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The escalating demand for free-form buildings presents a formidable technological hurdle in the realm of prefabrication manufacturing and assembly. This research draws inspiration from recent advancements in large language models (LLMs) and seeks to harness their transformative potential in tandem with Building Information Modeling (BIM) to advance the Design for Manufacture and Assembly (DfMA) method. The ultimate aim is to catapult the prefabrication industry into an era characterized by unparalleled design freedom and heightened efficiency. The research includes contributions from the following four areas: (1) A review of the literature on DfMA theories, specifically fabrication and construction. (2) The development of a BIM-based DfMA method framework, including the methodological basis, Design for Manufacturing (DfM), and Design for Assembly (DfA). (3) A pipeline for LLMs driven BIM-based DfMA method framework and a validation using the Decathlon Solar Team design-build practice at the University of Washington’s Lotus House. (4) An evaluation of 692 conversation scenarios to verify the feasibility of our proposal. We get a 91.1% user agreement on average based on GPT4. The research results could guide the workflow in building a lifecycle for DfMA practices in the future smart manufacturing era.

Free-form surfaces are commonly present in several engineering components, from molds to more sophisticated components of aeronautical engines. These parts are usually finished by machining, more specifically, ball-end milling. In this process, the contact between the tool and the part constantly changes along the toolpath, resulting in several manufacturing problems that damage the surface and compromise the performance of the part. Besides the ordinary cutting parameters, these machined surfaces are deeply influenced by the tool tip center and the elastoplastic deformation of the material through the shearing and plowing pair. Knowing the exact orientation of the tool in relation to the surface determines all aspects of the milling process and is necessary for process modeling. The current CAD/CAM software platforms is not able to predict such surface topography. In this direction, the current work presents a software routine developed and implemented on an open interface CAD/CAM software (Siemens® NX). The normal vectors of the surface to be machined, the cutter contact (CC), and cutting location (CL) data from the toolpath calculated by the CAD/CAM were used to obtain a complete discretization of the cutter-workpiece position along the toolpath. This information was used to predict the surface topography and identify the cutting-edge elements. Then, the developed model was used to evaluate the free-form surface of a blade milled on 5-axis together with confocal imaging analysis. The results show that the methodology developed can predict the topography aspects of a free-form machined surface and support the analysis of milling problems such as run-out.

We design and integrate free‐form metagratings with irregular nanoscale patterns into diffractive augmented reality (AR) waveguides to achieve simultaneous improvements in eye‐glow attenuation and outcoupling efficiency. The freeform metagrating demonstrates over 40% reduction in eye‐glow while enhancing outcoupling efficiency by 8% compared to the conventional binary grating. [ABSTRACT FROM AUTHOR]

Interpretability fosters trust when humans and artificial intelligence (AI) systems interact, and its value for neural networks in particular cannot be overstated. In this paper, we analyse the emergence and value of neural modularity as it relates to interpretability. We compare the modularity evolved through connectivity constraints in terms of network Q-scores and examine the interpretable qualities of the resultant networks with functional subset regression. The connectivity constraints compared here include those proposed by previous research as well as several novel variations formulated to express neuron input competition and connections per neuron variance. Networks were evolved using HyperNEAT on a free-form substrate. The results indicate that the connection costs successfully promote the evolution of neural modularity across a variety of tasks and show that the novel connection cost variations are competitive with previously explored connection costs. The interpretability assessment shows that while the evolved networks' interpretable qualities are task dependent, two of the compared connection costs deliver statistically different functional module overlap distributions. However, recovered subnetwork module accuracies remain low, highlighting the key points for future research. [ABSTRACT FROM AUTHOR]

Several recent business reports have described the global growth in demand for optical and photonic components, paralleled by technical reports on the growing shortage of skilled manufacturing staff to meet this demand. It is remarkable that producing ultraprecision surfaces remains so dependent on people, in contrast to other sectors of the economy, e.g., car manufacturing. Clearly, training can play some role, but ultimately, only process automation can provide the solution. This paper explores why automation is a challenge and summarizes multidisciplinary work aiming to assemble the building blocks required to realize automation.Highlights: Capturing polishing craft-expertise was academically successful, but commercially unviable due to personal privacy issues. Automating software communication between optical-design and manufacturing can minimise manufacturing cost and risk. Computational fluid dynamics of abrasive-slurries, plus real-time process-sensing, promises improved rocessconvergence. [ABSTRACT FROM AUTHOR]

The article reviews the results of experimental tests assessing the impact of process parameters of additive manufacturing technologies on the geometric structure of free-form surfaces. The tests covered surfaces manufactured with the Selective Laser Melting additive technology, using titanium-powder-based material (Ti6Al4V) and Selective Laser Sintering from polyamide PA2200. The evaluation of the resulting surfaces was conducted employing modern multiscale analysis, i.e., wavelet transformation. Comparative studies using selected forms of the mother wavelet enabled determining the character of irregularities, size of morphological features and the indications of manufacturing process errors. The tests provide guidelines and allow to better understand the potential in manufacturing elements with complex, irregular shapes.

The article reviews the results of experimental tests assessing the impact of process parameters of additive manufacturing technologies on the geometric structure of free-form surfaces. The tests covered surfaces manufactured with the Selective Laser Melting additive technology, using titanium-powder-based material (Ti6Al4V) and Selective Laser Sintering from polyamide PA2200. The evaluation of the resulting surfaces was conducted employing modern multiscale analysis, i.e., wavelet transformation. Comparative studies using selected forms of the mother wavelet enabled determining the character of irregularities, size of morphological features and the indications of manufacturing process errors. The tests provide guidelines and allow to better understand the potential in manufacturing elements with complex, irregular shapes. [ABSTRACT FROM AUTHOR]

Sheet metal or monolithic thin structured components with complex freeform geometries are used in wide range of applications in aerospace, marine and automobile sectors. Fabrication of such complicated geometries and profiles generally requires complex manufacturing setup (dies, jigs and punches) resulting in process inflexibility, in addition to huge tooling and equipment costs. In the present work, a novel process 'single point incremental bending' (SPIB) is proposed. In principle, it is similar to single point incremental forming process. SPIB is a die less bending operation where a solid hemispherical shaped single point tool is used to locally bend the sheet metal to a desired shape incrementally using a computer numeric controlled setup or certain robotic platforms. In addition to that, an experimental and finite element analysis based numerical study on the bending load patterns and trends in single point incremental sheet metal bending has been presented. Detailed investigation of various commercial sheet metals and various parametric effects on bending load is also performed. The influence of sheet material, material anisotropy and four major process parameters – sheet thickness, tool diameter, incremental bending angle and sheet height to length ratio on the bending loads is investigated. [ABSTRACT FROM AUTHOR]

High-precision measurement of lenses and mirrors of free-form surface figures is necessary owing to the increasing functionality of optical elements. Previously, we developed a nanoprofiler measurement technology. The nano-profiler calculates the form from a slope distribution on the measurement surface. The slope distribution is calculated from the measurement result of the optical system that directly measures the slope of the surface using laser light and a quadrant photodiode, as well as the rotary encoder output that indicates the position of the optical system and the object to be measured. The slope distribution and optical path length are required to calculate the form. The geometrical length is between the measured surface of the object and the photodetector's surface. The optical path length was designed to be 400 mm when the instrument was manufactured; however, because assembly errors were included, the optical path length must be calibrated to obtain measurements with higher accuracy. Therefore, we herein propose a multistep self-calibration method to calibrate the optical path length. In this method, a plurality of forms is measured on the surface to be measured while changing the optical path length by a known amount. The optical path length was estimated based on the results of the multiple form measurements. Before the evaluation was performed, the optimum measurement conditions for the evaluation were determined via simulation, and the optical path length was obtained from the actual measurement results under the optimum conditions. The results show that the optical path length is 399.698 mm, and the standard deviation of the calculated variation in the optical path length is 5.3 μm. • This paper reviews self-calibration method of the optical path length. • Multiple measured results are used for self-calibration. • The optimum measurement conditions for self-calibration were determined from prior simulations. • Self-calibration was performed with an actual instrument and the results were discussed. [ABSTRACT FROM AUTHOR]

Inspection of pipeline infrastructure is an essential part of pipeline integrity management to prevent from leakage and flow reduction is of great importance in water, gas, and oil distribution. However, current methods are limited in low resolution and low accuracy that fail to 3D reconstructions of pipelines. In this work, a theoretical laser propagation model based on a free-form laser profilometry method is established, and a fully functional laser system that incorporates a conic mirror within an integrated optical system containing all the elements necessary to retrieve the displacement information. The developed optical device exhibit high resolution, high accuracy, and high acquisition speed comparing with current technologies. Furthermore, the device can be completely sealed to be protected from the pipeline environment. This work paves the path towards autonomous laser scanners for underwater pipeline inspection. [ABSTRACT FROM AUTHOR]

In this paper, a simultaneous shape and topology optimization method is presented for designing multi-material structures. The whole shape and the layer's material distributions of a laminated shell structure composed of multi-materials are optimized. The free-form optimization method for shells and the generalized solid isotropic material with penalization (GSIMP) method are respectively employed and combined effectively for shape and topology optimization. Shape along with fictitious homogenized-density variations are used as design variables and simultaneously determined. In other words, the optimal topology is determined in the variable design surface optimized by shape optimization. Compliance is used as the objective functional and minimized under the volume and the area constraints for each material. The optimal design problem is formulated as a distributed-parameter optimization problem, and the sensitivity functions with respect to shape and density variations are theoretically derived. Both the optimal shape and density variations are determined with the unified H1 gradient method, where the sensitivity functions are respectively applied as the Robin condition, to the design surface and the domain in order to determine the optimal shape and topology simultaneously. Several numerical results including a comparison with the non-simultaneous methods are presented to show the effectiveness of the proposed method. With the proposed method, the optimal lighter and stiffer multi-material laminated shell structure can be obtained without any design parameterization, free of numerical instabilities such as checkerboard pattern and zigzag shape problems. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Integral planning of grid‐shell structures – canopy constructions for the new metro in Riyadh The construction of the metro in Riyadh, consisting of six lines, is one of the largest public infrastructure projects in the world. The route of line 2 runs both above and below ground. This makes two different types necessary for the free‐form roof structures: Fully air‐conditioned entrance pavilions, which offer easy access to the underground platforms of the "Shallow Underground"‐stations and shading structures for the above‐ground "At Grade"‐stations. The subject of the planning were free‐form grid shells for ten identical shallow underground and four different at grade stations with a total facade area of approx. 22 000 m2. In order to meet the high demands of customers in respect to digital planning and the tight time frame for planning, production and assembly, only a fully integral digital planning process came into question. [ABSTRACT FROM AUTHOR]

A parameter-free free-form optimization method to solve multidisciplinary shape optimization problems of solid structures is presented in this paper. The design objective is both to minimize the mean compliance of linear elastic structures and to control the temperature at arbitrary locations and time periods for arbitrary loadings and under volume constraint, simultaneously. The multidisciplinary design problem is formulated as a distributed-parameter shape optimization problem based on the variational method, and the global objective function is defined using an original normalized weighted sum method. The shape gradient density functions with respect to the shape variation are derived based on the material derivative and the adjoint variable methods. The shape gradient density functions theoretically derived are applied to the H1 gradient method, a gradient method in the function space, to obtain the optimal shape while maintaining the smoothness of the shape. Numerical examples are considered to demonstrate the validity and the effectiveness of the developed optimization method. [ABSTRACT FROM AUTHOR]

Abstract There are many factors in a common building project that are not relevant for free-form tall building projects, for example, the free-form planes or various shapes of buildings. Among the many risks present in particular in structural frameworks, the risk of delays is an important one and has a considerable effect on the entire project performance. Generally, a delay causes a decrease in constructability and an increase in cost, so eventually the productibility of the structural framework would decrease. Delay management of structural frameworks in free-form tall buildings is currently performed by project managers based on personal experience and intuition. This nonsystematic management results from the lack of data that are essential for the planning construction process reflected in the particular considerations of the free-form tall building. This study identified the delay factors that can occur in the structural framework of free-form tall building projects and analyzed priorities for delay management. First, the scope of free-form tall buildings was identified, and particular considerations for the structural framework in their construction were determined, such as plane, elevation, floor height, and structure. Delay factors for each category were recognized through interviews with experts with experience in such projects. To prioritize the delay factors, the occurrence and severity of each factor were surveyed. A risk priority number was calculated from the survey results, and the priority was analyzed. The results of this study could serve as preliminary data for the planning construction process of structural frameworks in free-form tall buildings.

The study focuses on the definition of a geometric methodology for the use of catoptric anamorphosis in contemporary architecture. The particular projective phenomenon is illustrated, showing typological-geometric properties, responding to mechanisms of light reflection. It is pointed out that previous experience, over the centuries, employed the technique, relegating its realisation exclusively to reflecting devices realised by simple geometries, on a small scale and almost exclusively for convex mirrors. Wanting to extend the use of the projective phenomenon and experiment with the expressive potential on reflective surfaces of a complex geometric free-form nature, traditional geometric methods limit the design and prior control of the results, thus causing the desired effect to fail. Therefore, a generalisable methodological process of implementation is proposed, defined through the use of algorithmic-parametric procedures, for the determination of deformed images, describing possible subsequent developments.

In this paper, a parameter-free optimization method for controlling the time-dependent response of frame structures is proposed. The proposing method deals with three optimization problems, including a vibration displacement minimization problem, a vibration displacement control problem, and a dynamic compliance minimization problem, which is the special case of the vibration minimization problems. These time-dependent optimum design problems are formulated as distributed-parameter optimization problems and the sensitivity functions for the shape variation to obtain the optimal shape are derived based on the material derivative method, Lagrange multiplier method, and the adjoint method. The derived sensitivity function is applied to the H1 gradient method for frames, which is a gradient method in the function space to determine the optimal shape variation. With the proposed method, the optimal shape for time-dependent response problems such as a forced vibration, a free vibration, or a transient response is obtained while minimizing the objective functional and maintaining the smoothness of a frame structure. Several numerical design examples including a continuous dynamic force or an impulse force as an input force are shown to verify and validate the effectiveness of the proposed method and the results are discussed. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate the use of the modified phase retrieval as a method for application in the measurement of small-slope free-form optical surfaces. This technique is a solution for the measurement of small-slope free-form optical surfaces, based on the modified phase retrieval algorithm, whose essence is that only two defocused images are needed to estimate the wave front with an accuracy similar to that of the traditional phase retrieval but with less image capturing and computation time. An experimental arrangement used to measure the small-slope free-form optical surfaces using the modified phase retrieval is described. The results of these experiments demonstrate that the modified phase retrieval method can achieve measurements comparable to those of the standard interferometer.

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.

Intertwined Reinforced Concrete – National Veterans Memorial and Museum, Ohio, USA The main structure of the National Veterans Memorial and Museum (NVMM) in Columbus, Ohio, USA consists of three concentric, freely shaped rings made of in‐situ concrete. Each of these rings is composed of a series of nested/intertwined arches. This design element, which is visible from the outside and inside, supports the roof of the 61m in diameter measuring building. In its inside, the building hosts galleries and event space, training and office space. Following the rings, an external ramp winds up onto the building's spacious roof terrace, which can be used for events and commemorations. The rings have been constructed in architecturally demanding exposed concrete quality. This article refers to free‐form concrete architecture of the past and features the special characteristics of the geometry and its effects on the reinforced concrete design, modelling and construction. [ABSTRACT FROM AUTHOR]

In this study, we propose a parameter-free free-form optimization method to control the time-dependent response of shell structures. The design objective is to minimize the dynamic compliance or to control the dynamic responses at arbitrary domains and times for an arbitrary time-dependent loading under volume constraint. The unsteady optimum design problems are formulated as a distributed-parameter shape optimization problem based on the variational method, and the shape gradient functions with respect to the shape variation in the normal direction to the surface are derived based on the material derivative and the adjoint variable methods. The shape gradient functions theoretically derived are applied to the H1 gradient method for shells, a gradient method in the function space. With the proposed approach, the optimum free form of the shell structures for the time-dependent response problems can be obtained while minimizing the objective functional and maintaining the smoothness of the form. Several shape design examples under a continuous dynamic force or an impulse force are demonstrated to show the effectiveness of the proposed method, and the results are discussed. [ABSTRACT FROM AUTHOR]

In recent years, with the popularity of vehicle display applications and consumers provide higher requirements for vehicle display resolution, appearance. of shape and touch operation. LTPS will be used by more and more OEMs. This research adopts reasonable sensor and architectures design to realize a narrow border, free‐form, incell‐touch vehicle display with LTPS technology. [ABSTRACT FROM AUTHOR]

Unchartered Waters for Engineers and Contractors Alike: Stuttgart's New Main Station and its Complex Geometry As part of the Stuttgart–Ulm railway project, Stuttgart Central Station is currently being completely refurbished and rebuilt. The old terminus station will be replaced by an underground through station. The so‐called "Kelchstützen" (chalice‐shaped columns) are a significant design element of the new underground station. These columns not only support the shell roof, but also provide natural lighting and ventilation for the interior. The present article describes the form finding and calculation of these unique geometries and explains how a technically and economically sustainable implementation was made possible by the structural engineers. [ABSTRACT FROM AUTHOR]

3D-designs of free-form buildings are developed using a computer due to difficulty of shape implementation. When producing free-form concrete panel (FCP) using materials such as GFRC (glass fiber reinforced concrete), engineers or manufacturers should precisely calculate the offset value or geometry of each member at the junction point of three or more FCPs before it is constructed. However, it is difficult to calculate offset geometry easily and quickly, and no research has been conducted on this topic. Therefore, the objective of this paper is to develop a solution of subordinate vertices for quality connections of external free-form concrete panels. The developed mathematical solutions practically support the production of FCPs with precise installation to ensure aesthetic quality of the building. This paper academically contributes to the automatic creation of joint details of FCPs implemented by BIM.

In this paper, we present a simultaneous optimization method of shape and topology for designing a light-weight plate and shell structure. The free-form optimization method for shells and SIMP method are respectively employed for shape and topology optimization, and combined effectively. Shape and fictitious homogenized-density variations are used as the design variables, and simultaneously determined in one iteration of the convergence process. With this method, the optimal topology is determined in the variable design surface optimized by shape optimization. Compliance is used as the objective functional, and minimized under the volume constraint. The optimal design problem is formulated as a distributed-parameter optimization problem, and the sensitivity functions with respect to shape and density variations are theoretically derived. Both the optimal shape and density variations are determined by the H1 gradient method, where the sensitivity functions are applied as the Robin condition to the design surface. With the proposed method, the optimal lighter and stiffer shell structure with smooth surface can be obtained without any design parameterization and numerical instabilities such as checkerboard and zigzag-shape problems.

Abstract: A typical approach to optimize wind turbine blades separates the airfoil shape design from the blade planform design. This approach is sequential, where the airfoils along the blade span are preselected or optimized and then held constant during the blade planform optimization. In contrast, integrated blade design optimizes the airfoils and the blade planform concurrently and thereby has the potential to reduce cost of energy (COE) more than sequential design. Nevertheless, sequential design is commonly performed because of the ease of precomputation, or the ability to compute the airfoil analyses prior to the blade optimization. This research compares 2 integrated blade design approaches. The precomputational method combines precomputation with the ability to change the airfoil shapes in limited ways during the optimization. The free‐form method allows for a complete range of airfoil shapes, but without precomputation. The airfoils are analyzed with a panel method (XFOIL) and a Reynolds‐averaged Navier‐Stokes computational fluid dynamics method (RANS CFD). Optimizing the NREL 5‐MW reference turbine showed COE reductions of 2.0%, 4.2%, and 4.7% when using XFOIL and 2.7%, 6.0%, and 6.7% when using RANS CFD for the sequential, precomputational, and free‐form methods, respectively. The precomputational method captures most of the benefits of integrated design for minimal additional computational cost and complexity, but the free‐form method provides modest additional benefits if the extra effort is made in computational cost and development time. [ABSTRACT FROM AUTHOR]

Various materials are used when fabricating free-form panels, including glass, aluminum, titanium, and glass fiber reinforced concrete (GFRC), in addition to steel and concrete. Concrete has excellent structural stability, constructability, and economic efficiency, as well as the advantages of shape, thickness, forming of the finished surface and homogeneity of material. As a result, fast, low-cost technology has been developed to ensure the quality of free-form concrete panels (FCPs). FCPs, like precast concrete members, are generally constructed during in-plant production, on-site transportation, and installation. However, if FCPs are produced in site, cost savings of approximately 20% can be achieved due to savings in transportation and overhead at plants. In order to produce and install FCPs in site with restricted time and area, it is necessary to analyze and systematically link the related processes and influence factors. The purpose of this study is to develop planning algorithms for the in-situ production of free-form concrete panels. For this study, the relationship between the factors affecting the production plan of FCPs was mathematically established. The algorithms proposed in this study support the quick and easy establishment of in-situ production plans, contributing to cost reduction, according to various influencing factors such as the number of CNC machines, number of production cycles, production time, production area, and lead time. [ABSTRACT FROM AUTHOR]

3D-designs of free-form buildings are developed using a computer due to difficulty of shape implementation. When producing free-form concrete panel (FCP) using materials such as GFRC (glass fiber reinforced concrete), engineers or manufacturers should precisely calculate the offset value or geometry of each member at the junction point of three or more FCPs before it is constructed. However, it is difficult to calculate offset geometry easily and quickly, and no research has been conducted on this topic. Therefore, the objective of this paper is to develop a solution of subordinate vertices for quality connections of external free-form concrete panels. The developed mathematical solutions practically support the production of FCPs with precise installation to ensure aesthetic quality of the building. This paper academically contributes to the automatic creation of joint details of FCPs implemented by BIM. [ABSTRACT FROM AUTHOR]

We have developed a thinnest QD film with honeycomb structure which can prevent edge deterioration when cut into various shapes. The honeycomb structure protect oxygen invasion from the edge, and also enhances stiffness of thin film. This QD film can be applied to narrow‐bezel and thin displays and free‐form displays. [ABSTRACT FROM AUTHOR]

Wire deformation and vibration are classical topics of WEDM research. Many high-added value components (aerospace, medical, automotive…) benefit from the very tight tolerances that can be achieved by using wire EDM. However, there are some particular conditions in which the required accuracy is not fulfilled, as in the case of low-radius circles cuts. An important example of this could be found in the well-known fir-tree form geometries. In this paper, direct measuring of the influence of wire deformation on part geometry is proposed. Classical methods presented in literature are optical or are based on measuring wire-lag using electrical contact between wire and workpiece. The idea that the effect of wire deformation can be directly measured by suddenly stopping the machine is developed in this contribution. Using this approach, the effect of wire deformation can be measured even when cutting circular paths of small radius. A complete set of experimental tests is presented under different WEDM cutting conditions; including the effect of low dielectric pressure, part radius and part thickness. Analysis of discharge patterns has also been carried out, so that the lack of accuracy in WEDM’ed parts can be correlated with the quality of discharges. Results show that wire deformation increases as much as 45% when cutting a circular interpolation of radius 0.8 mm if compared with a straight cut on a part of similar thickness. This fact has direct implications on the error caused by the tractrix effect when cutting small circular paths. Likewise, the relation between wire-lag and discharge type percentages (based ionization time) stablishes that, as the radius increases the percentage of discharges without ionization time raises, decreasing the one that has an ionization time above 10 μs. [ABSTRACT FROM AUTHOR]

Because of their superior mechanical, structural, and electronic properties, carbon nanomaterials (CNs) (e.g. graphene sheets and carbon nanotubes) are supposed to be base materials for nanoelectromechanical systems (NEMS). In the present work, we propose a structural optimization method of carbon nanomaterials by introducing topological defects, which consists of the molecular mechanics method, the free-form optimization method, the Phase-Field-Crystal (PFC) method, Voronoi tessellation, and molecular dynamics (MD) simulation. The C-C bonds of CNs are simulated as equivalent continuum beams by a combination of molecular and continuum mechanics, so the atomic structures of CNs can be treated as frame structures. We adopt the free-form optimization method for frames to determine the optimal shapes of CNs in stiffness maximization problem. For obtaining the stable atomic structures of the optimal shapes of CNs, topological defects are introduced in the optimal shapes of CNs using a combination of PFC method, Voronoi tessellation, and MD simulation. The numerical results show that the compliance of CNs can be significantly reduced according to the structural optimization method, which is helpful for designing CNs components in NEMS.

In this study, we propose an optimization method for the reaction forces control problem of shell structures in plastic range. The sum of squared error norms between reaction forces in the plastic range and the target forces are minimized under a volume constraint. The total strain theory is employed for simplicity under the assumption that the considered force or enforced displacement increases monotonically, so that the final deformation is path-independent. The optimum shape design problem is formulated as a distributed-parameter system, and we assume that a shell is varied in the out-of-plane direction to the surface whereas the thickness is not varied during the shape change. The shape gradient function and the optimality conditions for this problem are derived theoretically using the material derivative method and the adjoint variable method. The shape gradient function calculated from a non-linear finite-element analysis is applied to the H 1 gradient method for shells proposed by one of the authors to determine optimum shape variation. The optimal shape of a shell structure can be obtained without shape parameterization while maintaining surface smoothness. Numerical examples are presented to demonstrate the validity and practical utility of the proposed free-form optimization method. [ABSTRACT FROM AUTHOR]

The aim of this article is to introduce a bottom-up methodology for the modelling of free-form shapes in architecture that meet fabrication constraints. To this day, two frameworks are commonly used for surface modelling in architecture: non-uniform rational basis spline modelling and mesh-based approaches. The authors propose an alternative framework called generalised cyclidic nets that automatically yield optimal geometrical properties for the envelope and the structural layout, like the covering with planar quadrilaterals or hexagons. This framework uses a base circular mesh and Dupin cyclides, which are natural objects of the geometry of circles in space, also known as Möbius geometry. This article illustrates how complex curved shapes can be generated from generalised cyclidic nets. It addresses the extension of cyclidic nets to arbitrary topologies with the implementation of a 'hole-filling' strategy and also demonstrates that this framework gives a simple method to generate corrugated shells. [ABSTRACT FROM AUTHOR]

The gate driver circuit is successfully embedded in the active area of TFT‐LCD by novel pixel architecture. Circuit in the active area technology is suitable for freeform design or through‐hole LCD. Mechanical knob can be easily installed for intuitive operation and safe consideration in car display. [ABSTRACT FROM AUTHOR]

In this study, we propose a shape optimization method of a frame structure for maximizing the elastic buckling load. The 1st buckling load factor is maximized under a volume constraint. The problem is formulated as a distribute parameter shape optimization problem, and the shape gradient function for this problem is theoretically derived using the Lagrange multiplier method, the adjoint variable method and the formulae of the material derivative. The derived shape gradient function is applied to the H1 gradient method for frame structures, a gradient method in the Hilbert space, where the optimal shape variation is calculated as the displacement field of the fictitious linear elastic of the frame structure. With the proposed method, the free-form, or arbitrarily formed frame structures with large scale design variables can be optimized without any shape parametrization. The problems of repeated eigenvalue and Euler buckling of each member are also considered and solved. The results show the validity of the proposed method to determine the optimal free-form of a frame structure for the elastic buckling design.

As Constantin Brancuși (1876-1956) said „Simplicity is complexity itself“, simplicity and regularity through the use of basic geometric forms has always played a central role in architectural design, during the 20th century. A diachronic perspective, shows as the use of geometry and mathematics to describe built form provided a common basis for communication between the processes of design, fabrication and stability. Classic ways of representing geometry, based on descriptive methods, favor precise language of bidimensionality easy to represent in a rectangular coordinate system. In recent years, the importance of geometry has been re-emphasized by significant advances in the digital age, where computers are increasingly used in design, fabrication and construction to explore the art of the possible. Contemporary architecture transcend the limitations of Euclidean geometry and create new forms that are emerging through the convergence of complex systems, computational design and robotic fabrication devices, but which can also achieve higher levels of performance. Freeform architectural shapes and structures play an increasingly important role in 21st century architectural design. Through a series of examples, the paper relates to contemporary architectural explorations of complex, curvilinear surfaces in the digital age and discusses how it has required rethinking the mode in which we traditionally operate as architects. The analysis creates the possibility of comparisons between original and current design.

In this paper, a free form optimization method is proposed for achieving a desired static deformation of a frame structure. Deformation control is one of the important problems in stiffness design of frame structures, and it also enables to give a function to frame structures. As an objective functional, we introduce the sum of squared error norms to the desired displacements on specified members, and the assumption that each frame member varies in the off-axis direction. The shape gradient function and the optimality conditions for this problem are theoretically derived with the Lagrange multiplier method and the material derivative method. The optimal shape variation that minimizes the objective functional is determined as the displacement-field by applying the negative shape gradient function as fictitious external forces to the frame members. With the proposed method, the optimal arbitrarily formed frame structure can be obtained without any shape parameterization while maintaining the smoothness. The validity and practical utilities of this method for the static deformation control of frame structures are verified through design examples.

This paper presents a concept of deployable Pipe-Z (dPZ): a modular structural system which takes advantage of the robustness of rigid-panel mechanism and allows to create free-form links which are also reconfigurable and deployable. The concept presented can be applied for building habitats and infrastructures for human exploration of oceans and outer space. dPZ structures can adapt to changing requirements e.g. mission objectives, crew condition and technological developments. Furthermore, such lightweight and adaptable structural concept can assist in sustainable exploration development. After brief introduction, the concept of Pipe-Z (PZ) is presented. Next, the reconfigurability of PZ is explained and illustrated with continuous and collision-free transition from a PZ forming a Trefoil knot to a Figure-eight knot. The following sections introduce, explain and illustrate the folding mechanism of a single foldable Pipe-Z module (fPZM) and entire dPZ structure. The latter is illustrated with asynchronous (delayed) unfolding of a relatively complex Unknot. Several applications of PZ are suggested, namely for underwater and deep-space and surface habitats, for permanent, but in particular, temporary or emergency passages. As an example, a scenario of a failure of one of the modules of the International Space Station is presented where a rigid structure of 40 fPZMs bypasses the “dead link”. A low-fidelity prototype of a 6-module octagonal dPZ is presented; several folding schemes including concentric toric rings are demonstrated. Practical issues of pressurization and packing are briefly discussed. [ABSTRACT FROM AUTHOR]

Optimal design of structures with respect to their mechanical behavior is essential and basically required in structural engineering. In this study, we propose a non-parametric free-form optimization method based on the variational method to design frame structures composed of arbitrarily curved linear elastic members. The natural frequency maximization problem of frame structures is formulated as a non-parametric shape optimization problem under the volume constraint. Under the assumption that each member varies in the out-of-plane direction to its centroidal axis, the shape gradient functions and the optimality conditions are theoretically derived by the Lagrange multiplier method and the formulae of the material derivative. Then, the derived shape gradient functions are applied to a gradient method in the Hilbert space with a P.D.E (Partial Differential Equation) smoother, which is referred as the H 1 gradient method for frame structures. Moreover, a simple switching technique of the objective functional is presented for overcoming the discontinuity problem of repeated eigenvalues, which often appears in natural frequency maximization problem. With this combination of the three techniques, the optimal free-form frame structures owning smoothly curved members can be obtained without any preliminary shape parameterization, and the effectiveness and validity of the proposed method are verified through three design examples. [ABSTRACT FROM AUTHOR]

In the present work, in order to tackle the linear elastic buckling problem, we develop a shape optimization process based on a free-form optimization method to optimize a shell structure under out-of-plane and in-plane shape variations. The free-form optimization method is a node-based method in which mesh regularity can be maintained and shape design parameterization is not required. It has the advantages of sufficient efficiency for treating large-scale problems and the ability to realize a smooth shape. The buckling coefficient in buckling mode 1 is set as the objective function in the shape optimization problem. We consider repeated eigenvalues and volume constraint for the whole optimization process. Three numerical examples are presented in this work to illustrate the shape optimization algorithm and to show that it can increase the buckling strength substantially, especially under shape variation in the out-of-plane direction. [ABSTRACT FROM AUTHOR]

Considering the different thermal expansion coefficients of skins and cores, sandwich structures whose design optimization is performed have the potential for application in thermal actuators. In the present work, we propose a free-form optimization method for the design optimization of sandwich structures composed of two thermoelastic materials ( A and B ) for controlling their thermal displacements. We use the square displacements error norm between the thermal displacement and target displacement at the designated boundary as the objective function, and minimize it by optimizing the interface and the surface shapes of the sandwich structures under thermal load. We derive the shape gradient function by using the material derivative method and apply it to the free-form optimization method for determining the optimal shape. Two volume constraints, the total volume and volume of material A , are considered in the problem formulation. The numerical results show that the thermal deformation of the optimal sandwich structure can be well identified; this is helpful for applying sandwich structures in thermal actuators. [ABSTRACT FROM AUTHOR]

The objective of this research was to develop and compare various airfoil precomputational parameterization and analysis techniques for aerostructural optimization of wind turbine blades. The airfoils along the blade were added as optimization design variables through precomputational parameterization methods using thickness-to-chord ratios and blended airfoil family factors. The airfoils’ aerodynamic performance was analyzed with three methods of increasing fidelity: a panel method (XFOIL), Navier–Stokes-based computational fluid dynamics (RANS CFD), and wind tunnel data. The optimizations minimized mass over annual energy production ($m/AEP$) and thereby approximated the minimization of cost of energy. The results were compared to the NREL 5-MW reference turbine and a conventional optimization where the airfoils were fixed. Results showed an average $m/AEP$ reduction of 1.7% over conventional optimization methods. The primary benefit in adding the airfoil shape was through an increase in annual energy production (1.6%) with a similar decrease in turbine mass (1.8%). Using the precomputational airfoil parameterization methods provided significant reductions in the cost of energy with relatively minor additional computational cost. [ABSTRACT FROM PUBLISHER]

Design optimization of composite structures has been a significant topic of research over the recent years. In the present work, we propose a developed free-form optimization method for designing the shape of composite structures composed of dissimilar materials ( A and B ). In this shape design optimization, we use compliance as the objective function and minimize it under two volume constraints (total volume and volume of material A ). According to the proposed free-form optimization method, we theoretically derive the shape gradient function used in the compliance minimization problem, and determine the optimal interface and surface shapes of composite structures under external loading or body force without any shape parameterization. The optimal results of numerical examples show that the compliance of composite structures composed of dissimilar materials can be significantly reduced by using the proposed free-form optimization method. [ABSTRACT FROM AUTHOR]

Grid-shells are lightweight structures used to cover long spans with few load-bearing material, as they excel for lightness, elegance and transparency. In this paper we analyze the stability of hex-dominant free-form grid-shells, generated with the Statics Aware Voronoi Remeshing scheme introduced in Pietroni et al. (2015). This is a novel hex-dominant, organic-like and non uniform remeshing pattern that manages to take into account the statics of the underlying surface. We show how this pattern is particularly suitable for free-form grid-shells, providing good performance in terms of both aesthetics and structural behavior. To reach this goal, we select a set of four contemporary architectural surfaces and we establish a systematic comparative analysis between Statics Aware Voronoi Grid-Shells and equivalent state of the art triangular and quadrilateral grid-shells. For each dataset and for each grid-shell topology, imperfection sensitivity analyses are carried out and the worst response diagrams compared. It turns out that, in spite of the intrinsic weakness of the hexagonal topology, free-form Statics Aware Voronoi Grid-Shells are much more effective than their state-of-the-art quadrilateral counterparts. [ABSTRACT FROM AUTHOR]

The wire electro-discharge machining (WEDM) is a widely-used machining process suitable to achieve the increasingly demanding precision requirements imposed by industry. Nevertheless, the use of conventional WEDM machines under some complex geometrical conditions makes sometimes difficult to fulfill these requirements, which is a topic of interest in the manufacturing of high-added aerospace components. Different effects overlap to damage precision when cutting these geometries. In this work a study on the causes of dimensional deviations in small-radius circles has been carried out. The study focuses on two effects: wire-lag and concavity shape on the workpiece produced by electrostatic and electromagnetic forces. At the sight of the results, a classification of radius is proposed taking into consideration the main cause of lack of accuracy. It has been found that wire-lag effect must only be considered when machining circles of radius smaller than a certain value that can be established by simulations. For the conditions of the tests of this study, this value is 3 mm. It can also be stated that concavity effect is a function of machined radius. [ABSTRACT FROM AUTHOR]

A solar thermal concentrator system is proposed comprising a free-form-trough (FFT) reflector and a cylindrical heat-pipe receiver. The profile of the reflector is designed using a free-form surface creation (FFSC) method such that each incident ray is directed to a certain user-specified point on the heat-pipe surface. The light ray paths within the concentrator system are analyzed using a skew-ray tracing approach. A method is then proposed for optimizing the geometry of the concentrator system in such a way as to achieve a uniform irradiance distribution on the heat-pipe surface. The validity of the proposed optimization approach is demonstrated by means of ZEMAX/SolidWorks-Flow simulations. The results show that the proposed FFT concentrator yields a significant improvement in both the irradiance uniformity and the heating efficiency compared to conventional cylindrical-trough and parabolic-trough concentrators. [ABSTRACT FROM AUTHOR]

Free-form solar cells are cells of unconventional shapes ( e.g. hexagonal, leaf-shaped etc ). Their flexible shape adds to the aesthetics of the surroundings as well as allows to place them over objects where conventional solar cells might not fit. Evidently, these cells need to be efficient as well, and one of the important factors that controls their performance is the front metallization design. In this paper, we present the application of topology optimization (TO) to optimize the front metallization patterns for free-form solar cells. TO distributes the electrode material on the solar cell front surface in an efficient manner, such that the total power output is maximized. To demonstrate the capability of the proposed methodology, we use it to optimize front metal grids for several complex solar cell shapes e.g. circular, hexagonal, leaf-shaped, motorbike fairings, etc . The results presented here demonstrate the capability of TO to generate efficient designs for these free-form shapes. [ABSTRACT FROM AUTHOR]

For free-form structures with a single layer envelope, the node is subjected to axial load, as well as moment. The purpose of this paper is to develop and evaluate a new hollow spherical connector, termed the FREE (Flexible, Resilient, Efficient, Economic) node, for single layer free-form spatial envelopes. Reducing material and efficient shape are important points in the space structure node. Therefore, hollow spherical node sections with different holes were proposed and finite element analysis was performed, to determine the prototype among these parameters. The parameters are the size and shape of the hollow sphere. Bending experiments were also performed, to evaluate the structural capacities of the proposed node; and the corresponding test results were compared with finite element analysis. As a result, it may be said the proposed FREE node satisfied the required capacities. [ABSTRACT FROM AUTHOR]