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，可以用于汽车或工业机器人。因此，电缆的组成显著影响其机械性能。拉索各构件或各层之间的相互作用不仅会导致摩擦耗能，而且还会影响到各个加载方向上的刚度。在第一个工程部分中，发现弹塑性各向异性材料模型与全三维高次六面体单元相结合适合于模拟表现出各向异性特性的薄梁式结构。然而，对于复杂的截面，如同轴电缆，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，弯曲试验的重复性降低，这可以归因于导线在电缆中的不同取向。延续方案的目的是研究各层之间的相互作用的影响。为此，将对自组装电缆和工业电缆进行拉伸、扭转和弯曲测试。实验将在组件的每个级别分级进行。以类似的方式，工业电缆将被分层拆卸，并在拆卸的每个阶段进行测试。此外，还将构造一个新的样品夹持器，以固定各层之间的相对运动。在第一个项目部分，借助初始拉伸载荷，结果的重现性可以显著增加。这将在研究初始载荷的类型和幅度时进行系统的分析。为了建立行为模型，将对电缆的横截面进行逐层离散。在每一层上都将应用具有各个参数的单独材质模型。一方面用各向异性材料模型表示导体夹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表示保护层。参数的确定将类似于分层的实验测试。继续方案的另一个目的是研究电缆外表面与物体接触时的摩擦效应。通过将电缆沿接触伙伴的切线方向滑动以获得不同的表面，对其进行实验检验。为了提高Morar法描述接触的效率，采用自适应矩拟合法对接触力进行积分。此外，通过实现和研究用于自适应hp精化的历史数据的内插，改进了局部产生塑性的表示。

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.