed a low frequency, high amplitude response in impact tests which was not observed in quasi-static tests. All structural parameters were shown to affect the response, including the shell height, although thickness was of particular importance. Nondimensional ratios were not found that capture the behavior of convex shells over the entire range of data but the data indicates regimes where different ratios are important, especially the height-to-thickness ratio. Peak force is found to be an excellent damage resistance metric. Impact energy consumption of convex shells through structural deformation, resulting in lower peak forces, is observed to give convex shells improved damage resistance over plate specimens. However, at the barely visible impact damage (BVID) level, convex shells that do not undergo an instability can incur more nonvisible damage than plates at a given force. This damage behavior, which includes different damage distributions, is attributed to differences caused by compressive versus tensile membrane stresses. The general response and resulting local stress and damage state, with relative contributions from both membrane and bending effects, needs to be determined through careful analysis to better determine the important parameters in the response. The damage distribution through the thickness needs to be characterized through experimentation, and then related to the stress state through analysis.
Download or read book Dent Depth Characterization written by Brian Lee Wardle and published by . This book was released on 1996 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: The experimental impact and quasi-static response, including damage resistance, of various composite shell structures was investigated and reported in a previous document. As an addendum to that original work, the surface damage was characterized. This characterization was in the form of the depth of the dent, which supplements the lengths and area of the visibly damaged region obtained previously. Thus, a three-dimensional characterization of the surface of the impact site was obtained nondestructively. The dent depth measurements are compared with internal damage states previously obtained by the X-radiography technique to better understand the implications of "barely visible impact damage" (BVID). No correlation was found between internal (nonvisible) damage from the X-ray data and the measured characteristics of the surface damage, specifically depth of the dent. In the work previously reported, it was found useful to separate damage data with regard to the presence of shell instability in the response. Peak force was then found to correlate the resulting internal damage for both shell and plate specimens. However, dent depth shows no such general trend or correlation with peak force when the data is separated with regard to the presence of shell instability. This indicates that, for the cases considered, dent depth is not a good indicator of internal damage extent for thin (less than 2.4 mm, or 0.10") composite plate and shell structures.
Download or read book Study on the Crushing Response of Cylindrical Composite Shells Subjected to Transverse Loading written by Chang F-K and published by . This book was released on 1990 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation was performed to study the load-carrying capability of fiber-reinforced composite shells subjected to quasi-static transverse crushing loads. Both experimental and analytical work have been performed. Experiments on T300/934 and T300/976 graphite/epoxy materials were first conducted on composite cylinders subjected to crushing loads. An analytical model was also developed which was based on a progressive damage analysis. The model consists of a stress analysis and a failure analysis. Deformations, stresses, and strains in the composite cylinders were analyzed based on the large deformation theory. Damage accumulation and the residual stiffness and strength of the tubes were evaluated by a combination of appropriate failure criteria with property degradation models. Based on the model, a nonlinear finite element program, designated as "PDTUBE," was developed. The code is capable of assessing damage in the laminates and predicting residual stiffness and strength of composite cylinders subjected to transverse crushing loads. An excellent agreement was found between the computer simulations and the test results. A parametric study was also conducted to determine the effects of material properties, ply orientation, and geometries on the response of cylindrical composite shells.
Download or read book Parametric Study on the Response of Compression Loaded Composite Shells with Geometric and Material Imperfections written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-03 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a parametric study of the effects of initial imperfections on the buckling and postbuckling response of three unstiffened thinwalled compression-loaded graphite-epoxy cylindrical shells with different orthotropic and quasi-isotropic shell-wall laminates are presented. The imperfections considered include initial geometric shell-wall midsurface imperfections, shell-wall thickness variations, local shell-wall ply-gaps associated with the fabrication process, shell-end geometric imperfections, nonuniform applied end loads, and variations in the boundary conditions including the effects of elastic boundary conditions. A high-fidelity nonlinear shell analysis procedure that accurately accounts for the effects of these imperfections on the nonlinear responses and buckling loads of the shells is described. The analysis procedure includes a nonlinear static analysis that predicts stable response characteristics of the shells and a nonlinear transient analysis that predicts unstable response characteristics.Hilburger, Mark W. and Starnes, James H., Jr.Langley Research CenterSHELLS (STRUCTURAL FORMS); COMPRESSION LOADS; PARAMETERIZATION; CYLINDRICAL SHELLS; COMPOSITE STRUCTURES; FABRICATION; BUCKLING; NONLINEARITY; BOUNDARY CONDITIONS; ISOTROPY; DEFECTS; FINITE ELEMENT METHOD; GRAPHITE-EPOXY COMPOSITES; ELASTIC PROPERTIES
Download or read book Response of a fluid filled cylindrical shell of finite length to quasi static and dynamic loading written by Johnny Anthony Kopecky and published by . This book was released on 1966 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2005 with total page 960 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this jOint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 40 (thesis year 1995) a total of 10,746 thesis titles from 19 Canadian and 144 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 40 reports theses submitted in 1995, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.
Download or read book Parametric Study on the Response of Compression Loaded Composite Shells with Geometric and Material Imperfections written by Nasa Technical Reports Server (Ntrs) and published by BiblioGov. This book was released on 2013-07 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a parametric study of the effects of initial imperfections on the buckling and postbuckling response of three unstiffened thinwalled compression-loaded graphite-epoxy cylindrical shells with different orthotropic and quasi-isotropic shell-wall laminates are presented. The imperfections considered include initial geometric shell-wall midsurface imperfections, shell-wall thickness variations, local shell-wall ply-gaps associated with the fabrication process, shell-end geometric imperfections, nonuniform applied end loads, and variations in the boundary conditions including the effects of elastic boundary conditions. A high-fidelity nonlinear shell analysis procedure that accurately accounts for the effects of these imperfections on the nonlinear responses and buckling loads of the shells is described. The analysis procedure includes a nonlinear static analysis that predicts stable response characteristics of the shells and a nonlinear transient analysis that predicts unstable response characteristics.
Download or read book Dynamic Response of Composite Cylindrical Shells Under External Impulsive Loads written by Sunil George Pothula and published by . This book was released on 2009 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Dynamic pulse buckling, vibration and failure of laminated, composite cylindrical shells subjected to blast loading were studied. The dynamic response of the shells with orthotropic, symmetric, anti-symmetric and quasi-isotropic layups subjected to both uniform and asymmetric pressure pulse loading (side-on explosion) were examined by use of Fourier series and Lagrange's equation of motion. The solutions for the radial shell deformations were represented by Mathieu differential equations. Dynamic stability of the shells was determined from a Mathieu stability diagram. It was found that the stability of the shells were affected by lay-up, aspect ratio as well as impulse distribution. The stable vibration response of the orthotropic cylindrical shell with side-on explosion compared well with finite element solutions using an implicit dynamic analysis in ABAQUS Standard. First-ply failure of the orthotropic composite cylindrical shell was predicted using a modified Hashin-Rotem failure criterion. It was observed that the thinner shell were more likely to fail by dynamic instability, whereas the thicker shells were more likely to fail by first-ply failure."--Abstract.
Download or read book Numerical and Experimental Study of the Compression Response of Composite Cylindrical Shells with Cutouts written by Mark William Hilburger and published by . This book was released on 1998 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Response of Carbon based Composite Cylindrical Shells to a Point impact written by Saul Venner W. and published by . This book was released on 2001 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 38th AIAA ASME ASCE AHS ASC Structures Structural Dynamics and Materials Conference and Exhibit and AIAA ASME Adaptive Structures Forum written by and published by . This book was released on 1997 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Static and Thermal Response of Circular Cylindrical and Truncated Conical Thin Composite Shells written by Matthew Alan King and published by . This book was released on 1989 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effect of End Conditions on the Dynamic Response of Cylindrical Shells written by R. L. Chiapetta and published by . This book was released on 1960 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vibration of Shells written by Arthur W. Leissa and published by . This book was released on 1973 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: The vibrational characteristics and mechanical properties of shell structures are discussed. The subjects presented are: (1) fundamental equations of thin shell theory, (2) characteristics of thin circular cylindrical shells, (3) complicating effects in circular cylindrical shells, (4) noncircular cylindrical shell properties, (5) characteristics of spherical shells, and (6) solution of three-dimensional equations of motion for cylinders.
Download or read book Buckling and Damage Resistance of Transversely loaded Composite Shells written by Brian Lee Wardle and published by . This book was released on 1998 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental and numerical work was conducted to better understand composite shell response to transverse loadings which simulate damage-causing impact events. The quasi-static, centered, transverse loading response of laminated graphite/epoxy shells in a [±45n/0n]s layup having geometric characteristics of a commercial fuselage are studied. The singly-curved composite shell structures are hinged along the straight circumferential edges and either free or simply supported along the curved axial edges. Key components of the shell response are response instabilities due to limit-point and/or bifurcation buckling. Experimentally, deflection-controlled shell response is characterized via load-deflection data, deformation-shape evolutions, and the resulting damage state. Finite element models are used to study the kinematically nonlinear shell response, including bifurcation, limit-points, and postbuckling. A novel technique is developed for evaluating bifurcation from nonlinear prebuckling states utilizing asymmetric spatial discretization to introduce numerical perturbations. Advantages of the asymmetric meshing technique (AMT) over traditional techniques include efficiency, robustness, ease of application, and solution of the actual (not modified) problems. The AMT is validated by comparison to traditional numerical analysis of a benchmark problem and verified by comparison to experimental data. Applying the technique, bifurcation in a benchmark shell-buckling problem is correctly identified. Excellent agreement between the numerical and experimental results are obtained for a number of composite shells although predictive capability decreases for stiffer (thicker) specimens which is attributed to compliance of the test fixture. Restraining the axial edge (simple support) has the effect of creating a more complex response which involves unstable bifurcation, limit-point buckling, and dynamic collapse. Such shells were noted to bifurcate into asymmetric deformation modes but were undamaged during testing. Shells in this study which were damaged were not observed to bifurcate. Thus, a direct link between bifurcation and atypical damage could not be established although the mechanism (bifurcation) was identified. Recommendations for further work in these related areas are provided and include extensions of the AMT to other shell geometries and structural problems.
Download or read book Analysis of Thick Sectioned Composite Cylindrical Shells Under Hydrostatic Pressure written by FG. Yuan and published by . This book was released on 1993 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: This article describes the mechanical behavior of thick-sectioned composite laminated shells subjected to hydrostatic pressure. The analysis is based on the theory of cylindrical anisotropic elasticity using a stress function approach. Quasi-isotropic laminated shells are used to demonstrate the influence of shell thickness, stacking sequence, and number of repeating sublaminates on thestrain and stress response. The effect of residual stress on the behavior of the shells is also examined.
