International Journal of Experimental Design and Process Optimisation (5 papers in press)
Effect of overlap support characteristics on peel strength
of weld-bonded joints
by Wadea Ameen, A.M. Alsamhan, S.M. Darwish
Abstract: Bonded joints normally have a low peel tensile strength, since the stresses are concentrated on the small bond line. It has been proposed that adding a weld-bonded overlap support to the T-peel joint will enhance its peel strength tremendously. Since this support may increase the weight of the joint, a trade-off between weight increase (material type and thickness) and improved peel strength must be made.
The aim of the present work is to investigate the effect of the overlap support characteristics (material and thickness) on the stress distribution of the T-peel joint. Different materials with different thicknesses are considered in order to strengthen the T-peel joint. A finite element technique was used for evaluating the current models. The results showed that the peak stress decreases with increasing thickness and stiffness of the overlap support.
Keywords: T-peel joint; Weld-bonded joint; Overlap support; Finite element model.
Experimental measurement and modelling of surface roughness in turning with CaF2 solid lubricant assisted minimum quantity lubrication
by Mayurkumar Makhesana, Kaushik Patel
Abstract: To improve the quality of a product, it is important to evaluate, both experimentally and analytically, the factors affecting the machining process. In this context, the proposed work focuses on the modelling and analysis of surface roughness measured in a turning process with wet and minimum quantity solid lubrication (MQSL) approaches. In the MQSL application, micron-sized calcium fluoride (CaF2) solid lubricant powder particles are mixed in Society of Automotive Engineers (SAE) 40 cutting oil and applied to a machining zone. It also provides a predictive model for the minimization of the surface roughness in turning operations in wet and MQSL environments. The correlation between the cutting parameters and measured surface roughness in wet and solid lubricant assisted machining is determined. Results indicate that surface roughness is affected by feed, depth of cut followed by cutting speed. These outcomes can be used by the machining industry to use the best combination of parameters affecting surface roughness with the MQSL approach.
Keywords: Solid lubricant;Turning;Surface roughness.
Quantifying the effect of construction site factors on concrete compressive strength using designed experiments
by Jorge Santamaria, Vanessa Valentin, Gabriel Huerta
Abstract: Both structured and unstructured factors affect concrete compressive strength. Structured factors, e.g., raw materials, affect concrete production. Unstructured factors, e.g., local conditions, affect concrete quality during the construction phase. The effects of structured factors on concrete metrics are well understood, while there is limited understanding on the effects of unstructured factors. A full 2^5 factorial design was conducted to quantify the effect of five construction site factors including crew experience, compaction method, mixing time, curing humidity and curing temperature. A linear regression model was developed considering significant affecting factors. Model adequacy was evaluated through residual plots. The results indicate that compaction method, mixing time, curing humidity and curing temperature affect concrete compressive strength significantly, with curing temperature having the highest percent contribution (50.0%). The final regression model was used to create a decision-support tool that enables construction workers to find operating conditions and take corrective actions to preserve concrete quality.
Keywords: concrete; construction site factors; unstructured factors; compressive strength; prediction model; operating conditions.
On the mechanical characteristics and parametric optimization of friction stir welded magnesium AZ31B alloy
by Piyush Gulati, Dinesh Shukla
Abstract: Friction stir welding (FSW) is an effective joining technique to produce sound defect free welds. The various process and tool parameters play significant roles for producing sound welds and deciding the joint characteristics. In the present research work, the tensile strength (TS) and impact energy (IE) of friction stir butt-welded AZ31B magnesium alloy were investigated. The empirical relationships between the FSW input process parameters (tool rotational speed, tool welding speed and plunge depth) and the output responses (tensile strength and impact energy) were established. The welding conditions to maximize the tensile strength and impact energy were optimized and reported. The microstructure of the friction stir welded joints was investigated using optical microscopy and the grain size was also determined. Rotational speed was found as the most significant parameter for maximizing the tensile strength and impact energy. Further, the friction stirring of the selected base metal has affected the grain structure of the processed metal and an average reduction of 6
Keywords: Friction stir welding; magnesium; microstructure; tensile strength; impact energy; optical microscopy; plunge depth; rotational speed; welding speed.
OPTIMUM DESIGN FOR AN INCOMPLETE SECOND DEGREE MIXTURE MODEL
by Nripes K. Mandal, Manisha Pal
Abstract: Mixture experiments form an important part of research in areas like pharmaceutical, biometrics, agriculture, etc. Optimum mixture designs have been derived by many authors for mixture models due to Scheff
Keywords: Mixture design; incomplete model; D- and A-optimality criteria; optimum design.