Knowledge based support for manufacturing of microstructures

In the Institute of Applied Computer Science (IAI) in the Forschungszentrum Karlsruhe (FZK) information technologies are developed and applied to support the design and manufacturing process for micromechanical structures. The information related kernel of the computer integrated manufacturing (CIM) consists of different semantic domains. At the beginning of the whole manufacturing process, the designer has to construct the microstructure with a CAD system for mechanical construction. After application of design rule checks, based on heuristics from human experts, these constructions are the references for the quality control of the real fabricated structures. The knowledge in form of design rules needs as well deeper knowledge, stored in the different partial modes of the process model and the product model as well dynamical results of the different integrated tools for design, simulation and optimization. Especially this fact is the kernel to produce cost efficient because distinguishing between possible and impossible structures in a very early stage of manufacturing.     

Knowledge based support for manufacturing of microstructures

 In the Institute of Applied Computer Science (IAI) in the Forschungszentrum Karlsruhe (FZK) information technologies are developed and applied to support the design and manufacturing process for micromechanical structures. The information related kernel of the computer integrated manufacturing (CIM) consists of different semantic domains. At the beginning of the whole manufacturing process, the designer has to construct the microstructure with a CAD system for mechanical construction. After application of design rule checks, based on heuristics from human experts, these constructions are the references for the quality control of the real fabricated structures. The knowledge in form of design rules needs as well deeper knowledge, stored in the different partial modes of the process model and the product model as well dynamical results of the different integrated tools for design, simulation and optimization. Especially this fact is the kernel to produce cost efficient because distinguishing between possible and impossible structures in a very early stage of manufacturing. Received: 30 October 1995 / Accepted: 20 May 1996     

An architecture for an intelligent support system for design validation and manufacturing of aerospace components

This paper presents the architecture of a multi‐agent system that aims to support the design and manufacturing processes of composite material components for the aerospace, automobile, ship and other industries. The major goals are to accelerate the design process while minimising cost; support users in selecting the optimum material in terms of its properties, cost and environmental impact; and enhance the efficiency of the component manufacturing phase by extending the decision support capabilities of the existing real‐time monitoring software. An important requirement for achieving these objectives is to enable the more efficient utilisation of existing distributed information on composite materials. To this end, state‐of‐the‐art advances in metadata concepts were adopted and extended. By implementing metadata structures for each data category available, the searching and retrieval mechanisms are improved both in terms of speed and usage. In addition, large amounts of knowledge about the design and manufacturing processes themselves are incorporated into a multi‐agent environment in order to enhance the ability to support the user groups involved in the various stages of component design and manufacturing. In order to present the system architecture here, an example from the aerospace industry has been used.     

Developing distributed applications for integrated product and process design

A heterogeneous computing environment characterizes today's manufacturing situation. This is a stumbling block for the efficient implementation of manufacturing concepts such as integrated product and process design (IPPD). A computing environment for IPPD would require the seamless integration of the various product and process design software systems. The exchange of information between these systems should be efficient, compatible and synchronous. This article presents an approach for developing distributed manufacturing applications that are compatible and synchronized and thus, able to support IPPD. The approach involves the use of a common manufacturing application ‘middleware’, which is distributed between a central geometric modelling server and application clients. The portability of the middleware is ensured through the use of Java for code portability and XML for data portability. The compatible product model problem is solved through the use of common data structures developed using reusable application client classes. Efficient transfer of product data is proposed using compressed model information embedded in a product data XML schema. Synchronization of design changes among all applications is achieved through the creation of relationships on an Application Relationship Manager.     

Functionally heterogeneous porous scaffold design for tissue engineering

Porous scaffolds with interconnected and continuous pores have recently been considered as one of the most successful tissue engineering strategies. In the literature, it has been concluded that properly interconnected and continuous pores with their spatial distribution could contribute to perform diverse mechanical, biological and chemical functions of a scaffold. Thus, there has been a need for reproducible and fabricatable scaffold design with controllable and functional gradient porosity. Improvements in Additive Manufacturing (AM) processes for tissue engineering and their design methodologies have enabled the development of controlled and interconnected scaffold structures. However homogeneous scaffolds with uniform porosity do not capture the intricate spatial internal micro architecture of the replaced tissue and thus are not capable of capturing the design. In this work, a novel heterogeneous scaffold modeling is proposed for layered-based additive manufacturing processes. First, layers are generated along the optimum build direction considering the heterogeneous micro structure of tissue. Each layer is divided into functional regions based on the spatial homogeneity factor. An area weight based method is developed to generate the spatial porosity function that determines the deposition pattern for the desired gradient porosity. To design a multi-functional scaffold, an optimum deposition angle is determined at each layer by minimizing the heterogeneity along the deposition path. The proposed methodology is implemented and illustrative examples are also provided. The effective porosity is compared between the proposed design and the conventional uniform porous scaffold design. Sample designed structures have also been fabricated with a novel micro-nozzle biomaterial deposition system. The result has shown that the proposed methodology generates scaffolds with functionally gradient porosity.     

A semantic knowledge management system for laminated composites

The engineering of laminated composite structures is a complex task for design engineers and manufacturers, requiring significant management of manufacturing process and materials information. Ontologies are becoming increasingly commonplace for semantically representing knowledge in a formal manner that facilitates sharing of rich information between people and applications. Moreover, ontologies can support first-order logic and reasoning by rule engines that enhance automation. To support the engineering of laminated composite structures, this work developed a novel Semantic LAminated Composites Knowledge management System (SLACKS) that is based on a suite of ontologies for laminated composites materials and design for manufacturing (DFM) and their integration into a previously developed engineering design framework. By leveraging information from CAD/FEA tools and materials data from online public databases, SLACKS uniquely enables software tools and people to interoperate, to improve communication and automate reasoning during the design process. With SLACKS, this paper shows the power of integrating relevant domains of the product life cycle, such as design, analysis, manufacturing and materials selection through the engineering case study of a wind turbine blade. The integration reveals a usable product-life-cycle knowledge tool that can facilitate efficient knowledge creation, retrieval and reuse from design inception to manufacturing of the product.     

STEP-NC compliant process planning as an enabler for adaptive global manufacturing

Manufacturing firms are seeking more efficient methods of CNC manufacture. ISO14649 informally known as STEP-NC has been proposed as a high-level hierarchical manufacturing information model as a replacement for the low-level machining instructions of ISO6983 and RS274D. In this paper, the applicability of STEP-NC as an enabler for creating an adaptive global manufacturing system is examined. The overall framework of the system is presented followed by an outline of its information requirements. Suitability of STEP-NC to support each requirement is then studied with the necessary additions highlighted. Finally, a test component is used in conjunction with a prototype of the advanced global manufacturing system to demonstrate the applicability of the STEP-NC standard to support manufacturing information in such a system.     

Preliminary design and manufacturing planning integration using web-based intelligent agents

Software agents have been increasingly used in the product and process development in industry over the past years due to the rapid evolvement of the Internet technology. This paper describes agents for the integration of conceptual design and process planning. Agents provide mechanisms to interact with each other. This mechanism is important since both of those processes involve negotiations for optimization. A set of design and planning software agents has been developed. These agents are used in a computer-based collaborative environment, called a multi-agent platform. The main purpose of developing such a platform is to support product preliminary design, optimize product form and structure, and reduce the manufacturing cost in the early design stage. The agents on the platform have access to a knowledge base that contains design and planning rules. These rules are derived from an analysis of design factors that influence process and resource planning, such as product material, form, shape complexity, features, dimension, tolerance, surface condition, production volume, and production rate. These rules are used by process planning agents to provide process planners with information regarding selecting preliminary manufacturing processes, determining manufacturing resources, and constructing feedback information to product designers. Additionally, the agents communicate with WEB servers, and they are accessible by users through Internet browsers. During performing design and planning tasks, agents access the data pertinent to design and manufacturing processes by the programming interfaces of existing computer-aided design (CAD) and manufacturing system. The agents are supported by a developed prototype agent platform. The agents and the platform enable the information exchange among agents, based on a previously developed integrated design and manufacturing process object model.     

基于Web Services的数字化制造软资源支撑系统开发

通过分析档案管理系统的开发流程和需求,针对数字化制造软资源管理业务中存在的手工管理为主、设计和生产信息不流畅等管理现状,构建了基于Web Services的数字化制造软资源管理业务流程,提出了基于Web Services的数字化制造软资源支撑系统框架,并设计和实现了该系统。实验结果表明,该系统能够对图纸、文件等纸质、电子文件进行一体化管理,基于Web Services技术是构建数字化制造软资源支撑系统的有效方式。     

Digital twin-based designing of the configuration,motion, control,and optimization model of a flow-type smart manufacturing system

Digital twins can achieve hardware-in-the-loop simulation of both physical equipment and cyber model, which could be used to avoid the considerable cost of manufacturing system reconfiguration if the design deficiencies are found in the deployment process of the traditional irreversible design approach. Based on the digital twin technology, a quad-play CMCO (i.e., Configuration design-Motion planning-Control development-Optimization decoupling) design architecture is put forward for the design of the flow-type smart manufacturing system in the Industry 4.0 context. The iteration logic of the CMCO design model is expounded. Two key enabling technologies for enabling the customized and software-defined design of flow-type smart manufacturing systems are presented, including the generalized encapsulation of the quad-play CMCO model and the digital twin technique. A prototype of a digital twin-based manufacturing system design platform, named Digital Twin System, is presented based on the CMCO model. The digital twin-based design platform is verified with a case study of the hollow glass smart manufacturing system. The result shows that the Digital Twin System-based design approach is feasible and efficient.     

A teaching–learning based optimization approach for economic design of X-bar control chart

Being simple to use X-bar control chart has been most widely used in industry for monitoring and controlling manufacturing processes. Measurements of a quality characteristic in terms of samples are taken from the production process at regular interval and the sample means are plotted on this chart. Design of a control chart involves the selection of three parameters, namely the sample size (n), the sampling interval (h) and the width of control limits (k). In case of economic design, these three control chart parameters are selected in such a manner that the total cost of controlling the process is the least. The effectiveness of this design depends on the accuracy of determination of these three parameters. In this paper, a new efficient and effective optimization technique named as teaching–learning based optimization (TLBO) has been used for the global minimization of a loss cost function expressed as a function of three variables n, h and k in an economic model of X-bar chart based on unified approach. In this work, the TLBO algorithm has been modified to simplify the tuning of teaching factor. A MATLAB computer program has been developed for this purpose. A numerical example has been solved and the results are found to be better than the earlier published results. Further, the sensitivity analysis using fractional factorial design and analysis of variance have been carried out to identify the critical process and cost parameters affecting the economic design.     

Applications of group technology in distributed manufacturing

This paper discusses the systematic use of group technology (GT) to support important activities of distributed manufacturing including design indexing and retrieval, variant design, variant process planning, and design critiquing. We introduce an Object-Oriented Group Technology (OOGT) scheme, which captures design data critical to the product's manufacture. Our approach uses a STEP-based product information model to generate the OOGT data automatically. The latter are then used to conduct an efficient search for similar products manufactured by selected companies and to retrieve and use information about the manufacturing processes and performance of these similar products.     

Support slimming for single material based additive manufacturing

In layer-based additive manufacturing (AM), supporting structures need to be inserted to support the overhanging regions. The adding of supporting structures slows down the speed of fabrication and introduces artifacts onto the finished surface. We present an orientation-driven shape optimizer to slim down the supporting structures used in single material-based AM. The optimizer can be employed as a tool to help designers to optimize the original model to achieve a more self-supported shape, which can be used as a reference for their further design. The model to be optimized is first enclosed in a volumetric mesh, which is employed as the domain of computation. The optimizer is driven by the operations of reorientation taken on tetrahedra with ‘facing-down’ surface facets. We formulate the demand on minimizing shape variation as global rigidity energy. The local optimization problem for determining a minimal rotation is analyzed on the Gauss sphere, which leads to a closed-form solution. Moreover, we also extend our approach to create the functions of controlling the deformation and searching for optimal printing directions.     

Evaluating the application of augmented reality devices in manufacturing from a process point of view: An AHP based model

Augmented Reality (AR) systems in last few years show great potentialities in the manufacturing context: recent pilot projects were developed for supporting quicker product and process design, as well as control and maintenance activities. The high technological complexity together with the wide variety of AR devices require a high technological skill; on the other hand, evaluating their actual impacts on the manufacturing process is still an open question. Few recent studies have analysed this topic by using qualitative approaches based on an “ex post” analysis – i.e. after the design and/or the adoption of the AR system - for evaluating the effectiveness of a developed AR application. The paper proposes an expert based tool for supporting production managers and researchers in effectively evaluating a preliminary ex-ante feasibility analysis for assessing quantitatively most efficient single AR devices (or combinations) to be applied in specific manufacturing processes. A multi-criteria model based on Analytic Hierarchy Process (AHP) method has been proposed to provide decision makers with quantitative knowledge for more efficiently designing AR applications in manufacturing. The model allows to integrate, in the same decision support tool, technical knowledge regarding AR devices with critical process features characterizing manufacturing processes, thus allowing to assess the contribution of the AR device in a wider prospective compared to current technological analyses. A test case study about the evaluation of AR system in on-site maintenance service is also discussed aiming to validate the model, and to outline its global applicability and potentialities. Obtained results highlighted the full efficacy of the proposed model in supporting ex-ante feasibility studies.     

Expert systems: An application in flexible manufacturing

Flexible manufacturing systems (FMS) are needed to provide manufacturing operations with the capability to adjust, in real time, to changes in the manufacturing environment. Realization of the goals of flexible manufacturing is governed by the ability of the FMS to maintain adequate information on the factory to assist in generating scenarios from product planning to operations and performance. This leads to a view where the factory is represented as an integrated information system. To facilitate the analysis of information requirements and the design of information systems for flexible manufacturing, an expert support system (ESS) which can be used to model and study the various structures is described. This ESS uses the information cell model to build these information structures. Petri net representations of these structures and their interactions are then constructed. The ESS may now be used to exercise these models and study their performance using time and cost measures.     

Process planning strategies for solid freeform fabrication of metal parts

Process planning of additive manufacturing of metals is a research interest because of the applications of solid freeform fabrication of metal parts in industry. The strategy is to transform the model of the part into the combinations of 2D layers that will be deposited using different fabrication methods. Process planning for metal deposition in this paper consists of three major modules: spatial decomposition, slicing of the part, and toolpath generation for every slicing layer. Algorithmic improvements are proposed and implemented for these major modules. For spatial decomposition, 3D part decomposition based on modular boundary models and centroidal axis extraction methods are combined to decompose parts more robustly and reliably. For generating slicing layers, a planning process for building non-uniform layers is investigated to greatly increase the variety of the parts that can be manufactured without the need of support structure. For toolpath generation methods, optimization of the generated toolpath is studied especially for complex thin-wall structures to ensure the deposition quality. Experiments were carried out to evaluate the improvements of the major modules of process planning strategies for rapid manufacturing.     

Generative adversarial network for early-stage design flexibility in topology optimization for additive manufacturing

Topology optimization has become a valuable design tool for structures to be fabricated by additive manufacturing (AM). However, during early stage design, parameters are frequently evolving, resulting in multiple similar TO runs. Especially when design for manufacturing principles expand the parameter space, this iterative process is computationally burdensome, and does not take advantage of redundant information in each study. We introduce a deep learning-based framework that learns latent similarities between runs in a training set to predict near optimal designs, enabling efficient wholistic understanding of the problem setup space, which includes both loading conditions and, for the first time in this study, manufacturing process configuration. Learning was achieved using a conditional generative adversarial network (cGAN) trained on a dataset of randomized boundary conditions, loadings, and AM build orientations, and the corresponding optimal structures obtained through overhang-filtered TO. cGAN predictions showed good agreement with true optima. For even greater accuracy, predictions can be post-processed by applying a small number of TO iterations. Manifold learning techniques were used to provide further insight, and we were able to conclude that the cGAN error generally increases with distance between the load and the boundary conditions or build plate. Interestingly, in 9% of test cases, the cGAN generated structures with compliances better than the corresponding TO-calculated structures, often by as much as 50 % with an average of 7.8 %. That some of these structures appeared qualitatively different in form suggests the potential value of the approach in other domains such as generative design, where a range of alternate near-optimal designs are used to guide the ideation process.     

Feature extraction and volume decomposition for orthogonal layered manufacturing

Robust and efficient process planning techniques play an important role in CAD/CAM integration. These techniques need to be developed for each type of manufacturing processes owing to the unique characteristics of each of these processes. In this paper, we describe feature extraction techniques that can be applied to layered manufacturing (LM). The aim is to improve the LM process efficiency by considering the specific feature information of the model, which is normally neglected by previous researches. A feature-based LM system has been developed using these techniques. Based on the proposed orthogonal LM system, features extracted from the geometric analysis are defined in the LM domain, and the algorithm for process planning and volume decomposition based on the specific LM features is proposed and implemented.     

Automatic Hybrid Hierarchy Creation: a Cost-model Based Approach

While using hierarchical search structures has been proved as one of the most efficient acceleration techniques when rendering complex scenes, automatic creation of appropriate hierarchies is not solved yet. Well‐known algorithms for automatic creation of bounding volume hierarchies are not enough. Higher performance is achieved by introducing spatial uniform subdivision, although algorithms proposed up to now are not truly automatic, as they need some parameters to be adjusted. In this paper we present a full‐automatic hierarchy creation scheme that structures the scene in a hybrid way, combining bounding volumes and voxel grids in the same tree, selecting the search structure that best fits to each scene region. It uses no parameters at all. This efficient proposal relies on a new cost model that estimates the goodness of a hybrid hierarchy if used for rendering the scene. ACM CSS: I.3.7 Computer Graphics—Three‐Dimensional Graphics and Realism