Study on the evaluation model of serialized civil aircraft commonality index based on fuzzy set theory

Commonality, a typical commercial feature of serialized civil aircraft study and development, refers to a series of methods of reusing and sharing assets, which were developed based on broad similarity. The common design of serialized civil aircraft is capable of maximally saving R&D, production, operation, and disposal. To maximize the total benefits of manufacturers and operators, the common design of serialized civil aircrafts primarily exploits the commercial experience of serialized products in other fields (e.g., automobiles and mobile phones), whereas a scientific index system and quantitative evaluation model has not been formed. Accordingly, this study proposes a new civil aircraft commonality index evaluation model in accordance with fuzzy set theory and methods. The model follows two branches, i.e., attribute commonality and structural commonality, to develop a multi-level civil aircraft commonality index system. The proposed model can split the commonality into six commonality sub-intervals and build the corresponding standard fuzzy set with the characteristic attribute parameters of the civil aircraft as the elements. Next, based on considerable civil aircraft sample data, a fuzzy test is designed to yield the membership function of the fuzzy set. Thus, a model of evaluating civil aircraft commonality is constructed, taking the characteristic parameters of the civil aircraft to be evaluated as input, and selecting the degree of commonality of each level as output. Lastly, this study employs the evaluation model to evaluate the commonality of Boeing 757-200 with other civil aircrafts. Furthermore, the evaluated results well explain the actual situation, which verifies the effectiveness and practicability of the proposed model.

Application of Product Line Commonality Index (PCI) in a Family of Products

Currently many companies base their marketing strategy around a family of products. Thus, they regularly add new variations to products in order to meet changing market needs, or to attract new customers. Although the basic functionality remains unchanged across products, new features, aesthetic appearance and technologies are incorporated in each new product. This if it is not checked, can generate the “complexity of the product,” which leads to a loss of productivity or quality. Thus, the effective management of product variations in design and manufacturing is challenging. The key is minimizing the non-value added variations through models within a range of options without limiting customers. This article discusses the factors that contribute to the "complexity of the product” and this is done through the product line commonality index (PCI) , which measures the level of common parts in a product family. A case study of bicycle frame displays its implementation and functionality. The index shows the possibility that the products in a family share parts effectively (modularity) and reduces the total number of parts (multifunctionality).

Commonality Index of Outsourced Function Module Based on Generalized Dice Coefficient

Commonality analysis is the starting point of product family redesign, providing guidance for enterprises to improve commonality, reduce product cost and manufacturing complexity. Firstly, the component-based commonality indices introduced so far are analyzed and the deficiency in respect to commonality evaluation of outsourced function module is indicated. Then, the generalized performance matrix of outsourced function module is established and the commonality index based on generalized Dice coefficient is introduced. Finally, the calculation process is demonstrated by a case study of engine modules. The proposed index is of certain significance to reduce the types of outsourced module instances, save procurement and management cost and reduce the complexity of manufacturing systems.

Comprehensive Product Platform Planning (CP3) Using Mixed-Discrete Particle Swarm Optimization and a New Commonality Index

A product family with a common platform paradigm can increase the flexibility and responsiveness of the product-manufacturing process and help take away market share from competitors that develop one product at a time. The recently developed Comprehensive Product Platform Planning (CP3) method allows (i) the formation of sub-families of products, and (ii) the simultaneous identification and quantification of platform/scaling design variables. The CP3 model is founded on a generalized commonality matrix representation of the product-platform-plan. In this paper, a new commonality index is developed and introduced in CP3 to simultaneously account for the degree of inter-product commonalities and for the overlap between groups of products sharing different platform variables. To maximize both the performance of the product family and the new commonality measure, we develop and apply an advanced mixed-discrete Particle Swarm Optimization (MDPSO) algorithm. In the MDPSO algorithm, the discrete variables are updated using a deterministic nearest-feasible-vertex criterion after each iteration of the conventional PSO. Such an approach is expected to avoid the undesirable discrepancy in the rate of evolution of discrete and continuous variables. To prevent a premature stagnation of solutions (likely in conventional PSO), while solving the high dimensional MINLP problem presented by CP3, we introduce a new adaptive diversity-preservation technique. This technique first characterizes the population diversity and then applies a stochastic update of the discrete variables based on the estimated diversity measure. The potential of the new CP3 optimization methodology is illustrated through its application to design a family of universal electric motors. The optimized platform plans provide helpful insights into the importance of accounting for the overlap between different product platforms, when quantifying the effective commonality in the product family.

Shape Commonalization to Develop Common Platform for Product Family

Current market place is highly competitive and frequently changing, to survive companies need to quickly respond to the customers’ requirements. This challenging situation demands a robust platform design and development process to produce variety of products in the shortest possible time. The common components for a set of similar products under a family can be grouped into a common platform. Development of product platform requires measuring the similarity among a set of products. This paper presents an approach to measure the similarity among a set of CAD models of products to develop a common product platform. The measured similarity of geometries can allow designers to identify components that have the potential to be included in the common platform. The degree of similarity is determined by extracting the information and developing a suitable commonality index for a set of CAD models. The commonality index values are then used to determine the common platform for a set of assembly products by developing and calculating the Average Assembly Platform index value. The overall approach is followed by two case studies: Cell Phone casing models and Vacuum Cleaner models.

An Extension of the Commonality Index for Product Family Optimization

One critical aim of product family design is to offer distinct variants that attract a variety of market segments while maximizing the number of common parts to reduce manufacturing cost. Several indices have been developed for measuring the degree of commonality in existing product lines to compare product families or assess improvement of a redesign. In the product family optimization literature, commonality metrics are used to define the multi-objective tradeoff between commonality and individual variant performance. These metrics for optimization differ from indices in the first group: While the optimization metrics provide desirable computational properties, they generally lack the desirable properties of indices intended to act as appropriate proxies for the benefits of commonality, such as reduced tooling and supply chain costs. In this paper, we propose a method for computing the commonality index introduced by Martin and Ishii using the available input data for any product family without predefined configuration. The proposed method for computing the commonality index, which was originally defined for binary formulations (common / not common), is relaxed to the continuous space in order to solve the discrete problem with a series of continuous relaxations, and the effect of relaxation on the metric behavior is investigated. Several relaxation formulations are examined, and a new function with desirable properties is introduced and compared with prior formulations. The new properties of the proposed metric enable development of an efficient and robust single-stage gradient-based optimization of the joint product family platform selection and design problem, which is examined in a companion paper.

A Methodology to Support Product Family Redesign Using Genetic Algorithm and Commonality Indices

Many of today’s manufacturing companies are using platform-based product development to realize families of products with sufficient variety to meet customers’ demands while keeping costs relatively low. The challenge when designing or redesigning a product family is in resolving the tradeoff between product commonality and distinctiveness. Several methodologies have been proposed to redesign existing product families; however, a problem with most of these methods is that they require a considerable amount of information that is not often readily available, and hence their use has been limited. In this research, we propose a methodology to help designers during product family redesign. This methodology is based on the use of a genetic algorithm and commonality indices - metrics to assess the level of commonality within a product family. Unlike most other research in which the redesign of a product family is the result of many human computations, the proposed methodology reduces human intervention and improves accuracy, repeatability, and robustness of the results. Moreover, it is based on data that is relatively easy to acquire. As an example, a family of computer mice is analyzed using the Product Line Commonality Index. Recommendations are given at the product family level (assessment of the overall design of the product family), and at the component level (which components to redesign and how to redesign them). The methodology provides a systematic methodology for product family redesign.

Using Product Dissection to Integrate Product Family Design Research Into the Classroom and Improve Students’ Understanding of Platform Commonality

In this paper we describe a product dissection activity that has been developed for a graduate course on product family design to improve students’ understanding of platform commonality. Last spring, the product dissection activity served a second purpose, namely, it provided an opportunity to engage students in product family design research in the classroom by having them participate in a study to evaluate the variability in the Product Line Commonality Index (PCI), a commonality index from the literature. The product dissection activity consisted of five teams dissecting and analyzing three different families of products, each containing four products. Based on their results, we identified three main sources of the variability that occur during the dissection of the products and calculation of the PCI: different levels of dissection, parts omitted from the analysis, and different values for the factors used to compute the PCI. Recommendations for reducing the variability are given based on our findings. Finally, an assessment of the students’ learning reveals that the activity significantly improved their understanding of platform commonality.

A Comparison of Commonality Indices for Product Family Design

Today’s highly competitive and global marketplace is redefining the way companies do business: many companies are being faced with the challenge of providing as much variety as possible for the market with as little variety as possible between products. In order to achieve this, product families have been developed, allowing the realization of a sufficient variety of products to meet the customers’ demands while keeping costs relatively low. The challenge when designing a family of products is in resolving the tradeoff between product commonality and distinctiveness: if commonality is too high, products lack distinctiveness, and their individual performance is not optimized; on the other hand, if commonality is too low, manufacturing costs will increase dramatically. Toward this end, several commonality indices have been proposed to assess the amount of commonality within a product family. In this paper, we compare and contrast six of the commonality indices from the literature based on their ease of data collection, repeatability and consistency. Eight families of products are dissected and analyzed, and the commonality of each product family is computed using each commonality index. The results are then analyzed and compared, and recommendations are given on their usefulness for product family design. This study lays a foundation for understanding the relationship between different platform leveraging strategies and the resulting degree of commonality within a product family.