Indentation Contact Mechanics Applied to Characterizing and Analyzing The Mechanical Properties of Engineering Materials

压痕接触力学已经被广泛地应用于表征和分析金属、陶瓷和聚合物的机械性能。这些力学性能包括弹性、塑性、弹塑性、粘度、粘弹性和超塑性。项目的主要成果概述如下：(a)弹塑性接触力学（a1）锥体/锥形压头的弹塑性本构方程从理论上推导出来，并通过实验加以检验。（a2）从理论上提出了“真硬度”作为衡量塑性的指标，并通过实验证实了“真硬度”是表征“塑性”的有效微纳参数。（a3）工程材料弹塑性特性的测试方法和测试仪器较为发达。(b)粘弹性接触力学（b1）建立时变粘弹性接触力学的理论框架。（b2）理论推导了球形/锥体/锥形压头的粘弹性本构方程，并进行了实验验证。（b3）开发了室温至高温至1200℃范围内的粘弹性压痕试验系统，并应用于各种工程材料的粘弹性参数和流变功能的表征。(c)超塑性接触力学（c1）从理论上建立了描述细晶陶瓷超塑性变形和流动的“协同晶界滑动”模型。（c2）采用压痕接触力学对模型的有效性进行了实验验证。

Indentation contact mechanics has intensively as well as extensively been applied to characterizing and analyzing the mechanical properties of metals, ceramics, and polymers. These mechanical properties include elasticity, plasticity, elastoplasticity, viscosity, viscoelasticity, and superplasticity. The major results of the project are outlined, as follows :(a) Elastoplastic contact mechanics(a1) Elastoplastic constitutive equations for pyramidal/conical indenters were theoretically derived, and experimentally scrutinized.(a2) "True Hardness" as a measure for plasticity was theoretically proposed and experimentally confirmed as an efficient micro/nano-parameter for representing "plasticity".(a3) Test methods and test instrumentations were well-developed for elastoplastic characterization of engineering materials.(b) Viscoelastic contact mechanics(b1) Theoretical framework of time-dependent viscoelastic contact mechanics was constructed.(b2) Viscoelastic constitutive equations for spherical/pyramidal/conical indenters were theoretically derived, and experimentally scrutinized.(b3) Viscoelastic indentation test systems operating in the range from room temperature to elevated temperatures to 1200℃ were developed, and then applied to characterizing the viscoelastic parameters and rheological functions of various engineering materials.(c) Superplastic contact mechanics(c1) A model of "cooperative grain-boundary sliding" was theoretically developed for describing the superplastic deformation and flow of fine-grain-size ceramics.(c2) Indentation contact mechanics was applied to experimentally examine the validity of the model.