Due to its computational robustness and versatility, the phase field fracture model has become the preferred tool for predicting a wide range of cracking phenomena. However, in its conventional form, its intrinsic tension-compression symmetry in damage evolution prevents its application to the modelling of compressive failures in brittle and quasi-brittle solids, such as concrete or rock materials. In this work, we present a general methodology for decomposing the phase field fracture driving force, the strain energy density, so as to reproduce asymmetrical tension-compression fracture behaviour. The generalised approach presented is particularised to the case of linear elastic solids and the Drucker-Prager failure criterion. The ability of the presented model to capture the compressive failure of brittle materials is showcased by numerically implementing the resulting strain energy split formulation and addressing four case studies of particular interest. Firstly, insight is gained into the capabilities of the model in predicting friction and dilatancy effects under shear loading. Secondly, virtual direct shear tests are conducted to assess fracture predictions under different pressure levels. Thirdly, a concrete cylinder is subjected to uniaxial and triaxial compression to investigate the influence of confinement. Finally, the localised failure of a soil slope is predicted and the results are compared with other formulations for the strain energy decomposition proposed in the literature. The results provide a good qualitative agreement with experimental observations and demonstrate the capabilities of phase field fracture methods to predict crack nucleation and growth under multi-axial loading in materials exhibiting asymmetric tension-compression fracture behaviour.
翻译:由于其计算稳健性和多功能性,阶段场断裂模型已成为预测广泛裂缝现象的首选工具,然而,以其常规形式,其内在的紧张-压压在损害演变过程中的对称性使其无法用于模拟易碎和半易碎固体(例如混凝土或岩石材料)的压缩性故障的模型。在这项工作中,我们提出了一个将阶段场断裂驱动力、紧张能量密度分解为不对称的紧张-压碎性断裂变异行为的一般方法。所提出的一般方法特别针对线性弹性固体和德拉克-压碎性故障标准的情况。 所提出的模型在测量易碎裂变变过程中的压缩性故障的能力,通过数字化地实施由此产生的紧张性能源分解配制和特别感兴趣的四个案例研究来展示。 首先,我们深入了解了该模型在预测沙勒装载下的摩擦和变差效应的能力。第二,正在进行虚拟直接的剪裁试验,以评估不同压力水平下的骨折变结性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性硬性