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DNN-based Parameterization for B-Spline Curve Approximation 基于dnn的b样条曲线逼近参数化
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-06-18 DOI: 10.1016/j.cad.2025.103897
Wenqiang Tang , Zhouwang Yang
B-spline curve parameterization is a complex nonlinear and non-convex optimization problem. Traditional optimization methods often struggle with local minima and are computationally expensive, especially in high-dimensional spaces. We proposes a deep neural network (DNN)-based method to efficiently solve the parameterization problem in B-spline curve approximation. The designed parameterization network (PNet) maps the initial parameterization to an optimized one, transforming the problem into a search for suitable network parameters in a high-dimensional feature space. Due to the over-parameterization nature of DNNs, PNet is robust to initial conditions and less prone to local minima. Furthermore, the smooth regularization and top-K loss function are introduced to further enhance optimization performance. Experimental results show that PNet achieves high-precision approximation with remarkable efficiency, even for large-scale point clouds.
b样条曲线参数化是一个复杂的非线性非凸优化问题。传统的优化方法经常与局部最小值作斗争,并且计算成本很高,特别是在高维空间中。针对b样条曲线逼近中的参数化问题,提出了一种基于深度神经网络(DNN)的方法。所设计的参数化网络(PNet)将初始参数化映射到优化后的参数化,将问题转化为在高维特征空间中寻找合适的网络参数。由于深度神经网络的过度参数化特性,PNet对初始条件具有鲁棒性,并且不容易出现局部极小值。此外,还引入了平滑正则化和top-K损失函数,进一步提高了优化性能。实验结果表明,即使对于大规模点云,PNet也能以显著的效率实现高精度逼近。
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引用次数: 0
Recent advancement in conformal cooling channels: A review on design, simulation and future trends 保形冷却通道的最新进展:设计、模拟及未来趋势综述
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-06-11 DOI: 10.1016/j.cad.2025.103899
Soroush Masoudi , Barun K. Das , Muhammad Aamir , Majid Tolouei-Rad
The cooling phase of a moulded part plays a crucial role in the injection moulding (IM) process, accounting for 50 to 80 % of total cycle time, and significantly impacting the quality of moulded parts. During the last decade, the advancement of different additive manufacturing (AM) processes, especially metal 3D printing, has facilitated the production of mould parts, such as cores and cavities, with complex-shaped internal conformal cooling channels (CCCs). These innovative cooling systems exhibit significant potential to replace traditional straight-drilled cooling design, as they offer more efficient and uniform cooling performance by facilitating more effective heat transfer, considerably enhancing production quality and efficiency. Despite the growing attention being given to the design and manufacturing of CCC systems, there is still a lack of systematic and comprehensive classification, comparison and evaluation methodologies. This paper aims to review various types of conformal cooling channels, such as spiral, zigzag and nature-based designs, among others, and to provide an overview of advancements in design, process modeling and simulation of this new cooling technology. Previous studies have indicated that conventional straight-drilled cooling channels are likely to be replaced by CCCs, especially for complex and sensitive parts, due to their superior performance in reducing cycle times and enhancing product quality. The present study explores various challenges that arise when developing conformal cooling channels. These issues range from optimizing complex geometry to improving thermal performance through modelling. However, these challenges also present opportunities for innovation and advancement in mould design and manufacturing.
冷却阶段在注塑成型过程中起着至关重要的作用,占总周期时间的50%至80%,并对注塑件的质量产生重大影响。在过去的十年中,不同的增材制造(AM)工艺的进步,特别是金属3D打印,促进了模具零件的生产,如芯和腔,具有复杂形状的内部保形冷却通道(CCCs)。这些创新的冷却系统显示出取代传统直钻冷却设计的巨大潜力,因为它们通过促进更有效的传热来提供更高效和均匀的冷却性能,大大提高了生产质量和效率。尽管人们越来越重视CCC系统的设计和制造,但仍然缺乏系统和全面的分类、比较和评价方法。本文旨在回顾各种类型的保形冷却通道,如螺旋,之字形和基于自然的设计等,并概述了这种新型冷却技术的设计,过程建模和仿真的进展。先前的研究表明,由于CCCs在减少循环时间和提高产品质量方面的优越性能,传统的直钻冷却通道很可能被CCCs取代,特别是对于复杂和敏感的部件。本研究探讨了在开发保形冷却通道时出现的各种挑战。这些问题的范围从优化复杂的几何形状到通过建模提高热性能。然而,这些挑战也为模具设计和制造的创新和进步提供了机会。
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引用次数: 0
Two-stage physics-informed deep neural networks framework for form-finding of tensegrity structures 张拉整体结构寻形的两阶段物理信息深度神经网络框架
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-06-04 DOI: 10.1016/j.cad.2025.103898
Jin Wang, Mingliang Zhu, Zhiwei Miao
This paper proposes a two-stage optimization deep neural network method for form-finding of tensegrity structures, based on physical information. The total loss function of the neural network is constructed by comprehensively considering the physical information, including nodal residual forces, element length constraints, and minimum node distance. To enhance the learning ability of the neural network, a two-stage optimization model is adopted. In the first stage, the AdamW optimizer is employed for preliminary training of the network's hyperparameters, quickly reducing the loss values. Following the preliminary training, the l-BFGS optimizer is utilized in the second stage to refine the optimization and converge toward the optimal solution, resulting in the nodal coordinates that satisfy the structural equilibrium. The paper includes case studies on five different tensegrity models. The results show that the proposed two-stage physics-informed deep neural network (PIDNN) approach, utilizing dual optimizers, can efficiently and accurately perform form-finding for various tensegrity structures, including both single- and multi-stable models. The method provides reliable results, avoids complex finite element computations, and offers high computational efficiency.
提出了一种基于物理信息的张拉整体结构寻形的两阶段优化深度神经网络方法。综合考虑节点剩余力、单元长度约束、最小节点距离等物理信息,构建神经网络的总损失函数。为了提高神经网络的学习能力,采用了两阶段优化模型。在第一阶段,使用AdamW优化器对网络的超参数进行初步训练,快速降低损失值。在初步训练之后,第二阶段利用l-BFGS优化器对优化进行细化,并向最优解收敛,得到满足结构平衡的节点坐标。本文包括五种不同的张拉整体模型的案例研究。结果表明,利用双优化器的两阶段物理信息深度神经网络(PIDNN)方法可以高效准确地对各种张拉整体结构进行寻形,包括单稳定模型和多稳定模型。该方法计算结果可靠,避免了复杂的有限元计算,计算效率高。
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引用次数: 0
Sketch123: Multi-spectral channel cross attention for sketch-based 3D generation via diffusion models Sketch123:多光谱通道交叉关注通过扩散模型生成基于草图的3D
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-05-24 DOI: 10.1016/j.cad.2025.103896
Zhentong Xu , Long Zeng , Junli Zhao , Baodong Wang , Zhenkuan Pan , Yong-Jin Liu
With the development of generative techniques, sketch-driven 3D reconstruction has gained substantial attention as an efficient 3D modeling technique. However, challenges remain in extracting detailed features from sketches, representing local geometric structures, and ensuring generated fidelity and stability. To address these issues, in this paper we propose a multi-spectral channel cross-attention model for sketch reconstruction, which leverages the complementary strengths of frequency and spatial domains to capture multi-level sketch features. Our method employs a two-stage diffusion generation mechanism, additionally, a Sparse Feature Enhancement Module (SFE) replaces traditional down-sampling, reducing feature loss and enhancing detail preservation and noise suppression through a Laplace voxel smoothing operator. The Wasserstein distance introduced and integrated as part of the loss function, stabilizes the generative process using optimal transport theory to support high-quality 3D model reconstruction. Extensive experiments verify that our model surpasses state-of-the-art methods in terms of generation accuracy, local control, and generalization ability, providing an efficient, precise solution for transforming sketches into 3D models.
随着生成技术的发展,草图驱动的三维重建作为一种高效的三维建模技术得到了广泛的关注。然而,在从草图中提取细节特征、表示局部几何结构以及确保生成的保真度和稳定性方面仍然存在挑战。为了解决这些问题,本文提出了一种多频谱通道交叉注意模型用于草图重建,该模型利用频率域和空间域的互补优势来捕获多层次的草图特征。我们的方法采用两阶段扩散生成机制,此外,稀疏特征增强模块(SFE)取代传统的下采样,减少特征损失,并通过拉普拉斯体素平滑算子增强细节保存和噪声抑制。Wasserstein距离作为损失函数的一部分引入并集成,使用最优传输理论稳定生成过程,以支持高质量的3D模型重建。大量的实验证明,我们的模型在生成精度,局部控制和泛化能力方面超过了最先进的方法,为将草图转换为3D模型提供了高效,精确的解决方案。
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引用次数: 0
Face2Wear: An automatic and user-friendly facewear personalization framework with 3D symmetry-aware face registration using RGB-D selfies Face2Wear:一个自动和用户友好的面部个性化框架,使用RGB-D自拍照进行3D对称感知面部注册
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-05-09 DOI: 10.1016/j.cad.2025.103888
Jie Zhang , Luwei Chen , Hang Ren , Yan Luximon , Ping Li
The realm of personalized human wearable has undergone significant evolution. However, existing methodologies often lack in addressing crucial factors essential for comprehensive facewear customization, including automation, accuracy, convenience, and comfort. To bridge this gap, we propose an automated and user-friendly approach for ergonomic facewear personalized based on 3D face modeling and registration. Our approach involves the development of a user-friendly 3D face scanning technique utilizing RGB-D selfies captured by smartphone depth cameras, simplifying the process of personal data collection. Subsequently, we present a precise 3D symmetry-aware face registration method integrated with automatic facial landmark detection to produce parameterized 3D facial meshes featuring accurate symmetry panels. Additionally, we introduce a comfort-centric eyeglasses customization process to showcase its practical applications. Qualitative and quantitative comparisons with state-of-the-art techniques highlight the efficacy of our symmetry-aware registration method. Experimental findings also showcase the versatility of our approach across various scanning data. Evaluation results underscore the practical utility of our method in creating personalized eyeglasses with significantly enhanced comfort levels. Moreover, our method can be extended to other symmetric facewear designs, such as sunglasses, swimming goggles, and respirators.
个性化的人体可穿戴领域经历了重大的发展。然而,现有的方法往往缺乏解决全面的面部定制所必需的关键因素,包括自动化、准确性、便利性和舒适性。为了弥补这一差距,我们提出了一种基于3D人脸建模和配准的自动化和用户友好的人体工程学面部个性化方法。我们的方法包括开发一种用户友好的3D面部扫描技术,利用智能手机深度相机拍摄的RGB-D自拍,简化个人数据收集过程。随后,我们提出了一种精确的三维对称感知人脸配准方法,结合人脸自动地标检测,生成具有精确对称面板的参数化三维人脸网格。此外,我们还介绍了以舒适为中心的眼镜定制流程,以展示其实际应用。定性和定量比较与最先进的技术突出了我们的对称意识注册方法的有效性。实验结果也展示了我们的方法在各种扫描数据中的多功能性。评估结果强调了我们的方法在创造个性化眼镜方面的实用性,显著提高了舒适度。此外,我们的方法可以扩展到其他对称的面部设计,如太阳镜,游泳镜和呼吸器。
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引用次数: 0
Smooth surface finishing for 5-axis flank CNC machining of free-form geometries using custom-shaped tools 使用定制形状的刀具对自由几何形状的5轴侧面数控加工进行光滑表面加工
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-04-23 DOI: 10.1016/j.cad.2025.103887
Michal Bizzarri , Kanika Rajain , Michael Bartoň
Geometric modeling is traditionally a key part of an efficient manufacturing pipeline as one can decide, in virtual realm, what specific manufacturing tools to use and how to move them. Flank milling is the finishing stage of 5-axis Computer Numerically Controlled (CNC) machining, a stage where the machining accuracy is equally important as the smooth surface finish of the to-be-manufactured workpiece. The benchmark machining geometries such as propellers or blisks are doubly-curved surfaces and one typically needs several paths of the tool to get highly accurate surface finish. However, navigating a tool to move tangentially (i.e., in flank fashion) to the surface is very restrictive and in order to get highly accurate approximation, one typically has to compromise the smoothness across the neighboring paths.
To connect neighboring paths in smooth (G1-continuous) fashion using a conical tool is possible only for reasonably flat target geometries, such as spiral bevel gears, however, for a general free-form surface conical tools do not offer sufficient degrees of freedom. In this work, we consider generally curved, custom-shaped, cutting tools, whose shape is a design parameter computed by the proposed optimization-based framework to adapt their motions globally to the input free-form surface, supporting a feature of G1 connection across the neighboring paths. We demonstrate our algorithm on synthetic free-form surfaces as well as on industrial benchmark datasets, showing that optimizing the shape of the tool offers more flexibility to produce G1 connections between neighboring strips and outperforms conical tools both in terms of the approximation error and the smoothness.
传统上,几何建模是高效制造管道的关键部分,因为在虚拟领域中,人们可以决定使用哪些特定的制造工具以及如何移动它们。侧铣是五轴数控加工的精加工阶段,在这个阶段,加工精度与待加工工件的表面光洁度同等重要。螺旋桨或圆盘等基准加工几何形状是双曲面,通常需要刀具的多条路径才能获得高精度的表面光洁度。然而,导航工具切向移动(即以侧翼方式)到表面是非常严格的,为了获得高度精确的近似值,通常必须妥协相邻路径的平滑性。要以平滑(g1 -连续)的方式连接相邻的路径,使用圆锥工具只能用于合理平坦的目标几何形状,例如螺旋锥齿轮,然而,对于一般的自由曲面,圆锥工具不能提供足够的自由度。在这项工作中,我们考虑了通常弯曲的、自定义形状的切割工具,其形状是由所提出的基于优化的框架计算的设计参数,以使其运动全局适应输入自由曲面,支持相邻路径之间G1连接的特征。我们在合成自由曲面和工业基准数据集上演示了我们的算法,结果表明,优化工具的形状提供了更大的灵活性,可以在相邻条之间产生G1连接,并且在近似误差和平滑度方面都优于锥形工具。
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引用次数: 0
Parametric generators of geometric models and computational meshes of Francis turbines runners 混流式水轮机流道几何模型的参数化生成器及计算网格
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-04-21 DOI: 10.1016/j.cad.2025.103886
Bohumír Bastl
In this paper, we present a fully automatic approach to generate a geometric model of a Francis turbine runner wheel based on NURBS surfaces from given shape parameters and also a fully automatic approach to generate NURBS meshes of the inner parts of the runner wheel based on NURBS volumes. All the steps of the presented approaches are described in detail, including several challenges that need to be overcome, such as e.g. obtaining conformal parameterizations of streamsurfaces or automatic determination of suitable B-spline approximation curves for representing spatial blade profiles. NURBS meshes generated by the presented method are of good quality and can be used directly for numerical simulations of incompressible turbulent fluid flows based on isogeometric analysis, or, after simple conversion to hexahedral meshes, based on finite element method. The presented approaches can also be used in automatic shape optimization algorithms for Francis turbine runners based on gradient or gradient-free approaches.
在本文中,我们提出了一种基于NURBS曲面的基于给定形状参数的水轮机转轮几何模型的全自动生成方法,以及一种基于NURBS体积的转轮内部零件NURBS网格的全自动生成方法。详细描述了所提出的方法的所有步骤,包括需要克服的几个挑战,例如获得流表面的保形参数化或自动确定合适的b样条近似曲线来表示空间叶片轮廓。该方法生成的NURBS网格质量良好,可直接用于基于等几何分析的不可压缩湍流流动的数值模拟,也可简单转换为基于有限元法的六面体网格。所提出的方法也可用于基于梯度或无梯度方法的混流式水轮机转轮形状自动优化算法。
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引用次数: 0
Augmented Sphere Tracing for Real-time Editing Mega-scale Periodic Shell-lattice Structures 实时编辑超大规模周期壳晶格结构的增强球面跟踪
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-04-02 DOI: 10.1016/j.cad.2025.103876
Jiajie Guo, Ming Li
We propose an augmented sphere tracing (AST) pipeline that seamlessly integrates editing, rendering, and slicing of mega-scale periodic shell-lattice structures. Traditional STL-based pipelines face challenges such as time-consuming format conversions, high storage requirements, and complex blending issues between discrete lattice and shell components, often resulting in a loss of geometric accuracy. Alternatively, implicit-based pipelines excel at smooth modeling and robust Boolean operations but require inefficient and error-prone conversions of STL shells into implicit forms, complicating the rendering process. To address these issues, AST combines hybrid implicit lattice and mesh shell representations, eliminating the need for explicit 3D model construction and unnecessary geometric format conversions. It overcomes the major challenges of hybrid forms and mega-scale rendering by using an augmented tracing distance query that avoids costly signed distance field (SDF) calculations while preserving geometric details. Additionally, it employs a local tracing distance query within a single cell, leveraging lattice periodicity for efficiency. The pipeline also supports various types of shell-lattices in industrial applications, including blending, warping, field-directed distributions, region-specific cell types, and produces arbitrary directional slicing for manufacturing. As demonstrated by various examples implemented in WebGPU, AST archives high efficiency and accuracy in real-time rendering of shell-lattices with billions of beams on an RTX 3090, outperforming traditional pipelines in storage, frame time, and detail preservation.
我们提出了一种增强球面追踪(AST)流水线,可无缝集成超大规模周期性壳格结构的编辑、渲染和切片。传统的基于 STL 的流水线面临着各种挑战,如耗时的格式转换、高存储要求以及离散晶格和壳组件之间复杂的混合问题,这往往会导致几何精度的损失。另外,基于隐式的管道擅长平滑建模和稳健的布尔运算,但需要将 STL 壳体转换为隐式形式,效率低且容易出错,从而使渲染过程复杂化。为了解决这些问题,AST 结合了混合隐式晶格和网格外壳表示法,无需构建显式三维模型和进行不必要的几何格式转换。它通过使用增强追踪距离查询,避免了昂贵的符号距离场(SDF)计算,同时保留了几何细节,从而克服了混合形式和超大规模渲染的主要挑战。此外,它还在单个单元内采用局部追踪距离查询,利用晶格周期性提高效率。该管道还支持工业应用中各种类型的壳晶格,包括混合、翘曲、场定向分布、特定区域的单元类型,并为制造生产提供任意方向切片。正如在 WebGPU 中实施的各种示例所证明的那样,AST 在 RTX 3090 上对具有数十亿光束的壳网格进行实时渲染时,具有很高的效率和准确性,在存储、帧时间和细节保存方面都优于传统管道。
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引用次数: 0
A salient vector field-driven part orientation selection for multi-axis 3D printing 面向多轴3D打印的显著矢量场驱动零件方向选择
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-03-23 DOI: 10.1016/j.cad.2025.103877
Don Pubudu Vishwana Joseph Jayakody , Tak Yu Lau , Hyunyoung Kim , Kai Tang , Lauren E.J. Thomas-Seale
Part orientation is a crucial element that governs the impact of several manufacturing constraints in material extrusion-based additive manufacturing (AM). Although part orientation optimisation has been extensively investigated to improve the manufacturability in 2.5-axis AM configuration, its influence on material extrusion-based multi-axis AM remains underdetermined. In this paper, we propose a computational framework to find the optimal part orientation that maximises the compliance of the tool orientation vector field with respect to several constraints required for support-free multi-axis AM. By combining topological significance, mesh saliency and curvedness metrics, we introduce a new salient feature map to formulate the link between the part orientation and the tool orientation vector field compliance. Once the optimal orientation is computed, our method enables a direct computation of a compliant iso-tool orientation vector field for a set of input iso-tool path points. We demonstrate that the part orientation can indeed be changed to minimise tool angle variation whilst adhering to overhang angle constraints for a range of 3D mesh models. The effectiveness of the proposed method is validated by comparing our method with existing tool orientation vector field design methods. Our promising results reveal the potential in part orientation optimisation as a means to address manufacturing constraints in multi-axis tool path design.
在基于材料挤压的增材制造(AM)中,零件方向是决定几个制造约束影响的关键因素。尽管为了提高2.5轴增材制造配置的可制造性,零件取向优化已经得到了广泛的研究,但其对基于材料挤压的多轴增材制造的影响仍未确定。在本文中,我们提出了一个计算框架,以找到最佳的零件方向,最大限度地提高了刀具方向矢量场的顺应性,相对于无支撑多轴增材制造所需的几个约束。通过结合拓扑显著性、网格显著性和曲率度量,引入了一种新的显著特征映射,以建立零件方向与刀具方向矢量场柔度之间的联系。一旦计算出最佳方向,我们的方法就可以直接计算一组输入等刀路径点的柔性等刀方向向量场。我们证明,零件方向确实可以改变,以尽量减少刀具角度变化,同时坚持对一系列3D网格模型的悬垂角约束。通过与现有刀具方向矢量场设计方法的比较,验证了该方法的有效性。我们有希望的结果揭示了零件定向优化作为解决多轴刀具路径设计中制造限制的一种手段的潜力。
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引用次数: 0
Physically reliable 3D styled shape generation via structure-aware topology optimization in unified latent space 通过统一潜在空间的结构感知拓扑优化生成物理可靠的三维样式形状
IF 3 3区 计算机科学 Q2 COMPUTER SCIENCE, SOFTWARE ENGINEERING Pub Date : 2025-03-12 DOI: 10.1016/j.cad.2025.103864
Haroon Ijaz, Xuwei Wang, Wei Chen, Hai Lin, Ming Li
We propose a novel approach to structure-aware topology optimization (SATO) to generate physically plausible multi-component structures with diverse stylistic variations. Traditional TO methods often operate within a discrete voxel-defined design space, overlooking the underlying structure-aware, which limits their ability to accommodate stylistic design preferences. Our approach leverages variational autoencoders (VAEs) to encode both geometries and corresponding structures into a unified latent space, capturing part arrangement features. The design target is carefully formulated as a topology optimization problem taking the VAE code as design variables under physical constraints, and solved numerically via analyzing the associated sensitivity with respect to the VAE variables. Our numerical examples demonstrate the ability to generate lightweight structures that balance geometric plausibility and structural performance with much enhanced stiffness that outperforms existing generative techniques. The method also enables the generation of diverse and reliable designs, maintaining structural integrity throughout, via a direct smooth interpolation between the optimized designs. The findings highlight the potential of our approach to bridge the gap between generative design and physics-based optimization by incorporating deep learning techniques.
我们提出了一种结构感知拓扑优化(SATO)的新方法,以生成具有不同风格变化的物理上合理的多组分结构。传统的TO方法通常在离散的体素定义的设计空间中运行,忽略了底层的结构感知,这限制了它们适应风格设计偏好的能力。我们的方法利用变分自编码器(VAEs)将几何形状和相应结构编码到统一的潜在空间中,捕获零件排列特征。将设计目标细致地表述为物理约束下以VAE代码为设计变量的拓扑优化问题,并通过分析与VAE变量相关的灵敏度进行数值求解。我们的数值示例证明了生成轻量化结构的能力,该结构能够平衡几何合理性和结构性能,并且大大增强了刚度,优于现有的生成技术。该方法还可以生成多样化和可靠的设计,通过优化设计之间的直接平滑插值,始终保持结构的完整性。研究结果强调了我们的方法的潜力,通过结合深度学习技术,弥合生成设计和基于物理的优化之间的差距。
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引用次数: 0
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