Friction Stir Welding of Aerospace Alloys

Friction Stir Welding (FSW) is a solid state joining process which possesses a great potential to revolutionise the aerospace industries. Distinctive materials are selected as aerospace alloys to withstand higher temperature and loads. Sometimes these alloys are difficult to join by a conventional welding process but they are easily welded by FSW process. The FSW process in aerospace applications can be used for: aviation for fuel tanks, repair of faulty welds, cryogenic fuel tanks for space vehicles. Eclipse Aviation, for example, has reported dramatic production cost reductions with FSW when compared to other joining technologies. This paper will discuss about the mechanical and microstructure properties of various aerospace alloys which are joined by FSW process.

Relationship between environmental manufacturing practices and their competitive outcomes

In today’s competitive market providing products only in low cost and high quality is not enough. Environmental concern in manufacturing is also an important issue now. To attract investors and customers organizations need to practice environmental manufacturing. This study is focused to present the relationships between some specific environmental manufacturing practices and their relative specific competitive outcomes in the important and vast industry of garment’s knitting sector in Bangladesh. Although there are several studies on the impact of environmental practices on the organizations outcomes but they are less construable due to many limitations. This study explores the environmental manufacturing practices under two categories pollution prevention and product stewardship and shows their relative competitive outcomes and establishes the relation between them. Based on the surveys and research it is found that some competitive outcomes are positively affected by some of the practices. These findings are believed to motivate the companies to turn towards the green manufacturing.

Effect of Fe, Ni and Cr on the corrosion behaviour of hypereutectic Al-Si automotive alloy in 3.5% NaCl solution at different temperature and velocity

The main focus of this study is to examine and evaluate the effect of Fe, Ni and Cr on the corrosion behaviour of hypereutectic Al-Si automotive alloy in 3.5% NaCl solution. Experimental information are attained using conventional gravimetric measurements under different solution temperature and velocity and complemented by resistivity, optical micrograph, scanning electron microscopy (SEM) and X-ray analyzer (EDX) investigations. All the alloys show the negative corrosion rate due to formation of a very thin film of aluminum oxide and hydroxid on the surface. Intermetallic particles in the alloys play a major role in passivity. Temperature accelerates the corrosion and the higher velocity breakdown of the passive film. It also affects the resistivity of the alloys. The results from this study also indicate that the temperature and velocity increase the negative corrosion rate of the alloys due to higher rate of chemical reactions. SEM and EDX analysis indicate that the surfaces compose with a thin layer of aluminum oxide and hydroxide corrosion products.

Investigations for In-house prepared Biocompatible Feed Stock Filament of Fused Deposition Modelling: A Process Capability study

Fused deposition modelling (FDM) is one of the low cost additive manufacturing (AM) process. The feed stock filament of FDM is the only consumable in the process and by preparing (in-house) bio compatible feed stock filament the application domain can be increased. Some studies have reported the use of twin screw extrusion (TSE) process for preparation of bio compatible feed stock filament (comprising of polyvinyl chloride (PVC) and polypropylene (PP) and hydroxyapatite (HAp) particles) with improved mechanical, dimensional and thermal properties, for commercial FDM setup. But hitherto very less has been reported on process capability of in-house prepared biocompatible feed stock filament. In the present work statistical analysis (for tensile strength, hardness and dimensional accuracy) has been performed for investigations of process capability. The results have been also supported by control charts (X-chart and R-chart) based upon the best feedstock filament wire.

Effect of rolling on the fractional recrystallization behaviour of Al-Mg and Al-Mg-Zr alloys

One set of Al–Mg and Al-Mg-Zr alloys are directly cold rolled and other set of those alloys are hot rolled and then cold rolled using a laboratory rolling mill. The effect of rolling on the fractional recrystallization of the alloys has been investigated using the micro-hardness variation. Isothermally annealed samples are also studied using JMAK type analysis to see if there exists any correlation between experimental and JMAK type analysis. From the microstructure, it is observed that the Al-Mg alloy becomes almost fully recrystallized state after annealing at 600°K for 60 minutes. The results also show that recrystallization fraction obtained by the two methods, shows the higher variation in zirconium added Al-Mg alloy as compared to the Al-Mg alloy. The fractional recrystallization of the cold rolled Al-Mg-Zr alloy is significantly lower than that of cold rolled Al-Mg alloy and hot and colled rolled Al-Mg-Zr, owing to the presence of fine Al3Zr precipitates. These metastable L12 Al3Zr precipitates are thermally stable at high annealing temperatures.

Lean Implementation: The Progress and the future challenges of Apparel Industry to achieve the Manufacturing Competitiveness

Apparel industry plays an important role in the economic and social development of Bangladesh. This is now a multi-billion dollar manufacturing and export industry in Bangladesh. Its contribution to the foreign exchange earnings, poverty alleviation through creating employment opportunities and empowerment of women is remarkable. However, global competition and unstable market conditions prompted manufacturers to review their traditional manufacturing strategy. In today’s competitive business world, manufacturers are using Lean Manufacturing (LM) technique in order to improve performance and competitiveness. Lean Manufacturing (LM) is a holistic and sustainable approach of manufacturing system used for creating value for customers through eliminating waste in the manufacturing processes. This conceptual paper addresses the concept of lean manufacturing, its benefits and the challenges of implementing lean manufacturing.

FLOW CONTROL USING MOVING SURFACE AT THE LEADING EDGE OF AEROFOIL

Flow control is a significant topic of research in the field of aviation. Researchers in this field are continuously trying their best to find various flow control strategies in order to extract aerodynamic benefits by applying them. Applying moving surface at the leading edge of aerofoil is a type of strategy among the various types of active flow control strategies. In the present research work a rotating cylinder is added on the leading edge of the aerofoil as a moving surface in order to control the flow over its surface. The moving surface boundary layer control is applied to NACA 0018 airfoil for investigating its aerodynamic benefits and effectiveness. The moving surface is created by rotating a smooth cylinder at the leading edge of the aerofoil. The peripheral velocity of the cylinder injects momentum to the upper surface boundary layer of the aerofoil and thus delays its separation. This results in the gain in both the maximum lift coefficient and the stall angle. The work has been done at four different Reynolds Number i.e., at Re = 1.4 X 10^5, 1.85 X 10^5, 2.3 X 10^5, 2.8 X 10^5 at different angles of attack.

Intelligent Prediction of Fault Severity of Tractor’s Gearbox by Time-domain and Frequency-domain (FFT phase angle and PSD) Statistics Analysis and ANFIS

This study presents an approach to intelligent fault prediction based on time-domain and frequency-domain (FFT phase angle and PSD) statistical analysis, Principal component analysis (PCA) and adaptive Neuro-fuzzy inference system (ANFIS). After vibration data acquisition, the approach consists of three stages is conducted. First, different features, including time-domain statistical characteristics, and frequency-domain statistical characteristics are extracted to get more fault detection information. Second, three components by a principal component analysis are obtained from the original feature set. Finally, these three components are inputted into ANFIS for a development model of identifying different abnormal cases. The proposed approach is applied to fault diagnosis of gearbox's number one gear of MF285 tractor, and the testing results show that the proposed model can reliably predict different fault categories and severities.

COMPARISON OF SOME STATISTICAL FORECASTING TECHNIQUES WITH GMDH PREDICTOR: A CASE STUDY

Demand forecasts are extremely important for manufacturing industry and also needed for all type of business and business suppliers for distribution of finish products to the consumer on time. This study is concerned with the determination of accurate models for forecasting cement demand. In this connection this paper presents results obtained by using a self-organizing model and compares them with those obtained by usual statistical techniques. For this purpose, Monthly sales data of a typical cement ranging from January, 2007 to February, 2016 were collected. A nonlinear modelling technique based on Group Method of Data Handling (GMDH) is considered here to derive forecasts. Forecast were also made by using various time series smoothing techniques such as exponential smoothing, double exponential smoothing, moving average, weightage moving average and regression method. The actual data were compared to the forecast generated by the time series model and GMDH model. The mean absolute deviation (MAD, mean absolute percentage error (MAPE) and mean square error (MSE) were also calculated for comparing the forecasting accuracy. The comparison of modelling results shows that the GMDH model perform better than other statistical models based on terms of mean absolute deviation (MAD), mean absolute percentage error (MAPE) and mean square error (MSE).

Development of the wave spectrum of the northern region of the Bay of Bengal based on Indian National Centre for Ocean Information Services (INCOIS) moored buoy data

The wave spectrum of the northern region of the Bay of Bengal is developed and analyzed. A meticulous analysis shows variations of the wave spectrum of this region in the four meteorological seasons namely spring (March, April, May), summer (June, July, August), autumn (September, October, November) and winter (December, January, February). Real time wave data have been collected from a moored buoy of Indian National Centre for Ocean Information Service (INCOIS) located at 89.675° E longitude and 18.191° N latitude. Varyingtwo-parameter (mean wave period and significant wave height) wave spectra for the four seasons are obtained and formulae for all the four spectra are derived. The adequacy of the different spectra is indicated by comparing with different wave spectra of known formulations.