Friction stir welded butt joints optimization

Friction stir welding is an emergent technique that still lacks optimization studies in the literature. Optimum parameters are of prime importance for future investigations, as it will allow for consistent and sound welds. This is of even greater relevance for industrial applications, as for friction stir welding to become a mainstream joining technology. This paper presents an optimization study of friction stir welded butt joints through the Taguchi method. The most influent welding parameters and their trends were identified. The process optimization for the selected aluminium alloy was achieved and the best parameters combination to accomplished quality welds was selected. The parameters combination that lead to higher mechanical stiffness were: 1000 min^–1, 290 mm/min, 0.15 mm from the probe to the root surface and a shoulder/probe diameters ratio of 2 (shoulder diameter of 12 mm). Equations to estimate joint properties were derived by multiregression.     

Nachweis und Verfolgung von Membran‐Fouling

Membrane fouling is a negative contamination effect: compounds in the feed solution settle on the membrane surface or in the pores, limiting the efficiency and separation performance of the membranes. This effect occurs for different membrane types such as reverse osmosis, ultra‐, nano‐ and microfiltration membranes. A method is presented how membrane fouling can be identified and tracked based on the zeta potential calculated from flow measurements.     

Optimization of dry sliding wear parameters of AA336 aluminum alloy-boron carbide and fly ash reinforced hybrid composites by stir casting process

Boron carbide (10 wt%) and fly ash (5 wt%) particles are reinforced in AA336 aluminium alloy by stir casting process. Microstructure of samples are investigated and dry sliding wear factors viz., load (10 N–50 N), sliding distance (500 m–2500 m) and sliding velocity (1 ms⁻¹–5 ms⁻¹) are considered. Response surface methodology is used to design the experiments and wear weight loss of samples is measured. Regression equation is developed to predict the weight loss. Analysis of variance, significance test and confirmation test are used to find the significant wear parameters which affects the weight loss and the wear factors are optimized for obtaining lowest weight loss. Microstructure of samples showed uniform dispersion of particles in AA336 aluminium alloy. Wear test results showed that weight loss increased with increasing load and sliding distance. However, weight loss of samples decreased with increasing sliding velocity. Optimum dry sliding wear factors are found to be a load of 18.1 N, sliding distance of 905.4 m with a sliding velocity of 4.18 ms⁻¹.     

Optimization of process parameters of friction stir spot welding of polycarbonate sheets and morphological analysis

Friction stir spot welding has a great impact on the joining process of thermoplastics. In this work, effects of varying rotational speed, plunge depth, and dwell time were investigated on polycarbonate sheets and a filler sheet was utilized to reduce the keyhole size of friction stir spot welded joints. The welding parameters were arranged according to Taguchi L₉ orthogonal design of experiments to determine the optimum levels of process parameters. Lap shear tests were performed to examine the mechanical properties. Using analysis of variance and signal to noise ratio, influences of each welding parameter on the lap joint shear load were evaluated. According to achieved results, tool rotational speed has the highest effect while plunge depth has minimum effect on the mechanical behavior of friction stir spot welded joints. Optimum process parameters were attained as 1000 min⁻¹ for rotational speed, 10.5 mm of plunge depth, and 40 s of dwell time. Optimized process parameters showed 15 % improvement compared to the initial welding parameters. Cross-sectional appearances of welded samples which play an important role in determining lap joint shear load were analyzed by morphological and visual comparisons. Failure modes of the fractured samples for lowest, moderate and highest lap joint shear loads were also observed.     

A study on the parametric optimization of drawing metal stamping process for aluminum alloy tailgate parts using response surface methodology

The tailgate-extension in a vehicle is a part that connects the upper and lower parts of the tailgate. Since this part does not require high strength, aluminum must be used in order to reduce the weight of the vehicle. However, when choosing aluminum, it is difficult to satisfy the shape quality with the existing manufacturing process. Therefore, this study was conducted for the purpose of optimizing the draw metal stamping process for the development of tailgate extensions for vehicles using aluminum. The response surface methodology was utilized to optimize the draw metal stamping process. The process design parameters were established as blank holding force, coefficient of friction and die speed. Finally, the reliability of the optimization process and finite element analysis was secured by conducting field experiments to review the derived optimal process conditions.     

Analysis of tribological behaviour of aluminum-titanium carbide-basalt metal matrix composite

In the recent years, particulate reinforced aluminum based matrix composites are playing an important role in automobile and aerospace applications due to their enhanced properties. In this work, an attempt has been made to optimize the tribological behaviour of aluminum 7075 matrix reinforced with titanium carbide (3 percent weight) and basalt particles (2 percent weight) using Taguchi based grey relational analysis. Composites are fabricated according to american society for testing materials standard using stir casting method dry sliding wear tests were carried out using pin on disc apparatus as per Taguchi's L9 orthogonal array. Grey relational analysis was used to obtain the optimum process parameters for multiple quality characteristics such as wear rate and coefficient of friction. Then significant contribution of wear parameters was determined by analysis of variance. A confirmatory test was carried out to validate the test result. Finally, the micro structural investigation on the worn surfaces was performed by scanning electron microscope.