ABSTRACT

Fully mechanics based solutions are proposed to compute the bending fatigue response of asphalt mixture, based on a combination of the simplified viscoelastic continuum damage (S-VECD) theory, the classical beam theory and numerical modelling. Firstly, an S-VECD-based material constitutive model for ABAQUS is customised and validated against standard uniaxial S-VECD tests. It is able to produce fatigue damage parameters at each cycle with a given strain level. Then, based on the beam theory and strain-dependent fatigue damages at cross-section, new analytical functions are derived to calculate the flexural stiffness and bending moment. For verification, 4PB fatigue tests are conducted at different temperatures, strain levels and rest periods. With the S-VECD constitutive model, 4PB fatigue are also modelled in ABAQUS corresponding to all test conditions. Applying new analytical functions, the resultant flexural stiffness development curves are produced and compared with experimental outcome. The proposed analytical-modelling method demonstrates satisfactory accuracy at predicting flexural stiffness development curves before the initiation of bottom crack, which can also be directly interpreted by the modelling output. The work established a methodology framework for utilization of VECD theory for asphalt's bending fatigue characterization, with potential of reduced testing cost and improved mechanical compatibility.

摘要

基于简化粘弹性连续损伤 (S-VECD) 理论、经典梁理论和数值建模的结合，提出了基于全力学的解决方案来计算沥青混合料的弯曲疲劳响应。首先，针对标准单轴 S-VECD 测试定制并验证了基于 S-VECD 的 ABAQUS 材料本构模型。它能够在给定应变水平的每个循环中产生疲劳损伤参数。然后，基于梁理论和截面应变相关的疲劳损伤，推导了新的解析函数来计算抗弯刚度和弯矩。为了验证，4PB 疲劳测试在不同的温度、应变水平和休息时间进行。使用 S-VECD 本构模型，4PB 疲劳也在 ABAQUS 中建模，对应所有的测试条件。应用新的解析函数，生成弯曲刚度发展曲线并与实验结果进行比较。所提出的分析建模方法在预测底部裂缝开始之前的弯曲刚度发展曲线方面表现出令人满意的准确性，这也可以通过建模输出直接解释。该工作建立了利用 VECD 理论进行沥青弯曲疲劳表征的方法框架，具有降低测试成本和提高机械相容性的潜力。所提出的分析建模方法在预测底部裂缝开始之前的弯曲刚度发展曲线方面表现出令人满意的准确性，这也可以通过建模输出直接解释。该工作建立了利用 VECD 理论进行沥青弯曲疲劳表征的方法框架，具有降低测试成本和提高机械相容性的潜力。所提出的分析建模方法在预测底部裂缝开始之前的弯曲刚度发展曲线方面表现出令人满意的准确性，这也可以通过建模输出直接解释。该工作建立了利用 VECD 理论进行沥青弯曲疲劳表征的方法框架，具有降低测试成本和提高机械相容性的潜力。