SLIDING FRICTION WEAR BEHAVIOUR OF SEASHELL PARTICULATE REINFORCED POLYMER MATRIX COMPOSITE – MODELING AND OPTIMIZATION THROUGH RSM AND GREY WOLF OPTIMIZER

In this work, the friction wear behaviour of seashell particles reinforced in thermoplastic polymer Nylon-6 is investigated.. Seashells were collected from the seashores, uniform size 75 µm is obtained using mechanical ball milling and vibrating sieve. Various proportions of seashells such as 12, 15 and 18% by weight are added to nylon-6 and the polymer composites wear performance in dry sliding is studied as per ASTM G99 standard, loss of material in wear, friction coefficient and interface temperature are optimized. For experiment design Response surface methodology (RSM) based Box-Behnken method (BBD) is adopted and multi-objective analysis is performed using desirability analysis. Observation shows that interface temperature is highly influenced by rotational speed (41.61%), % reinforcement of seashells influences the wear loss significantly (35.71%) and coefficient of friction is influenced greatly by rotational speed (41.48%)and % reinforcement of seashells (18.18%). A novel metaheuristic algorithm Grey wolf optimizer is used for constrained optimization, which shows that for 0.3 CoF and 25°C interface temperature as constraint wear loss is 35.77 microns for % reinforcement of seashell as 3.59, whereas for 0.3 CoF and 30°C interface temperature wear loss is 28.99 microns for a seashell reinforcement of 18%.

Modeling and Optimization of Cut Quality Responses in Plasma Jet Cutting of Aluminium Alloy EN AW-5083

The plasma jet cutting process has a high potential for the machining of aluminium and its alloys. Aluminium is well known as a highly thermally conductive and sensitive material, and because of that there exist uncertainties in defining process parameters values that lead to the best possible cut quality characteristics. Due to that, comprehensive analysis of process responses as well as defining optimal cutting conditions is necessary. In this study, the effects of three main process parameters—cutting speed, arc current, and cutting height—on the cut quality responses: top kerf width, bevel angle, surface roughness Ra, Rz, and material removal rate were analyzed. Experimentations were conducted on aluminium EN AW-5083. In order to model relations between input parameters and process responses and to conduct their optimization, a novel hybrid approach of response surface methodology (RSM) combined with desirability analysis was presented. Prediction accuracy of developed responses regression models was proved by comparison between experimental and predicted data. Significance of process parameters and their interactions was checked by analysis of variance (ANOVA). Desirability analysis was found as an effective way to conduct multi-response optimization and to define optimal cutting area. Due to its simplicity, the novel presented approach was demonstrated as a useful tool to predict and optimize cut quality responses in plasma jet cutting process of aluminium alloy.

Laboratory Evaluation of Rheological Properties of Asphalt Binder Modified by Nano-TiO2/CaCO3

Nanomaterials have a great potential for enhancing the performance of base asphalt binder. This study aims to promote the application of nano-TiO2/CaCO3 in bitumen and presents a study on rheological properties for TiO2/CaCO3 nanoparticle-bitumen. In this study, a series of laboratory experiments have been performed for bitumen with different nano-TiO2/CaCO3 dosages. Nano-TiO2/CaCO3-modified bitumen with optimum dosage was prepared for viscosity, dynamic shear rheometer (DSR), and beam bending rheometer (BBR) for assessing temperature sensitivity of bitumen, and the low-medium-high-temperature performances were analyzed for TiO2/CaCO3 nanoparticle-bitumen as well. Results show that bituminous mechanical properties were enhanced by TiO2/CaCO3, and based on the overall desirability analysis of various conventional tests, the reasonable dosage of nano-TiO2/CaCO3 was recommended as 5% by weight of base bitumen. Adding nano-TiO2/CaCO3 was beneficial to improve the viscosity and reduce the temperature sensitivity of bitumen. The capacities of bituminous rutting resistance as well as medium-temperature fatigue resistance were enhanced by the addition of nano-TiO2/CaCO3. However, BBR test shows that bituminous anticracking is reduced slightly. On this basis, the Burgers model is selected for clarifying the decrease in anticracking performance; that is, nano-TiO2/CaCO3 increased the stiffness modulus while increasing the viscosity of bitumen.