Bio-composite materials have taken an extensive interest in research over the years due to their excellent properties, such as excellent mechanical and physical properties, stiffness, and low density/lightweight. The exceptional properties of bio-composite materials have had a widespread application in several industries, such as; the packaging industry, construction, automotive, and other related engineering fields. This research investigates mechanical, physical, and microstructure properties of Sansevieria Trifasciata (STE) natural fiber, -reinforced Vinyl Ester (STF/VE) bio-composite. The mechanical and physical properties of STF/VE bio-composites, including the tensile strength and density, are investigated through fibre preparation, orientation, and fibre volume fraction parameters. The STF/VE bio-composite tensile strength coupon is manufactured using the bio-composite transfer moulding (BTM) process and with pressure moulding. The Taguchi experimental design and analysis of variance (ANOVA) are selected to investigate the effect of variables on the mechanical properties model. The alkali preparation of STF, unidirectional fibre orientation, and fibre volume fraction improve tensile strength. Non-alkali treatment and random fibre orientatio, on the other hand, result in a reduction of density. The results of the ANOVA analysis show that the fibre volume fraction (wt.%) is the variable that most significantly affects the tensile strength and density responses, with contributions of 50.57% of tensile strength and 51.34% of density, respectively. Based on the optimization results, the STF/VE with alkali treatment, unidirectional, and 15 w.t.% is chosen as the best bio-composite formulation, with the best tensile strength-density balance. It indicates that the optimum parameter was successfully achieved among the samples examined in this work.

This paper demonstrates the optimization of resistance spot welding on different connections of galvanized steel sheets and low carbon steels. The zinc coating on galvanized steel sheets will have an effect to reduce the welding ability in the resistance welding process. The practical Taguchi experimental technics were used by implemented adequately to optimize input factors, namely squeezing time, welding current, welding time and holding time. Statistical software implemented an analysis of variance (ANOVA) and multilinear regression to investigate and evaluate the significant input factors and compare them with the experimental output factors of resistance spot welding. The 'signal to noise ratio' (S/N ratio) results shows that the welding time and the welding current are the most significant factors on the output. The delta values ​​of welding time and welding current are 3.15 and 2.25, respectively. The ANOVA results showed that welding current and welding time are the most contributing factors by 23.5% and 51.4%, respectively. Taguchi recommends an optimal squeezing time of 20 cycles, a welding current of 27 kA, a welding time of 36 cycles, and a hold/cooling time of 15 cycles. The highest output reaches a tensile shear strength of 5762.04 N on the third iteration. The present research has successfully identified significant variable inputs for resistance spot welding, namely welding current and welding time. In the future, the relevant research may use our corresponding results to improve the RSW practical procedure for other significant impacts.