Stress tests on cylinders and aluminum panels

An optimization study of composite stiffened cylinders is discussed. The mathematical model for the buckling has been coupled successfully with the optimization program AESOP. The buckling analysis is based on the use of the smeared theory for the buckling of stiffened orthotropic cylindrical shells. The loading, radius, and length of the cylinder are assumed to be known parameters. An optimum solution gives the value of cross-sectional dimensions and laminate orientations. The different types of buckling modes are identified. Mathematical models are developed to show the relationships of the parameters

Analysis of transient, linear wave propagation in shells by the finite difference method

The applicability of the finite difference method to propagation problems in shells, and the response of a cylindrical shell with cutouts to both longitudinal and radial transient excitations are investigated. It is found that the only inherent limitation of the finite difference method is its inability to reproduce accurately response discontinuities. The short wave length limitations of thin shell theory create significant convergence difficulties may often be overcome through proper selection of finite difference mesh dimensions and temporal or spatial smoothing of the excitation. Cutouts produce moderate changes in early and intermediate time response of a cylindrical shell to axisymmetric pulse loads applied at one end. The cutouts may facilitate the undesirable late-time transfer of load-injected extensional energy into nonaxisymmetric flexural response

Generic Misalignment Aberration Patterns in Wide-Field Telescopes

Axially symmetric telescopes produce well known "Seidel" off-axis third-order aberration patterns: coma, astigmatism, curvature of field and distortion. When axial symmetry is broken by the small misalignments of optical elements, additional third-order aberration patterns arise: one each for coma, astigmatism and curvature of field and two for distortion. Each of these misalignment patterns is characterized by an associated two-dimensional vector, each of which in turn is a linear combination of the tilt and decenter vectors of the individual optical elements. For an N-mirror telescope, 2(N-1) patterns must be measured to keep the telescope aligned. Alignment of the focal plane may require two additional patterns. For N = 3, as in a three mirror anastigmat, there is a two-dimensional "subspace of benign misalignment" over which the misalignment patterns for third-order coma, astigmatism and curvature of field are identically zero. One would need to measure at least one of the two distortion patterns to keep the telescope aligned. Alternatively, one might measure one of the fifth-order misalignment patterns, which are derived herein. But the fifth-order patterns are rather insensitive to misalignments, even with moderately wide fields, rendering them of relatively little use in telescope alignment. Another alternative would be to use telescope pointing as part of the alignment solution.Comment: 50 pages, 13 figures, Accepted for Publication in PAS

Computer program analyzes Buckling Of Shells Of Revolution with various wall construction, BOSOR

Computer program performs stability analyses for a wide class of shells without unduly restrictive approximations. The program uses numerical integration, finite difference of finite element techniques to solve with reasonable accuracy almost any buckling problem for shells exhibiting orthotropic behavior

Buckling of shells of revolution with various wall constructions. Volume 2 - Basic equations and method of solution

Basic equations and method of solution for computerized analysis of shells of revolution with axisymmetric collapse and nonsymmetric bifurcation buckling behavio

Buckling of shells of revolution with various wall constructions. Volume 3 - User's manual for BOSOR

Computer program for analysis of shells of revolution with axisymmetric loadin

Buckling of shells of revolution with various wall constructions. Volume 1 - Numerical results

Numerical results of buckling of shells of revolution for computer progra

Culture Shifting at Warp Speed: How the Law, Public Engagement, and Will & Grace Led to Social Change for LGBT People

(Excerpt) This Article concludes that in order for culture shifting to occur, there has to be active engagement in advocacy on multiple fronts. The pace of cultural change would have been significantly slower if advocates had not pursued litigation, legislation, and public engagement strategies. Rule shifting and culture shifting would also have occurred more slowly but for the vigorous efforts of LGBT equality opponents. The competing advocacy efforts on both sides of LGBT issues have resulted in lawsuits and laws limiting the rights of the LGBT community in some instances and granting rights in others. These advocacy efforts created a national conversation which has resulted in a cultural sea change