A new model was developed to predict the mechanical properties of St22 grade cold rolled deep drawing steel by gene expression programming. To obtain a dataset to find out the effect of reduction rate on the mechanical properties of cold rolled and galvanized steel sheet, an experimental program was constructed in the real production plant by keeping all other process parameters constant. The training and testing data sets of gene expression programming model were obtained from the test results. For gene expression programming model, mechanical properties (yield strength, ultimate tensile strength and elongation) before cold rolling, chemical composition, initial sheet thickness and reduction rate were used as independent input variables, while mechanical properties after cold rolling (yield strength, ultimate tensile strength and elongation) were used as dependent output variables. Before constructing the gene expression programming models for dependent variables, dataset was analyzed using the analysis of variance and statistically significant (P ≤ 0.1) independent parameters, i.e. initial sheet thickness, reduction rate, initial yield strength, initial tensile strength, elongation and Mn content were used in gene expression programming model. Different models were obtained for each dependent variable depending on the significant independent variables using the training dataset and accuracy of the best models was verified with testing data set.The predicted values were compared with experimental results and it was found that models are in good agreement with the experimentally obtained results.

This paper describes the designing and manufacturing process of a complex special utility vehicle (SUV) using the methodical design approach for which the basics were explained decades ago in Germany. The application steps of the design methodology with comprehensive data are clearly outlined and the experiences gained during the project along with the authors' experiences in design research and design practice over 25 years are generously shared. This paper contributes to the methodical approach laid by Pahl & Beitz with an industrial example proving its applicability in real engineering design applications. The proposed solutions for difficulties encountered in the process are especially valuable and applicable for SMEs (small and medium-sized enterprises) in the field. Such details are reported with comprehensive discussions in this paper.

Resistance spot welding is an extensively used production process in the industry. The joint strength of sheet metal parts bonded by resistance spot welding is expected to be sufficient. Furthermore, it is desirable that the appearance of the welding area be acceptable on visible surfaces. In regard to having an adequate surface appearance on the welded area, is necessary to remove the color changes on the unpainted surfaces and to eliminate the indentations caused by the welding pressure. In this study, an objective evaluation was performed using the color measurements of the test samples joined with resistance spot welding. The effects of welding parameters on surface appearance were investigated and the most suitable settings for the appearance of the welded surface were discussed.

In this study, an experimental investigation of the electrospinning process has been conducted using two successive Taguchi experimental designs, namely L 18 (3 5) and L 9 (3 4) for the electrospinning setups with a rotating drum and a stationary plate, respectively. The processing parameters are; concentration of poly(vinyl alcohol) in aqueous solution, applied voltage, distance between the needle and the collector, flow rate of the polymer solution and the rotational speed of the collecting drum. The primary process setup is used to analyse the effects of the parameters to the diameter of nanofibers and its standard deviation (SD), through examinations of the range analysis and graphical interpretations. The secondary process set up is used to gather the data to verify the results and to compare the effects of the collecting methods on the process outputs. A short literature review of the publications on which parameter effects were analysed by statistical methods is also presented.

Bu çalışmada, AISI 304 ostenitik paslanmaz çeliğinden imal edilmiş sac plakaların nokta direnç kaynağı kullanılarak bağlanması işleminde etken parametreler incelenmiştir. En uygun kaynak parametrelerinin seçilmesinin yanı sıra kaynak bağı sonrasında çeliğin yüzeyinde en az kaynak izi kalması amaçlanmıştır. Kaynak sonrası oluşan çekirdek bölgesi renk ölçüm teknikleri kullanılarak analiz edilmiş ve ardından elde edilen sonuçlar uzman bir kaynakçının verdiği puanlar ile karşılaştırılmıştır. Nokta direnç kaynağının dayanımı da kesme testi yardımıyla kontrol edilmiştir. Bu çalışma, imalat öncesinde uygun estetik görünüm ve dayanım için yapılacak olan ön imalatların planlanmasında ve değerlendirilmesinde kaynak olacaktır. İmalat sonrasında ise ek işçilik gerektirmeden hem estetik hem de yeterli dayanıma sahip kaynak bağlarının gerçekleştirilmesi için sunulan yaklaşımın faydalı olacağı düşünülmektedir. Çalışmanın, kaynak işlemi esnasında bağlantı bölgesi estetik görünümünün objektif değerlendirilmesi amacıyla anlık ölçülmesi ve raporlanması için gelecekteki çalışmalara örnek olması da hedeflenmektedir. Anahtar Kelimeler: Nokta direnç kaynağı, izsiz kaynak, görüntü işleme, AISI 304, görsel kontrol, kesme testi Determination of welding mark appearance of welded 304 stainless steel sheets using different welding electrodes and the effect of welding parameters on mechanical properties