Master of Science in Mechanical Engineering (MSME)
Composite materials have been widely used in the ship-building, aerospace and construction industries because of their distinct advantages of low weight, high stiffness, and high strength to weight ratios. These properties are due to the low weight of the epoxy core matrix and high strengths of the glass/carbon fibers. Composite pipes used in various applications are traditionally spherical in cross-section. In this study, non-conventional cross-sectioned composite pipes [i.e. rectangular and triangular cross-sections] have been proposed, fabricated, tested and analyzed because of their ability to be bundled without loss of space. The behaviors of these pipes under an internal pressure test and a four-point bend test have been studied and its failure mechanisms have been investigated. A novel fabrication technique to fabricate the non-conventional pipes has been introduced by custom designing an adaptive filament winder. This machine consists of a stationary mandrel around which filament matrix was wound by the simultaneous rotary and translational motion of a hubless wheel. The pipes fabricated are subjected to internal pressure and four point bend tests. The four-point bend tests were conducted with hollow specimens and specimens filled with glass beads. It has been found that, the rectangular pipes had better load carrying abilities than the triangular pipes because of larger area and lower stress concentrations. There is an effective transfer of load radially in the pipes filled with glass beads, subjected to four-point bend tests. The pipes also show a linear variation of the load curve until the point of failure. Finite Element Analysis is conducted on these pipes to validate the experimental results using ANSYS. A finite element model is created using Shell 99 element type and the material properties and loading conditions are accurately specified to simulate the actual test conditions. Parametric studies are conducted by varying the fillet radius and orientation of the glass fibers. It has been found that the value of the peak stress decreased with an increase in the radius of the fillet. Also, the rectangular pipes have lower peak stress values compared to the triangular pipes. The optimum fiber orientation has been established between 53⁰ and 57⁰. The effect of these parameters was analyzed and general conclusions are drawn based on the experimental and numerical results.
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Ramachandran, Prashanth, "Experimental and numerical modeling of stresses in non-conventional cross-sectioned composite pipes" (2009). LSU Master's Theses. 4020.