Computer-Aided Design最新文献

{"title":"Partition-based Print Sequence Planning and Adaptive Slicing for Scalar Field-based Multi-axis Additive Manufacturing","authors":"Tak Yu Lau ,&nbsp;Li Chen ,&nbsp;Dong He ,&nbsp;Zhaoyu Li ,&nbsp;Kai Tang","doi":"10.1016/j.cad.2023.103576","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103576","url":null,"abstract":"<div><p>While multi-axis additive manufacturing is found to be a good solution to the inherent limitations of conventional 2.5D additive manufacturing, it is a much more sophisticated process. Among different existing multi-axis process planning algorithms, we are interested in those based on a scalar field, in which print slices are the iso-surfaces of a scalar field embedded in the 3D model. In this paper, we propose a partitioned-based print sequence planning algorithm and an adaptive slicing algorithm, which together determine a complete multi-axis printing process for an arbitrary solid model. The first algorithm iteratively subdivides the model into a set of components such that a collision-free print sequence can be established among the components. The second algorithm then extracts print slices from each component such that all these slices satisfy the self-support condition. Since an arbitrary model may not satisfy both the self-support and collision-free requirements, we also define certain critical printability rules at the beginning to check whether a given input model with its associated scalar field is printable. The generated print slices and print sequence by the proposed two algorithms are guaranteed to be printable. Furthermore, a shorter total fabrication time and a better surface quality are achieved. Physical experiments of four test models are performed on a homebuilt multi-axis FDM printer, whose results verify the capabilities of the proposed algorithms.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49711092","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 Review of a B-spline based Volumetric Representation: Design, Analysis and Fabrication of Porous and/or Heterogeneous Geometries","authors":"Gershon Elber","doi":"10.1016/j.cad.2023.103587","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103587","url":null,"abstract":"<div><p>The needs of modern (additive) manufacturing (AM) technologies can no longer be satisfied by geometric modeling tools that are based on boundary representations (B-reps) - AM requires the representation and manipulation of interior heterogeneous fields and materials. Further, while the need for a tight coupling between design and analysis has been recognized as crucial almost since geometric modeling (GM) was conceived, contemporary GM systems only offer a loose link between the two, if at all.</p><p>For more than half a century, the (trimmed) Non-Uniform Rational B-spline (NURBs) surface representation has been the B-rep of choice for virtually all the GM industry. Fundamentally, B-rep GM has evolved little during this period. In this work, we review almost a decade of research and development in extending this boundary representation to a B-spline based, volumetric representation (V-rep) that successfully confronts the existing and anticipated design, analysis, and manufacturing foreseen challenges. We have extended all fundamental B-rep GM operations, such as primitive and surface constructors, and Boolean operations, to trimmed trivariate V-reps. This enables the much-needed tight link between the designed geometry and (iso-geometric) analysis on one hand and the full support of (additive) manufacturing of porous, (graded-) heterogeneous and anisotropic geometries, on the other. Examples and applications of V-rep GM, that span design, analysis and optimization, and AM, of lattice- and micro-structure synthesis as well as graded-heterogeneity, are demonstrated, with emphasis on AM.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49733278","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":"Co-design Optimization of Moving Parts for Compliance and Collision Avoidance","authors":"Amir M. Mirzendehdel,&nbsp;Morad Behandish","doi":"10.1016/j.cad.2023.103547","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103547","url":null,"abstract":"<div><p>Design requirements for moving parts in mechanical assemblies are typically specified in terms of interactions with other parts. Some are purely kinematic (e.g., pairwise collision avoidance) while others depend on physics and material properties (e.g., deformation under loads). Kinematic design methods and physics-based shape/topology optimization (SO/TO) deal separately with these requirements. They rarely talk to each other as the former uses set algebra and group theory while the latter requires discretizing and solving differential equations. Hence, optimizing a moving part based on physics typically relies on either neglecting or pruning kinematic constraints in advance, e.g., by restricting the design domain to a collision-free space using an unsweep operation. In this paper, we show that TO can be used to co-design two or more parts in relative motion to simultaneously satisfy physics-based criteria and collision avoidance. We restrict our attention to maximizing linear-elastic stiffness while penalizing collision measures aggregated in time. We couple the TO loops for two parts in relative motion so that the evolution of each part’s shape is accounted for when penalizing collision for the other part. The collision measures are computed by a correlation functional that can be discretized by left- and right-multiplying the shape design variables by a pre-computed matrix that depends solely on the motion. This decoupling is key to making the computations scalable for TO iterations. We demonstrate the effectiveness of the approach with 2D and 3D examples.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49733487","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":"Symmetrization of 2D Polygonal Shapes Using Mixed-Integer Programming","authors":"Jin Huang,&nbsp;Jantien Stoter,&nbsp;Liangliang Nan","doi":"10.1016/j.cad.2023.103572","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103572","url":null,"abstract":"<div><p>Symmetry widely exists in nature and man-made shapes, but it is unavoidably distorted during the process of growth, design, digitalization, and reconstruction steps. To enhance symmetry, traditional methods follow the <em>detect-then-symmetrize</em> paradigm, which is sensitive to noise in the detection phase, resulting in ambiguities for the subsequent symmetrization step. In this work, we propose a novel optimization-based framework that jointly detects and optimizes symmetry for 2D shapes represented as polygons. Our method can detect and optimize symmetry using a single objective function. Specifically, we formulate symmetry detection and optimization as a mixed-integer program. Our method first generates a set of candidate symmetric edge pairs, which are then encoded as binary variables in our optimization. The geometry of the shape is expressed as continuous variables, which are then optimized together with the binary variables. The symmetry of the shape is enforced by the designed hard constraints. After the optimization, both the optimal symmetric edge correspondences and the geometry are obtained. Our method simultaneously detects all the symmetric primitive pairs and enhances the symmetry of a model while minimally altering its geometry. We have tested our method on a variety of shapes from designs and vectorizations, and the results have demonstrated its effectiveness.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49711116","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":"Surface And Hypersurface Meshing Techniques for Space–Time Finite Element Methods","authors":"Jude T. Anderson ,&nbsp;David M. Williams ,&nbsp;Andrew Corrigan","doi":"10.1016/j.cad.2023.103574","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103574","url":null,"abstract":"<div><p>A novel method is introduced for constructing two-dimensional (2D) surface meshes embedded in three-dimensional (3D) space time <em>and</em> 3D hypersurface meshes embedded in four-dimensional (4D) space time. In particular, we begin by dividing the space–time domain into time slabs. Each time slab is equipped with an initial plane (hyperplane), in conjunction with an unstructured simplicial surface (hypersurface) mesh that covers the initial plane. We then obtain the vertices of the terminating plane (hyperplane) of the time slab from the vertices of the initial plane using a space–time trajectory-tracking approach. Next, these vertices are used to create an unstructured simplicial mesh on the terminating plane (hyperplane). Thereafter, the initial and terminating boundary vertices are stitched together to form simplicial meshes on the intermediate surfaces or <em>sides</em> of the time slab. After describing this new mesh-generation method in rigorous detail, we provide the results of multiple numerical experiments which demonstrate its validity and flexibility.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49733574","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":"Point Pair-Based Expression of Cutter Swept Envelopes in Five-Axis Milling","authors":"Ye Ding,&nbsp;Yongxue Chen","doi":"10.1016/j.cad.2023.103588","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103588","url":null,"abstract":"<div><p>This paper proposes an efficient method of formulating cutter swept envelopes in five-axis milling based on conformal geometric algebra. The surface of the rotary cutter is represented as a canal surface, as the envelope of a one-parameter family of spheres. The swept envelopes generated by the general rigid motion of the cutter can be regarded as the envelopes of a two-parameter family of spheres. With the help of the dual representations of spheres and planes in conformal space, a point pair-based expression of the swept envelopes is formulated analytically, which represents two surfaces uniformly. By using the present method, the swept surfaces of a conical cutter, a drum-shaped cutter, and a toroidal cutter are illustrated. As an application, two types of collision detection methods for 5-axis milling are presented based on the point pair-based envelope expression. The benchmark examples demonstrate that the use of the proposed envelope expression significantly improves computational efficiency.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49711095","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":"Automatic Design of Overflow System for Preventing Gas Defects by Considering the Direction of Molten Metal Flow","authors":"Daichi Minamide ,&nbsp;Ken’ichi Yano ,&nbsp;Masahiro Sano ,&nbsp;Takahiro Aoki","doi":"10.1016/j.cad.2023.103586","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103586","url":null,"abstract":"<div><p>In die casting, gas defects occur if the molten metal entrains the gas inside the shot sleeve and mold and remains inside the product after filling. Therefore, an exhaust system such as an exhaust runner or overflow is generally designed at the die casting mold to discharge the gas-entrained molten metal outside the mold completely. In addition, an overflow has a broader designable area than an exhaust runner has and can discharge the gas-entrained molten metal, which an exhaust runner cannot. Therefore, designing the overflows at appropriate positions and volumes in die casting is essential. In recent years, research regarding the design of the overflow positions has been conducted by combining optimization theory and computational fluid dynamics (CFD). However, optimizing the overflow positions only can cause gas defects in the product and the unnecessary discharge of molten metal due to the overflow volume excess. Moreover, applying those methods is difficult because the analysis to verify the exhaust system includes the entire mold as the analysis domain, which increases calculation time. In this research, we propose the automatic overflow design system to discharge the gas-entrained molten metal inside the product completely by estimating the direction of molten metal flow and evaluating the efficiency of overflow design positions. Finally, we verified the effectiveness of the proposed system by actual die casting experiments using the proposed overflow shape.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49710808","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":"Deep Neural Implicit Representation of Accessibility for Multi-Axis Manufacturing","authors":"George Harabin,&nbsp;Amir M. Mirzendehdel,&nbsp;Morad Behandish","doi":"10.1016/j.cad.2023.103556","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103556","url":null,"abstract":"<div><p>One of the main concerns in design and process planning for multi-axis additive and subtractive manufacturing is collision avoidance between moving objects (e.g., tool assemblies) and stationary objects (e.g., part unified with fixtures). The collision measure for various pairs of relative rigid translations and rotations between the two pointsets can be conceptualized by a compactly supported scalar field over the 6D non-Euclidean configuration space. Explicit representation and computation of this field is costly in both time and space. If we fix <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mi>m</mi><mo>)</mo></mrow></mrow></math></span> sparsely sampled rotations (e.g., tool orientations), computation of the collision measure field as a convolution of indicator functions of the 3D pointsets over a uniform grid (i.e., voxelized geometry) of resolution <span><math><mrow><mi>O</mi><mrow><mo>(</mo><msup><mrow><mi>n</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>)</mo></mrow></mrow></math></span> via fast Fourier transforms (FFTs) scales as in <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mi>m</mi><msup><mrow><mi>n</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>log</mo><mi>n</mi><mo>)</mo></mrow></mrow></math></span> in time and <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mi>m</mi><msup><mrow><mi>n</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>)</mo></mrow></mrow></math></span> in space. In this paper, we develop an implicit representation of the collision measure field via deep neural networks (DNNs). We show that our approach is able to accurately interpolate the collision measure from a sparse sampling of rotations, and can represent the collision measure field with a small memory footprint. Moreover, we show that this representation can be efficiently updated through fine-tuning to more efficiently train the network on multi-resolution data, as well as accommodate incremental changes to the geometry (such as might occur in iterative processes such as topology optimization of the part subject to CNC tool accessibility constraints).</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49710980","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":"Fast High-Order Mesh Correction for Metric-Based Cavity Remeshing and a Posteriori Curving of P2 Tetrahedral Meshes","authors":"L. Rochery,&nbsp;A. Loseille","doi":"10.1016/j.cad.2023.103575","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103575","url":null,"abstract":"<div><p>A new high-order mesh correction method is introduced. Using the simplex algorithm, it maximizes directly the minimum of all control coefficients depending on a control point. This method provides the global optimum as quickly as to evaluate the <span><math><mo>min</mo></math></span> 8 times on average. The basic principle is applicable to all common element types (tetrahedra, hexahedra pyramids, prisms) and degrees. Meshes are corrected globally using this simplex-based Jacobian corrector in iterative smoothing.</p><p>Riemannian edge length minimization is presented for metric-based high-order mesh curving. It is consistent with log-Euclidean metric interpolation, which is extended to high-order meshes. The interpolated metric field is differentiated analytically, with applications to other geometric quantities (quality, Jacobian conformity). Edge length minimization is fast and flexible as it can be used with metrics deriving from adaptation or e.g. propagated surface metrics.</p><p>The cavity operator is a general topological operator that can apply insertions, collapses and generalized swaps. It is extended to <span><math><msup><mrow><mi>P</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> meshes through a modular approach with curvature applied in two steps. Prescribed curvature is the result of CAD/<span><math><msup><mrow><mi>P</mi></mrow><mrow><mn>3</mn></mrow></msup></math></span> surrogate projection on the boundary and of metric-based curvature in the interior. Necessary curvature results from simplex-based correction of the curved cavity. Both curvature schemes can easily be replaced by alternatives.</p><p>Several 3D numerical results on difficult academic and realistic CFD test-cases are presented. <span><math><msup><mrow><mi>P</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> tetrahedral meshes with up to 20M tetrahedra are corrected with curved boundary in between 10 s and 3 m30 s depending on target minimum Jacobian determinant.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49711190","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":"Hybrid Optimization-based Cutting Simulation for Soft Objects","authors":"Shi Chen ,&nbsp;Runze Yang ,&nbsp;Long Ma ,&nbsp;Minfeng Xu ,&nbsp;Yuanfeng Zhou","doi":"10.1016/j.cad.2023.103561","DOIUrl":"https://doi.org/10.1016/j.cad.2023.103561","url":null,"abstract":"<div><p>Cutting simulation for soft objects is a crucial technology in surgical simulators. The capabilities of a virtual surgery system are determined by the cutting efficiency and simulation performance. Taking both into full consideration, we present a real-time soft object cutting simulation method. The surface-volume model coupling a triangular mesh with a tetrahedral mesh is used as the geometric model. To drive deformable soft objects, we utilize position-based dynamics. The simulation incorporates a flexible progressive cutting technique that updates the topology and produces the cut surface simultaneously with the movement of the virtual scalpel. The incision’s tension and constraint are applied to the simulation steps, ensuring that the incision opens automatically and retains its shape without the need for complicated control. A hybrid optimization is performed to improve the cut mesh and reduce ill-conditioned sliver tetrahedrons while keeping the simulation in parallel. Experiments demonstrate that our method can provide stable and efficient soft object cuttings and the objects can maintain good performance in the subsequent simulation. Additionally, we apply the human slice data to generate real textures for the cut surface and employ a force feedback device to introduce the haptic effect, further enhancing the cutting simulation efficacy.</p></div>","PeriodicalId":50632,"journal":{"name":"Computer-Aided Design","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49761559","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}