Modelling, simulation and experimental investigation of cables

电缆是由各种组件组成的复杂系统，用途广泛，例如用于汽车或工业机器人。因此，电缆的组成对其机械性能有显著影响。索各构件或各层之间的相互作用不仅会引起摩擦耗能，而且会影响索在各个加载方向上的刚度。在项目的第一部分中，我们发现弹塑性各向异性材料模型与全三维高阶六面体单元相结合，适合于模拟具有各向异性行为的薄梁状结构。然而，对于像同轴电缆这样的复杂截面，各向异性不足以描述弯曲情况下各层之间的相互作用。在拉伸试验中，这种相互作用可以看作是粘滑效应，其中可以观察到拉力的振荡。此外，弯曲试验的再现性降低，这可能是由于电缆中导体的朝向不同。延拓方案的目的是研究各层之间相互作用的影响。为此，将对自组装电缆和工业电缆进行拉伸、扭转和弯曲试验。实验将在装配的每一级分层进行。以类似的方式，工业电缆将分层拆卸并在拆卸的每个阶段进行测试。此外，将构造一个新的样本支架，使层之间的相对运动是固定的。在第一个项目部分，在初始拉伸载荷的帮助下，结果的可重复性可以显着增加。这将在关于其类型和振幅的初始载荷的研究中进行系统的分析。为了模拟这种行为，电缆的横截面将逐层离散。在每一层一个单独的材料模型与单独的参数将被应用。一方面用各向异性材料模型来表示导体层中产生的强各向异性，另一方面用各向同性弹塑性材料模型来表示防护套。参数将以与实验测试类似的分层方式确定。延拓方案的另一个目的是研究电缆外表面与物体接触时摩擦力的影响。它将通过在不同表面的接触伙伴上切线滑动电缆进行实验检验。为了提高砂浆法描述接触的效率，采用自适应矩拟合方法对接触力进行积分。此外，通过实现和研究历史数据的自适应hp-细化插值，改进了局部产生的塑性的表示。

Cables are complex systems that consist of various components and are versatile enough to be used, for example, in automobiles or in industry robots. The composition of the cable thereby influences its mechanical properties significantly. The interaction between the components or layers of a cable results not only in energy dissipation due to friction but also influences the stiffness in various loading directions. In the first project part it was found that an elasto-plastic anisotropic material model in combination with fully 3d high-order hexahedral elements is appropriate for modelling thin beam like structures exhibiting an anisotropic behaviour. However, for a complex cross section such as for coaxial cables, the anisotropy is not sufficient to describe the interaction between the layers in bending situations. The interaction can be seen in tensile tests as the stick-slip effect, where an oscillation of the tensile force can be observed. Moreover, the reproducibility of the bending tests was reduced, which could be attributed to the different orientation of the conductors in the cable.The aim of the continuation proposal is to study the effect of the interaction between the individual layers. To this end tensile, torsion and bending tests will be conducted on self-assembled cables and industrial cables. The experiments will be conducted hierarchically at each level of the assembly. In a similar way an industrial cable will be hierarchically disassembled and tested at each stage of disassembly. Moreover, a new sample holder will be constructed such that the relative motion between the layers is fixed.In the first project part the reproducibility of the results could be increased significantly with the help of initial tensile loads. This will be analysed systematically in a study of the initial loading regarding its type and amplitude.To model the behaviour the cross-section of the cable will be discretised layer by layer. On each layer a separate material model with individual parameters will be applied. On the one hand the strong anisotropy arising in the layers containing the conductors is represented by the anisotropic material model, while on the other hand the protective jacket will be represented with an isotropic elasto-plastic material model. The parameters will be identified similarly to the experimental tests in hierarchic fashion.Another aim of the continuation proposal is to study the effect of friction when the outer surface of the cable is in contact with an object. It will be experimentally examined by gliding the cable tangentially against a contact partner for varying surfaces. To improve the efficiency of the mortar method describing the contact, an adaptive moment fitting scheme is used for the integration of the contact forces. Further, the representation of locally arising plasticity is improved by implementing and investigating the interpolation of the history data for adaptive hp-refinement.