Neng Wan

A subassembly identification method for truss structures manufacturing based on community detection

Purpose – The purpose of this paper is to present an automated method for complicated truss structure subassembly identification. Design/methodology/approach – A community-detecting algorithm is introduced and adapted to reach the target. The ratio between oriented bounding boxes of parts is used as the weight to reflect the compact degree of assembly relationships. The authors also propose a method to merge nodes together at cut-vertex in model, by which the solving process could be accelerated. Findings – This method could identify the subassemblies of complex truss structures according to the specific requirements. Research limitations/implications – This research area is limited to truss structures. This research offers a new method in assembly sequences planning area. It could identify subassemblies in complex truss structures, with which the existing method is not adequate to deal. Practical implications – This method could facilitate the complex truss structures assembly planning, lower the human e...

The High Precision Blade Electrochemical Machining Simulation and Cathode Optimization Based on Isogeometric Method

The simulation and optimization of electrochemical machining is an important means to improve processing quality. However, the fragmented nature of geometric modeling and numerical analysis model, restricts the application proportion. Aiming at this problem, it is refined that the scientific problem of coordination modeling between CAD and CAE based isogeometric method. In this paper, the unified model is established based NURBS basis functions to solve the problems that the geometric parameterization and the infliction of boundary conditions. And the optimization efficiency is promoted by improved optimization model using the convex hull characteristic of NURBS basis function. At last, a confluent design method is realized for the blade electrochemical machining process.

Study on Key Technologies of Aero-Engine AMRO Support System

In order to solve the digitalized management problem of aero-engine in the whole lifecycle, a framework of aero-engine AMRO supporting system is put forward. Management of assembly, maintenance, repair and overhaul are involved. Modeling and integration of aero-engine status data, assembly process management, on-spot operation guide, online education support, integration and synchronization of data and fault diagnosis support are regarded as key enabling technologies and studied deeply. Correspondent solutions are given respectively. The assembly digitalization sub-system and the IETM sub-system are developed to validate the proposed system. And close-loop controlling of single aero-engine information is achieved, and the study provides technology support for improving level of aero-engine status digitalized management.

Key Technologies of Network Collaborative Modeling Based on B/S Structure

To achieve lightweight network collaborative modeling on the client, this paper designs the collaborative modeling architecture based on B/S structure. Considering the product CAD model information can’t be shared on the network, the XML technology is applied to build the middle model expression format which converts the CAD model to the middle model that can be shared among collaborative clients on the network. To solve the problem that the middle model is too huge to transmit on the limited internet bandwidth, the face representation method based on loops is proposed. With this method, the size of the middle model shared on the network can be reduced greatly. The structure of bidirectional inquiring between the feature information and the geometric element information is established in geometric models, and the problem that how to get modified features, topology relationship and geometric elements after design models have been changed is solved.

Isogeometric Analysis of Heat Transfer in Fluids

This paper is devoted to the numerical simulation of heat transfer in fluids. We develop a numerical formulation based on isogeometric analysis that permits straightforward construction of higher order smooth NURBS approximation. Firstly, we introduce the partial differential equation (PDE) which servers as basis for the whole paper. Then, we introduce Lagrange multiplier method to deal with essentional boundary contions accroding to the nature of NURBS basis function. After getting the Equivalent integral equation, the isogeometric solving format is established based on the idea of isoparametric which is the necessary fundamentals of Isogeometric Analysis. We also discuss the programming algorithm of isogeometric analysis based on Matlab. Finally, a numerical example in two dimensions is presented that illustrate the effectiveness and robustness of our approach.

An intelligent method to generate liaison graphs for truss structures

Liaison graph is a necessary prerequisite of assembly sequence planning for mechanical products. Traditionally, it is generated via shape matching of joints among parts, but this strategy is invalid to truss structures because they lack patterns for shape matching. In this context, this article presents an intelligent method based on support vector machine to obtain liaison graphs of truss products automatically. This method defined three kinds of oriented bounding boxes to embody the relationships of the joints in truss structures. Based on them, a series of factors are deduced as training data for support vector machine. Furthermore, two algorithms are introduced to calculate oriented bounding boxes to facilitate the data extraction. By these processes, this method established the knowledge of joints and realized the intelligent construction of liaison graph without shape matching reasoning. To verify the effect of the method, an experimental implementation is presented. The results suggest that the proposed method could recognize most joint types and construct liaison graph automatically with sufficient sample training. The correct recognition rate is more than 85%. Comparing with back-propagation neural network, support vector machine is more accurate and stable in this case. As an alternative method, it could help the engineers to arrange the assembly plan for truss structures and other similar assemblies.

Research on service planning of distributed heterogeneous design resources

The composition and reuse of distributed design resources is the key issue in collaborative operation of complicated products. In the first place, a collaborative service framework aiding design resources reuse is established to help encapsulate reusable resources. Meanwhile, to realize interoperability between function and data of heterogeneous resources, shared ontology and private ontology are separately built for different design disciplines and tool resources within the disciplines. Then, collaborative service planning is divided into different stages. And generating algorithm serving planning program is proposed to obtain feasible program collection of service composition. Finally, taking design of aero engine compressor as an example, the effectiveness of collaborative service planning algorithm is verified by providing an atomic service ontology instance.

Machining Process Knowledge Discovery Technology: On the Basis of MBD Process Model

To tackle process knowledge discovery difficulty in machining process, this paper studies knowledge discovery method of 2.5–dimensional machining characteristics based on process model with model based definition technology, and finds out machining process design knowledge with the natural structured process description ability of MBD process model. Firstly, the composition of machining geometry ontology and process ontology is analyzed. Secondly, decision tree between ontology are obtained by analyzing abundant samples of MBD process model. Thus, the process and method of reasoning from geometry ontology to process ontology is achieved. Finally, the validity of process knowledge discovery method is exemplified with a group of MBD process models.

Research of 3D Machining Procedure Model Parameterized Modeling Method

To achieve the purpose of machining process design base on 3D models，it is proposed a procedure modeling method with allowance figure in this paper. At first, the parameterized modeling process of 3D machining procedure model is presented, and the modeling method with allowance figure is described in detail. Then, the Petri model mapped to the modeling process of 3D machining procedure is created and illustrated. At last, through an instance, it declares that technologist can use this method to create a group of 3D machining procedure parameterized models that contain the inter-part correlations.

The Key Technology Research of Knowledge Modeling Method for Complex Product Design

The purpose of this paper is to build knowledge description model for complex product design. In order to uniform the semantic of glossary in design process, an extensive glossary semantic tree is built up and the corresponding semantic similarity calculation algorithm is proposed. The complex design knowledge can be divided into instance pattern, chart pattern, formula pattern and rule pattern. The knowledge models are proposed for these four pattern knowledge models. At last, a design knowledge modeling and reusing system for complex product is achieved, and the design knowledge can be inherited by it.