Design for tolerance of electro-mechanical assemblies

Tolerancing decisions can profoundly impact the quality and cost of electro-mechanical assemblies. Existing approaches to tolerance analysis and synthesis in design entail detailed knowledge of geometry of the assemblies and are mostly applicable during advanced stages of design, leading to a less than optimal design process. During the design process of assemblies, both the assembly structure and associated tolerance information evolve continuously. Therefore, significant gains can be achieved by effectively using this information to influence the design of the assembly. Motivated by this, we identify and explore two goals for future research that we believe can enhance the scope of tolerancing for the entire design process. The first goal is to advance tolerancing decisions to the earliest possible stages of design. This issue raises the need for effective representation of tolerancing information during different stages of design and for effective assembly modeling. The second goal addresses the appropriate, synergistic use of available methods and best practices for tolerance analysis and synthesis, at successive stages of design. Pursuit of these goals leads to the definition of a multilevel approach that enables tolerancing to be addressed at successive stages of design in an incremental fashion. The resulting design process, which we call the design for tolerance process, integrates three important domains: (1) design activities at successive stages of design; (2) assembly models that evolve continuously through the design process; (3) methods and best practices for tolerance analysis and synthesis. We demonstrate major steps of our proposed approach through a simple, yet illustrative, example.

In product design fields where the demand for an efficient usability is critical to its final success, it is essential to integrate user requirements into the design process from the earliest design stages. Particularly in the medical context, it is essential to systematically control the design phases in order not to neglect the strict constraints related to engineering design quality, safety, and usability requirements for the end user. Hence, in this work, an integrated user-centered product design and process simulation method is proposed. This method is aimed at enriching the state of the art in integrated product design and process simulation in the early design stages, as well as providing a novel design example of a device thought for medical contexts. The case study consists in the design of an intercom, aimed at improving patient-doctor communication in the case of bedridden patients on with helmet for Continuous Positive Airway Pressure (CPAP) therapy during COVID-19 pandemic emergency. Patients undergoing helmet-assisted ventilation are often immersed in a highly noisy environment, unable to fully communicate their needs to the doctors. Intercom devices are addressed to the doctors for improving ease communication with the patient. The proposed user-centered design for manufacturing and assembly proved to be efficient in such a complex design context.KeywordsUser-centered designIntegrated product and process design methodProcess simulation

A plant alarm system is one of important elements in a third layer of an independent protection layers (IPLs). Management of the plant alarm system has become identified as one of key issues because of disasters caused by alarm floods. The Instrumentation, Systems and Automation Society (ISA) has proposed an alarm management standard. And some methods of alarm limits setting or nuisance alarms reduction obtained through each plant improvement activities have been proposed. But, explicit definition of a plant alarm system design process to properly manage the plant alarm system has not been proposed. Plant alarm systems are not always designed using whole information about their plants, because a concreteness and quantity of information is varied along with stages of their plant design. Requirements for each safety instrumented system may not be satisfied if the design of the plant alarm system was started after all stages of the plant design had been completed. The stages of the plant alarm system design should be carried out concurrently with the stages of the plant design. Therefore, the design process of the plant alarm system should be clarified corresponding to available information at each stage of the design. To clarify the design process of the plant alarm system, a framework is necessary to express design activities with tools, available information and output. So, a business process model (BPM) as the framework for the plant alarm system design will be developed. In this paper, we tried to express a BPM for the design of a plant alarm system. Even if the developed BPM is incomplete, the BPM approach has following merits; design rationale for the plant alarm system can be specified and stored, and the plant alarm system can be designed logically. The stored design rationale and the logically designed plant alarm system are very useful for management of change of the plant alarm system and ensuring consistency with other safety instruments. In future work, a BPM for a plant alarm system design will be improved to properly manage the plant alarm system throughout the plant lifecycle.

Design for energy efficiency in early stages: A top-down method for new product development

Buildings account for nearly 40% of the global process and industrial greenhouse gas emissions, and within the building sector. And within the building sector, nearly 72% of the CO2 emissions are due operational carbon demand in the building sector. To meet the goals set out in the Paris Accord, we need to halve carbon emissions by the end of this decade: an aggressive and ambitious timeline. It has become an immediate and urgent need to design and construct buildings that are minimally intrusive in their impact on the environment and operate efficiently. Improvement of the building's energy performance must begin at the early design stage as the potential for sustainable intervention in the project's early phases is higher. The opportunity to improve building performance as the design progresses, is constantly reducing, while the cost of optimization is constantly increasing. One of the major design variables impacting the performance at the early phase is the building morphology/form and its associated variables. Sensible optioneering of the building form and its variables at the early stages of design - especially the conceptual design stage - can help improve the performance of the design early on in the design process at minimum cost. However, for effective early-phase design optimisation, there is a need to develop tools/methods that allow instantaneous evaluation of a large design sample space without much “lag” between the design and performance evaluation workflows. Also, in regular early phase sustainable design workflows, multiple stakeholders - like the designer, the performance analyst, etc. - are involved, which leads to a cognitive divide in the design process. For instance, while the architect designs the initial conceptual massing with a functional design intuition, the performance analysts suggest design interventions with a performance oriented design intuition. This cognitive divide leads to a dipartite design cognition in early phase design. The underlying premise of this research is to support the notion of blurring the dichotomy between conflicting design intuitions through exploring Human + Artificial Intelligence (AI) synergies and their underlying foundational technological requirements with respect to early phase design, to enable intuitive high performance design scenarios with a centralized design cognition where there are no other stakeholders other than the designer and the design environment. With the paradigm shift of other industries towards Machine Learning (ML) and AI, recent research advances in ML and the increasing availability of Big-data in the AEC industry have bolstered multivariate problems like building performance evaluation to a great extent. Design optioneering with instantaneous performance feedback through a ML method called Surrogate Modelling is an upcoming and promising methodology, which delivers feedback based on knowledge through available data, rather than simulation. Also, paradigms in Concurrent Human Machine Interaction (HMI) have explored avenues of augmenting the architectural design process through data-driven approaches. The type of data (input-output pairs) forming the basis for these paradigms depend on the target problem at hand. For early phase performance optimization - especially energy use optimization - Building Energy Model (BEM) forms the primary data. The US Department of Energy defines BEM as a versatile, multipurpose tool that is used in new building and retrofit design, code compliance, green certification, qualification for tax credits and utility incentives, and even real-time building control. BEM is also used in large-scale analyses to develop building energy-efficiency codes and inform policy decisions. A comprehensive BEM dataset that is large and accessible can support the growing interest in ML and HMI research in the high performance building design field. However, common techniques to acquire large BEM datasets like manual 3D energy modeling and simulation, 3D scanning, etc. are very tedious and time consuming. Also, existing datasets are usually incomplete, inconsistent and very difficult to access, owing to data privacy and open-access issues. And lastly, these datasets are fixed, static and cant be easily reproduced for different use case scenarios, nor scalable to adapt to needs. This research aims to tackle this problem by introducing a novel framework to generate custom problem-specific synthetic BEM dataset that generates a user defined amount of context specific 3D early phase building geometries and their associated BEM models, that is suitable for ML and HMI research. Synthetic datasets generated with this framework offer flexibility and customization in the generation process, making these datasets modular, reproducible and scalable. The framework uses the concepts of Generative Design, Geometry Manipulation, Simulation and Computational Automation to build the dataset. The dataset is qualified through the concepts of Preservationism and Sustainability, which are discussed in further sections of this article. The research identifies the importance and multifacetedness of the impact of building geometry on its performance, and demonstrates the application of generated synthetic BEM datasets by developing an enactive, conversational design environment that allows the designer to make real-time sustainable design decisions based on instantaneous machine feedback, for an intuitive, centralized design intuition.

The process of design, or project execution, can formally be viewed as the development of a prototype or prototype of a proposed or possible object or its state. The design process is based on professional knowledge, achievements in science, technology, technological advances, and mathematical methods for solving engineering problems, the basics of art, economics, pricing policy, inventive activity, regulations, legislation and much more. The beginning of the design is determined by the presence of the main provisions on the proposed object and the sources of its financing. As a result, investment feasibility studies and other studies are usually carried out prior to project development. There are relevant rules for the selection of projects, tenders are considered and the documents are finally approved. Design includes many systems, as well as the knowledge of engineers - this is an integral part of the overall investment process, the main participants of which are the Investor, the Customer, the construction department (Contractor) and the design company. Abroad, design is one of the most important stages in the implementation of urban development projects. Studies have shown that about 15% of the project budget is spent on correcting design errors, and more than 50% of project changes are due to poor design in the early stages [1, 2]. This article analyzes the design process in various foreign countries, such as the USA, Great Britain, France, Germany, Singapore, Bulgaria, based on publicly available materials (regulatory documents, tender documentation, guidelines, websites of architectural bureaus and official websites of regional and city administrations). The approach to determining the cost of architectural design for the conclusion of work contracts is considered in two ranges: 1) Range of territory – documents containing development projects for elements of the planned structure of the city. Architectural and urban planning concepts, depending on the type of documentation adopted in the country; 2) Development range (buildings) – a document that defines the development project for the elements of the planned structure of the city, as well as architectural, functional, technical and constructive solutions for capital construction projects. Depending on the type of document adopted in the country, it can be draft, design or working. The study of foreign practice of organizing the process of architectural and construction design has revealed a number of principles that can guide the authorities in ensuring high quality in the development and implementation of urban development projects.

Integrated process design: A generic control theory/design based framework

Today supply chain management has become one of the crucial factors for gaining and sustaining a competitive advantage. Enterprises that can more effectively manage their supply chain network have a higher likelihood of success in the marketplace. To this end, companies need not only make the “make” or “buy” decisions but also differentiate across potential suppliers in order to improve operational performance, and hence, supplier selection is one of the key decisions aiding effective supply chain management. Many studies have also pointed out that the integration of product and supply chain is a key factor for profitability and efficiency. However, prior studies mostly address supply chain performance after the creation of a new product; and only a few studies discuss when and how to incorporate supply chain decisions during product design. In the studies that cover product design, product family and product platform concepts are presented as enabling vehicles for mass customization, which require a considerable investment, and hence might be out of reach for small to medium size enterprises (SME). Accordingly, there is a need to develop a methodology that can consider manufacturability and supply chain issues at the product design stage. This paper presents a graph theory based optimization methodology to tackle this problem. The supplier selection issue is considered by evaluating its impact on both engineering (e.g., process planning) and operational performance (e.g., cost and time), which are then aggregated as the supply chain performance at the conceptual design stage. A case study in the bicycle industry demonstrates the advantages of this methodology. The synchronized structure of the supply chain and the product design results in simultaneous optimization of both design and supply chain decisions during the early design stages.

The quality of the design has been recognized as one of the key factors to the success of the engineering project. However, engineers need to repeatedly perform design tasks, such as processing information, to produce an appropriate design result. Such a design process involves many activities and lead into one or several iterative loops. Consequently, the sequence of performing design activities should be properly planned to avoid unnecessary loops. Design Structure Matrix (DSM) is one of the widely used methods to describe the design process. By employing DSM, the relationships and the sequence of the design activities can be identified. In this research, several principles of evaluating the design process are developed. In addition, fast messy Genetic Algorithm (fmGA) is employed along with the proposed evaluation principles and DSM to determine the optimal design process. Results show, based on the proposed evaluation principles, the impact of the iteration loops can be clearly identified. Furthermore, with the proposed optimization model and its computer implementation, engineers can find the optimal design process for the large-scale design project efficiently and effectively. the proposed evaluation principles and DSM to determine the optimal design process. Results show, based on the proposed evaluation principles, the impact of the iteration loops can be clearly identified. Furthermore, with the proposed optimization model and its computer implementation, engineers can find the optimal design process for the large-scale design project efficiently and effectively.

In product design and manufacturing process planning, we prefer the “best” product design out of all feasible designs, which is called the optimal design. Optimization techniques have become the major quantitative tools in engineering design and decision-making process. Process optimization is a process that adjusts a current process to optimize some specified sets of parameters without violating constraints. The most common goals are minimizing cost while maximizing profit and efficiency. This chapter introduces the formulation of a design problem as an optimization statement incorporated with the design constraints. Essential computational methods for solving the optimization statements with demonstrated examples are also discussed.

PurposeThree-dimensional computer-aided design (CAD) assembly model has become important resource for design reuse in enterprises, which implicates plenty of design intent, assembly intent, design experience knowledge and functional structures. To acquire quickly CAD assembly models associated with specific functions by using product function requirement information in the product conceptual design phase for model reuse, this paper aims to find an approach for structure-function correlations analysis and functional semantic annotation of mechanical CAD assembly model before functional semantic-based assembly retrieval.Design/methodology/approachAn approach for structure-function correlations analysis and functional semantic annotation of CAD assembly model is proposed. First, the product knowledge model is constructed based on ontology including design knowledge and function knowledge. Then, CAD assembly model is represented by part attributed adjacency graph and partitioned into multiple functional regions. Assembly region and flow-activity region are defined for structure-function correlations analysis of CAD assembly model. Meanwhile, the extraction process of assembly region and flow-activity region is given in detail. Furthermore, structure-function correlations analysis and functional semantic annotation are achieved by considering comprehensively assembly structure and assembled part shape structure in CAD assembly model. After that, a structure-function relation model is established based on polychromatic sets for expressing explicitly and formally relationships between functional structures, assembled parts and functional semantics.FindingsThe correlation between structure and function is analyzed effectively, and functional semantics corresponding to structures in CAD assembly model are labeled. Additionally, the relationships between functional structures, assembled parts and functional semantics can be described explicitly and formally.Practical implicationsThe approach can be used to help designers accomplish functional semantic annotation of CAD assembly models in model repository, which provides support for functional semantic-based CAD assembly retrieval in the product conceptual design phase. These assembly models can be reused for product structure design and assembly process design.Originality/valueThe paper proposes a novel approach for structure-function correlations analysis and functional semantic annotation of mechanical CAD assembly model. Functional structures in assembly model are extracted and analyzed from the point of view of assembly structure and function part structure. Furthermore, the correlation relation between structures, assembled parts and functional semantics is expressed explicitly and formally based on polychromatic sets.

Design for Disassembly principles have become more integrated in architecture, by expressing materials, form, and structural assembly through their methods of connection and utilizing pure materials, with reuse and recycling capabilities. Therefore, the research focuses on investigating the importance of using the DFD concept to enhance the design construction process and to study how to include DFD principles in the design process’s phases. The research methodology applied the quantitative method in the main survey (questionnaire), to suggest the systematic framework of DFD by including its guidelines in different design stages according to its importance.

Engineering geologists and geotechnical engineers need the right tools to efficiently investigate, analyse, model and share their geological understanding of expected ground conditions with the wider project team as and when new data becomes available. National large-scale infrastructure projects like High Speed Two (HS2) provide significant technical ground and engineering design challenges but they are complicated by the large multi-disciplinary teams working across many offices, companies, time zones, with a variety of stakeholders. On such projects keeping an auditable and detailed record of all the data and models becomes difficult and at times, incredibly protracted and cumbersome particularly where there are numerous ongoing ground investigations producing constantly evolving datasets. This highlights the challenge and need for teams to effectively communicate changes in ground investigation (GI) data and other outputs with key stakeholders in near “real-time”, allowing risks and opportunities to be characterised and value engineering exercises to be undertaken. This paper describes the innovative application of several software packages to systematically manage GI data and ground models through successive design stages. It will showcase the use of 4D ground modelling complemented by in-house Python coding and bespoke apps to support the wider GI data management vision on the project. These digital innovations enabled the team to produce higher quality ‘BIM’ deliverables, communicate more clearly and expediently with stakeholders and deliver controlled and robust ground models in 4D. The innovations also enabled the onsite GI team to adapt the GI on site to the best advantage of the project according to the ground conditions encountered. The ability to integrate, dynamically link, share, manage, track, and audit models in one eco-system has brought many benefits including time and cost savings, and risk reduction. These digital innovations have benefited HS2 Phase One in scheme design and will continue to provide that into detailed design, construction and operation of the railway. The benefits will also be felt beyond HS2 to any future infrastructure project where the collection, processing and interpretation of ground data is undertaken.

Associated with manufacturing and assembly processes, inevitable geometric deviations have a decisive influence on the function and quality of products. Therefore, their consideration and management are important tasks in product development. Moreover, to meet the demand for short development times, the front-loading of design processes is indispensable. This requires early tolerance analyses evaluating the effect of deviations in a design stage, where the product’s geometry has not yet been finally defined. Since such an early tolerance consideration allows quick and economic design changes seeking for robust designs, it is advisable that the design engineer, who is entirely familiar with the design, should take this step. For this purpose, this paper presents an easy-to-use CAD-based tolerance analysis method for skeleton models. The relevant part deviations are represented by varying geometric dimensions with externally driven family tables. The approach comprises the strength of vector-based methods but does not require an expensive set-up of tolerance analysis models. Particularly, the novelty of this method lies in the CAD-internal sampling-based tolerance analysis of simple geometries without the use of expensive CAT software. This enables designers to evaluate the effect of tolerances already at the preliminary design stage. Using a case study, the presented approach is compared with the conventional vector-based tolerance analysis.

PurposeThe generic design environment for a flexible printed‐circuit board assemblies (PCBA) remanufacturing cell contains four interrelated complex design domains. Mechanical design domains are really complex and the use of well‐proven mechanical product design methodologies does not help the designer. Hence, this paper aims to develop a generic systematic design methodology for a flexible PCBA remanufacturing cell.Design/methodology/approachThe study investigates the use of conventional mechanical product design techniques for the design of a flexible PCBA rework (remanufacturing) cell. It indicates problems and the weaknesses when conventional product design techniques are used for the development of flexible manufacturing systems (FMS). It then provides a new systematic mechanical design methodology for designing a flexible PCBA rework (remanufacturing) cell. The design methodology is intended to be generic in order to apply successfully to any FMS design.FindingsConventional product design methodology cannot be used directly for the design of a flexible PCBA remanufacturing cell. Hence, two design methodologies were developed: the generic FMS mechanical design methodology and a specific FMS design methodology for a PCBA rework cell. The first one was developed based on the tasks of the conventional product design process integrated with new design tools. The generic design methodology was then extended to obtain the second methodology for a PCBA rework cell design. Both of the methodologies were applied to a flexible PCBA rework cell design problem. Both design methodologies eliminated unusable design solutions at the early design stages of the conceptual design process and made the design process easier.Practical implicationsThe generic and specific design methodologies provide a better design environment, even for less specialized FMS designers.Originality/valueThe design methodologies may help for the commercialization of a flexible PCBA remanufacturing cell that may be used for SM rework and assembly.