用自编码器加速弹性结构拓扑优化,预测初值显著减少迭代次数。
A surrogate model for topology optimisation of elastic structures via parametric autoencoders
- 通过自编码器将参数化问题映射到低维隐空间,快速生成近优解
- 相比高保真优化器平均减少53%迭代次数,目标函数误差低于4%
- 适合需要快速生成结构设计的工程应用,尤其擅长外推未知参数域
针对线性弹性结构在参数化载荷与边界条件下的拓扑优化,提出一种基于代理模型的算法。该方法不直接学习状态或伴随问题的参数解或优化轨迹,而是构建整个优化流程的代理模型。首先,利用前馈网络学习系统参数到由编码器-解码器块定义的隐空间的映射,预测给定配置下的准最优拓扑,作为均质化法优化得到的高保真拓扑的代理。随后,将预测拓扑作为初始猜测,采用计算高效的惩罚中间设计变量值并满足控制方程的算法进行修正,以消除代理模型引入的误差和伪影,实现物理一致性优化。评估了不同架构的逼近与泛化能力。结果表明,该方法在测试时外推至训练与验证域之外仍能实现平均迭代次数降低53%,目标函数最优值偏差低于4%。
原文摘要 · Abstract (English)
A surrogate-based topology optimisation algorithm for linear elastic structures under parametric loads and boundary conditions is proposed. Instead of learning the parametric solution of the state (and adjoint) problems or the optimisation trajectory as a function of the iterations, the proposed approach devises a surrogate version of the entire optimisation pipeline. First, the method predicts a quasi-optimal topology for a given problem configuration as a surrogate model of high-fidelity topologies optimised with the homogenisation method. This is achieved by means of a feed-forward net learning the mapping between the input parameters characterising the system setup and a latent space determined by encoder/decoder blocks reducing the dimensionality of the parametric topology optimisation problem and reconstructing a high-dimensional representation of the topology. Then, the predicted topology is used as an educated initial guess for a computationally efficient algorithm penalising the intermediate values of the design variable, while enforcing the governing equations of the system. This step allows the method to correct potential errors introduced by the surrogate model, eliminate artifacts, and refine the design in order to produce topologies consistent with the underlying physics. Different architectures are proposed and the approximation and generalisation capabilities of the resulting models are numerically evaluated. The quasi-optimal topologies allow to outperform the high-fidelity optimiser by reducing the average number of optimisation iterations by $53\%$ while achieving discrepancies below $4\%$ in the optimal value of the objective functional, even in the challenging scenario of testing the model to extrapolate beyond the training and validation domain.
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