The influence of pressure reduction rates on the damage behaviour ofhydraulic components

降压率对液压元件损伤行为的影响

• 批准号: 449676223
• 负责人: Professor Dr.-Ing. Marcus Geimer
• 金额: --
• 依托单位: Institutsteil Mobile Arbeitsmaschinen
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/449676223?language=en
• 关键词: influence; pressure; reduction; rates; damage

The proposed research project generates scientific findings on crack formation behaviour of a component in contact with hydraulic fluid at pressure reduction rates of up to 1,000,000 bar/s. The main objective of the project is to create an understanding of the effects that lead to premature failure due to high-pressure degradation rates. The current state of research is contradictory with its presented theories and results. The differences between the theories are investigated on a macro- and microscopic level. Thus, the hypothesis of the wedge effect of oil on components with pressure-induced deformation can be verified or falsified. Within this research project the theoretical fundamentals can be developed which lead to a damage theory for those hydraulic components.Based on own preliminary work, the effects occurring in the crack gap are simulated with the help of simulation methods and further analysed. The focus will be on the investigation of the crack closing behaviour during pressure reduction under consideration of realistic pressure reduction rates and crack geometries. As an object of investigation, crack growth is conceivable with the simplified geometry of a high-pressure measuring port of an axial piston pump closed with a threaded plug. A fluid-structure interaction model is used as a simulation approach, which can interact the occurring mechanical and fluidmechanical processes. With the aid of a fluid-structure interaction model and with extension of the same with regard to the closing behaviour of the gap, the modelling of crack propagation and the modelling of small gap heights, an understanding of the described crack behaviour is built up and damage mechanisms are investigated. By applying similarity theories, substitute systems (variation of geometry and oil viscosity) are derived, which show a physically comparable behaviour under congruent loading while reducing the required computing resources. The simulation results serve the derivation of the analytical fundamentals for a safe prediction of the component load as a function of the pressure drop rate. Furthermore, the simulation is able to identify the underlying damage mechanisms of accelerated crack growth.By exemplary pressure pulse tests of the considered components the parametrisation of the simulation model and the verification of the assumptions are verified. Component samples are prepared and pointed cracks are induced. The pressure pulses are generated in accordance with the loads occurring in the simulation, taking valid standards into account.

拟议的研究项目产生了关于与液压流体接触的部件在高达1，000，000 bar/s的减压速率下的裂纹形成行为的科学发现。该项目的主要目标是了解高压降解率导致过早失效的影响。目前的研究状况与其提出的理论和结果是矛盾的。理论之间的差异进行了研究，在宏观和微观层面上。因此，可以验证或证伪油对压力引起变形的部件的楔效应的假设。在本研究项目中，可以发展的理论基础，导致这些液压元件的损伤理论。在自己的初步工作的基础上，发生在裂纹间隙的影响进行了模拟的帮助下，模拟方法和进一步分析。重点将是在考虑现实的减压率和裂纹几何形状的情况下，在减压过程中的裂纹闭合行为的调查。作为研究对象，可以想象，在用螺纹塞封闭的轴向活塞泵的高压测量端口的简化几何形状下裂纹扩展。一个流体-结构相互作用模型被用作一种模拟方法，它可以相互作用发生的机械和流体力学过程。借助于流体-结构相互作用模型，并在差距的闭合行为、裂纹扩展的建模和小间隙高度的建模方面对其进行扩展，建立对所描述的裂纹行为的理解，并研究损伤机制。通过应用相似理论，替代系统（几何形状和油粘度的变化）的推导，这表明在一致的负载下，同时减少所需的计算资源的物理可比的行为。模拟结果用于推导分析基本原理，用于安全地预测作为压降率的函数的部件负载。通过对所考虑构件的典型压力脉冲试验，验证了仿真模型的参数化和假设的正确性。制备了构件试样，诱发了点裂纹。压力脉冲根据模拟中出现的负载产生，并考虑有效标准。