Computer-Aided Design最新文献

{"title":"Singularity structure simplification for hex mesh via integer linear program","authors":"Junyi Duan ,&nbsp;Xiaopeng Zheng ,&nbsp;Na Lei ,&nbsp;Zhongxuan Luo","doi":"10.1016/j.cad.2023.103654","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103654","url":null,"abstract":"<div><p>Topology optimization of hexahedral (hex) meshes has been a widely studied topic, with the primary goal of optimizing the singularity structure. Previous works have focused on simplifying complex singularity structures by collapsing sheets/chords. However, these works require a large number of checks during the process to prevent illegal operations. Moreover, the employed simplification strategies are not based on the topological characteristics of the structure, but rather on the rank of the components that can be simplified. To overcome these problems, we analyze how topology operations affect the degree of edges in hex meshes, and introduce a fast and automatic algorithm to simplify the singularity structure of hex meshes. The algorithm relies on sheet operations, using mesh volume as a metric to assess the degree of simplification. Moreover, it designs constraints to prevent illegal operations and employs integer linear program to plan the overall optimization strategy for a mesh. After that, we relax the singularity constraints to further simplify the structure, and handle unreasonable singularities via sheet inflation operation. Our algorithm can also improve singularity structure without merging singularities by adjusting the singularity constraint conditions. Numerous experiments demonstrate the effectiveness and efficiency of our algorithm.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"168 ","pages":"Article 103654"},"PeriodicalIF":4.3,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computational Segmentation of Timber Slabs with Free Column Placement","authors":"Luis Orozco ,&nbsp;Hans Jakob Wagner ,&nbsp;Anna Krtschil ,&nbsp;Jan Knippers ,&nbsp;Achim Menges","doi":"10.1016/j.cad.2023.103650","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103650","url":null,"abstract":"<div><p><span><span>Modular floor slabs<span> must be subdivided into prefabricable, transportable segments. This slab segmentation process conventionally uses a rectangular pattern, particularly for timber buildings. Regular segmentation patterns and strict column grids are ideal for rectangular building shapes, but restrict timber buildings to only some architectural uses, and are unideal for urban infill. Unfortunately, planning and constructing multi-storey </span></span>wood buildings<span> without a strict grid is still challenging. There is therefore a conflict between the desired column placement and the constraints imposed by building systems. This article investigates novel methods for segmenting timber floors supported by irregular column layouts. It proposes six different segmentation methods<span> that are informed through Co-Design by structural, material waste, and transportation requirements. Co-Design allows for the direct integration and automated feedback of such diverse criteria into the early building design<span> phase. These methods are based on three well-known computational approaches: Single-Objective Optimisation, Parametric Modelling, and Agent-Based Modelling. They could also be applied to other non-timber prefabricated floor systems. The segmentation methods are demonstrated on two example floor slabs with irregular column layouts, one with a </span></span></span></span>rectilinear<span> and the other with an irregular outline. The methods are compared using quantitative proxies for cost, fabrication time, architectural adaptability, and assembly complexity. More benchmark testing is needed, but initial results showed that the most efficient segmentations cannot adapt to irregular layouts, emphasising the need for a more adaptable approach to modular timber construction.</span></p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"168 ","pages":"Article 103650"},"PeriodicalIF":4.3,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138448360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Survey of Methods for Converting Unstructured Data to CSG Models","authors":"Pierre-Alain Fayolle ,&nbsp;Markus Friedrich","doi":"10.1016/j.cad.2023.103655","DOIUrl":"10.1016/j.cad.2023.103655","url":null,"abstract":"<div><p><span><span>The goal of this document is to survey existing methods for recovering or extracting CSG (Constructive Solid Geometry) representations from unstructured data such as 3D point-clouds or polygon meshes<span>. We review and discuss related topics such as the segmentation and fitting of the input data. We cover techniques from solid modeling for the conversion of a polyhedron to a CSG expression and for the conversion of a B-rep to a CSG expression. We look at approaches coming from </span></span>program synthesis, evolutionary techniques (such as </span>genetic programming<span> or genetic algorithm), and deep learning. Finally, we conclude our survey with a discussion of techniques for the generation of computer programs involving higher-level constructs, representations, and operations for representing solids.</span></p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"168 ","pages":"Article 103655"},"PeriodicalIF":4.3,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138515704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Generation of 3D Surface Meshes for NURBS-Enhanced FEM","authors":"Xi Zou,&nbsp;Sui Bun Lo,&nbsp;Ruben Sevilla,&nbsp;Oubay Hassan,&nbsp;Kenneth Morgan","doi":"10.1016/j.cad.2023.103653","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103653","url":null,"abstract":"<div><p>This work presents the first method for generating triangular surface meshes in three dimensions for the NURBS-enhanced finite element method. The generated meshes may contain triangular elements that span across multiple NURBS surfaces, whilst maintaining the exact representation of the CAD geometry. This strategy completely eliminates the need for de-featuring complex watertight CAD models and, at the same time, eliminates any uncertainty associated with the simplification of CAD models. In addition, the ability to create elements that span across multiple surfaces ensures that the generated meshes are highly compliant with the requirements of the user-specified spacing function, even if the CAD model contains very small geometric features. To demonstrate the capability, the proposed strategy is applied to a variety of CAD geometries, taken from areas such as solid/structural mechanics, fluid dynamics and wave propagation.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"168 ","pages":"Article 103653"},"PeriodicalIF":4.3,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0010448523001859/pdfft?md5=aa73b2fdb16a955d05ef18c16fb021a0&pid=1-s2.0-S0010448523001859-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138466073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accurate Detection and Smoothness-Oriented Avoidance Method of Singularity in 5-Axis CNC Machining","authors":"Lei Wu ,&nbsp;Jinting Xu ,&nbsp;Hebing Xing ,&nbsp;Yuwen Sun","doi":"10.1016/j.cad.2023.103652","DOIUrl":"10.1016/j.cad.2023.103652","url":null,"abstract":"<div><p>As an inherent flaw in the kinematic chain<span> mechanism of 5-axis machine tools, singularity can induce dramatic changes in machine axes motion and unfavorable fluctuations in feedrate. For effective singularity avoidance, it is desirable to first achieve accurate and efficient singularity detection and then eliminate the singularity without impairing tool orientation smoothness. This paper presents a novel approach for accurately detecting and smoothly avoiding the singularity in 5-axis CNC machining. In the detection method, two exclusion criteria are presented to efficiently exclude most non-singular segments of the tool orientation spline, and a curve intersection-based algorithm is thus developed to accurately identify the singular segments. In the singularity avoidance method, a concept of admissible tool orientation annulus (ATOA) is introduced, which serves to confine the range and magnitude of the tool orientation spline’s adjustments, and a local adjustment algorithm is then developed to enable the escape of the tool orientation from the singular region with controllable direction and deviation, while maintaining its continuity and smoothness. The effectiveness of singularity avoidance and the kinematic performance of the tool orientation modified by our method, are comparable to a state-of-the-art singularity avoidance algorithm. Finally, the conducted experiments validate the proposed method.</span></p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"167 ","pages":"Article 103652"},"PeriodicalIF":4.3,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135764224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstruction and Preservation of Feature Curves in 3D Point Cloud Processing","authors":"Ulderico Fugacci,&nbsp;Chiara Romanengo,&nbsp;Bianca Falcidieno,&nbsp;Silvia Biasotti","doi":"10.1016/j.cad.2023.103649","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103649","url":null,"abstract":"<div><p>Given a 3D point cloud, we propose a method for suitably resampling the cloud while reconstructing and preserving the feature curves to which some points are identified to belong. The first phase of our strategy enriches the cloud by approximating the curvilinear profiles outlined by the feature points with piece-wise polynomial parametric space curves through the use of the Hough transform. The second phase describes how the removal of a point or its insertion can be performed without affecting the approximated profiles and preserving the enriched structure of the cloud. The combination of the two steps provides multiple possibilities for processing a point cloud by varying its size or improving its density homogeneity without affecting the retrieved feature curves. The various capabilities of our approach are investigated to produce simplification, refinement, and resampling techniques whose effectiveness is evaluated through experiments and comparisons.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"167 ","pages":"Article 103649"},"PeriodicalIF":4.3,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0010448523001811/pdfft?md5=56e2bae1adadd3264b869b2675026fbc&pid=1-s2.0-S0010448523001811-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92057929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IF-TONIR: Iteration-free Topology Optimization based on Implicit Neural Representations","authors":"Jiangbei Hu ,&nbsp;Ying He ,&nbsp;Baixin Xu ,&nbsp;Shengfa Wang ,&nbsp;Na Lei ,&nbsp;Zhongxuan Luo","doi":"10.1016/j.cad.2023.103639","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103639","url":null,"abstract":"<div><p>Topology optimization holds great significance as a research topic in the field of mechanical engineering, aiming to design and optimize structures to achieve desired performance while adhering to specific constraints. However, its high computational complexity and iterative optimization process severely impact the efficiency, which presents substantial obstacles to its practical applications. To tackle this challenge, recent research is dedicated to the advancement of iteration-free topology optimization methods that leverage neural networks and deep learning, aiming to directly predict optimal structures through optimization problem configurations. In this paper, we propose IF-TONIR, a novel data-driven topology optimization method that utilizes implicit neural representations. Our approach employs signed distance fields to represent structures, offering compact and smooth representations that effectively eliminate the checkerboard phenomenon commonly observed in density-based methods. IF-TONIR leverages Conditional Variational Autoencoders, which use a CNN-based encoder and a MLP-based decoder to learn and reconstruct optimal structures. We employ the features extracted from physical information as conditions to guide the decoder in generating optimal structures that adhere to specific design domain shapes and boundary conditions. Furthermore, we propose the integration of a topological loss based on persistent homology to train the model. This loss function effectively penalizes the existence of structural disconnections in the reconstructed output, thereby enhancing the overall physical reliability of the generated structures. Various experiments have demonstrated that our iteration-free topology optimization method based on implicit representations can accurately identify regions of high strain energy and generate continuous structures with low compliance. The methods also holds the theoretical capability of outputting optimal structures at any desired resolution. Our code and dataset are available on <span>https://github.com/jbHu67/IF-TONIR.git</span><svg><path></path></svg></p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"167 ","pages":"Article 103639"},"PeriodicalIF":4.3,"publicationDate":"2023-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92057930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Texture-Driven Adaptive Mesh Refinement with Application to 3D Relief","authors":"Jiaze Li ,&nbsp;Shengfa Wang ,&nbsp;Eric Paquette","doi":"10.1016/j.cad.2023.103640","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103640","url":null,"abstract":"<div><p>A high-quality 3D relief requires an appropriate refinement that has accurate carving boundaries with a limited number of added polygons. Most existing refinement methods cannot be applied to 3D reliefs directly, as they exhibit a mixture of problems such as not accurately following the texture contours, creating ill-shaped triangles, and excessively increasing the polygon count. We introduce an efficient texture-driven method to adaptively refine a mesh for 3D reliefs. From the user-provided binary texture, we conduct a feature-preserving self-adaptive sampling of texture contours. Our other inputs are a 3D mesh and the mapping of that mesh to texture space. We adapt a constraint-driven Red–Green subdivision to locally subdivide the mesh around the contours. Then, we conduct the adaptive mesh refinement by introducing a feature-adaptive <span><math><msqrt><mrow><mn>3</mn></mrow></msqrt></math></span>-subdivision. Finally, we apply the proposed algorithm to 3D reliefs, which enables generating a distinct relief. The presented method can attain accurate 3D relief while maintaining good mesh quality without the necessity of a high-resolution input. When compared to alternative approaches, ours consistently demonstrates superior polygon quality and maintains relief boundaries that closely follow the texture contours.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"167 ","pages":"Article 103640"},"PeriodicalIF":4.3,"publicationDate":"2023-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92057928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fabric mechanical parameters for 3D cloth simulation in apparel CAD: A systematic review","authors":"Xiaoqun Dai ,&nbsp;Yan Hong","doi":"10.1016/j.cad.2023.103638","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103638","url":null,"abstract":"<div><p>The primary objective of 3D virtual garment simulation within apparel CAD systems is to generate a highly realistic garment that accurately conform to the human body. However, due to the complexity of textile mechanics, variations in measurement technology, and the absence of standardized units of mechanical parameters, there exists considerable confusion surrounding the implementation of mechanical parameters in cloth simulation. Consequently, the accuracy of cloth simulation varies significantly among different apparel CAD systems. This research article aims to enhance the understanding of the fabric mechanical behaviors, measurement techniques, and parameters essential for cloth simulation. To achieve this objective, we first present a concise overview of current garment simulation in apparel CAD systems, focusing on the utilized mechanical parameters and methods for simulation accuracy evaluation. Subsequently, we delve into the fundamental principles of mechanical behavior, discussing measurement methodologies and proposing parameter unifications along with appropriate data ranges. Finally, we conduct a comprehensive review of cloth models and the requisite parameters, while also exploring simulation-based approaches for parameter estimation. This work provides crucial insights into fabric mechanical parameters essential for achieving accurate 3D virtual garment simulation. The findings and information presented herein can be effectively utilized to enhance the precision and fidelity of apparel CAD systems, thereby facilitating advancements in virtual garment design and production.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"167 ","pages":"Article 103638"},"PeriodicalIF":4.3,"publicationDate":"2023-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134666843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interface-Based Search and Automatic Reassembly of CAD Models for Database Expansion and Model Reuse","authors":"Lucas Vergez,&nbsp;Arnaud Polette,&nbsp;Jean-Philippe Pernot","doi":"10.1016/j.cad.2023.103630","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103630","url":null,"abstract":"<div><p><span><span>This paper introduces a new framework for reassembling CAD models of mechanical parts. The generated CAD assemblies are well-constrained, with collision-free parts, and they are ready-to-use for downstream applications. First, input dead CAD models candidate for the reassembly are sorted following a part-by-part interface-based </span>identification algorithm that is capable of characterizing each part according to the assembly slots and interfaces it offers. The slots are then hashed, and the resulting keys are used for fast search of parts in the database. Thus, the parts that can be assembled are quickly identified, and their assembly can be considered according to various scenarios. To support the reassembly steps and satisfy the constraints associated with the specified interfaces, a collision-free kinematic </span>constraint solver<span> is also proposed. During the reassembly steps, the geometry of the slots can also be automatically modified to adjust their dimensions, in order to ensure a perfect fit and to avoid interference at the level of the interfaces. The resulting database can also be further expanded while modifying the relative positions/orientations of the assembled parts. The approach is illustrated on several test cases covering different exploitation scenarios, ranging from simple model reuse to database expansion for machine learning-based applications. Such an automatic reassembly process is particularly innovative, and it clearly paves the way for smart assembly procedures.</span></p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":"167 ","pages":"Article 103630"},"PeriodicalIF":4.3,"publicationDate":"2023-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92057931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}