Search

This study presents the optical design of light guide prisms for automotive tail light applications to obtain the optimum luminous intensity and the illuminance uniformity. The design was achieved using optical design software, SPEOS. By considering the axial luminous intensity and legal requirements, the optimum prism angles of light guides were determined by simulations. After determining the prism angles, the effect of different surface roughness on the luminous intensity and the illuminance uniformity was investigated. The light guides designed by considering data from the simulation were manufactured as prototypes and their photometrical measurements were made. These measurements were compared to the simulation results. It was observed that simulation and prototype results are well in agreement with each other. Furthermore, it was found that as the surface roughness increases both the luminous intensity decreases and the illumination becomes more uniform. T.C. Sanayi ve Teknoloji Bakanlığı (0143.STZ.2013-1) Farba Otomotiv A. Ş.

The surface quality of the parts is one of the major objectives of the use of the high-speed milling (HSM). Tool path interpolations affect the machining operation of complex parts in HSM. In this paper, the influence of the different types of interpolation of the computer-aided manufacturing (CAM) on the surface roughness in the HSM machining of free forms is studied. To do this, a simulation tool of the surface texture for each type of interpolation is proposed. Then, experimental measurements expressing surfaces condition are carried out. To validate our approach, theoretical results with experimental ones are compared. As results, CAM interpolations of tool paths have demonstrated an important impact on the surface texture. In fact, a simulation prediction tool has confirmed the advantages of using polynomial interpolations in order to ameliorate the quality of the machined surface.

This article describes the conceptual design process of an equestrian centre, presenting the covered stadium of the building complex in detail, designed it as a free-form, wide-span steel structure. The main goal of this study is to present the application of the parametric design method through a case study and to examine the interoperability opportunities between architectural and structural design software.

This paper presents a data-driven free-form modelling method dedicated to the parametric modelling of buildings with complex shapes located in particularly valuable Old Town Centres, using Airborne LiDAR Scanning (ALS) data and aerial imagery. The method aims to reconstruct and preserve the input point cloud based on the relative density of the data. The method is based on geometric operations, iterative transformations between point clouds, meshes, and shape identification. The method was applied on a few buildings located in the Old Town Centre of Bordeaux (France). The 3D model produced shows a mean distance to the point cloud of 0.058 m and a standard deviation of 0.664 m. In addition, the incidence of building footprint segmentation techniques in automatic and interactive model-driven modelling was investigated and, in order to identify the best approach, six different segmentation methods were tested. The segmentation was performed based on the footprints derived from Digital Surface Model (DSM), point cloud, nadir images, and OpenStreetMap (OSM). The comparison between the models shows that the segmentation that produces the most accurate and precise model is the interactive segmentation based on nadir images. This research also shows that in modelling complex structures, the model-driven method can achieve high levels of accuracy by including an interactive editing phase in building 3D models.

Elastostatics of laminated and functionally graded (FG) sandwich open cylindrical shells is studied using a refined higher order shear and normal deformation theory. Displacement based approach with twelve middle surface displacement parameters representing bending and membrane response of cylindrical shell is considered. An extended thickness criterion, (h/R)2 ≪ 1, is used to make the present theory more reliable over large range of thickness ratios of shell. Basic equations are obtained using minimum potential energy principle and solved subsequently with Navier solution method for cylindrical shells with all edges diaphragm supported. Two kinds of FG sandwich panels are considered having FG layer with Voigt’s rule of mixture following power law gradation of volume fraction. Results show an excellent accuracy with the three dimensional results available in literature for laminated shells. Also, superiority of present formulation over other higher order theories is shown by carrying out a number of comparative studies.

The project “Brick-topia” was based on a combination of the latest structural analysis and form-finding computational tools with traditional, cheap and effective construction techniques. It is the result of innovation to fight against budget and time. The initial budget was 3000 euros and only seven weeks was the time to look for sponsors, design the pavilion, plan the construction phases and build it. The whole process of designing, decision on the materials, structural analysis and construction is presented in the paper, including exploration on new form-finding methods to redesign a project in situ and research on a new formwork system using scaffolding, cardboard, wire and steel rods and having a cutter as main tool., Case Studies in Structural Engineering, 2, ISSN:22143998

Raman spectroscopy is a powerful tool for analytical measurements in many applications. Traditional Raman spectroscopic analyses require bulky equipment, considerable time of signal acquisition and manual sampling of substances under test. In this paper, we take a step from bulky and manual consuming laboratory testing towards lab-on-chip (LOC) analyses. We miniaturize the Raman spectroscopic system by combining a free-form reflector based polymer LOC with a customized Raman probe. By using the confocal detection principle, we aim to enhance the detection of the Raman signals from the substance of interest due to the suppression of the background Raman signal from the polymer of the chip. Next to the LOC we miniaturize the external optical components, surrounding the reflector embedding optofluidic chip, and assemble these in a Raman probe. We evaluate the misalignment tolerance of internal optics (LOC) and external optics (Raman probe) by non-sequential ray tracing which shows that off-axis misalignment is around +or-400mum and the maximum working distance of our Raman probe is 71mm. Using this probe, the system could be implemented as a portable reader unit containing the external optics, in which a low-cost, robust and mass manufacturable microfluidic LOC containing a freeform reflector is inserted, to enable confocal Raman spectroscopy measurements.

RESUMEN: En esta tesis doctoral se propone la aplicación de técnicas metaheurísticas basadas en Simulated Annealing para la reconstrucción eficiente y automática de curvas y superficies de forma libre. Este problema tiene un interés evidente en muchos campos de la ciencia y la ingeniería, desde problemas de visualización científica hasta la tomografía computerizada o la resonancia magnética. Es también una tecnología clave en los procesos de diseño y la producción industrial asistidos por computador (CAD/CAM). La obtención de los parámetros relevantes para la reconstrucción lleva a un problema de optimización continuo, no lineal, de muy alta dimensión para nubes muy grandes de puntos dato y que normalmente es multimodal. Por ello, es un problema de muy difícil resolución. De hecho, tanto las técnicas clásicas de optimización como las heurísticas han fracasado hasta la fecha a la hora de obtener una solución satisfactoria y de forma totalmente automática del problema general. Para solventar estas dificultades, en esta tesis doctoral proponemos el uso de técnicas metaheurísticas basadas en Simulated Annealing, un método surgido a partir del proceso termodinámico del recocido de metales usando simulaciones de Monte Carlo y ampliamente utilizado para la resolución de problemas de optimización, tanto continuos como discretos. ABSTRACT: Reverse engineering has become ubiquitous in the computer-aided design and manufacturing industry (CAD/CAM). One of the most sought after tools in many industries and scientific fields is the ability to build a digital model from a 3D-scanned real world object. In this Thesis, we propose a methodology to automatically find an optimal free-form model that fits a given point cloud. Our methodology is based on three techniques, namely: least-squares regression, the Simulated Annealing optimization algorithm and two information sciences criteria. The first step consist of transforming the geometrical problem of reconstructing the shape of data into an optimization problem taking advantage of the least-squares regression procedure. The resulting problem turns to be a non-linear system of very difficult solution. To overcome the minimization of such a challenging functional we make use of the Simulated Annealing algorithm, a powerful meta-heuristic that mimics the thermodynamics behind the cooling of a metal. By means of this stochastic-driven optimization method, we retrieve the functional architecture of our baseline spline model. These two steps are repeated for a range of baseline splines of varying complexity. Finally, we search the best among these candidate models by means of either the Akaike or Bayes Information Criteria.

The paper reviews possibilities of application of structural performance-based methods for production of geometrically complex, non-conventional architectural forms. Starting from the fact that advanced digital technologies and multidisciplinary approach have significantly changed traditional relations in design process, this work indicates at potentials of application of methods, procedures and tools initially not designed for architectural production. Based on biological paradigm, morphogenetic strategies in the field of architecture represent dynamic operation-based form-finding methods. The focus of the paper will be on conceptualization of morphogenetic procedure for production of integrated morphologic solutions which are characterized by optimal form-structure interdependence. The procedure is based on isogeometric concept, which enables integration of CAD and FEA. Compared to the conventional FEA, in which geometric interpolation is carried, the isogeometry analysis is based on exactly defined initial geometry, thus enabling design, analysis and refinement of models by using a single data type, which considerably facilitates and accelerates the process of repeated analysis of variant forms. The objective of this paper is to confirm the thesis that transposition, advancement and integration of creative tools affect reconsideration of conventional approaches, methods and procedures, thus enabling innovation and optimization of the design process. Radom se razmatra mogućnost upotrebe metoda zasnovanih na strukturalnim performansama u produkciji geometrijski kompleksnih nekonvencionalnih arhitektonskih formi. Polazeći od činjenice da su napredne digitalne tehnologije i multidisciplinarni pristup u značajnoj meri izmenili tradicionalne relacije procesa projektovanja, ukazuje se na potencijale korišćenja metoda, procesa i alata koji inicijalno nisu namenjeni arhitektonskoj produkciji. Bazirane na biološkoj paradigmi, morfogenetske strategije u oblasti arhitekture predstavljaju dinamične operaciono-zasnovane metode za pronalaženje forme (form-finding). Težište rada biće na koncipiranju morfogenetske procedure za dizajn integrisanih morfoloških rešenja koje karakteriše optimalna međuzavisnost forma-struktura. Procedura se zasniva na korišćenju izogeometrijskog koncepta, kojim je omogućena integracija CAD i FEA. Za razliku od klasične FEA, u kojoj se vrši interpolacija geometrije, u izogeometriji analiza se vrši na osnovu egzaktno definisane početne geometrije, čime je omogućen dizajn, analiza i podešavanje modela upotrebom jedinstvenog tipa podataka, a što značajno olakšava i ubrzava proces uzastopnih analiza varijantnih formi. Rad je u funkciji potvrđivanja teze da transpozicija, unapređenje i integracija kreativnih alata utiču na preispitivanje konvencionalnih pristupa, metoda i procedura omogućavajući inovaciju i optimizaciju samog procesa projektovanja.