Ultrasonic welding is gaining popularity for joining of thin and DISSIMILAR materials and foils in the fabrication of automotive Li-ion battery packs because of excellent efficiency, high production rate, high welding quality, etc. Precise control of the parameters of the welding process plays an important role in achieving good joint quality. Numerical simulation can greatly help control the main input parameters such as frequency, clamping pressure, friction coefficient, and vibration amplitude. In this present work, a three-dimensional thermo-mechanical Finite Element (FE) model is proposed using ABAQUS/EXPLICIT for the DISSIMILAR Al to Cu weld to predict the deformation and temperature as output parameters during welding process by varying input parameters. The simulation results showed that the clamping pressure, vibration frequency and friction coefficient have a great influence on heat production during the process which was critical to determine the final quality of the welded joint. Studies also showed that increased clamping force and welding frequency led to increased deformation.

The electrochemical behavior of the weld nugget zone (WNZ) in copper-brass plates was studied in this paper. These plates were welded by the friction stir lap welding method in 1M NaCl solution at low heating input (450 rpm-25 mm/min) and high heating input (710 rpm-16 mm/min) by using the electrochemical impedance spectroscopy (EIS) and Tafel polarization at ambient temperature. The morphology of nugget zone corroded surfaces was analyzed by SEM (scanning electron microscopy) technique. The welding process appeared to decrease the corrosion resistance of the welded nugget regions through increasing the welding heat input. The results from EIS measurements presented the welded joints of NZ which showed higher and lower values respectively than brass and copper. Due to changing of microstructural of weld nugget zone during welding process, the Icorr of nugget zone enhances with increasing welding heat input. In fact, the surface corrosion morphology analysis revealed that the surface of welded sample by high heating input was shielded with a roughly porous corrosion layer rather than the surface of the welded sample at low heating input.

Several studies on photovoltaic systems focused on how it operates and energy required in operating it. Little attention is paid on its configurations, modeling of mean time to system failure, availability, cost benefit and comparisons of parallel and series–parallel designs. In this research work, four system configurations were studied. Configuration I consists of two sub-components arranged in parallel with 24 V each, configuration II consists of four sub-components arranged logically in parallel with 12 V each, configuration III consists of four sub-components arranged in series–parallel with 8 V each, and configuration IV has six sub-components with 6 V each arranged in series–parallel. Comparative analysis was made using Chapman Kolmogorov’s method. The derivation for explicit expression of mean time to system failure, steady state availability and cost benefit analysis were performed, based on the comparison. Ranking method was used to determine the optimal configuration of the systems. The results of analytical and numerical solutions of system availability and mean time to system failure were determined and it was found that configuration I is the optimal configuration.

Scaling methods have been developed to describe the spatial variability of soils. Among them, physically based methods are more desirable in which the scaling factors can be estimated from the soil physical properties. Assuming that the pore size distribution of soils is lognormally distributed, Kosugi and Hopmans developed a physically based method to scale the water retention curve. However, similar to the previous methods, application of this method is limited to the similar soils. To alleviate this limitation, in this paper, a physically based method is proposed for DISSIMILAR soils. Using this method, data of a wide textural range of soils can be scaled without the similarity condition and can be represented by a unique exponential reference curve. This method was validated using 487 sets of soil retention curves taken from UNSODA database including all the textural classes from sand to clay. The results showed that the proposed method had a better performance in scaling the retention curves than that of Kosugi and Hopmans. The criteria defined here for scaling error was obtained equal to 0.074 and 0.105 for the proposed and Kosugi-Hopmans method, respectively. In addition, it was shown that, in contrast to the previous methods, the scaling error of the proposed method does not depend on the soil texture and all the soils have an equal chance for being scaled.

In this research, gas tungsten arc welding of DISSIMILAR joint between 4130 low alloy steel and AISI 201 austenitic stainless steel was investigated. Four filler METALS i. e. ERNiCr-3, ER 309L, ER 308L and ER 80SB2 were used. After welding, microstructural features of various areas and also fracture surfaces were examined using optical microscopy and scanning electron microscopy. Tensile test was conducted in order to study the mechanical properties of each joint. It was found that ERNiCr-3 is fractured from fusion zone and the others were fractured from 4130 base metal. Also, some second phase particles such as NbC were seen in the ERNiCr-3 weld joint. SEM observation showed that the fracture behavior of ERNiCr-3 weld joint is semi brittle and the others are ductile. The fusion zone of ERNiCr-3 weld joint was fully austenitic and consisted of equiaxed grains and no crack was seen in this area. The fusion zone of ER 308L and ER 309L were composed from cellular dendrite and finally ER 80S-B2 weld joint was consisted of lath martensite.

Today, the demand for joining DISSIMILAR METALS of aluminium and steel to reduce the vehicle weight in the automotive, aerospace and shipbuilding industries has witnessed rapid growth. In the present study, 5083 aluminum alloy was joined to galvanized steel and plain carbon steel with 4043 and 4047 filler METALS by using the welding-brazing hybrid method. The brittle intermetallic compound (IMCs) layer formed in the interface of steel-weld seam was found to have significant influence on the joint strength. The results also indicated that increasing heat input enhanced the thickness of IMCs layer. The thickness of IMCs layers, as measured from microstructural images, was in range of 2-6 mm. Further, the results obtained from microstructural observation showed that with equal weld heat input, the thickness of IMCs layer for the joint produced with 4047 filler metal was approximately half of that obtained for the joint produced with 4043 filler metal. The highest mechanical resistance (of about 170 MPa) was obtained for aluminum to galvanized steel joint with 4047 filler metal. Moreover, in this joint, the failures occurred in the welded seam and for aluminum to plain carbon steel joint, it was in the interface of steel-weld seam. The results obtained by Energy dispersive x-ray spectrometry analysis of IMCs layer for aluminum to galvanized steel joint showed the presence of the FeAl3 intermetallic compound. This was confirmed by x-ray diffraction analysis of the fracture plane.

Mechanical properties of DISSIMILAR weld joints between GOST09ch16N4B (a martensitic stainless steel) and AISI 4130 thin sheets made by gas tungsten arc welding (GTAW) were studied using ER410NiMo and ER100S-G filler METALS in post weld heat treated conditions. Heat treatment cycles consisted of austenitization at 900, 950 and 1000 oC for 1 h and this was followed by oil cooling and tempering at 400 and 500 oC for 1 h. Tensile tests and microhardness measurements were carried out to evaluate the mechanical properties. The base METALS, heat affected zones (HAZs) and fusion zones were observed by optical microscope and scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS). Based on the results, it was found that the joints strength and microhardness profiles were almost independent of austenitization temperature, but they were affected by the tempering temperature. Increasing the tempering temperature led to the reduction in the hardness of AISI 4130 and the joints strength. Tensile samples were fractured in the base METALS. Furthermore, the fracture was shifted from GOST09ch16N4B to AISI 4130 with increasing the tempering temperature. Crack initiation from delta-ferrite led to the fracture in GOST09ch16N4B. Strength and elongation obtained from different PWHTs indicated that tempering at 400 oC resulted in acceptable tensile properties for the weldments made with both filler METALS.

Overlapped strips of titanium grade 2 and aluminum 3105-O alloy were welded together under an innovative spot-like pulse laser procedure. The tactile seam tracking on ring paths yielded reliable weld  t-up of 1 and 0. 5 mm thickness strips. Since the welding parameters of Ti-Al were narrow, three welding speeds of 4, 5, and 6. 67 mm. s-1 were chosen for the pretest conditions. The microstructural investigations showed that intermetallic compound Ti3Al formed in the Ti-rich fusion zone. Cracks formed in the Al-rich fusion zone as a result of TiAl3 precipitation. Dimple fracture occurred at 6. 67 mm. s-1 welding speed. Longer mixing time at Ti-Al interface occurred at lower welding speeds of 4 and 5 mm. s-1, which led to the formation of thicker intermetallic compounds and more massive crack generation. It also increased the hardness of the fusion zone and resulted in brittle fracture type during the tensile test. The highest strength was achieved with a welding speed of 4 mm. s-1, which was a result of more massive weld nugget and lower porosity.

Lap joints of commercially pure magnesium plates to aluminium plates (Magnesium plate on the top, and Aluminium plate, grade 1100, on the bottom side) were conducted by friction stir welding using various traveling and rotation speeds of the tool to investigate the effects of the welding parameters on the joint characteristics and strength. Defect-free lap joints were obtained in the welding traveling speed range of 40-80 mm/min, and rotational speed range of 1200-1600 rpm. The shear tensile strength of Mg/Al joints increased as a result of decreasing the welding speed from 120 to 40 mm/min at constant rotation speed of 1600 rpm. Defects such as surface grooves, excessive flash, tunnels, and voids were observed if the joints prepared out of the mentioned range. The effects of the welding parameters are discussed metallographically based on observations with optical and scanning electron microscopes.