On Crossley's contribution to the development of graph based algorithms for the analysis of mechanisms and gear trains

This paper celebrates a particular branch of Crossley's early work dedicated to Mechanism Science, which deals with a rigorous introduction of Graph Theory to the study of some fundamental and intrinsic properties of kinematic chains and mechanisms. Although such idea gave its main outcome in Type and Number Synthesis (which has been much better and extensively described in another paper of the present special issue) some other intriguing side effects appeared, later in Mechanism Science, which yielded several results, and are still in the center of research and industrial world interest, such as, to name but a few, the automatic generation of the equations governing kinematic, static force and dynamic analysis of mechanisms and geared trains, the power flow analysis, the computation of the efficiency and, finally, the never fully explored structure-to-function mapping, which the present contribution points out to be still a challenge in the field

Product Planning techniques: investigating the differences between research trajectories and industry expectations

According to several literature sources, Product Planning is acknowledged as a primary driver of future commercial success for new designed products, and it is schematically constituted by the identification of business opportunities and the selection of most promising alternatives. Despite the recalled relevance of Product Planning, it emerges that a marginal quantity of companies have adopted formal methods to carry out this task. The paper attempts to provide a major understanding about such a limited implementation of Product Planning techniques and other open issues emerging from the analysis of the literature concerning the initial phases of engineering design cycles. The presented study investigates the claimed benefits of methods described in the literature, the level to which such tools are diffused through educational programs in Technical Institutes, the expectations and the demands of a sample of enterprises with respect to new tools supporting Product Planning. It emerges that, whereas existing methods strive to fulfil relevant properties according to the perception of the companies, limitations come out in terms of the transfer of the proposed techniques and their perceived reliability

Functional and Behavioral Product Information Representation and Consistency Validation for Collaboration in Product Lifecycle Activities

Information models that represent the function, assembly and behavior of artifacts are critical in the conceptual development of a product and its evaluation. Much research has been conducted in this area; however, existing models do not relate function, behavior and structure in a comprehensive and consistent way. In this work, NIST\u27s Core Product Model (CPM) and the Open Assembly Model (OAM) are extended to integrate product information including function and behavior, with an emphasis on assembly, throughout all phases of product development. For function and flow classification, the NIST functional taxonomy is used to maintain consistency with the literature. The consistency validation of product information, and the verification of modified product information are discussed; these processes ensure that the product information has no contradictions and allows tracing through associations without any deficiency or disconnection. In other words, the information model has to be complete in terms of traceability of function, behavior, spatial relationships, etc., in order to support all information exchange activities. The product information representation provides a mechanism for capturing product information and storing it in a database. This representation schema also provides necessary information for any future decision making activities in the End of Life (EOL) environment, such as the replacement or reuse of any part or subassembly. When there is a need to replace one artifact with another, one must consider all of the associations of the existing artifact with other artifacts and the environment, not just functional and space requirements, and the relevant modification(s) of the associated objects has to verified. So one can manage product lifecycle activities in different perspectives by knowing how the product information is interconnected in various domains and how its characteristics affect each other

A FRAMEWORK FOR FUNCTION SPECIFICATIONS-TO-CONCEPTUAL FORM TRANSLATION TOOL IN FUNCTION-ORIENTED MECHANICAL DESIGN SYSTEMS

Design is functionality driven. All products and parts have some intended reason behind their existence. Although computer aided systems have made considerable advances in capturing and representing geometrical shape, not much progress has been made in capturing and modeling product functionality and its physical realization. This research proposes a methodology to assist designers during the first stages of design. This methodology provides a framework to help the designer translate functional specifications into conceptual forms. This research develops a translation tool to model functionality and to carry out conceptual design with the aid of the computer. This tool serves as a bridge between the conceptual design phase and the detailed design phase of a product. The translation tool developed in this research supports the conceptual design phase by providing a functional data model, a function server model, and a conceptual product model. The functional model includes the use of operands and relations to define and capture product functionality. The function server model represents the physical realization of the specified functions. The conceptual product model organizes and documents the product information in both the functional and the physical domains. The knowledge base for the function servers is stored in a function driven database. This database allows the designer to view design possibilities that may never have occurred to them.Models provided in this work have been implemented as a relational database system by using MySQL. A web-based graphic user interface is developed with PHP to provide an interactive environment for modeling and for searching the function driven database. Propagation of functional and physical information to downstream design activities has been enabled by the use of the XML data format. The models and concepts developed in this research are validated through a case study of a realistic mechanical device

SUPPORTING FUNCTIONALITY-BASED DESIGN IN COMPUTER-AIDED DESIGN SYSTEMS

Designs are conceptualized in terms of the functions they need to accomplish. The need for a new product design arises as a result of the identification of a new functionality to be accomplished by the product. That is, design is functionality driven. However, existing CAD tools are not equipped to capture functionality or reason in such a fashion to support design for product functionality. This research proposes a new design formalism to enable functionality-driven design of mechanically engineered products. This procedure provides a methodology that allows a designer to model product functionality and to carry out conceptual design with the aid of a computer. It also serves as a bridging tool between the conceptual design phase and detailed design phase of a product. Thus, the primary objective of this research is to develop a methodology that will support the following activities in CAD systems: functionality modeling, functionality data structuring, and form conceptualization.The functionality modeling methodology developed in this work includes the use of operands, operators, and coupling bonds to describe product functionality in CAD systems. The Universal Modeling Language (an object-oriented programming technique) is used to model product functionality in computer systems. The tools developed in this research provide a means of modeling and propagating product functionality information to downstream design activities. The propagation of functionality as a constraint is achieved using Extensible Markup Language (XML) data files. These tools also provide a mechanism for verifying and enforcing constraints on solid CAD models. The functionality definition interface is implemented with a customized Microsoft Visio graphics engine.The tools developed in this research provide a means of modeling and propagating product functionality information to downstream design activities. It also provides a mechanism for verifying and enforcing constraints on solid CAD models. The functionality definition interface is implemented with a customized Microsoft Visio graphics engine

A computational theory for the generation of solutions during early conceptual design

Advancement in technology is usually made by building on previous experiences and learning from past successes and failures. However, knowledge transfer in the broad field of product design is often difficult to accomplish. Research has shown that successful component configurations, observed from existing products, can be dissected and stored for reuse; but few computational tools exist to assist designers during the conceptual phase of design. Many well-known manual methods (e.g. brainstorming, intrinsic and extrinsic searches, and morphological analysis) rely heavily on individual bias and experience and are often time intensive, laborious tasks that may not catch solutions that are functionally analogous, but seemingly unrelated. This research presents an automated concept generation tool that augments traditional activities during the conceptual phase of design --Abstract, page iii

A fuzzy front end model for concurrent specification in new product development

This research reports on the development of a new model for an early design stage in new product development (NPD) programmes called the Fuzzy Front End (FFE). The new FFE model aims at overcoming two kinds of limitations identified in previous FFE models. The first limitation concerns current trends in FFE model improvement including the need for a data-driven model, and to address agile development, incremental and radical NPDs, balanced explicitness and responsiveness characteristics, and balanced procedural and performative structures. The second limitation concerns deficiencies in the performance structure and operating mechanism regarding contextual performance and concurrent collaboration. This means that performances in the FFE do not systematically link with each other, either in a single functional domain or multidimensionally across diverse functional domains, but instead exist independently. A pragmatic-prescriptive model has been functionally embodied by analysing real-world FFE scenarios using inductive reasoning. The model is data-driven with a performative structure wherein parameters can interlock for contextual performance and concurrent collaboration throughout the entire FFE process. With this interlocking structure, once an initial parameter is produced, all remaining parameters considered from both perspectives can be obtained successively. This model allows performers to explicitly understand the purpose and roles of parameters and their relationships from both perspectives when processing parameters. The model thus leads to more agile FFE execution by reducing the iterative work needed to correct defective parameters which have not been handled with contextual performance and concurrent collaboration in mind but instead exist independently. A theoretical-descriptive model, produced by validating the developed pragmatic-prescriptive model, using deductive reasoning, consists of mathematical formulas, providing the underlying concept of an overall FFE as well as that of its parts. Consequently, the pragmatic-prescriptive model can serve as functional performance guidance, while the theoretical-descriptive model can serve as conceptual performance guidance when employing the pragmatic-prescriptive model.Open Acces

Knowledge-based inventive conceptual design

Conceptual design is the first phase of the design process. Most basic functions of a new product and the solutions for solving design problems are generated in this critical phase, which will affect the attributes in the later detailed design process. Conceptual design, especially the process of concept generation, is an innovation process that is achieved by human intelligence. The intuition and experience of designers play a significant role during the design process which is hard to be replaced by computer-aided tools or artificial intelligence technology. TR1Z is an inventive problem-solving tool to help people improve creativity. It is applied in this work to generate creative design concepts. The TRIZ inventive principles are extended by integrating other TRIZ tools and TRIZ-derived tools. These principles are also restructured by the inspiration of I-Ching. The Behaviour-Entity representation of inventive principles enables the generation of new and innovative solutions based on TRIZ. The TRIZ Contradiction Matrix (CM) and inventive principles are then used to develop the TRIZ-based concept generation approach by adding constraints to the standard Behaviour-Entity representation of TRIZ. This approach is developed to retrieve modified TRIZ inventive principles and to generate new solutions by re-organising the BEC (Behaviour-Entity-Constraint) representation of principles according to the conflicting design requirements. Finally, a negotiation-based approach is integrated with an existing no-compromise approach to develop a knowledge-based system for automatically detecting and resolving conflicts. The recommendation is given as an output arranged by weight to help the designer improve creativity and efficiency for concept generation and conflict resolution in conceptual design. The approach is implemented by using a rule-based language, JESS. A case study of aircraft fuselage layout design is presented to demonstrate the benefits of using this conflict resolution system.EThOS - Electronic Theses Online ServiceGBUnited Kingdo