Review of optimal design of composite structures under uncertainty

This study represents optimization of hollow circular, rectangular and airfoil composite beam by using sub problem approximation method in ANSYS. A three dimensional static analysis of large displacement type has been carried out for hollow circular, rectangular and airfoil composite beams. Weight of beam was objective function, material parameter, geometrical, ply thickness, ply angles and load. In order to validate the results, one loop of simulation is benchmarked from results in literature. Ultimately, best set of optimized design variable is proposed to reduce weight under static loading condition

Concept Design and Reliability

The paper outlines an approach to concept design that integrates the development of the design specification with multi-objective concept development. ‘Excursions’ are undertaken to explore particular aspects of the design, e.g., reliability, in order to help create a concept that is strong in the salient design requirements. The paper then considers reliability as a principal design requirement. Existing reliability evaluation methods are reviewed with respect to their suitability for use in concept design. The paper then describes an approach, an ‘excursion’, that can be used to improve the reliability of a concept. The reliability excursion comprises a systematic method of evaluation and a reliability analysis toolbox. The research reported is an element of a larger concept design activity that itself forms part of a substantial project on integrated product design undertaken at the Polhem Laboratory, Lulea Technical University, Sweden and at UMIST, UK

Improved utility and application of probabilistic methods for reliable mechanical design

In a modern product development process such as in the automotive and aerospace sectors, extensive analytical and simulation approaches often are used to assess the ability of a design in fulfilling its requirements. Consideration of uncertainty in such situations is critical in ensuring a reliable design is produced. Probabilistic methods facilitate an improved understanding of design performance through characterization of uncertainty in the design parameters. The probabilistic methods developed over the past several decades have a range of capabilities and modes of application, for example, to predict reliability, for optimization, and to perform sensitivity studies, but have yet to be taken up routinely by industry due to a number of reasons. In this paper, issues that have typically inhibited their use or prevented a successful outcome are addressed through a systematic framework for improved utility and successful application of probabilistic designing for mechanical reliability

Modelling Green VTOL Concept Designs for Reliability and Efficiency

All-electric and hybrid-electric aircraft are a future transport goal and a possible ‘green’ solution to increasing climate-related pressures for aviation. Ensuring the safety of passengers is of high importance, informed through appropriate reliability predictions to satisfy emerging flight certification requirements. This paper introduces another important consideration related to redundancy offered by multiplex electric motors, a maturing technology which could help electric aircraft manufacturers meet the high reliability targets being set. A concept design methodology is overviewed involving a symbolic representation of aircraft and block modelling of two important figures of merit, reliability, and efficiency, supported by data. This leads to a comparative study of green aircraft configurations indicating which have the most potential now, and in the future. Two main case studies are then presented: an electric tail rotor retrofitted to an existing turbine powered helicopter (hybrid) and an eVTOL aircraft (all-electric), demonstrating the impact of multiplex level and number of propulsion channels on meeting target reliabilities. The paper closes with a summary of the important contribution to be made by multiplex electric machines, well as the advancements necessary for green VTOL aircraft sub-systems, e.g., power control unit and batteries, to improve reliability predictions and safety further

Axiom-based Potential Functional Failure Analysis for Risk-free Design

Abstract. Quality and reliability of product is not established completely in detail design process, but is brought out essentially in the course of conceptual design. A potential functional failure analysis method to improve reliability of product based on design axiom in the stage of conceptual design was introduced in this paper. This method provided designers with an analytical and non-probabilistic tool to evaluate the result of conceptual design from the opinion of design axioms. Functional failure modes can be identified by function analysis based on the ideality axiom, the independence axiom and the information axiom. These potential functional failures point out working direction for the latter improving design. A speedy cutting off valve in the TRT (Top Gas Pressure Recovery Turbine) system is studied as an example to illustrate this method's potential

Reliability Modeling and Assessment of Component with Multiple Weak Sites under Complex Loading

A component with multiple weak sites is widely used in practical engineering and the existence of multiple weak sites can significantly decrease the component reliability. On the other hand, only a few components bear static loading and most components bear dynamic loading. In this paper, a reliability model of isomorphic component with multiple weak sites is built based on an order statistics model and the influences of strength decentrality and loading decentrality on isomorphic component with multiple weak sites are discussed. Furthermore the influence of loading times is studied in detail. The results show that unlike a component with only one weak site, not only does the failure of a component with multiple weak sites have a relationship with the safety margin, but there also exist relationships with the number of weak sites, the loading roughness, and loading times. The work in this paper is of some guiding significance in reliability design and assessment of a component with multiple weak sites under complex loading