FINITE ELEMENT ANALYSIS, AND DESIGN OPTIMIZATION OF SINGLE SHAFT TRIPLE JAW PLASTIC SHREDDER ROTOR

Abstract

Plastic waste causes serious environmental pollution and exhaustion of landfill space. One of the main reasons for this plastic-based waste is the lack of a full recycling process. In the recycling process shredding is one of the crucial stages where the main size reduction takes place. The size reduction in single shaft shredder is done by shearing and/or crushing the plastic between stationary blades that are bolted on to the casing and rotating blades mounted on the rotor. In this thesis work the effort is taken on finite element analysis, and design optimization of shredder rotor. In the conceptual design, three concept variants, namely flat arrangement, scissor arrangement, and staggered arrangement were considered and evaluated by assigning performance criteria. According to the considered criteria, their weighting percentages were found to be 65.42%, 64.42%, and 66.75% respectively. As a result, due to the higher weighting the staggered arrangement is selected as an appropriate concept for further analysis. In the same manner for attaching the shaft with the blade carriage three different types of shafts, namely, cylindrical, hexagonal, and splined shaft were considered and analyzed on ANSYS®V19R1. The static structural analysis is conducted on three of them with the same loading and boundary conditions. Accordingly, the maximum deformation result are 0.040 mm, 0.003 mm, and 0.028 mm whereas, the equivalent Von-Mises stress for cylindrical, hexagonal, and splined shaft are 216.92 MPa, 45.483 MPa, and 45.478 MPa respectively. As the splined shaft coupled with the blade carriage has lower deformation and stress. Thus, it is considered as the best mechanism. The topology optimization of blade carriage after smoothing resulted with 17.5% mass reduction. For the parametric optimization of blade carriage of the rotor, five input and three output parameters were considered to parametrically optimize the blade carriage. From Design Exploration response surface, response surface optimization, were conducted. The parametric optimization, which was conducted on the blade carriage resulted in three candidate parameters from which the best candidate is used with little approximation to remodel the blade carriage. The optimized parameters of the carriage are P1=9mm, P2 = 52.5 mm, P4 = 31 mm, P5 = 51 mm, P6 = 162.5 mm.