动载作用下沥青混凝土的非线性疲劳损伤

发布时间：2018-04-14 08:27

本文选题：沥青混凝土 + 动态弹性模量场　；参考：《合肥工业大学》2017年硕士论文

【摘要】：现行的沥青混凝土疲劳寿命预估多采用室内弯拉或间接拉伸疲劳试验,但是试验具有周期长、成本较高、技术手段难以推广等不足。因此,通过有限元方法结合疲劳损伤力学进行研究具有实际意义,能更好地解释沥青路面在重复动载下的破坏机理。首先,根据不同加载速率下沥青混凝土的单轴压缩荷载-变形曲线,建立相同加载工况的有限元模型,反算出对应加载时刻的动态弹性模量,从而得到以加载速率和应力状态为自变量的动态弹性模量场模型,并编写相应的VUMAT子程序。将其应用于沥青混凝土劈裂试验表征其材料非线性;将其应用于沥青混凝土三分点加载弯拉试验,用来预估不同加载速率下的弯拉强度。其次,编写三参数粘弹性模型VUMAT子程序,对不同应变率加载下的沥青混凝土应力-应变曲线识别出对应的粘弹性参数,得到率相关粘弹性参数模型,并用相同试验的另一组数据验证模型的正确性。将其应用于沥青混凝土的弯拉和间接拉伸两种工况进行仿真,得到的最大弯拉应力幅值与试验强度进行比较,验证其适用性。再次,在率相关粘弹性参数模型的基础上,建立以沥青混凝土层底弯拉应力为自变量的疲劳损伤模型,并对弯拉和间接拉伸两种工况的疲劳寿命进行预估,且与传统的S-N曲线预估法进行比较。最后,根据骨料二维轮廓和五截面法构建三维数值骨料,将待投骨料几何模型预先离散为网格形式进行投放;根据沥青砂浆在不同应变率下的应力-应变曲线,得到应变率相关的粘弹性参数公式;采用以沥青砂浆第一主应力为自变量的细观疲劳损伤模型,分析沥青混凝土在动载作用下的多点损伤分布。
[Abstract]:The current fatigue life of asphalt concrete is mainly estimated by indoor flexural fatigue test or indirect tensile fatigue test, but the test is short of long cycle, high cost and difficult to be popularized.Therefore, it is of practical significance to study the fatigue damage mechanics by means of finite element method, which can better explain the failure mechanism of asphalt pavement under repeated dynamic loads.Firstly, according to the uniaxial compression load-deformation curve of asphalt concrete under different loading rates, the finite element model of the same loading condition is established, and the dynamic elastic modulus corresponding to the loading time is calculated back.The dynamic elastic modulus field model with the loading rate and the stress state as the independent variable is obtained and the corresponding VUMAT subprogram is written.It is applied to the splitting test of asphalt concrete to characterize its material nonlinearity, and to the flexural tensile test of asphalt concrete under three-point loading to predict the flexural tensile strength at different loading rates.Secondly, the three-parameter viscoelastic model VUMAT subroutine is written to identify the corresponding viscoelastic parameters for the stress-strain curves of asphalt concrete under different strain rates, and the rate-dependent viscoelastic parameter model is obtained.Another set of data from the same experiment was used to verify the correctness of the model.The maximum flexural stress amplitude of asphalt concrete is compared with the test strength to verify its applicability.Thirdly, on the basis of the rate-dependent viscoelastic parameter model, the fatigue damage model is established, which takes the bending tensile stress of asphalt concrete bottom as the independent variable, and the fatigue life of the flexural tension and indirect tension is forecasted.And compared with the traditional S-N curve prediction method.Finally, according to the two-dimensional profile of aggregate and the five-section method, the three-dimensional numerical aggregate is constructed, and the geometric model of the aggregate is discretized as a grid form, and the stress-strain curve of asphalt mortar at different strain rates is obtained.The viscoelastic parameter formula related to strain rate is obtained and the multi-point damage distribution of asphalt concrete under dynamic loading is analyzed by using the meso-fatigue damage model with the first principal stress of asphalt mortar as the independent variable.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.42

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