Multiphysics Simulation of Laser Cladding Process to Study the Effect of Process Parameters on Clad Geometry

AbstractThe present work reports two-dimensional simulation of laser cladding process to understand the influence of process parameters on clad geometry formation for better process optimization. The application deals with pure copper powder cladding of SS316L substrate for process feasibility for thicker coating layers by CO2 laser. For this purpose, first mathematical model is developed and dealt numerically using multi-physics software. Conservation equation of energy, momentum and mass of this process are coupled through the temperature variable and solved to adapt the laser cladding process. The boundary conditions due to the laser melting process of dissimilar materials have to be deal with complex assumptions are applied in mathematical modelling to simplify problem due to the different materials properties. The deformation of free surface is calculated using moving mesh by the way of ALE (Arbitrary Lagrangian and Eulerian) method. In addition, thermo-capillary forces and their effect on fluid flow inside the melt pool are also considered in modelling to complete the process optimization. Thermal and stress distributions due to the process are also evaluated in the developed process simulation. The results provide approximate information about the effect of each selected parameters on clad geometry formation. The influence of process parameters have shown the best choice of optimization

Analysis and performance of edge filtering interrogation scheme for FBG sensor using SMS fiber and OTDR

Abstract An interrogation technique for fiber Bragg grating (FBG) sensor is devised with customized in-line edge filtering single-multi-single mode fiber (SMS) component and optical time-domain reflectometer (OTDR). The performance of the proposed SMS-OTDR interrogation is established by temperature and strain sensing analysis of a standard FBG. The temperature and strain sensitivity values which are verified by theoretical analysis are estimated as 1.01 × 10−2 dB/℃ and 3.9 × 10−4 dB/µɛ respectively. Furthermore, we have optimized and achieved controlled etching on FBG and tested it for hiking the sensitivity. Using the etched FBG, an enhanced temperature and strain sensitivity of 6.7 × 10−2 dB/℃ and 3.2 × 10−3 dB/µɛ covering the range of 20–200 °C and 100–2015 µɛ respectively are also recorded and analysed by this integration method. Eventually, the efficiency and cost-effectiveness of the proposed method are compared with various reported techniques and presented here

SIMULATION OF HYBRID LASER-TIG WELDING PROCESS USING FEA

Hybrid welding technology has wide advantages in welding to improve speed, weldability of special materials, increasing depth of weld. Less defects of the weld, less bead widths, less temperature, less distortion and less residual stresses are seen. In this study, a three-dimensional Finite Element Model is developed for butt joints for SS316L. The heat flux models of double ellipsoidal surface heat flux of TIG process and lateral heat to the thickness face of laser process are used to model combined TIG and Laser welding processes for simulating. Total heat is distributed as surface heat flux and lateral heat flux, which can be incorporated in modelling with the proportion for Hybrid laser-TIG welding process. The transient thermal analysis, with thermally dependent properties, is performed to achieve the temperature distribution during the process; later, it is used to apply for the mechanical analysis of distortion and stresses. Uniform distortion along the weld with edge deformations is found. Residual stresses will maintain structural integrity with minimum 1.3 factor of safety. In this study, to save computing time, symmetric conditions were used for analyzing only half the product

Exploring multi-party collaboration towards shared value across a platinum mine

The mining industry and its related activities presents a major source of income for many developed and developing countries. Despite this, the negative sentiment of the impacts of mining on the environment and communities that surround it are rising. Corporate Social Responsibility (CSR) programs largely legislated, are meant to address these impacts, yet to date, the ability for CSR to sustainably impact communities is a positive way is limited. CSR is considered an expense to companies and therefore regarded as unsustainable. An alternative to CSR is the concept of Shared Value, which speaks to a mutually beneficial relationship between a company and its stakeholders. The purpose of this research was to explore how multi parties, namely company, community and government, could, via collaboration, work together to achieve shared value across the context of a Platinum Mine in Limpopo, South Africa. It was found through this research that significant barriers exist to the concept of shared value. Some of the barriers are physical in nature (basic service and infrastructure for communities lacking) and other barriers relate to the condition of the relationship between the parties and impact of there-of. It was found that multi-party collaboration is not present. The study has found that if the concept of shared value is explored in the chosen context, it is vital that the relational aspects of trust, engagement, transparency and mutual respect are addressed and achieved. It has also been found that the concept of shared value in the theoretical context of present literature might not be attainable in this context due to the institutionalization and legislated nature of CSR in South Africa, therefore any implementation in this context will be in the form of a hybrid between the 2 concepts (Shared value and CSR).Mini Dissertation (MBA)--University of Pretoria, 2018.zk2019Gordon Institute of Business Science (GIBS)MB

CSR and shared value in multi-stakeholder relationships in South African mining context

PURPOSE : Mining is surrounded by controversy, in spite of corporate social responsibility (CSR) projects. This study aims to explore the theory on CSR and shared value (SV) and identified a gap in an approach to implementing CSR and SV. Perceptions of multi-stakeholder relationships in the South African mining context were elicited. DESIGN/METHODOLOGY/APPROACH : A qualitative research design included 17 semi-structured interviews with 3 stakeholder groups, including members of the community, government representatives and mining management and secondary data of company documents on CSR. FINDINGS : The qualitative research revealed important gaps between CSR and SV theoretical frameworks, normative ethical approaches and operationalizing of these at the mine to the detriment of effective multi-stakeholder relationships. PRACTICAL IMPLICATIONS : Mines have to engage with the community and government stakeholders proactively and build relationships. SOCIAL IMPLICATIONS : Ethical normative approaches have to be considered. Government has to take note of this study’s findings with regards to negative consequences of institutionalized CSR for trust between mines and communities. ORIGINALITY/VALUE : The literature review differentiates theoretically between normative and instrumental stakeholder theory, philanthropic and business case CSR, SV and their implicit normative ethical approaches. The semi-structured interviews revealed legacy issues and lack of engagement between mine and community as main barriers to multi-stakeholder relationships and raised important questions on normative ethical approaches to CSR and SV. The direct and indirect barriers by government, community and mine management are identified and differentiated.http://www.emeraldinsight.com/loi/srjhj2022Gordon Institute of Business Science (GIBS

Mechanical and metallurgical properties of co2 laser beam inconel 625 welded joints

In the frame of the circular economy, welding of Ni‐based superalloys has gained increasing importance when applied, for instance, to repairing highly expensive components widely used in strategical sectors, such as the defense and aerospace industries. However, correct process parameters avoiding metallurgical defects and premature failures need to be known. To reach this goal, Inconel 625 butt‐welded joints were produced by CO2 laser beam welding and different combinations of process parameters. The experimental investigation was carried out with three parameters in two levels with an L4 orthogonal array. Laser power, welding speed, and shielding gas flow rate were varied, and the results were reported in terms of mechanical properties, such as microhardness, tensile strength, distortion, residual stress, and weld bead geometry, and metallurgy. At a lower welding speed of 1 m/min, the full penetration was observed for 3.0 kW and 3.3 kW laser powers. However, sound welds (porosity‐free) were produced with a laser power of 3.3 kW. Overall, the obtained full‐penetration specimens showed a tensile strength comparable with that of the parent material with residual stresses and distortions increasing with the increase in heat input

Mechanical and Metallurgical Properties of CO2 Laser Beam INCONEL 625 Welded Joints

In the frame of the circular economy, welding of Ni-based superalloys has gained increasing importance when applied, for instance, to repairing highly expensive components widely used in strategical sectors, such as the defense and aerospace industries. However, correct process parameters avoiding metallurgical defects and premature failures need to be known. To reach this goal, Inconel 625 butt-welded joints were produced by CO2 laser beam welding and different combinations of process parameters. The experimental investigation was carried out with three parameters in two levels with an L4 orthogonal array. Laser power, welding speed, and shielding gas flow rate were varied, and the results were reported in terms of mechanical properties, such as microhardness, tensile strength, distortion, residual stress, and weld bead geometry, and metallurgy. At a lower welding speed of 1 m/min, the full penetration was observed for 3.0 kW and 3.3 kW laser powers. However, sound welds (porosity-free) were produced with a laser power of 3.3 kW. Overall, the obtained full-penetration specimens showed a tensile strength comparable with that of the parent material with residual stresses and distortions increasing with the increase in heat input