混凝土轴心受拉试件细观数值模拟

Mesoscopic Numerical Simulation of Axial Tensile Specimen of Concrete

为在细观层次研究混凝土轴心受拉状态下的损伤破坏机理,基于ANSYS参数化设计语言,建立了能够表征混凝土骨料随机分布和细观相材料力学参数非均匀性的混凝土轴心受拉试件细观数值模型.通过数值模拟,得到了混凝土内部微裂缝产生、发展直至试件断裂的演化过程和应力—应变曲线.结果表明,对于混凝土轴心受拉试件,虽然受到均匀拉应力的作用,但是由于骨料分布的随机性和细观相材料力学性质的差异,试件内应力和应变分布并不均匀,裂缝扩展存在弥散、集中、局部化阶段.骨料的存在既是导致裂缝产生的根源之一,又可在一定程度上阻碍裂缝的发展.本文的数值方法可以克服物理试验加载时难以对中的局限,弥补宏观层次采用均匀化方法研究的不足,有利于揭示混凝土轴心受拉损伤的破坏机理.

In order to investigate the damage and failure mechanism of concrete under axial tension, the numerical model of axial tensile concrete specimen with random distributed aggregate and meso-phases nonhomogeneous material mechanical parameters was established by the ANSYS parametric design language. The evolution process from the micro-crack appearance to growth and the final fracture of the concrete specimen, as well as the stress-strain curve were obtained through the numerical analysis. According to the analyzed results, although uniform tension stress was loaded on the axial tensile specimen of concrete, the distribution of stress and strain in the specimen is non-uniform because of the random distribution of aggregates and the difference of the mechanical properties of meso-phase materials. Th dispersion stage, concentration stage and localization stage during ere are three stages, i. e. , the propagation process of crack. Aggregates form weak interface, one hand which results in concrete crack, in other hand, the existence of aggregates has obstruction to the development of concrete crack. In physical test, it is difficult to load on the accurate center of specimen, and there is deficiency on homogenization method of concrete on macro level, the numerical method proposed in this paper can solve these problems, and is advantageous in revealing the damage and failure mechanism of concrete.