论文标题
基于自动分化,伴随方法和加速线性代数的结构形状优化的框架
A framework for structural shape optimization based on automatic differentiation, the adjoint method and accelerated linear algebra
论文作者
论文摘要
形状优化在结构工程中具有重要意义,因为有效的几何形状会提高结构的更好性能。但是,基于梯度的形状优化在结构和建筑设计中的应用是有限的,这部分是由于梯度评估的难度和复杂性。在这项工作中,提出了基于自动分化(AD)的有效框架,提出了伴随方法和加速线性代数(XLA),以促进基于梯度的形状优化的实施。通过实现高性能计算(HPC)库JAX来实现该框架。我们利用AD在灵敏度分析阶段进行梯度评估。与数值差异相比,AD更准确。与分析和符号分化相比,AD更有效,更易于应用。另外,伴随方法用于降低灵敏度计算的复杂性。我们提出的有效的编程体系结构可以利用XLA功能,这可以提高梯度评估。提出的框架还支持硬件加速器,例如GPU。该框架应用于拱门的形式和不同形式的网格壳的形式:受曼海姆多哈尔的启发,四点支撑的烤架和类似冠层的结构。使用了两种几何描述方法:通过Bézier表面进行非参数和参数描述。考虑了非受限和约束形状优化问题,其中前者通过梯度下降解决,后者通过顺序二次编程(SQP)求解。通过这些示例,提出的框架被证明能够为结构工程师提供更有效的形状优化工具,从而为建筑环境提供更好的设计。
Shape optimization is of great significance in structural engineering, as an efficient geometry leads to better performance of structures. However, the application of gradient-based shape optimization for structural and architectural design is limited, which is partly due to the difficulty and the complexity in gradient evaluation. In this work, an efficient framework based on automatic differentiation (AD), the adjoint method and accelerated linear algebra (XLA) is proposed to promote the implementation of gradient-based shape optimization. The framework is realized by the implementation of the high-performance computing (HPC) library JAX. We leverage AD for gradient evaluation in the sensitivity analysis stage. Compared to numerical differentiation, AD is more accurate; compared to analytical and symbolic differentiation, AD is more efficient and easier to apply. In addition, the adjoint method is used to reduce the complexity of computation of the sensitivity. The XLA feature is exploited by an efficient programming architecture that we proposed, which can boost gradient evaluation. The proposed framework also supports hardware acceleration such as GPUs. The framework is applied to the form finding of arches and different free-form gridshells: gridshell inspired by Mannheim Multihalle, four-point supported gridshell, and canopy-like structures. Two geometric descriptive methods are used: non-parametric and parametric description via Bézier surface. Non-constrained and constrained shape optimization problems are considered, where the former is solved by gradient descent and the latter is solved by sequential quadratic programming (SQP). Through these examples, the proposed framework is shown to be able to provide structural engineers with a more efficient tool for shape optimization, enabling better design for the built environment.