Here we quantify the time-dependent mechanical properties of a linear viscoelastoplastic material under contact loading. For contact load relaxation, we showed that the relaxation modulus can be measured independently of concurrent plasticity exhibited during the loading phase. For indentation creep, we showed that the rate of change of the contact creep compliance [dot over L](t) can be measured independently of any plastic deformation exhibited during loading through [dot over L](t) = 2a(t)ḣ(t)/P[subscript max], where a(t) is the contact radius, h(t) is the displacement of the contact probe, and Pmax is the constant applied load during the creep phase. These analytical relations were compared with numerical simulations of conical indentation creep for a viscoelastoplastic material and validated against sharp indentation creep experiments conducted on polystyrene. The derived relations enable extraction of viscoelastic material characteristics, even if sharp probes confer concurrent plasticity, applicable for a general axisymmetric contact probe geometry and a general time-independent plasticity.
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机译：在这里，我们量化了在接触载荷下的线性粘弹性材料的时间依赖性机械性能。对于接触负载弛豫，我们表明，可以独立于加载相期间呈现的并发塑性测量的松弛模量。对于缩进蠕变，我们表明，接触蠕变顺应性Δ（t）的变化率可以独立于在加载通过[点OV]（t）= 2a（t）ḣ期间表现出的任何塑性变形。 （t）/ p [下标max]，其中a（t）是触点半径，h（t）是接触探针的位移，并且Pmax是蠕变期间的恒定施加的负载。将这些分析关系与用于粘弹性材料的锥形压痕蠕变的数值模拟进行了比较，并验证了在聚苯乙烯上进行的尖锐缩进蠕变实验。衍生关系使得粘弹性材料的提取，即使尖锐的探针赋予并发塑性，也适用于通用轴对称接触探针几何形状和一般的时间无关的可塑性。
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