The Mechanical Modeling Of Indentation Creep Test And Creep Characterization

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.