【作者】 刘硕；

【导师】 孙毅；

【作者基本信息】 哈尔滨工业大学 ， 固体力学， 2007， 硕士

【摘要】 压痕实验是一种可以检测和评定材料多种力学性能的实验方法。通过压痕实验可以连续测定材料的载荷-位移曲线,进而评定其硬度,弹性模量,屈服强度,塑性等性能。由于它简单易行,成本低廉,可信度高,在同一试件上可以多次实验,能弥补传统实验方法的不足又不具破坏性等种种优点,压痕实验在各行各业都有着广泛的应用,业已成为工业界和科研领域对材料性能表征的标准方法和研究手段。本文采用压痕实验来研究材料的蠕变性能。目前获得材料蠕变参数的标准实验是单轴拉伸蠕变测试,需要大量的试样和测试时间,而采用压痕蠕变测试技术仅需要很小体积的材料,试样的制备也非常简单。另外对于薄膜这类本身体积很小的材料,或者难于加工的陶瓷等高硬度或者脆性材料以及类似于铅之类的非常软的材料,如果仅需要考察材料的局部的蠕变性能,也只能通过压痕蠕变来获得其蠕变性能参数。因此采用压痕实验来研究材料蠕变是非常有意义的。应用Zwick ZHU 2.5压痕仪器对一种力学性能未知的有机玻璃分别进行了压痕实验和压痕蠕变实验,得到其载荷—位移曲线和压痕深度—时间曲线,从曲线中取得数据进行处理,得到了该有机玻璃的弹性模量和蠕变指数。对实验过程进行了有限元仿真,对比弹性模量和蠕变指数的仿真值,仿真结果与实验结果相比非常接近,证明了用有限元的方法来仿真压痕实验是非常可靠的。最后提出了一种通过压痕蠕变实验和有限元仿真相结合来计算材料的蠕变常数的方法。通过有限元仿真曲线与实验曲线的对比表明:本文提出的采用压痕实验来计算材料蠕变参数的方法是准确可行的,其计算结果可以满足工程的需要。这说明用压痕实验来测量材料蠕变性能是准确可行的,由于压痕实验适用于难以加工成标准试件的材料,可以表征材料表面微区力学性能,具有经济方便、可信度高、不具破坏性等种种优点,假以时日必将发展成为测量材料蠕变性能的标准实验。更多还原

【Abstract】 Indentation test has seen a broader application in physics, materials science, mechanics and other areas. With it, the structure, mechanics and dynamics response of materials to external loading can be determined. Thus it can be employed to obtain many mechanical properties, such as the hardness, elastic modulus, yield strength, plastic properties etc. In addition, due to its simple implementation, low cost, high validity and the possibility of many tests on one specimen, indentation experiment is regarded as a standard technique in industry and scientific research field.In this paper, we take indentation test to study the creep properties of materials. Early method, which depends on uniaxial tensile to obtain the creep parameters, usually requires a large mount of samples and time. However, those drawbacks prevent its applications on many specimens, such as film with small volume, ceramic, stiff or brittle materials and some soft materials like plumbum, etc. Therefore indentation test, which needs only a small specimen, can be employed to evaluate the creep properties. The preparation of samples is also very simple. In addition, if we want to consider the local creep properties, indentation test is the only way to achieve that. From the description above, indentation test is a very significant experimental technique to study the creep of materials.Zwick ZHU 2.5 indentation apparatus is employed to do some indentation experiments and indentation creep experiments for organic glass with the unknown mechanical properties, its load-displacement curve and the indentation depth-time curve are obtained, the data of the curve are processed, and then the elastic modulus and creep exponential of the organic glass are obtained. Then the experimental process of finite element simulation is made, contrast elastic modulus and creep exponential value of the simulation, Simulation results compared with the experimental results are very close, the finite element method is proved that simulation indentation experiment is very reliable. Finally a method is presented to calculate the creep constant with the creep experiment and FEM combined. Compared with finite element simulations and experimental data, the validity of our technique has been proved, i.e., the calculation method proposed to calculate creep parameter by indentation experiment is feasible and the calculated results can satisfy the need of the engineering. That indicates that measuring materials creep properties by the indentation test is feasible, and indentation experiment is apply to process the materials which can not be made into standard samples, it can characterize the surface micro-mechanical properties, and it has a lot of advantages, such as economically convenient, high credibility, not destructive and so on, it will become the standard experiment to test the material’s creep properties in the future.更多还原