Investigation of the damage caused by wire contact points and its influence on the safety of running high-strength ropes

该研究项目的目的是有助于澄清具有不同静态钢丝强度的动态加载（运行）钢丝绳的失效原因，特别关注钢丝接触点和压椭圆的影响。目前，在运行绳索的绳索技术中，绳子的张力载荷与绳索的标称强度相比，被认为是疲劳行为的重要指标。这导致了对使用寿命的错误估计，特别是在高强度钢丝绳的情况下，正如文献和我们自己的初步调查结果所显示的那样。目前认为钢丝绳强度越高，使用寿命越长的预测是错误的；其实是降低了使用寿命！先前忽略了不同强度钢丝的不同变形能力，从而假定了使用寿命估计中的这种矛盾。在初步的研究中，对于单个钢丝绳，基于应变的使用寿命考虑可以解决现有的问题，并提供可靠的，安全相关的设计。根据初步试验，我们假设钢丝绳的断裂也是由于超过了钢丝绳的临界伸长而引起的。在申请的研究项目中，将开发一种新的确定损伤形成和绳索破坏的方法。对于该方法的开发，将使用相关科学中已经使用的方法，即部件失效受最大可容忍塑性变形的限制。这意味着部件在运行过程中积累的塑性应变，包括之前的变形，决定了损伤的发展，最终决定了使用寿命。计划研究项目的解决方法是，不同强度的绳索在拉伸试验中的相对应力-应变曲线可以得到其使用寿命的指示，直到断裂。目的是证明不同强度钢丝的塑性变形对其制成的绳的使用寿命的影响。特别关注的是接触点和压椭圆对绳索疲劳行为的形成和影响。这种新颖的研究方法将被调查和验证。

The objective of the research project is to contribute to the clarification of the cause of failure in dynamically loaded (running) wire ropes with different static wire strengths, with special focus on the influence of wire contact points and press ellipses.Currently, in rope technology for running ropes, the rope tension load in comparison with the nominal rope strength is regarded as significant for the fatigue behaviour. This leads to an incorrect estimation of service life, especially in the case of high-strength wire ropes, as shown by the literature and the results of our own preliminary investigations. The current prediction that higher wire strengths lead to an increased rope service life is wrong; in fact, the service life is reduced! This contradiction in the estimation of service life is presumed in the previous neglect of the different deformability of wires of different strengths.In preliminary investigations it could be shown for the individual rope wire that a strain-based consideration of service life can solve the existing problem and provide a reliable, safety-related design. Based on the preliminary tests, we assume that rope failure is also caused by exceeding a critical elongation in the rope wires. In the research project applied for, a new method for determining the formation of damage and rope failure is to be developed. For the development of the method, the approach already used in related sciences, namely that component failure is limited by a maximum tolerable plastic deformation, is to be used. This means that the plastic strain accumulated during component operation, including previous deformations, determines the damage development and finally the service life. The solution approach of the planned research project is that indications of the service life of ropes of different strengths can be obtained from their relative stress-strain curves in tensile tests until breakage. The aim is to prove the influence of the plastic deformation of wires of different strengths on the service life of a rope manufactured from them. Special attention is focused on the formation and effect of contact points and press ellipses on the fatigue behaviour of ropes. This novel research approach will be investigated and validated.