Modelling of metalic seal seats

静密封阀座在许多流体应用中是非常重要的机械元件。他们的基本任务是防止不必要的泄漏。密封阀座可分为软密封(主要基于弹性体)和硬密封触点(即金属触点)。尽管硬密封金属触点的组成非常简单，但到目前为止，还不可能根据设计和运行参数可靠地预测泄漏。硬密封组件的一个重要应用可以在阀座阀门中找到。这种阀门的一种常见用途是在移动液压中作为负载保持阀，以防止意外的与安全相关的机器移动。阀座阀门的设计是基于专家的专业知识和经验。这导致尺寸朝向安全侧，从而导致密封座在S作用力和几何形状方面尺寸过大。其结果是不必要的大安装空间，降低了动力学，并且大多数情况下阀门的疲劳强度有限。所谓的接触力学理论能够对软密封接触进行建模，并能正确预测由此产生的泄漏。本项目的目的是将接触力学理论应用于硬密封接触，推导出描述金属密封阀座的通用模型。其结果是一个具有物理动机的理论概念，其中包括塑性变形和表面粗糙度等参数。为了开发和验证通用接触模型，将设计和建造试验台，以便分别调查不同的参数并将测量结果与模型进行比较。此外，还进行了多维有限元和CFD模拟，以获得无法测量的验证参数。得到了描述硬密封接触的改进模型，并通过实际应用试验台进行了验证。从科学的角度，提出了描述接触副之间接触机理的方法。另一方面，为金属密封阀座的深入发展和阀座阀门的整体进步奠定了基础。这是通过开发一种描述硬-硬接触接触机理的方法来实现的。该方法和结果可望应用于具有类似接触区域(过盈配合、螺栓连接等)的其他工程领域。

Static sealing seats are machine elements of high importance in a number of fluid applications. Their essential task is to prevent unwanted leakage. Sealing seats can be classified into soft sealing, mostly based on elastomers, and hard sealing contacts, i.e. metallic contacts. Even though the composition of a hard sealing metallic contact is very simple, it is impossible to reliably predict the leakage based on design- and operating parameters to this date.An important application for hard sealing components can be found in seat valves. One common use of this valve type is in mobile hydraulics as load holding valves in order to prevent accidental safety relevant machine movements. The design of a seat valve is based on expert know-how and experience. This leads to a dimensioning towards the safe side and therefore to an oversizing of the sealing seat regarding it´s force and geometry. The result is an unnecessary large installation space, decreased dynamics and most times a limited fatigue strength of the valve.A new approach to describe two contact partners was developed by Dr. Bo Persson. The so-called contact mechanics theory is able to model soft sealing contacts and predict the resulting leakage correctly.Goal of this project is to apply the contact mechanics theory for hard sealing contacts and derive a general model to describe metallic sealing seats. The result is a theoretical concept with a physical motivation which includes parameters such as plastic deformation and surface roughness. For the development and validation of the general contact model, test rigs will be designed and built in order to investigate varying parameters separately and to compare the measurements with the model. Additionally, multi-dimensional FEM and CFD simulations are performed to obtain parameters for the validation, which cannot be measured. The results lead to an enhanced model describing hard sealing contacts, which is validated consecutively by a real application test rig.Scientifically, the description of the contact mechanics between two contact partners is advanced on the one hand. On the other hand the basis for a profound development of metallic sealing seats and the holistic advancement of seat valves is established. This is achieved by the development of a method which describes the contact mechanics of hard-hard-contacts. This method together with the resulting findings is expected to be applicable to other engineering fields with similar contact areas (interference fit, bolted connections etc.).