Decision Support System Classification And Its Application In Manufacturing Sector: A Review

The purpose of this paper is to review decision support system application trend in manufacturing sector. Following the introduction of decision support system, the paper has discussed the application of decision support system in manufacturing sector and identifies the trend in term of decision support system types and their application types. In year 2011 until 2015, the most preferred decision support system were developed by using the model application. It also been found that, most of the developed decision support system are used to support evaluation activities in manufacturing operations. This review provides research trend on decision support system for the recent five years (2011 -2015) in the context of decision support system application in manufacturing industry

Laser Based Processes in Modern Production System

The main objective of this research is to establish ultrashort pulsed laser in micro-drilling of fuel injector nozzles. The design of the internal nozzle flow is fundamental for the spray development and therefore in the air–fuel mixing and combustion processes due to the increasing concern for environment protection. Currently, micro-EDM is used to drill micro-holes for fuel injector nozzles. Anyhow this consolidated process is recently facing new challenges which mainly concern the flexibility in changing the hole geometry and the decrease in process time. Laser based techniques are now in attention as alternative to micro-EDM. The aim is to see whether a particular drilling technique other than EDM is able to fulfill the requirement of flow stability and atomization of the spray. This implies evaluating how the surface texture is varying as a function of process parameters and compare the conventional drilling technique with other available alternatives from the point of view of surface quality, edge sharpness and the surface microstructure. Concerning holes characterization, the Scanning Electron Microscopy (SEM) technique allows a rapid survey of large sample areas, but it does not reveal the depth of defects and the three dimensional (3D) surface textures of machined specimens. Therefore, it is needed to find out a reliable and robust measuring technique to acquire 3D topography of the drilled surfaces yielding a better understanding of the size, shape and distribution of peaks and valleys along with their dependence on the adopted process parameters. Based on the correlation between surface texture and process parameters obtained by experimental study, a drilling strategy is proposed with the aim to reduce coking deposition to avoid the risk of nozzle clogging. Finally, as a part of fabrication of efficient fuel injector, the dissimilar welding of stainless steel is studied and analyzed to develop weld bead without surface defects

Optimising non-destructive examination of newbuilding ship hull structures by developing a data-centric risk and reliability framework based on fracture mechanics

This thesis was previously held under moratorium from 18/11/19 to 18/11/21Ship structures are made of steel members that are joined with welds. Welded connections may contain various imperfections. These imperfections are inherent to this joining technology. Design rules and standards are based on the assumption that welds are made to good a workmanship level. Hence, a ship is inspected during construction to make sure it is reasonably defect-free. However, since 100% inspection coverage is not feasible, only partial inspection has been required by classification societies. Classification societies have developed rules, standards, and guidelines specifying the extent to which inspection should be performed. In this research, a review of rules and standards from classification bodies showed some limitations in current practices. One key limitation is that the rules favour a “one-size-fits-all” approach. In addition to that, a significant discrepancy exists between rules of different classification societies. In this thesis, an innovative framework is proposed, which combines a risk and reliability approach with a statistical sampling scheme achieving targeted and cost-effective inspections. The developed reliability model predicts the failure probability of the structure based on probabilistic fracture mechanics. Various uncertain variables influencing the predictive reliability model are identified, and their effects are considered. The data for two key variables, namely, defect statistics and material toughness are gathered and analysed using appropriate statistical analysis methods. A reliability code is developed based Convolution Integral (CI), which estimates the predictive reliability using the analysed data. Statistical sampling principles are then used to specify the number required NDT checkpoints to achieve a certain statistical confidence about the reliability of structure and the limits set by statistical process control (SPC). The framework allows for updating the predictive reliability estimation of the structure using the inspection findings by employing a Bayesian updating method. The applicability of the framework is clearly demonstrated in a case study structure.Ship structures are made of steel members that are joined with welds. Welded connections may contain various imperfections. These imperfections are inherent to this joining technology. Design rules and standards are based on the assumption that welds are made to good a workmanship level. Hence, a ship is inspected during construction to make sure it is reasonably defect-free. However, since 100% inspection coverage is not feasible, only partial inspection has been required by classification societies. Classification societies have developed rules, standards, and guidelines specifying the extent to which inspection should be performed. In this research, a review of rules and standards from classification bodies showed some limitations in current practices. One key limitation is that the rules favour a “one-size-fits-all” approach. In addition to that, a significant discrepancy exists between rules of different classification societies. In this thesis, an innovative framework is proposed, which combines a risk and reliability approach with a statistical sampling scheme achieving targeted and cost-effective inspections. The developed reliability model predicts the failure probability of the structure based on probabilistic fracture mechanics. Various uncertain variables influencing the predictive reliability model are identified, and their effects are considered. The data for two key variables, namely, defect statistics and material toughness are gathered and analysed using appropriate statistical analysis methods. A reliability code is developed based Convolution Integral (CI), which estimates the predictive reliability using the analysed data. Statistical sampling principles are then used to specify the number required NDT checkpoints to achieve a certain statistical confidence about the reliability of structure and the limits set by statistical process control (SPC). The framework allows for updating the predictive reliability estimation of the structure using the inspection findings by employing a Bayesian updating method. The applicability of the framework is clearly demonstrated in a case study structure

Reuse of steel and aluminium without melting

Carbon dioxide emissions must be dramatically reduced to avoid the potentially dangerous effects of climate change. The steel and aluminium industries produce large amounts of carbon dioxide, accounting for 6% of anthropogenic emissions. Previous studies have shown that in these industries there is limited scope for further improvements in energy efficiency. Material efficiency strategies can, however, further reduce emissions. This thesis focuses on materially efficient reuse without melting. A scoping study of current reuse found three opportunities, an examination of which forms the basis of this thesis: reusing components at end of product life; extending the lifespan of products; and reusing manufacturing scrap. The opportunity to reuse components has received little attention to date and there is no clearly defined set of strategies or barriers to enable assessment of appropriate component reuse; neither is it possible to predict future levels of reuse. This thesis presents a global assessment of the potential for reusing steel and aluminium components. A combination of top-down and bottom-up analyses is used to allocate the final destinations of current global steel and aluminium production to final products. A substantial catalogue has been compiled for these products characterizing key features of steel and aluminium components including design specifications, requirements in use, and current reuse patterns. To estimate the fraction of end-of-life metal components that could be reused for each product, the catalogue formed the basis of a set of semi-structured interviews with industrial experts. The results suggest that approximately 30% of steel and aluminium used in current products could be reused. Barriers against reuse are examined, prompting recommendations for redesign that would facilitate future reuse. In order to understand how product lifespans can be extended it must first be understood why products are replaced. A simple framework with which to analyse failure is applied to the products that dominate steel use, finding that they are often replaced because a component/sub-assembly becomes degraded, inferior, unsuitable or worthless. In light of this, four products, which are representative of high steel content products in general, are analysed at the component level, determining profiles of cumulative steel mass over the lifespan of each product. The results show that the majority of the steel components are underexploited – still functioning when the product is discarded. In particular, the potential lifespan of the steel-rich structure is typically much greater than its actual lifespan. Evidence from twelve case studies, in which product or component life has been increased, is used to tailor life-extension strategies to each reason for product failure, providing practical guidelines for designers. There is currently no commercial method of reusing small manufacturing scrap; however, previous research has demonstrated that extruded profiles can be created from small clean aluminium scrap, the scrap fragments solid-state welding together when extruded. In order to evaluate potential applications for these profiles four case studies are conducted in collaboration with aluminium producers and product manufacturers. It was found that strong and formable profiles could be produced from scrap. However, contaminated scrap sources, unreliable bonding and poor surface quality limited their potential for commercial use. No model exists for solid-state weld strength that is applicable to scrap extrusion. This prevents optimisation of the existing extrusion process and the development of new, potentially better, processes. Subsequently, this thesis presents a new model of weld strength as a function of relevant deformation parameters. The model is evaluated using a new experiment in which the deformation conditions can be varied independently. The experiments establish the basic relationships between deformation parameters and weld strength. The model correctly predicts these trends with predicted weld strengths typically lying within the experimental error range. The technical assessment of reuse presented in this thesis demonstrates the scope of potential change. If implemented, the opportunities presented would greatly increase the reuse of steel and aluminium, reducing the emissions emitted from liquid metal production in conventional recycling

Tube hydroforming of steel for automotive applications.

Tube hydroforming has the potential to produce large structural automotive components which may be utilised for weight reduction in future generation vehicles, by replacing stamped and spot-welded steel assemblies. However, limited implementation of this technology has taken place for Body-In-White (B-I-W) components, due to the complexity of the process and low levels of confidence and knowledge of the technology. This is coupled with assembly issues that this technology presents for B-I-W construction. In contrast the application of this technology for sub-frame and chassis component applications has been successful, principally due to the less stringent assembly requirements and proven cost and performance related benefits. The tube hydroforming process utilises forming fluid, under high pressure, to stretch a tube blank into the shape of a die cavity. The application of the internal pressure may be accompanied by axial feeding of the tube ends to push additional tube material into the die cavity. Close control of process parameters and the die design are essential to produce successful, defect-free components. However, the behaviour and response of steel and the influence of friction under these forming conditions are unknown entities. On the basis of a critical review of literature, a research programme was initiated to engage some of the key forming issues inhibiting wide-scale implementation of steel tube hydroforming for BIW automotive applications. The principal aims of the project were to identify the fundamental influences of steel properties on the tube hydroforming process and to develop a mathematical model of the process for steel tube. The research programme entailed small-scale formability tests and large-scale experimental trials, accompanied by the development of analytical and finite element (FE) models of the tube hydroforming process for various steel grades. The analytical and FE models could be used as design aids in the development of automotive BIW hydroformed components. The research project identified significant changes in both mechanical properties and surface characteristics as a result of the Electric Resistance Welding (ERW) tube manufacturing process. This in turn had a significant impact upon the hydroforming behaviour of the steel tubes. An analytical forming limit curve (FLC) model evaluated in this thesis was deemed to provided a robust means of predicting splitting or excessive thinning of a tube hydroformed component as a result of die geometry, tube material or processing conditions. The FE models developed, which incorporated the analytical FLCs, illustrated that the tube hydroforming process could be predicted with a high level of confidence for simple components