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.
Post-Buckling Test Response and Analysis of Fiber Composite Grid-Stiffened Structures
Abstract : A composite grid-stiffened cylindrically curved panel was fabricated and tested in static compression. Joint tension test coupons were fabricated from an unused portion of the panel construction and tested to failure in direct tension (rib/skin pull-off). Pre- and posttest analyses were performed to assess initial and overall buckling response. Comparisons to test data were made to assess: 1) the influence of skin pocket buckling on overall structure response, 2) the predictability of overall structure response through the range of operational load application, and 3) probable causes of failure in this test panel and in future tests with rib and skin configuration optimized for specific spacecraft fairing applications.
A thin circular plate normally and uniformly loaded over a concentric elliptic patch
ABSTRACT This paper is concerned with the small transverse displacement of a thin circular plate elastically restrained along the circular boundary and subject to uniform normal pressure distributed over the area of an ellipse concentric with the plate. The method of complex potentials is used and the general assumptions relating to the small deflexion theory of thin plates are adopted. Explicit formulae for the bending and twisting moments and shearing forces are given at any point on the boundary and at the centre of the plate.