论文标题
对称弹性框架分叉分析的群体理论方法
A group-theoretic approach to the bifurcation analysis of elastic frameworks with symmetry
论文作者
论文摘要
我们提出了一种用对称性的弹性框架分叉分析的一般方法。尽管对对称性分叉问题的组理论方法是众所周知的,但它们在弹性框架背景下的实际实现并不直接。我们考虑包含Cosserat杆组合的框架,主要难度是由于存在(横截面)旋转场而引起的非线性配置空间。我们通过一位作者先前开发的单杆公式避免这种情况,从而将管理方程式嵌入到线性空间中。场方程包括所有杆方程的组装,并在关节处得到兼容和平衡条件。我们在对称组的动作下证明了它们的均衡性,并且在线性空间环境中,群体理论方法的实现现在是自然的。所有潜在的通用,对称性分叉均被预测。然后,我们采用一个开源路径遵循代码,该代码可以检测并计算简单的,二二二匹配的分叉;多个分叉点超出了其能力。对于后者,我们构建了由适当的子结构实现的对称性降低的问题。简单地将多个分叉化渲染,并且遵循路径的代码再次适用。我们首先分析了一个简单的三脚架框架,提供了我们方法论的所有细节。然后,我们通过相同的方法处理六边形空间框架。三脚架和六角圆顶都表现出简单和双分叉点。
We present a general approach to the bifurcation analysis of elastic frameworks with symmetry. While group-theoretic methods for bifurcation problems with symmetry are well known, their actual implementation in the context of elastic frameworks is not straightforward. We consider frames comprising assemblages of Cosserat rods, and the main difficulty arises from the nonlinear configuration space, due to the presence of (cross-sectional) rotation fields. We avoid this via a single-rod formulation, developed earlier by one of the authors, whereby the governing equations are embedded in a linear space. The field equations comprise the assembly of all rod equations, supplemented by compatibility and equilibrium conditions at the joints. We demonstrate their equivariance under the symmetry-group action, and the implementation of group-theoretic methods is now natural within the linear-space context. All potential generic, symmetry-breaking bifurcations are predicted apriori. We then employ an open-source path-following code, which can detect and compute simple, onedimensional bifurcations; multiple bifurcation points are beyond its capabilities. For the latter, we construct symmetry-reduced problems implemented by appropriate substructures. Multiple bifurcations are rendered simple, and the path-following code is again applicable. We first analyze a simple tripod framework, providing all details of our methodology. We then treat a hexagonal space frame via the same approach. The tripod and the hexagonal dome both exhibit simple and double bifurcation points.