Uncertainties and Reliability of Multiphysical Systems

IncertFia - ISSN 2514-569X - © ISTE Ltd

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In certain industries, the different operations are very complex, and a small error may lead to a catastrophe. So, there is a strong need to establish an effective maintenance program to avoid any possible error. A concept called Reliability-Centered Maintenance (RCM) was found in the 1960s and initially oriented towards maintaining aircrafts. The objective of this overview is to present the different difficulties when implementing RCM strategy in other industrial fields. So, we first present some RCM concepts and next deal with the most used assessment methods such as Risk Priority Number (RPN) method and Military Standard one. Failure Mode and Effect Analysis (FMEA) as a structured approach is used next to discover potential failures that may exist within a product design or production process. Far away from aviation industry, a coffee maker is considered as an illustrative example to provide the newcomers with a simplified way to implement the RCM concepts in different industrial sectors. Several failure modes considering MSG-3 standard are presented to provide the suitable preventive maintenance actions. Finally, a discussion and future perspective section provides some critical points and future propositions when implementing this strategy in other industrial fields such as additive manufacturing.

The main objective of this paper is to study the performance of a methodology based on the multiple relaxation time Lattice Boltzmann Method (MRT-LBM) to solve the two-equation turbulence model k - ϵ, and accurately treat incompressible flow at high Reynolds numbers (Re) in regions with curved corners and boundaries. To achieve this objective, we opted for wall-driven flow in a semicircular cavity. On the basis of the numerical results obtained and presented in this article, the model shows its ability to capture the formation of primary, secondary and tertiary vortices as the Reynolds number Re increases, and this presents a good agreement with the literature.

FDM technology in 3D printing is a significant advancement in additive manufacturing, offering various benefits such as mass reduction, design freedom, and rapid prototyping. However, the mechanical behavior of parts depends on printing parameters. While popular and cost-effective, FDM has limitations like print time and surface finishes. Optimization of parameters, such as temperature and extrusion speed, is crucial for mechanical properties of parts. Thoughtful choices can enhance strength through density and infill pattern. Ongoing research in this field is vital for more diverse and customized applications in industries like medicine and aerospace.

Topology optimization for additive manufacturing is a rapidly evolving field that holds immense potential for revolutionizing design processes. By leveraging the capabilities of additive manufacturing, designers can explore complex geometries and intricate structures that were previously unattainable. Furthermore, the integration of additive manufacturing constraints into topology optimization methods allows for the creation of optimized designs that are not only aesthetically pleasing but also functionally superior. Additionally, this article examines the difference between the topological optimization methods most frequently and the inherent constraints of additive manufacturing that need to be which must be integrated into topological optimization formulations.

The aim of this paper is to review different methods used to evaluate additive manufacturing (AM) technologies, in particular fused deposition modeling (FDM) technique. Thus, various methods are presented. Moreover, some published scientific works related to these methods are discussed. A comparative study of these optimization methods is also carried out including their strengths and drawbacks. Despite some limitations of these methods due to FDM technology constraints, this paper shows their importance in obtaining optimal selection of 3D printing parameters.

During the last two decades, the different developments of Reliability-Based Topology Optimization (RBTO) can be divided into two groups. The first group called developments from a point of view ’topology optimization’, leading to different layouts with decreasing rigidity (increasing compliance) levels which is considered as a drawback of these methods. In addition, some researchers consider that there is no physical meaning when representing the limit state function by the prescribed volume constraint. However, the second group, being called developments from a point of view ’reliability analysis’, often leads to same layouts with increasing rigidity (or decreasing compliance) levels. The single drawback of these methods is to provide the same layouts with different thickness. Some researchers consider that this finding does not represent any importance since a detailed design stage is required to control the structural rigidity. To overcome both drawbacks, Reverse Optimum Safety Factor (ROSF) approaches are presented here to combine the two points of view to generate several layouts with increasing rigidity levels. These strategies are applied to the total hip replacement at the conceptual design stage. This way several types of hollow stems are generated considering the daily loading cases. The ROSF approaches are compared with the previous Inverse Optimum Safety Factor (IOSF) approaches. The results show that despite both approaches leading to several layouts, the ROSF approaches provide layouts with increasing rigidity (or decreasing compliance) levels. In addition to this advantage, the developed approaches lead to a decrease of material quantity in some cases (higher rigidity and less material quantity). The resulting hip stems can be additively manufactured to guarantee the configuration optimality without performing shape and sizing optimization procedures.