Design and Evaluation of a Reinforced Advanced-Grid Stiffened Composite Structure
Abstract : A composite grid-stiffened structure concept was selected for the payload fairing of the Minotaur launch vehicle. Compared to previous designs, this concept is lighter weight and requires reduced manufacturing costs. Various failure mechanisms were examined for the composite grid-stiffened structure. The controlling criterion for this design was determined to be joint peel-off failure. The identification of this failure mechanism and the assessment of bounding strains to control it, required extensive test and analysis effort. The final fairing design incorporated an undesirably thick skin to reduce the strain between the skin and ribs. This project investigated a means of controlling joint failure of the un-reinforced grid-stiffened structure in an effort to reduce the skin thickness. Implementing lightweight foam inserts between the stiffeners on the interior of the fairing delayed failure to higher loads. A foam reinforced test panel, designed with equal mass to the current structure, withstood a substantially greater compressive force. The alternative concept also demonstrated an improved response, failing in global buckling instead of experiencing early failure due to joint strain.
Composite, Grid-Stiffened Panel Design for Post Buckling Using Hypersizer (Trademark)
Abstract : Due to weight and cost goals. a grid-stiffened panel concept is being used for redesign of a structural component on the Minotaur OSP space launch vehicle. By designing the structural panels to carry operational loads past the point of initial buckling (local post- buckling). the resulting grid stiffened panel concept is lighter and 300- less costly to manufacture than other design candidates such as the existing honeycomb sandwich panel concept flown today. During June 2001 in Seattle. Boeing performed a structural certification experiment of a composite, grid stiffened, cylindrical panel loaded in axial compression. Pretest predictions were made for linear elastic (bifurcation) buckling, and non-linear post buckling. The tools used for pretest analysis were HyperSizer(Registered). and the FEM based tools MSC/NASTRAN(TradeMade) and STAGS(TradeMade). Local buckling of the facesheet triangular shaped skin pocket occurred at a load of around 230 (lb/in). The test panel was able to sustain considerable additional loading. with post buckling failure occurring at 1320 (lb/in). The HyperSizer post buckling pretest prediction was 1300 (lb/in), the STAGS pretest prediction was 1250 (lb/in), and the MSC/NASTRAN pretest prediction ranged from 1425 to 2000 (lb/in). HyperSizer's implementation of local post buckling based on an effective width approach is presented.
Only the Third Heaven?: 2 Corinthians 12.1-10 and Heavenly Ascent
CHAPTER 1 General Introduction PART 1: Texts of Heavenly Ascent CHAPTER 2 Introduction: Heavenly Ascent Texts: A History of Scholarship CHAPTER 3 Jewish Apocalyptic Texts Pre-70 AD CHAPTER 4 Jewish Apocalyptic Texts Post-70 AD. CHAPTER 5 The New Testament CHAPTER 6 Post-Biblical Early Christian Apocalypses CHAPTER 7 The Nag Hammadi Codices CHAPTER 8 The Hekhalot Literature CHAPTER 9 Conclusions to Part One PART 2: 2 Corinthians 12:1-10 and Heavenly Ascent CHAPTER 10 2 Corinthians 12: 1-10 as a Heavenly Ascent CHAPTER 11 2 Corinthians 12.1-10 as a Subversion of the Heavenly Ascent CHAPTER 12 General Conclusions.