无定形水化硅酸钙纳米压痕模拟及卸载段处理

基于预测水泥及其水化物体积性能的简化物理模型Wittmann模型，结合分子动力学研究方法，构建水 化硅酸钙(C-S-H)凝胶模型用来模拟纳米压痕实验．在弛豫阶段使用高温淬火方法将模型转变为无定形态，并 测定模型高温淬火前后的径向分布函数，确定了无定形态下的水化硅酸钙(C-S-H)压痕模型，计算得出荷载深 度曲线 （P-h 曲线）．考虑到高温淬火对模型内粒子热力学运动的影响以及带来的位错效应，分别采用 OliverPharr方法与 Cheng-Cheng 方法对荷载深度曲线的卸载段进行分析处理．其中 Oliver-Pharr方法计算得到硬度 H 为 0.92 GPa，折合模量 Er为 29.56 GPa；Cheng-Cheng方法计算得到折合模量 Er为(34.92±7.57) GPa．与文献结 果及标准试块实验结果进行对照，探究两种计算方法的合理性及适用范围，并提出研究展望

Simulation of Nanoindentation and Analysis of Unloading Section of Amorphous Calcium Silicate Hydrate (C-S-H)

Based on the Wittmann model, which is a simplified physical model to predict the volume performance of cement and its hydration, and combined with the molecular dynamics method, a calcium silicate hydrate (C-S-H) gel model was constructed to simulate the nano indentation test. In the relaxation stage, the model was transformed into an amorphous form by high-temperature quenching method, and the radial distribution function before and after high-temperature quenching was measured to determine the indentation model of calcium silicate hydrate (C-S-H) of amorphous form, leading to the attainment of the load depth curve (P-h curve). In consideration of the dislocation effect caused by high temperature quenching which has an influence on the thermodynamic motion of particles in the model, the unloading section of the load depth curve was analyzed and treated by both the Oliver-Pharr method and the Cheng-Cheng method. The hardness H calculated by Oliver-Pharr method was 0.92 GPa and the reduced modulus Er was 29.56 GPa. The reduced modulus Er calculated by Cheng-Cheng method is (34.92±7.57) GPa. The rationality and application range of the two calculation methods were explored by comparing the results with those in the literature as well as from the experiments on standard blocks. Finally some research prospects were given