Numerical and experimental development of an “Accelerated Repeated Rolling Wheel Load Simulator” (ARROWS)

在考虑移动荷载的柔性路面的机械设计中，特别注意实现对沥青层中由于拉伸应力而产生的疲劳现象的真实描述。如果由此产生的外部载荷超过沥青的抗疲劳性，则发生疲劳开裂。微观和宏观裂纹的萌生与温度和应力高度相关。然而，目前的实验装置表现出的应力状态和裂纹扩展的机制，强烈不同于那些存在于真实的路面。数值方法仅限于再现和描述潜在现象的单个组成部分，或者通常需要进一步发展以获得适用的结果。因此，建议的研究项目的数值实验方法和现实再现的沥青层的荷载条件下移动荷载的追求。“加速重复滚动轮荷载模拟器”（ARROWS）的数值和实验开发是研究项目的核心，旨在准确了解沥青层路面结构的使用寿命和疲劳敏感性。重点是实现对真实的加载场景下裂纹形成和裂纹扩展的真实描述，包括量级、加载速度和加载进展。在联合研究项目的初始阶段，应提供数值验证（模拟静态轮胎通过的加载条件以及由于开发的ARROWS测试设备），并将各自的加载条件进行相互比较。同时，进行了试验装置的数值概念（设计细节，操作稳定性）。此外，该装置的实验概念将进一步发展。该研究项目的重点是移动荷载下沥青混合料路面的损伤和愈合现象的实验表征和数值表示。在此基础上，应开发一个数值模型，以便对大量加载循环和长试验持续时间进行长期预测。进行实验，以确定模型参数的沥青（材料和结构）的短期和长期行为的精确描述。初始结构试验允许对所选模拟方法的长期行为预测质量进行评估;这是基于通过建造按比例缩放的ARROWS装置进行的实时加速试验。最后，将检查所获得的洞察力的假设，一个未缩放的，全尺寸的ARROWS设备的可移植性。

In the mechanistic design of flexible pavements under consideration of moving loads, particular attention is paid to achieving a realistic description of fatigue phenomena in asphalt layers due to tensile stresses. If the resulting external loading exceeds the fatigue resistance of the asphalt, fatigue cracking occurs. The initiation of micro and macro cracks is highly temperature dependant as well as stress dependant. However, current experimental setups exhibit stress states and mechanisms of crack propagation that differ strongly from those present in real pavements. Numerical approaches are limited to a reproduction and depiction of single components of the underlying phenomena or generally require further development to allow for applicable results. Therefore, the proposed research project a numerical-experimental approach and a realistic reproduction of loading conditions of asphalt layers under moving loads are pursued. The numerical and experimental development of an “Accelerated Repeated Rolling Wheel Load Simulator” (ARROWS) represents the core of the research project and aims to allow for accurate knowledge on the service life as well as the fatigue susceptibility of pavement structures with asphalt layers. The focus is on realising a realistic depiction of crack formation and crack propagation under real loading scenarios including magnitude, loading velocity and loading progressions.In the initial phase of the joint research project a numerical validation (simulation of the loading conditions from stationary tyre passes and due to the developed ARROWS testing device) shall be provided and the respective loading conditions are to be compared with one another. Simultaneously, the numerical conception of the testing device is carried out (design details, operative stability). Furthermore, the experimental conception of the device will be further developed. The focus of the research project is the experimental characterisation and the numerical representation of damage and healing phenomena of asphalt mixtures in pavements under moving loads. Based on this, a numerical model shall be developed to allow for long term predictions with a large number of loading cycles and long test durations. Experiments are conducted to identify the model parameters for a precise description of short-term and long-term behaviour of asphalt (material and structure). Initial structural tests allow for an evaluation of the prediction quality of the selected simulation approach for long-term behaviour; this is based on real-time accelerated testing by means of the construction of a scaled ARROWS device. Finally, the attained insight will be inspected with regard to transferability of assumptions to an unscaled, full-sized ARROWS device.