Increased Reliability for Industrially Relevant Automatic Crack Growth Simulation with the eXtended Finite Element Method

该项目将提供新的计算建模工具，使从事安全关键结构的工程师能够合理评估裂纹起裂和裂纹扩展的影响。到目前为止，这些问题仍然难以解决。这项研究将使人们对裂缝传播有前所未有的了解，从而提供更保守的设计，最重要的是避免服务中不可预测的灾难性故障。扩展有限元法（XFEM）是一种革命性的模拟工具，用于对不连续结构进行建模，与传统方法相比，它所需的工程时间可能要少一个数量级。然而，这种新方法需要大量的可靠性改进才能进入工业应用。通过利用最近的理论和数值发展，并与未来的用户携手合作，该项目有可能为XFEM提供所需的准确性和鲁棒性，使其成为结构完整性预测的新选择工具，并协调准确性和计算可追溯性。裂缝或缺陷几乎总是存在于工程结构中。例如，在航空航天工程中，在飞机的使用寿命期间（起飞、飞行和降落），这些裂缝将在施加于结构的力的影响下增长。工程师们如何确保在裂缝越来越大的情况下，飞机仍能安全运行？他们的想法是定期检查飞机，监测主要裂缝。下一个问题是要知道飞机应该多久检查一次，以防止两次检查之间发生灾难性故障。为了回答这个问题，工程师必须能够评估裂缝对结构造成致命影响所需的时间（飞行次数）。如果飞行次数为1000次，最大巡检间隔应小于1000次。为了估计故障发生的时间，工程师们使用计算机方法，通过各种简化方法对结构的行为进行建模：这就是所谓的损伤容限分析（DTA）。然而，今天，现有的软件仍然无法为工程师提供一个合理的工具来评估结构的损伤容忍度。这项研究的长期目标是提供这种工具，它可以为工程师模拟裂缝的方式提供一种范式转变，即足够的精度不会等同于难以处理的计算时间或人力。

This project will deliver new computational modelling tools that will allow engineers working onsafety critical structures to rationally assess the effects of crack initiation and crack propagation. Suchproblems have to date remained intractable. The research will permit unprecedented understanding of crackpropagation, thereby delivering less conservative designs, and, most importantly avoid unpredictedcatastrophic failures in service. This is possible by building upon the recent success of the extended finite elementmethod (XFEM), which has emerged as a revolutionary simulation tool for modelling discontinuities and has the potential to require an order of magnitude less engineering time than conventional methods.Yet, this new method requires much reliability improvements to invade industry. By leveraging recent theoreticaland numerical developments and working hand-in-hand with future users, this project has the potential toprovide XFEM with the accuracy and robustness it requires to become the new tool of choice for structuralintegrity predictions and reconcile accuracy and computational tractability.Cracks or defects are almost always present in engineering structures. In aerospace engineering for instance, during the life of the aircraft (take offs, flights and landings), these cracks will grow under the influence of the forces applied to the structure. How do engineers ensure that, despite these growing cracks, the aircraft can still be operated safely? The idea is to regularly inspect the aircraft to monitor the major cracks. The next question is to know how often should an aircraft be inspected to prevent catastrophic failure between two inspections. To answer this question, engineers must be able to evaluate the time (number of flights) it takes for the cracks to become fatal to the structure. If it takes 1,000 flights, the maximum inspection interval should be less than 1,000. To estimate the time to failure, engineers use computer methods, where they model the behaviour of the structure using various simplifications: this is known as Damage Tolerance Analysis (DTA).However, today, existing software are still unable to provide engineers with a rational tool to assess the tolerance of a structure to damage. The proposed research has the long-term goal to provide this tool which could provide a paradigm shift in the way engineers think about simulating fracture, whereby sufficient accuracy would not be synonymous with intractable computational time or manpower.