Conceptual Design Phase Research Articles

Application of a modular topology optimization framework to an aerospace bracket design

Abstract In aerospace industry, optimizing designs has become inevitable in terms of weight and performance requirements. Topology optimization is the most suitable optimization type for use in the conceptual design phase. Even though academic topology optimization algorithms have a modular structure (open to development), they are often useable for a regular design domain. Alternatively, commercial topology optimization software products, on the other hand, are very useful in terms of their solution speed, accuracy, and ability to handle complex or irregular design domains. However, the user is restricted with the optimization algorithms available in the software, and these software do not usually have a modular structure. In this study, a modular topology optimization framework that combines useful features of the academic codes (e.g., modularity) and the commercial software tools (e.g., capability of easily handling complex design domains) is developed. The developed framework is tested on two popular academic topology optimization problems, followed by aerospace bracket design problem. It is observed that the proposed framework usually provides lower objective function values and converges to the optimum result in fewer iterations than the Altair Optistruct topology optimization software.

Packaging design for the circular economy: A systematic review

The concept of circular economy has been ubiquitous over the past five years and has been steadily gaining a consensus as a new paradigm. Circular economy covers a wide spectrum of topics ranging from waste management, through materials to supply chain, amongst which packaging is an essential part for achieving a truly circular economy. It has been emphasised that resources should be kept in closed loops, thereby generating zero waste. However, largely due to the nature of packaging materials and designated usage, the packaging industry is built on a linear model where packaging is designed, produced, consumed and disposed of. This creates substantial amount of waste, which is now a growing concern for the earth ecosystem. To enable a smooth transition from a linear to a circular system, packaging design has been recognised as the fundamental stepping-stone towards a circular economy. In this study, an extensive literature review is performed, investigating the growing body of research on packaging design in relation to circular economy. This paper reviews the state-of-the-art research on packaging design, including design rules, guidelines, considerations and tools that can be applied in the design process for achieving a circular economy. A circular packaging design framework is then proposed, summarising the findings and showing (i) the factors that determine material selection, (ii) the design strategies, guidelines and considerations to be taken into account in the conceptual design and design development phases, and (iii) the tools and indicators to assist design validation and assessment of packaging circularity. Finally, future research trends in various aspects including material selection, design guidelines to facilitate recycling, design assessment tools, design education and policy making are discussed.

Design exploration by using a genetic algorithm and the Theory of Inventive Problem Solving (TRIZ)

This paper presents a computational design exploration method called GA+TRIZ, which aids designers in defining the design problem clearly, making a parametric model where pertinent variables are included, obtaining a series of suitable solutions, and resolving existing conflicts among design objectives. The goal is to include the designer's qualitative and performance-based quantitative design goals in the design process, while promoting innovative ideas for resolving contradictory design objectives. The method employed is a Genetic Algorithm (GA), earlier implemented in an automated design exploration process called ParaGen, in combination with the Theory of Inventive Problem Solving (TRIZ), a novel methodology to assist architects and structural engineers in the conceptual phase of design. The GA+TRIZ method promotes automated design exploration, investigation of unexpected solutions, and continuous interaction with the computational generating system. Finally, this paper presents two examples that illustrate how the GA+TRIZ method assists designers in problem structuring, design exploration, and decision-making.

Liquid Metals Heat-Pipe solution for hypersonic air-intake leading edge: Conceptual design, numerical analysis and verification

Embedded propulsion systems will allow future hypersonic aircraft to reach amazing levels of performance. However, their peculiar small-radius air-intake leading edges pose serious challenges from the aerothermodynamic, design, integration, and manufacturing standpoints. This paper discloses the methodology developed in the framework of the H2020 STRATOFLY project and specifically tailored to support the conceptual and preliminary design phases of future high-speed transportation systems. The methodology implements an incremental approach which includes multi-fidelity design, modelling and simulation techniques. The specific application to the MR3, a Mach 8 waverider configuration with an embedded dorsal mounted propulsive subsystem, is reported. Different alternative solutions have been thoroughly analysed, including five liquid metals as fluids (Mercury, Caesium, Potassium, Sodium and Lithium) and relative wick and case materials (Steel, Titanium, Nickel, Inconel® and Tungsten) and three leading-edges materials (CMC, Tungsten with low emissivity painting and Tungsten with high emissivity painting). The analysis of the heat transfer limits (the capillary, entrainment, viscosity, chocking and boiling limits) carried out for all five fluids and relative compatible materials, together with a more accurate FEM analysis, suggest the adoption of a Nickel–Potassium liquid metal heat pipe completely integrated in a platelet air-intake leading edge made of CMC material. Ultimately, the effectiveness of the adopted solution throughout all mission phases has been verified with a detailed numerical model, built upon an electrical analogy.

Simultaneous aircraft sizing and multi-objective optimization considering off-design mission performance during early design

Traditional aircraft conceptual design primarily involves determination of top-level sizing parameters, resulting in an initial design which satisfies specified point-performance constraints while flying the so-called design mission. In practical scenarios, commercial aircraft are also expected to operate optimally in the actual missions they fly which may drastically differ from the design mission. To improve performance and reduce operating costs, optimization shall be performed using specific objectives from the on-design mission and from one or more representative off-design reference mission(s). Such multi-mission optimizations may result in different designs for the same performance constraints. Moreover, the size of aircraft and choice of reference mission(s) may also have an effect in the difference resulting from such multi-mission optimizations. This paper solves a series of multi-objective on-design and multi-mission optimization problems in the conceptual design phase on aircraft spanning a range of size-classes, using the Non-dominated Sorting Genetic Algorithm II (NSGA-II). Results shed light on the design differences between formulations that exclusively consider design mission metrics of interest from the ones that consider metrics of interest from disparate, as-flown, i.e., off-design missions. In addition, results also reveal the impact of off-design mission weightings on the designs obtained from the optimization problems.

Safety-Related Instrumentation and Control Pilot Upgrade: Initial Scoping Phase Implementation and Lessons Learned

In May 2016, the U.S. Nuclear Regulatory Commission (NRC) staff provided a digital instrumentation and control (I&C) regulatory infrastructure integrated action plan to the NRC for approval. One of the objectives of that plan was to establish a clear regulatory structure with reduced regulatory uncertainty to enable the expanded safe use of digital I&C in commercial nuclear reactors while continuing to ensure safety and security. To achieve this end, the NRC, with collaboration from industry, developed a streamlined License Amendment Request Alternate Review (AR) process for safety-related (SR) digital I&C upgrades. In spite of this effort, the industry has remained reluctant to perform such I&C upgrades because of perceived regulatory and financial risks associated with being the first or an early adopter of the AR process for SR I&C upgrades. The U.S. Department of Energy Light Water Reactor Sustainability Program at the Idaho National Laboratory performed Initial Scoping Phase research to help break this impasse by supporting a SR I&C Pilot Upgrade, working with MPR Associates, ScottMadden Inc., and Exelon Generation. Exelon’s Limerick Generating Station (LGS) was selected as the target for this research. This paper summarizes the Initial Scoping Phase engineering and operations, licensing, and project management activities necessary to bound the scope, schedule, and estimated cost of the project sufficiently to enable utility management authorization of Conceptual Design Phase activities. These efforts and associated products are intended to provide a template to support larger industry efforts to perform similar upgrades as a foundation stone for a digital transformation that will improve plant safety, reliability, and operational performance while lowering plant total cost of ownership. As a result of the combined effort of Exelon Generation and research participants, Conceptual Design Phase activities for the subject upgrade at LGS were approved by Exelon. The U.S. Department of Energy also awarded a $50 million cost share award to Exelon in order to pave the way for SR I&C modernization and associated control room upgrades across the U.S. nuclear fleet. Additional research reports are planned for the Conceptual Design Phase, Detailed Design Phase, and the Implementation Phase of the LGS project to document the process followed and promulgate lessons learned to industry.

Conceptual Design of a Hybrid Hydrogen Fuel Cell/Battery Blended-Wing-Body Unmanned Aerial Vehicle—An Overview

The manuscript presents the conceptual design phase of an unmanned aerial vehicle, with the objective of a systems approach towards the integration of a hydrogen fuel-cell system and Li-ion batteries into an aerodynamically efficient platform representative of future aircraft configurations. Using a classical approach to aircraft design and a combination of low- and high-resolution computational simulations, a final blended wing body UAV was designed with a maximum take-off weight of 25 kg and 4 m wingspan. Preliminary aerodynamic and propulsion sizing demonstrated that the aircraft is capable of completing a 2 h long mission powered by a 650 W fuel cell, hybridized with a 100 Wh battery pack, and with a fuel quantity of 80 g of compressed hydrogen.

Methodology for Early Design Phase Cost and Performance Trade-Off Analysis of a New Variant in a Product Family

AbstractGiven the Industry 4.0 trend towards smaller lot sizes and large product families, there is a need to increase the design efficiency in terms of cost and lead time. Design decisions taken in the early or conceptual design phases are shown to have the greatest impact on the final product cost, however the choices and trade-offs are often made in an ad-hoc way. This paper presents a structured methodology for formalizing early stage product design knowledge, which is key for designing and evaluating new variants in a product family in the early stages of the design process.

Towards Integrated Safety Analysis as Part of Traceable Model-Based Systems Engineering

AbstractCurrently systems grow in complexity and more aspects, such as socio-technical aspects or the obligation to produce proof become more important. Both require a safety analysis on the system level early in the design process. System overview is provided by MBSE, while safety analysis is provided for example by FMEA. Both processes are executed organizationally and timely separated from each other. This research proposes a concept and a tool integration at the concept design phase, during system definition and functional decomposition and evaluates the effect and its potential applicability.

Harnessing the Complexity for Vehicle System Design at the Concept Design Phase of an Aircraft

AbstractAircraft vehicle systems enable an aircraft to fly safely throughout a mission. Generating feasible vehicle system architectures at the aircraft concept design phase is complex. Aspects from various complex systems theories are used to provide different insights into this complexity. To address this complexity, a framework based on industrial reality that can used recursively is presented. The framework employs various design theories to harness the complexity of vehicle system design at the concept design phase of an aircraft.

A frequency-time domain method for annual energy production estimation in floating wind turbines

A new method is proposed to estimate a floating wind turbine’s annual energy production (AEP) using frequency and time-domain design techniques. The approach demonstrated herein estimates the AEP by performing a convolution between the floating platform response and the response power operators (RPOs) that map the average power produced by the turbine as a function of the amplitude and frequency of the platform motions. One advantage of this approach is that it can be performed early in the conceptual design phase to help discover design space trade-offs between the platform and rotor design. The methodology is applied to the IEA Wind 15 MW WindCrete spar-buoy model using OpenFAST. The RPOs are obtained by prescribing single-DOF platform motions to the turbine with a given amplitude and frequency. This methodology is then validated by comparing the AEP estimation from the RPOs with the AEP estimation from fully-coupled simulations. The results indicate that the method is able to estimate the value of AEP for a realistic sea-state and regular waves. However, further validation is needed as, in the first case, the turbine is moving too little and, in the second case, the contribution of the controller may be dominant.

Colored Petri Net Modelling and Evaluation of Drone Inspection Methods for Distribution Networks.

The UAV industry is developing rapidly and drones are increasingly used for monitoring industrial facilities. When designing such systems, operating companies have to find a system configuration of multiple drones that is near-optimal in terms of cost while achieving the required monitoring quality. Stochastic influences such as failures and maintenance have to be taken into account. Model-based systems engineering supplies tools and methods to solve such problems. This paper presents a method to model and evaluate such UAV systems with coloured Petri nets. It supports a modular view on typical setup elements and different types of UAVs and is based on UAV application standards. The model can be easily adapted to the most popular flight tasks and allows for estimating the monitoring frequency and determining the most appropriate grouping and configuration of UAVs, monitoring schemes, air time and maintenance periods. An important advantage is the ability to consider drone maintenance processes. Thus, the methodology will be useful in the conceptual design phase of UAVs, in monitoring planning, and in the selection of UAVs for specific monitoring tasks.

Conceptual Design of Jain University Sailplane Based on Concurrent Engineering Within Aerospace Engineering Curriculum

There is ever growing interest in the design of high-performance sailplanes since the start of the last century. Sailplanes or gliders form an example of sustainable engineering in aeronautics as there is practically little to no carbon footprint. Concurrent Engineering (CE) as a design methodology is adopted and implemented for the conceptual design phase of this project. Concurrent Engineering involves simultaneous sharing of data within various teams, thereby increasing productivity and reducing time for product design. As the project involves extensive data sharing and periodic design iterations, it was imperative that interrelationships between the different groups are handled properly through the implementation of flowcharts even before the start of the project. Efficient methods of sailplane design based on Concurrent Engineering methodology within an education curriculum have been applied. This paper reports ongoing progress made within the sailplane project management.

The pre-concept design of the DEMO tritium, matter injection and vacuum systems

In the Pre-Concept Design Phase of EU-DEMO, the work package TFV (Tritium – Matter Injection – Vacuum) has developed a tritium self-sufficient three-loop fuel cycle architecture. Driven by the need to reduce the tritium inventory in the systems to an absolute minimum, this requires the continual recirculation of gases in loops without storage, avoiding hold-ups of tritium in each process stage by giving preference to continuous over batch technologies, and immediate use of tritium extracted from tritium breeding blankets. In order to achieve this goal, a number of novel concepts and technologies had to be found and their principal feasibility to be shown.This paper starts from a functional analysis of the fuel cycle and introduces the results of a technology survey and ranking exercise which provided the prime technology candidates for all system blocks. The main boundary conditions for the TFV systems are described based on which the fuel cycle architecture was developed and the required operational windows of all subsystems were defined. To validate this, various R&D lines were established, selected results of which are reported, together with the key technology developments. Finally, an outlook towards the Concept Design Phase is given.

Status of maturation of critical technologies and systems design: Breeding blanket

The scope of the EUFOfusion Work Package Breeding Blanket is to develop a blanket concept for the EU DEMO reactor; this includes the blanket segments inside the Vacuum Vessel and the related Tritium Extraction/Removal Systems. In the Pre-Concept Design (PCD) Phase, two concepts have been selected as candidates; a solid and a liquid breeder blanket cooled with helium and water, respectively. The design of these two blanket systems has been adapted to the DEMO plant design developed in the PCD Phase and performances assessed. A large R&D programme has been implemented with the scope to evaluate different technologies for these blankets; including the development of breeders, tritium extraction and cooling technologies, and the manufacturing of the blanket system. A major milestone in the subsequent Concept Design Phase is the final selection of the blanket concept for DEMO.

Aerodynamic design and evaluation of an open-nose supersonic drone

The objective of this paper is to investigate the efficiency of a proposed supersonic drone configuration, in terms of drag, ram recovery, and fundamental flight performance factors. Sustainable supersonic cruise at Mach 1.6 is the major segment of the mission profile which affects the overall geometry resulting from the conceptual design phase, a tailless delta drone with an open-nose forebody, lofted around the inlet which consists of an analytical compression surface and a S-duct diffuser. Because the aerodynamics of this unconventional configuration is unknown, a series of CFD simulations using the ANSYS Fluent solver is coupled to the design process to predict both internal and external aerodynamics as a proof of the concept. The simulations indicate that the drone’s overall drag is significantly lower than the other configurations with side or underside integrated inlets while the inlet pressure recovery is adjusted to maximize the engine thrust. The parasite drag at design speed is about 0.022 which is considerably lower than conventional configurations and the pressure recovery more than 0.96 is possible by applying the boundary layer bypass. A comparative study, with a developed thrust model, shows that the configuration satisfies mission requirements and exceeds them at transonic and supersonic flight phases.

Optimization and prediction in the early design stage of office buildings using genetic and XGBoost algorithms

Incorporating intelligent optimization algorithms in the early stages of office building design facilitates a better response to the local climate. The indoor and outdoor thermal performances of office buildings, such as solar radiation, indoor lighting, and outdoor thermal comfort, must be jointly evaluated during the conceptual design phase. Based on the technical framework of “performance-based generative architectural design”, this study constructs a data-driven workflow for comprehensive performance assessment and rapid prediction of office buildings. The method was then applied to an office building in the hot summer and cold winter regions of China. Based on a total of 6000 data samples generated by the iterative process of genetic optimization, this study achieved a precision of 0.77, recall of 0.59, and F-1 score of 0.75 for categorical prediction by the XGBoost algorithm. The method facilitates the optimization potential of integrated solar and thermal performances in the early design phase of office buildings while significantly improving the efficiency of interaction and feedback between design decisions and their performance evaluation.

A Non-Parametric Histogram Interpolation Method for Design Space Exploration

AbstractA novel algorithm is presented to aid designers during the conceptual design phase of a new engineering product by rapidly assessing new areas of the design space. The algorithm presented here develops a polynomial chaos-based meta-model that allows the designer to estimate the probability distribution for a candidate design’s performance without requiring additional experiments or simulations. Probabilistic equivalence is used to map either a probability density function or a cumulative distribution function, continuous functions, into a reduced space in which interpolation functions can be developed. Data harvested from experiments or evaluations of an expensive computer code are used to train the meta-model. An advantage of this method over other histogram interpolation methods is that it is non-parametric: the training data are not assumed to belong to a particular family of probability distribution. The algorithm was validated using a standard benchmark test with synthetic data in a continuous-discrete design space. Finally, we exploited the variance of the Gaussian process emulators used as interpolation functions in order to develop a statistic that quantified the level of uncertainty associated with the algorithm’s estimates. This is a key feature if the algorithm is to be of practical use.

Recirculation of Parallel-Connected Planetary Gear Trains

Recirculation is expected to be identified for its possibility to dramatically decrease the efficiency of planetary gear trains (PGTs). However, it exhibits an unexplained connection with the structure, making it challenging to identify without tedious computation through tooth and speed ratios, thus complicating the design process. This study employs a generic model utilizing the mechanical balance principle and reveals the fundamental laws of the previously unexplained connection for parallel-connected ring-sun-type PGTs. Two necessary and sufficient conditions, torque and structure, were proven for multi-stage and two-stage PGTs without recirculation, respectively. This shows that the structure, specifically whether the links are central gears or carriers, and the connections between them directly impact the recirculation of these PGTs. A geometric model representing the structure and kinematics was developed to visualize the power flow. Thus, the recirculation of parallel-connected ring-sun-type PGTs can be predicted without calculations. Our results provide the underlying insights to understanding recirculation from the structural connection viewpoint, thereby contributing to the conceptual design phase where the task is to select the kinematic structure and the gear size is unknown.

Maturation of critical technologies for the DEMO balance of plant systems

The Pre-Concept Design (PCD) of the Balance of Plant (BoP) systems of the EU-DEMO power plant is described in this paper for both breeding blanket (BB) concepts under assessment, namely the Water Cooled Lithium Lead (WCLL) BB and the Helium Cooled Pebble Bed (HCPB) BB. Moreover, the results of a preliminary evaluation of a number of BoP variants are discussed.This paper outlines the steps of the BoP design development, highlighting the project objectives and the strategy for their achievement under the very challenging requirements which include, among others, the intermittent nature of the DEMO plasma heat source.The main achievements during the PCD Phase will be reported together with the development plan for the Concept Design (CD) Phase to reach a mature (feasible) BoP concept for DEMO.