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面向增材制造的晶格结构优化:制造约束驱动及帕累托前沿构建

Lattice Structure Optimization for Additive Manufacturing: Manufacturability-Driven Design and Pareto Front Construction

  • 摘要: 晶格超材料为轻量化与多功能结构设计提供了重要支撑,增材制造为复杂晶格几何的实现提供了技术条件。然而,面向增材制造的多物理晶格单胞设计仍面临两方面问题:一方面,现有方法难以在有限计算预算下高效构建覆盖充分的多目标帕累托前沿;另一方面,悬垂、封闭空腔和受限排粉通道等制造约束压缩了可行设计空间。为此,提出制造约束驱动的晶格结构优化方法及帕累托前沿构建方法。首先,在逆均匀化框架下将制造约束以可微形式嵌入拓扑优化,在同一优化过程中兼顾物理性能与制造可行性;然后,提出渐进式帕累托前沿构建机制,由密度生成网络学习高质量晶格结构的潜在表示,对相邻非支配解的潜在表示进行插值,并将解码结果作为后续拓扑优化的初始密度场。新获得的非支配解用于更新网络和样本集,推动可制造帕累托解集逐步扩展。三维周期晶格单胞上的实验表明,在相同的1000次优化预算下,网络初始化策略优化成功率为92.60%,而随机初始化策略为78.30%;网络初始化策略获得916个可制造样本,超过随机初始化策略的776个;同时,网络初始化策略的帕累托前沿超体积指标为0.078 7,高于随机初始化策略的0.067 5。结果表明,所提方法能够在考虑制造约束的条件下高效构建多物理性能帕累托前沿,并获得覆盖范围更充分的可制造非支配解集。

     

    Abstract: Lattice metamaterials provide an important foundation for lightweight and multifunctional structural design, while additive manufacturing enables the fabrication of complex lattice geometries. However, multiphysics lattice unit-cell design for additive manufacturing still faces two challenges. First, existing methods struggle to efficiently construct multi-objective Pareto fronts with adequate coverage under limited computational budgets. Second, manufacturing constraints, including overhangs, enclosed cavities, and restricted powder-removal channels, reduce the feasible design space. To address these challenges, a method driven by manufacturing constraints is proposed for lattice structure optimization and Pareto front construction. First, manufacturing constraints are incorporated into topology optimization in a differentiable form within an inverse homogenization framework, allowing physical performance and manufacturability to be considered within the same optimization process. Then, a progressive Pareto front construction mechanism is developed. A density generation network learns latent representations of high-quality lattice structures; the latent representations of neighboring nondominated solutions are interpolated, and the decoded density fields are used to initialize subsequent topology optimization. Newly obtained nondominated solutions are used to update the network and the sample set, progressively expanding the set of manufacturable Pareto solutions. Experiments on three-dimensional periodic lattice unit cells show that, under an identical budget of 1,000 optimization runs, the network initialization strategy achieves an optimization success rate of 92.60%, compared with 78.30% for random initialization. It yields 916 manufacturable samples, compared with 776 obtained through random initialization. The Pareto front obtained through network initialization has a hypervolume of 0.078 7, exceeding the value of 0.067 5 obtained through random initialization. These results demonstrate that the proposed method can efficiently construct Pareto fronts for multiple physical properties while accounting for manufacturing constraints and obtain manufacturable nondominated solution sets with broader coverage.

     

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