Abstract—For the life cycle of products, the global unified multidisciplinary model is the core of the simulation optimization. It can effectively organize relative information, manufacturing resources and processes within the life cycle of products. The information has some differences in the content, format and pattern. So a consistent approach to describe the data and data relationships is needed. Using the unified modeling language Modelica based on the equation’s character and its support for discrete mechanism, the product life cycle-oriented and unified multidisciplinary model is established by studying the unified modeling mechanism of the multi-domain coupled complex products. The model can implement the simulation optimization in the entire life cycle and the multi-domain. Aiming at the complex multifunctional loaders integrated by machinery, electronics, control and hydraulic pressure, this paper explores the simulation and optimization of the design process, manufacturing process and data management in the full life-cycle on the basis for studying the full life-cycle modeling method. That lays the foundation of the overall simulation and optimization.

I. INTRODUCTION ITH the development of engineering technology, the modern electromechanical products, such as aerospace, automobile, engineering machinery and so on, become

increasingly complex. In order to improve design efficiency and to push products to the market as soon as possible, the academic and business circles gradually pay attention to the simulation technology. The introduction of simulation optimizes the traditional design processes. However, the current simulation technology is mainly used in the product’s design stage. Only a partial rationalization of the design process has been difficult to ensure the products’ competitive advantage in the international market. Therefore, the simulation and optimization technology must be applied to the entire life-cycle process of products.

Currently, the results of the single-disciplinary optimization are frequently integrated for the complex multidisciplinary products. However, on one hand, it is difficult to get the overall optimal performance of the complex products. On the other hand, it does not consider the full life-cycle integrated optimization including the designing, manufacturing, using, recycling stages. To implement the simulation and optimization of the product’s overall life cycle, a unified model must be built which can run through the development, designing, manufacturing, using and recycling stages of the full life cycle. It is the foundation of the

Manuscript received April 8, 2010. This work was supported by National

Natural Science Foundation of China (No.60873106 and No.60903087). Chen Guojin, Su Shaohui, Gong Youping, and Zhu Miaofen are with

Hangzhou Dianzi University, Xiasha, Hangzhou, China, 310018 (phone: 0571-86919051; e-mail: chenguojin@163.com).

multi-domain simulation and optimization. Compared with the traditional product’s model, the life cycle-oriented models include not only the geometric information, but also the non-geometric information of the product’s functional requirement, technology, maintenance and management [1-4]. In view of this situation, the paper puts forward the theory and method of modeling, simulating and optimizing for the complex multidisciplinary products in the overall life cycle, and establishes the multidisciplinary merged models that embody the characteristics of different stages and levels for the complex products in the overall life cycle to simulate and optimize the product’s formation process.

II. PRODUCT’S DATA MODEL IN THE ENTIRE LIFE CYCLE The data model is an important prerequisite for

successfully implementing the simulation and optimization system of the product’s life-cycle, also is a foundation for building a complex virtual model. With the virtual model, different types of information can be processed in the product's full life cycle to effectively achieve the simulation and optimization.

Figure 1 represents the sectional content of a product’s model. In the product’s model, each component or each document can be associated with the project. By DoMR (document master record), all kinds of information, such as standards, guidelines, customer orders, overall design reports and demand specifications are all associated with the project. PMR (part master record) is related with MMR (model master record), and DrMR (drawing master record) is related with DoMR. Using MMR, the CAD models can be linked in the product documentation. The task of DrMR is that all engineering drawings, IGES files, and other related information are linked in the product documentation and the assembly plans and instructions, etc. can be used to link DoMR with PMR. Using the same approach, each component can be described perfectly. The whole product structure can be described by the structured method.

Figure 2 indicates the principle that the corresponding three-dimensional model, engineering drawings and the planning process are generated automatically on the basis of the main model, the main figure and the main process planning of the coupling’s components. When a row of data (equivalent to a specific part’s size) in the thing’s characteristic table is combined with the master model, the main project drawing and master planning process of the standard modules, the three-dimensional model, engineering diagram and process planning of the specific part can automatically generated. The main model of the coupling creates the variant parts 001, 002 and 003 under the influence of the customer orders 001, 002 and 003. The ETO product

The Product Life Cycle-oriented Modeling Method Guojin Chen, Shaohui Su, Youping Gong, and Miaofen Zhu

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Third International Workshop on Advanced Computational Intelligence August 25-27, 2010 - Suzhou, Jiangsu, China

978-1-4244-6337-4/10/$26.00 @2010 IEEE

configurator produces the ETO product 001, 002 and 003 corresponding to the variant parts of the specific coupling by combining the thing’s characteristic data of the part 001, 002

and 003 in the thing’s characteristic table and the customer orders 001, 002 and 003.

PMR

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Fig. 1. Sectional content of product’s data model.

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Fig. 2. Configured variant design based on thing’s characteristic table.

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III. UNIFIED MULTIDISCIPLINARY MODELING MECHANISM OF COMPLEX PRODUCT

Modelica is a language based on the equation, which can be easily expressed by the physical knowledge based on mathematical formulas [5]. On the basis of the existing visual drag-and-drop modeling, the expansion of its system function is easy to realize top-down modeling or designing for a complex system. Providing the establishment of an "empty part" and its connected definition and expanding the Modelica language can adapt to the compatibility for the empty part’s expression and connection mechanism. And providing the unfolding and reconstructing mechanism of an empty part achieves the hierarchical construction of complex models.

However, the line graphs, tables, data files, databases, and knowledge repository based on rules are still difficult to qualify. In order to achieve the integration of knowledge in many fields, Modelica’s data types need to be extended, and the relevant addressable rules are provided. By interpolation, identification, database connectivity, and discrete treatment to the rule’s knowledge, the knowledge is changed ultimately into the unified formal description of the objects, functions and equations.

Professional tool integration is a key issue on the modeling and simulating platform for the multi-domain physical systems. It directly concerns the systemic applicability. The basic means is that calling the external functions achieves the integration through the development of specialized interfaces.

For the parametric modeling and management of the multi-domain model, utilizing Modelica’s parameter type can easily change the information of the parameter values, units and parameter descriptions, manage the parameter’s scope (inner/outer), continuity (discrete/continuous), openness (public/protected), as well as inspect and process the parameter’s interval constraint and conflict.

IV. UNIFIED MULTIDISCIPLINARY MODEL BASED ON THE PRODUCT’S OVERALL LIFE CYCLE

The unified multidisciplinary model based on the product’s overall life cycle is the basis of the simulation and optimization. Figure 3 describes the unified multidisciplinary model from the two dimensions of the product’s life cycle and multidisciplinary field. Taking BOM as a carrier for mapping between different phases of the life-cycle, the models in different fields are integrated through the uniform descriptions of constraints.

The multi-function loader is a complex system in which mechanical, electronic, hydraulic and control systems are

assembled. It has a significant multi-disciplinary coupling characteristic. Therefore, the CAE performance analysis of

Product’s designing Product’s machining

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Fig. 3. Unified multidisciplinary model based on the product’s overall life cycle.

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complex products can not be only limited to the dynamic field of mechanical multi-body systems, and must be integrated into the multi-field coupling problems of the mechanical,

electrical, hydraulic, and control factors. Figure 4 is the development process diagram of the multi-function loader based on the full life-cycle.

A. Simulation and Optimization of Designing Process for Multi-function Loader

In the multi-function loader’s designing stage, the

involving contents include not only the modeling and analysis of product’s geometry, static, dynamic, manufacturability, assembly and so on. But in order to reduce the product’s development time and lower the development costs, various kinds of modeling and simulation need to be integrated as shown in Figure 5. In the structural designing stage, the component’s designing parameters can be modified and be re-simulated, and the analysis, optimization of the component’s designing parameters can be directly done to improve the designing quality. The simulate experiments using the simulation models can reduce the numbers of development and testing, save the designing expenditures and shorten the designing cycles. The simulate experiments of the simulation models can also be used to replace the hazardous and difficult testing, or to simulate the accident, and so on.

B. Simulation and Optimization of Manufacturing Process for Multi-function Loader

By identifying and mining the geometric, structural, functional, and process similarity for the multi-function loader, the methods of standardization, modulization and seriation can modularize the multi-function products and the corresponding manufacture systems. The various kinds of parts and components designed and produced modularly can be directly assembled into the products needed by customers using a set of advanced operations for the modular assembly processes. The manufacturing process simulation mainly builds the simulation model of the manufacturing process with the kinetic and dynamic characteristics. The testing of the model can visually observe the manufacturing process and its physical properties, such as characteristic parameters and motility patterns. The manufacturing process modeling

General systemic parameters

Virtual Prototyping design

Finite element analysis

Dynamics analysis

Simulation of system operation

Simulation ofmachining process

Assembly processing

Environmental parameters

Existing products technical data

Stability and safety evaluation

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Failure predictionand redundant design

Fig. 4. Development process diagram of the multi-function loader based on the full life-cycle.

Contentment?

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experiment and performance evaluation

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Fig. 5. Simulation and optimization of designing process for multi-function loader.

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and simulation stresses the multi-disciplinary integration of the manufacturing process modeling and simulation. The establishment of the simulating systems for machinery, control, hydraulic collaboration can achieve the integration of the manufacturing process modeling, the simulation system and the production system, restore failures in real time, and rapidly respond to change, automatically adjust the production process to improve adaptability.

C. Full Life-cycle Data Management for Multi-function Loader

In general, the multi-function loader’s designing process can be described both in time and in space. From the time point of view, the life cycle of the multi-function loader can be divided into the stages of requirement definition,

conceptual design, detailed design, production planning, manufacturing, assembly, sales services, and operation maintenance. In order to strengthen the developer’s collaboration and the information flow in the different stages, the management resources include, (1) the basic resource data of simulation, such as the information and documentation for all kinds of elements, components, and members and their associated attribute, various types of environmental modeling and data, (2) the resources and data related with the specific simulating projects, such as the related elements, components, members and their key parameters, three-dimensional geometric solid model, environment model and evaluation model, etc., and the documents of the project planning, the documentation and data in simulation processes.

The common interface to the various disciplines is built in the Modelica specification. The constraint equations corresponding to the physical components are established in the statement of the constitutive equations. The relationship of the topological connections between the physical components is expressed in the connections between the interfaces. The components’ hierarchical structure library of different disciplines is built, and the object-oriented model of the multi-function loader is formed for the object-oriented analysis and design. The compound knowledge in the multi-function loader’s model is uniformly expressed by the

constraint concepts of equations, algorithms and annotations so as to combine the physical models in the systemic level and the simulation models in the structural level. The unified multi-disciplinary model of the configurable products is established using the containment and relationship of the object-oriented ideological organization and modeling expression. The theory of the traditional constraint programming and constraint propagation is expanded to maintain the information of the corresponding model unchanged. According to the sparse features for the correlation matrices of equations and variables, the solving

ETO multi-disciplinarySimulating model

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Fig. 6. Building and solving process of the entire unified model.

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sequences of sub-systems are got using the decomposition method based on the graph theory or the symbolic algebra to reduce and decompose the large-scale equations. The serialized sub-problems are the downsizing differential and algebraic equation groups, or the simple differential equation groups, or the simple algebraic equation groups. For the strong coupling sub-problems in the large scale, the equations must be further reduced and decoupled by the combination strategies of stripping and broken-ring to speed up the pace of solving sub-problems. For the sub-problems of the differential and algebraic equations of the high-index value, the high-index problem is converted into the low-index form using the structural analysis method of declining indicator to conduct the numerical solution. The entire unified model and the solution process is as shown in Figure 6.

V. CONCLUSION The core of the simulation optimization based on the

overall product’s life cycle is the global unified multidisciplinary model. It can effectively organize the related information, manufacturing resources and processes in the product’s life cycle. With the size and complexity of the products increasing, the involved disciplines are more and more. The models of the product’s designing and manufacturing processes need to be established to simulate and optimize for the overall product’s life cycle. Through the creation of the complex products’ unified multi-disciplinary model for the whole life cycle, it is simulated and optimized from the time span and from the space span.

The entire life cycle-oriented product’s model need to cover the geometric information and non-geometric information, including the model data, process data and resource data from the product’s planning until the entire product’s death. The information in the content, format and pattern has some differences in the need for a consistent approach to describe the relationship between data and data. Using the unified modeling language Modelica based on the equation’s character and its support for discrete mechanism, the product life cycle-oriented and unified multidisciplinary model is established by studying the unified modeling mechanism of the multi-domain coupled complex products. That provides the basis for the overall simulation and optimization of products.

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[3] A. Li, “Knowledge-based environment-oriented model of product lifecycle,” China Mechanical Engineering, vol. 14, no. 4, pp. 295–299, 2003.

[4] W. Chen et al, “Research on the technology of life-cycle product modeling,” Machine Tool & Hydraulics, vol. 3, no. 1, pp. 33–36, 2000.

[5] P. Fritzson, P. Bunus, “Modelica–a general object-oriented language for continuous and discrete-event system modeling and simulation,” in Proc. 35th Annual Simulation Symposium, San Diego, USA, 2002.

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