Mechanical Engineering

A non-linear cumulative fatigue model was developed for estimating the fatigue life of high strength aluminum alloy 7049 in high cycle fatigue (HCF) and low cycle fatigue (LCF) regimes with different laser surface coatings. These coatings are water laser peening and the black paint laser peening (bPLP). The results of the application the new non-liner model to the experimental data that the proposed model is quite applicable for interaction cumulative fatigue with laser coating. The paper also indicated that the fatigue limit increased by 2.59 due to bpLp while it reduced by 2.3 due to WLP.The new non linear model showed satisfactory prediction for bpLp cumulative fatigue loading.

The effect of penstock diameter on shaft power was studied as part of an ongoing development of a simplified pico-hydropower system with water recycling. The speeds of the turbine and alternator shafts and volume of water displaced were measured for each penstock diameter and nozzle area ratio. The shaft power, flow rate and efficiency of the turbine were computed. The mean efficiencies were 0.776 and 0.510 for penstocks diameters 0.0762 and 0.0381 m respectively. Hence, larger penstock diameters with small nozzle area ratios favor optimal system operation. The results show that the system can potentially impact Nigeria’s energy mix positively

The main purpose of this study is to analysis the thermomechanical behavior of the dry contact between the brake disc and pads during the braking phase. The thermal-structural analysis is then used coupling to determine the deformation and the Von Mises stress established in the disc, the contact pressure distribution in pads. The results are satisfactory when compared with those of the specialized literature.

In this work the void fraction for oil-water mixture are measured by using radiation source 137Cs with activity of 0.636 µCi. The plastic-tube contain the mixture are putting interior beaker and subjected into radiation to measure the void fraction. There are many applications industries, such as, oil and gas pipelines, heat exchangers etc.

In metalworking, rolling is a metal forming process in which metal stock is passed through a pair of rolls. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its recrystallization temperature, then the process is termed as hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is termed as cold rolling. In terms of usage, hot rolling processes more tonnage than any other manufacturing process, and cold rolling processes the most tonnage out of all cold working processes. This article describes the use of advanced tubing inspection NDT methods for boiler and heat exchanger equipment in the petrochemical industry to supplement major turnaround inspections. The methods presented include remote field eddy current, magnetic flux leakage, internal rotary inspection system and eddy current.

Explosion welding (EXW) is a solid state (solid-phase) process where welding is accomplished by accelerating one of the components at extremely high velocity through the use of chemical explosives. This process is most commonly utilized to clad carbon steel plate with a thin layer of corrosion resistant material (stainless steel, nickel alloy, titanium, or zirconium). Due to the nature of this process, producible geometries are very limited. They must be simple. Typical geometries produced include plates, tubing and tube sheets. Explosion welding or bonding is a solid-state welding process that is used for the metallurgical joining of dissimilar metals. The process uses the forces of controlled detonations to accelerate one metal plate into another creating an atomic bond. Explosion bonding can introduce thin, diffusion inhibiting interlayer such as tantalum and titanium, which allow conventional weld-up installation. In addition, explosive welding is considered a cold-welding process, which allows metals to be joined without losing their pre-bonded properties.

In this paper, the laser beam welding is studied and Aluminium temperature field is gained in this process. The thermal effect of laser beam that specially depends on the laser type and temperature field of it in workpiece, is the main key of analysis and optimization of this process, from which the main goal of this paper has been defined. Utilizing laser as a method to join plastic components is growing in popularity. There are two laser welding mechanisms, keyhole mode and conduction mode. Keyhole welding is widely used because it produces welds with high aspect ratios and narrow heat affected zones. However keyhole welding can be unstable, as the keyhole oscillates and closes intermittently. This intermittent closure causes porosity due to gas entrapment. Conduction welding, on the other hand, is more stable since vaporisation is minimal and hence there is no further absorption below the surface of the material. Conduction welds are usually produced using low-power focused laser beams. This results in shallow welds with a low aspect ratio. In this work, high-power CO2 and YAG lasers have been used to produce laser conduction welds on 2mm and 3mm gauge AA5083 respectively by means of defocused beams. Full penetration butt-welds of and 3mm gauge AA508 using this process have been produced. It has been observed that in this regime the penetration depth increases initially up to a maximum and then decreases with increasing spot size.

Chemical vapour deposition (CVD) is a widely used method for depositing thin films of a large variety of advanced materials. Applications of CVD range from the fabrication of microelectronic devices to the deposition of protective coatings but also optoelectronic films, decorative coatings.

In submerged arc welding (SAW), selecting appropriate values for process variables is essential in order to control heat-affected zone (HAZ) dimensions and get the required bead size and quality. Also, conditions must be selected that will ensure a predictable and reproducible weld bead, which is critical for obtaining high quality. In this investigation, mathematical models were developed to study the effects of process variables and heat input on various metallurgical aspects, namely, the widths of the HAZ, weld interface, and grain growth and grain refinement regions of the HAZ. The color metallography technique and response surface methodology were also used.The thermal effect of Submerged Arc that specially depends on the electrical arc, flux type and temperature field of it in workpiece, is the main key of analysis and optimization of this process, from which the main goal of this paper has been defined. Numerical simulation of welding process in SIMPELC method and by ANSYS software for gaining the temperature field of copper, the effect of parameter variation on temperature field and process optimization for different cases of Submerged Arc are done. The influence of the welding parameter for each mode on the dimensions and shape of the welds and on their ferrite contents is investigated.

This contribution aims to validate a newly developed add-on module to a commercial simulation software, which enables the prediction of the microstructure and mechanical properties of aluminum cast alloys under different casting conditions. The simulation of the casting process and the resulting microstructure and mechanical properties, permits a reduction of experimental testing and providing the best solution of process and material selections, thereby making the design and development process more cost efficient. The simulation results are compared with the investigation of the micro structural and mechanical behaviors of an As-Cast Aluminum cylinder head processed by semi permanent gravity die casting. It is demonstrated that the predictions made by the simulations are comparable to the experimental results. In order to further enhance the quality of the simulation tool, it is of significance to gain more experience from comparisons with complex castings of different aluminum alloys, where the microstructure as well as the mechanical properties are carefully evaluated.