Simulation-based layout optimization for multi-station assembly lines

Journal of Intelligent Manufacturing - This article presents a novel approach for the automated 3D-layout planning of multi-station assembly lines. The planning method is based on a comprehensive...     

The daylighting dashboard – A simulation-based design analysis for daylit spaces

This paper presents a vision of how state-of-the-art computer-based analysis techniques can be effectively used during the design of daylit spaces. Following a review of recent advances in dynamic daylight computation capabilities, climate-based daylighting metrics, occupant behavior and glare analysis, a fully integrated design analysis method is introduced that simultaneously considers annual daylight availability, visual comfort and energy use: Annual daylight glare probability profiles are combined with an occupant behavior model in order to determine annual shading profiles and visual comfort conditions throughout a space. The shading profiles are then used to calculate daylight autonomy plots, energy loads, operational energy costs and green house gas emissions. The paper then shows how simulation results for a sidelit space can be visually presented to simulation non-experts using the concept of a daylighting dashboard. The paper ends with a discussion of how the daylighting dashboard could be practically implemented using technologies that are available today.     

Current daylighting design practice: a survey

What are the current daylighting design practices among design teams with an explicit interest in sustainable design? A survey was undertaken: (1) to understand which daylight performance indicators and design tools are currently used by design practitioners to integrate daylighting in their projects; (2) to identify the additional information needed beyond that available in current design guides; and (3) to advise on the content and format of a new daylighting design guide that addresses these needs. The responses obtained from 177 participants showed that over 90% of the practitioners surveyed support the development of a new daylighting design guide that would provide online access to both simple calculation methods as well as more advanced daylighting design tools. Survey results also showed that a variety of non-standardized daylight prediction methods – primarily rules of thumb – are currently being used, and that there is no commonly acknowledged method of how to assess the performance and quality of a daylighting system in terms of energy savings, glare prevention, daylight factors, and the view to the outside.

Quelles sont actuellement les pratiques conceptuelles en matière d'éclairage naturel dans les bureaux d'étude s'intéressant de manière explicite à la conception durable? Une étude a été entreprise pour (1) comprendre quels indicateurs de performances d'éclairage naturel et outils de conception sont actuellement utilisés par les bureaux d'étude pour intégrer l'éclairage naturel dans leurs projets; (2) identifier les informations complémentaires nécessaires en plus de celles qui sont disponibles dans les guides de conception; (3) conseiller sur le contenu et le format d'un nouveau guide de conception sur l'éclairage naturel pour répondre à ces besoins. Les réponses fournies par 177 participants montrent que plus de 99% des praticiens interrogés sont en faveur de la préparation d'un nouveau guide de conception sur l'éclairage naturel qui donnerait accès en ligne à la fois à des méthodes de calcul simples et à des outils de conception d'éclairage naturel plus complexes. Les résultats de cette enquête montrent également que plusieurs méthodes de prédiction de l'éclairage naturel non normalisées, principalement empiriques, sont actuellement utilisées et qu'il n'existe aucune méthode reconnue d'évaluation des performances et de la qualité d'un système d'éclairage naturel en termes d'économies d'énergie, de prévention de l'éblouissement, de coefficient d'éclairage diurne et de vue sur l'extérieur.

éclairage naturel, paramètres de l'éclairage naturel, guide de conception, pratiques conceptuelles, outils de conception, indicateurs de performances, conception durable     

Evaluation of interconnected production sites taking into account multidimensional uncertainties

The production sites of international companies are becoming increasingly interconnected. Due to the uncertainty of multiple factors, determining a location is a strategic choice entailing high financial risk. For this reason, a method for site evaluation was developed allowing multidimensional, i.e., both quantitative and qualitative, uncertainties to be taken into account. The uncertainties are modeled with both probability and fuzzy-set theory and integrated into a modular-structured monetary calculation model. For the analysis and interpretation of evaluation results, methods have been developed which allow risk assessment. The developed method provides a way to handle existing location risks and can thus ensure the success of manufacturing companies in the long term.     

Further potentials of CAQ tools for fault handling in automotive manufacturing processes

The example of automotive body-in-white production is used to illustrate further potentials for automated fault handling in operative quality control. A review of pertaining literature on process modeling and control suggests some trends and future practices in research and industry. The paper discusses current results of a research project aimed at devising novel process and knowledge modeling concepts for online fault diagnosis and recovery. The proposed approach differentiates between three different tasks: fault recognition, fault identification, and decision and feedback. The paper thus presents a possible basis for future automation of fault analysis and recovery tasks in a variety of manufacturing environments.     

Automatic programming of robot-mounted 3D optical scanning devices to easily measure parts in high-variant assembly

In times of increasing product variance and demand for highest quality, 100% inspection of parts is often mandatory along the supply chain and the incoming goods control of assembly processes, respectively. A promising approach to reach this goal is the use of robot-assisted measurement systems. However, such systems require high efforts to program the robot for every new part and thus are seldom implemented in high-variant assembly systems. Consequently, this work proposes a system for automated programming of robot-mounted optical scanning devices. Additionally, algorithms to automatically extract measurement features and generate collision-free robot scanning paths from CAD models are described.     

Local laser heat treatment of ultra high strength steels to improve formability

Ultra high strength steels are of enormous interest especially in the automotive industry due to their potential in realising light weight structures and improving the crash behaviour. However the poor formability of these steels limits their application for many parts in the car body. A solution to this limitation can be a local heat treatment using a laser beam to soften the material where a high formability is needed. Laser treatment was performed using a Nd:YAG laser with 3 kW maximum power. The output power was temperature controlled to achieve a constant temperature level during the heat treatment. Large areas are treated by scanning the surface with the laser beam. The materials under investigation are dual phase (DP), retained austenite (RA) and martensitic (MS) steels with a tensile strength of 600–1,200 MPa. The microstructure of DP steels consists of martensite and ferrite. RA steels contain ferrite, martensite and additionally a certain amount of retained austenite which transforms into martensite during plastic flow. MS steels are fully martensitic which gives them the highest yield strength of all UHS steels. The various steels were provided as not galvanised sheets (hot or cold rolled) with a thickness of 1.5 mm. Depending on material and process parameters tempering of martensite, formation of ferrite and transformation of retained austenite to martensite are observed as a result of the heat treatment. Tensile tests of DP 600, DP 1000 and MS-W 1200 reveal a significant reduction in yield and tensile strength and an increase in elongation after LHT. The effect is due to tempering of martensite and in the case of MS-W also due to an increase in volume fraction of ferrite. Tensile tests of RA-K 700 reveal a minor reduction in yield and tensile strength and a decrease in elongation. This can be attributed to the lower content of retained austenite which has transformed into martensite during LHT. From this result it can be expected that LHT is not beneficial for high deformation degrees. Deep drawing of a mock-up geometry using MS-W 1200 and RA-K 700 showed a significant decrease in slide force (~20%) compared to the initial condition. This results show that laser heat treatment has the potential to improve formability of UHS steels.     

Temperature measurements of expansion products from shock compressed materials using high-speed spectroscopy

Results from spectral radiance measurements using optical multi-channel analyzer over the visible and near infrared regime provide estimates of temperature from expansion products resulting from shocked materials. Specifically, we have made spectral radiance measurements over the wavelength regime of 300–1500 nm. Experiments conducted on aluminum, cerium, and Composition-B high explosive span a wide regime of E/E_v, where E is the internal energy increase of the shocked material, and E_v, is the specific energy required to vaporize the material. For the materials investigated, the ratio is ∼1, 3 and 5 for aluminum, cerium, and Composition-B, respectively. The basic assumption made to deduce these temperatures is that the debris cloud is radiating as a blackbody with emissivity of one and independent of the wavelength. We are also assuming that the probe is monitoring the debris, which is at a single temperature and that there is no spatial temperature gradient. Temperatures at or above the boiling point are confirmed for aluminum and cerium, while the results for Composition-B provide the time-dependent temperature expansion history for shocked Composition-B over the stress regime of 28–130 GPa. These are the first measurements of temperature obtained from the expansion products from materials that have been shocked to very high pressures.     

复杂技术产品的协同开发

以机床为例，介绍了一个计算机辅助产品开发的方案。应用该方法，在同步工程技术的基础上，能快速地实现复杂技术产品的协同开发，并使产品开发的风险最小。