Saied Darwish

Critical assessment of weld-bonded technologies

Abstract It is well established that weld-bonded joints enhance the fatigue as well as the corrosion resistance of resistance welded joints. In the present work, both techniques of weld-bonding, namely, weld-through and flow-in, have been evaluated. Metallic fillers at optimum percentages were also tried in order to enhance the electrical conductivity of the adhesive material. The present work demonstrated that the flow-in technique is far better when compared with the weld-through technique, both from economical as well as technological points of view.

Finite element modeling of weld-bonded joints

Abstract The present work aimed at predicting the strength of weld-bonded joints having square or spew fillet adhesive layer. For comparison purposes, adhesive bonded and resistance spot-welded joints were also included in this study. The present work demonstrated that, the major principal stress predicted in joints having spew fillet adhesive layer is lower than that predicted in joints having adhesive layer with square edges. Consequently, it is advised to use adhesive layer having spew fillet to strengthen weld-bonded joints.

Design rationale of weld-bonded joints

The aim of the present work is to study the most influential parameters governing the strength of weld-bonded joints. The thickness and elastic modulus of adhesive, the stress concentration factor and the adherent materials, were all considered and their effectiveness evaluated. The present work demonstrated that for rationale design of weld-bonded joints, adhesives with the less Youngs modulus available should be coupled with maximum permissible gap thickness.

Strength prediction of weld-bonded joints

The present work aimed at predicting the strength of weld-bonded joints. For comparison purposes, adhesive-bonded and resistance spot-welded joints were also included in this study. The present work demonstrated that, the major principal stress predicted in spot-welded joints is nearly five to six times, when compared with those associated with weld-bonded and adhesive-bonded joints, respectively The present work also demonstrated the effective role played by the adhesive layer in strengthening weld-bonded joints.

Weldbonding strengthens and balances the stresses in spot-welded dissimilar thickness joints

Abstract Often in spot welding, the metals to be joined are similar or the thicknesses of the sheets to be joined are similar or both. The aim of the present work is to analyze spot-welded dissimilar thickness joints. The finite element technique was used for the analysis of the present work. The present work gives that the stresses are more concentrated towards the thinner part of a spot-welded dissimilar thickness joint, however, the introduction of an adhesive layer in conjunction with the spot weld nugget, resulted in strengthening and balancing the stresses on both members of the joint.

Laser Ablation and Laser-Hybrid Ablation Processes: A Review

Laser beam machining (LBM) has proven its applications and advantages over almost all the range of engineering materials. It offers its competences from macro-machining to micro- and nano-machining of simple-to-complex shapes. The hybrid approaches in laser ablation have demonstrated much improved results in terms of material removal rate, surface integrity, geometrical tolerances, thermal damage, metallurgical alterations, and many more. The flipside of LBM is the existence of universal problems associated with its thermal ablation mechanism. In order to alleviate or reduce the inherent problems of LBM, a massive research has been done during the past decade in order to build a relatively new route of laser-hybrid processes. This paper reviews the research work carried out so far in the area of LBM and its hybrid processes for different materials and shapes. The article also highlights the research gaps and future research directions in the context of laser and laser-hybrid ablation.

Characteristics of weld-bonded commercial aluminum sheets (B.S. 1050)

The aim of the present work is directed towards the manufacturing and characteristics of weld-bonded commercial aluminum sheets. Dynamic response (natural frequency and damping), nugget size, and tensile shear strength were tested and reported. The present work demonstrates a tremendous improvement in tensile shear strength associated with higher damping capacity for weld-bonded joints. However, the natural frequency seems to be independent on shear strength as well as joining technique (spot welding or weld bonding).

Manufacturing and characteristics of brass damping sheets

Abstract In the present work, the weld-through weld-bonding technique has been adopted for manufacturing brass damping sheets. Spot-welding parameters, namely welding current, electrode force and welding cycles, have been optimized and reported for these sheets. The tensile strength, fatigue strength, microhardness measurements and microstructure examination are performed and reported.

Micro-hardness of spot welded (B.S. 1050) commercial aluminium as correlated with welding variables and strength attributes

Abstract In the present work, experiments planned on the basis of statistical experimental design were carried out to study the influence of welding parameters (welding current, welding time, electrode force and sheet thickness) on the microhardness and strength of spot joints. Tensile shear strength, microhardness and nugget area of spot-welded commercial aluminium sheets (B.S. 1050) were measured, reported and correlated.

Laser Ablation Process Competency to Fabricate Microchannels in Titanium Alloy

Laser ablation is one of the competent machining processes to fabricate microfeatures in variety of engineering materials. This study has been progressed to evaluate the process capability of generating microchannels of various sizes (50 × 50 µm, 100 × 100 µm, 200 × 100 µm, and 1000 × 500 µm) in titanium alloy (Ti6Al4V) using Nd:YAG laser. Channels top width, bottom width, depth, and taperness are examined as the four process responses against three laser based parameters to the naming of laser intensity, repetition rate, and scan speed. All the geometrical dimensions are measured through photographic snapshots of SEM of each fabricated channel. The results reveal that the selection of channel size is critical to achieve the desired machining geometries. Wider sized channels (such as 200 × 100 and 500 × 1000 µm) are experienced as more flexible to be generated than narrower sized channels (50 × 50 and 100 × 100 µm). The precise parametric combination is the key to realize more tight dimensional enormities with respect to the targeted machining elements. The most appropriate parametric combinations that can generate the respectable results are explored and applied for machining of different channel sizes.