Geometric effects of sustainable auxetic structures integrating the particle swarm optimization and finite element method

The development of new materials based on industrial wastes has been the focus of much research for a sustainable world. The growing demand for tyres has been every year exacerbating environmental problems due to indiscriminate disposal in the nature, making a potentially harmful waste to public health. The incorporation of rubber particles from scrap tyres into polymeric composites has achieved high toughness and moderate mechanical properties. This work investigates the geometric effects (thickness, width and internal cell angle) of auxetic structures made of recycled rubber composites based on experimental and numerical data. The response surface models integrated with the swarm intelligence and finite element analysis were proposed in order to obtain a range of solutions that provides useful information to the user during the selection of geometric parameters for reentrant cells. The results revealed the cell thickness ranges from 39-40 mm and 5.98-6 mm, and the cell angle range from -0.01 to -0.06º maximize the ultimate strength. The same parameters were able to optimize the modulus of elasticity of rubber auxetic structures, excepting for the angle factor which must be set between -30º and 27.7º. The optimal Poisson's ratio was found when the cell angle ranged from -30º to -28.5º, cell width ranged from 5-5.6 mm and 2 mm in thickness

Influence of different types of sharpening in straight flute drills on burr formation

Drilling is among the most important manufacturing processes in modern industry. Information on the dynamics of the drilling process is very important to define optimum input parameters. The minimization of burrs is a great challenge in drilling process. Current analysis was carried out with stepped solid carbide drills with straight flutes in drilling of the aluminum alloy A306. Burr height was measured at hole exits and evaluated with ANOVA technique. Results showed that the feed rate and cutting speed variation exhibited significant influence while sharpening was the most important parameter on burr formation.

<b>Effects of different cutting strategies on G-ratio in through-feed center-less grinding

Grinding is the main manufacturing process used in finishing operations. Center-less grinding is widely used in the production of auto parts e.g. roller bearings, valve stem and stem of shock absorbers. Center-less grinding is used in large-scale production due to shorter time and higher flexibility. However, the set-up of the grinder is complex and slow, and depends on the operators’ ability. The choice of the best parameters in the process is important to define exactly the cutting strategy and to optimize the process. Current study analyzes the input parameters: feed rate and type of materials on the responses G-ratio, surface roughness, and roundness. Thus, stems of shock absorbers were used as work pieces on the shop floor. Cutting speed and grinding wheel type were constant. The input parameters comprised feed rate and type of materials (1025 and 1045). Responses were surface roughness, roundness error and G-ratio. Results demonstrated that the kinds of tested material was the parameter that most influenced G-ratio and surface roughness. Moreover, feed rate had little influence on the quality of the work pieces, mainly on roundness error