Improving reuse of in-service information capture and feedback

The adoption of the PSS business model means that the designing company has greater scope and motivation to learn from experience of its products in use to improve their core design and engineering capabilities. Continuous improvement, however, depends crucially upon the implementation of effective Knowledge and Information Management (KIM) systems within a dynamic learning environment that impinge on diverse communities throughout the product lifecycle. This paper consolidates literature reviews and presents our empirical observations relating to the current KIM systems and practices within large aerospace and manufacturing companies. In particular, we discuss issues and experiences from a case study to enhance reuse of in-service feedback conducted with an aerospace company. The case study involves the organisation of inservice records to expedite retrieval and knowledge discovery

Uncertainty modelling of a suspension unit

Many organizations are increasingly relying on design simulation rather than expensive and time-consuming prototype testing for product evaluation. However, uncertainties in analytical and computational methods need to be understood in order to improve confidence in their use, and models need to be validated. This paper presents a case study of a MacPherson strut automotive suspension analysis, and evaluates the uncertainties in the modelling of this complex dynamic problem using a simplified analytical model and a complex computational model. In both cases, variability in design variables is characterized using probabilistic design methods. As a first step, the model variables are described by assumed datasets, which are collated from several sources such as tolerances specified in drawings, expert opinion, published data, etc. Measurement of the properties of the suspension system components is then performed (spring stiffness, damping coeffcient, etc.), and the statistical parameters so obtained are used in probabilistic calculations for specified time sequences from measured test track road load data. The results are used to accumulate evidence of uncertainties in analytical and computational methods, to correlate predicted results to experimental data for vehicle chassis top mount force, and to derive sensitivity measures. A response surface function is approximated which is useful for parametric studies for new variants of the system studied. Sources of uncertainty in this case study and methods for improving the correlations are then suggested

Development and characterisation of error functions in design

As simulation is increasingly used in product development, there is a need to better characterise the errors inherent in simulation techniques by comparing such techniques with evidence from experiment, test and inservice. This is necessary to allow judgement of the adequacy of simulations in place of physical tests and to identify situations where further data collection and experimentation need to be expended. This paper discusses a framework for uncertainty characterisation based on the management of design knowledge leading to the development and characterisation of error functions. A classification is devised in the framework to identify the most appropriate method for the representation of error, including probability theory, interval analysis and Fuzzy set theory. The development is demonstrated with two case studies to justify rationale of the framework. Such formal knowledge management of design simulation processes can facilitate utilisation of cumulated design knowledge as companies migrate from testing to simulation-based design

Facilitating design learning through faceted classification of in-service information

The maintenance and service records collected and maintained by engineering companies are a useful resource for the ongoing support of products. Such records are typically semi-structured and contain key information such as a description of the issue and the product affected. It is suggested that further value can be realised from the collection of these records for indicating recurrent and systemic issues which may not have been apparent previously. This paper presents a faceted classification approach to organise the information collection that might enhance retrieval and also facilitate learning from in-service experiences. The faceted classification may help to expedite responses to urgent in-service issues as well as to allow for patterns and trends in the records to be analysed, either automatically using suitable data mining algorithms or by manually browsing the classification tree. The paper describes the application of the approach to aerospace in-service records, where the potential for knowledge discovery is demonstrated

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

Component-based records: a novel method to record transaction design work

The growing pressures from global competitive markets signal the inevitable challenge for companies to rapidly design and develop new successful products. To continually improve design quality and efficiency, companies must consider how to speed design processes, minimise human-errors, avoid unnecessary iterations, and sustain knowledge embedded in the design process. All of these issues strongly concern one topic: how to make and exploit records of design activities. Using process modelling ideas, this paper introduces a new method called component-based records, in place of traditional design reports. The proposed method records transaction elements of the actual design processes undertaken in a design episode, which aims to continually improve design quality and efficiency, reduce designers’ workload for routine tasks, and sustain competitiveness of companies

Uncertainty in through-life costing-review and perspectives

Estimating through-life cost (TLC) is an area that is critical to many industrial sectors, and in particular, within the defense and aerospace where products are complex and have extended life cycles. One of the key problems in modeling the cost of these products is the limited life-cycle information at the early stage. This leads to epistemic and aleatory uncertainty within the estimation process in terms of data, estimation techniques, and scenarios analysis. This paper presents a review of the uncertainty classification in engineering literature and the nature of uncertainty in TLC estimation. Based on the review, the paper then presents a critique of the current uncertaintymodeling approaches in cost estimation and concludes with suggestion for the requirement of a different approach to handling uncertainty in TLC. The potential value of imprecise probability should be explored within the domain of TLC to assist cost estimators and decision makers in understanding and assessing the uncertainty. The implication of such a representation in terms of decision making under risk and decision making under uncertainty is also discussed

Application of faceted classification to in-service records

Information about the functional or operational performance of the product through life is useful in providing validation and updating of knowledge assumed at the design stage. The collection and exploitation of feedback from experience in service allows engineers to reassess and refine their original assumptions, and this new understanding in turn informs the next design cycle. Current feedback documentation of in-service occurrences (issues, requests, etc.) is found to be inconsistent, thus reducing the ability to reuse operational information for design improvements. We argue that enhanced information representation and organisation not only allows for improved retrieval in general but also provides a suitable basis for analysis and inference of design-induced issues from the information collection. The paper will discuss an approach to information organisation based on faceted classification to enhance retrieval and reuse of in-service information feedback

Taking account of information maturity in assessing product risk

We focus on the product development process based on virtual prototyping, which allows earlier evaluation of product performance. Uncertainty in information and in the behavioural models used by designers may introduce the risk of under- or over- achieving the product requirements. Two aspects of uncertainty are considered: uncertainty in information content, such as a design parameter that is characterised by a tolerance (10±2mm ) and in the behavioural models used to assess the proposed design. Maturity is defined as uncertainty in the context of the design parameters and behavioural models that may evolve in the course of the design process, such as a dimension that has not been fixed and a simplified model that needs to be refined. Risk assessment typically accounts for the content uncertainty (variability) but not the maturity of design information. We propose a method for enriching risk assessment taking into account the maturity of information in risk assessment

Western blot gels for AP, PP and FP cell culture medium (CM).

<p>The results using cultured medium not only further confirmed the results using cells and tissues (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030026#pone-0030026-g007" target="_blank">Figure 7</a>, only expressed in AP and PP, but not in FP), but also showed that S100A4 and LGALS1 were the secreted molecules. AP, antlerogenic periosteum; PP, pedicle periosteum; and FP, facial periosteum.</p