Browsing by Author "Gurumoorthy, B."

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Characterization of Polyolefin – Alumina compounded mix for FDC processing
(2000) Bhat, V.V.; Geetha, K.; Das, R.N.; Gurumoorthy, B.; Umarji, A.M.
Fused deposition of ceramics (FDC) uses thermoplastic binder and ceramic blend as feed material. The geometry of the fused deposition machine restricts the workability of the FDC feed material, which is in the form of a filament. The feasibility of the usage of these filaments is mainly based on the viscosity at the working temperature and the compressive modulus of the feed material at near room temperature. The polymers based on Polyethylene (PE), having two molecular weights 3,000 (LDWAX) and 341,000 (LDPE) were mixed in various weight proportions by solvent method using toluene as solvent, to develop a binder system for Fused Deposition Modeling of alumina. Variation of viscosity as a function of composition, temperature and solid loading was measured using spindle viscometer and capillary rheometer. Dilatometric thermal expansion of 50 Vol% alumina compounded binders is measured up to 120°C. The pronounced softening of the compounded mixture is observed beyond 70°C, when the volume % of LDWAX is in excess of 50% total binder content. The compression strength decreases from 720 N to 310 N for pellet having 1.2cm diameter and 1.5 aspect ratio, when the percentage of LDWAX varies from 40 to 70% in the binder composition. The suitability of the compounded mix of LDWAX and LDPE binder with 40 Vol. % alumina for FDC is being evaluated in a StratasysTM1600 machine.
Formulation of Lamination Conditions and Interface Studies using Acrylic Binder System for LOM 9
(2000) Das, Anirban; Dasgupta, Niladri; Gurumoorthy, B.; Umarji, A. M.
A multicomponent binder-plasticiser system based on acrylates was formulated for making flexible tapes of Alumina (58 volume %), to be used for Laminated Object Manufacturing. Optimum lamination parameters were arrived at by viscosity measurement of the binder-plasticiser system and dilatometry of the compounded tapes . Lamination was done at five different temperatures (75, 85, 90, 95 and 110°C) with solvent (toluene-butanol) spray and under three different pressures ( below 50 psi). The interlaminar strength was measured and interface studies were made using SEM .The shrinkage along the Z direction during lamination was in the range of 1.7-3.5%. Highest interlaminar strength and defect free lamination could be achieved at the intermediate temperature of 90o C, due to sufficient reduction of polymer viscosity and presence of solvent.
Robot-aided selective embedding of a spatially steered fiber in polymer composite parts made using vat photopolymerization
(University of Texas at Austin, 2023) Khatua, Vivek; Gurumoorthy, B.; Ananthasuresh, G.K.
Fiber-Reinforced Polymer Composite (FRPC) parts are predominantly laminates, shells, or surfaces wound with 2+D fiber patterns even after the emergence of additive manufacturing. Making FRPC parts with embedded continuous fibers in 3D is not reported previously even though topology optimization demonstrates that such designs are optimal. Earlier attempts in 3D fiber reinforcement include making parts with channels into which fibers are inserted or coextruding fiber with resin. In this work, A Vat-Photopolymerization Machine, and a process for concurrent embedding of spatially steered continuous fibers inside the matrix is developed. A single continuous fiber was embedded spatially using a robot to gradually steer the fiber as the part is built layer upon layer. An example of a fiber embedded along a helix in a cylindrical matrix is included in this work. Furthermore, a hinge effect was demonstrated when a fiber was embedded at a place that has substantial bending about the axis of the fiber.