Untersuchungen zur Homogenisierung von Spannungsfeldern bei adaptiven Schalentragwerken mittels Auflagerverschiebung
Untersuchungen zur Homogenisierung von Spannungsfeldern bei adaptiven Schalentragwerken mittels Auflagerverschiebung
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适应 Schalentragwerken mittels Auflagerverschiebung 时的均匀化
DOI：
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发表时间：
2014
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通讯作者：
Stefan Neuhäuser
中科院分区：
文献类型：
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作者：
Stefan Neuhäuser
壳结构是轻量化结构领域中最重要的结构类型之一。假设提供了适当的几何形状和支撑条件，壳结构主要通过在其横截面上均匀分布的应力的发展来承受外力。这种所谓的膜应力状态使壳结构能够以低自重跨越很远的距离。壳结构的有效承载性能与其几何形状密切相关。在定义形状的载荷情况下，找形方法可以确定接近理想的几何形状。自重通常被认为是这种控制载荷情况。然而，当为了节约资源，自重被尽可能地减少时，临时可变和不均匀分布的荷载占主导地位。这种载荷偏离了形式定义载荷情况，导致弯矩，应力分布的不均匀性以及应力集中。在结构设计过程中，这种荷载条件通常需要应用额外的材料。这种材料在时间和地点上都是不均匀的，只有在需求高峰的极少数情况下才被充分利用。自适应结构的概念是基于这样一种方法，即工程结构的行为不是在初始设计阶段一次性确定的，而是通过主动组件的集成持续控制结构响应。结构的激活主要集中在力和应力状态的操纵，位移以及振动的控制。这种方法允许结构对时间和空间变化的荷载作出反应，以优化荷载承载性能。因此，结构元件的设计可以大大降低需求，理想情况下，与被动结构相比，可以节省大量材料。本文的研究课题是点支壳结构承载性能的主动控制。这种操作的目标是应力场的均匀化和控制设计的最大应力的最小化。在所提出的工作的背景下，研究了支撑的主动位移作为这种操作的手段。使用数值优化程序确定最佳激活过程。对全局随机过程（模拟退火算法）和基于梯度的确定性算法进行了研究和比较。由于结构位移较大，考虑了非线性效应
Shell structures represent one of the most important structural typologies in the field of lightweight structures. Assuming proper geometry and support conditions are provided, shell structures carry external forces primarily via the development of stresses evenly distributed over their cross section. This so-called membrane state of stress enables shell structures to span large distances with low self-weight. The efficient load-carrying behaviour of a shell structure is strongly correlated to its geometry. Form-finding methods, under the application of a form-defining load case, allow for the determination of nearly ideal geometries. Self-weight is commonly considered to be this governing load case. When, however, in the interest of the conservation of resources, self-weight is reduced to the greatest extent possible, temporally variable and unevenly distributed loads predominate. Such loads deviate from the form-defining load case and lead to bending moments, inhomogeneities in the stress distribution as well as stress concentrations. During the design of the structure, such loading conditions typically require the application of additional material. This material is stressed inhomogeneously with respect to both time and location, and is utilized fully only on the rare occasions of peak demand. The concept of adaptive structures is based on the approach that the behaviour of an engineering structure is not established once during the inital design phase, but rather that the structural response is controlled continuously via the integration of active components. The activation of the structure focuses on the manipulation of the force and stress states, the displacements as well as the control of vibrations. This approach allows the structure to react to temporally and spatially variable loads with the goal of optimising the load-carrying behaviour. The design of the structural elements can thus be carried out for significantly reduced demands, ideally resulting in substantial material savings in comparison with passive structures. The subject of this dissertation is the active manipulation of the load-carrying behaviour of point-supported shell structures. The goal of this manipulation is the homongenisation of the stress fields and the minimisation of the maximum stresses governing the design. Within the context of the work presented, the active displacement of the supports is investigated as a means for this manipulation. The optimal activation processes are determined using numerical optimisation procedures. Both a global, stochastic procedure (Simulated Annealing algorithm) as well as a deterministic, gradient-based algorithm are investigated and compared. Due to the large displacements of the structure, nonlinear effects are considered