Abstract The non-destructive quantification of the mechanical properties of solid materials is a growing research topic for many applications. It could be used for monitoring material performance during the whole lifecycle of a component, for when sampling is limited or impossible or for applications that require sample identification. In this paper a portable instrument for non-destructive viscoelastic characterization of polymers, based on instrumented indentation, is presented, its aim is to allow a real-time assessment of viscoelastic storage and loss moduli (E’ and E”) directly in-situ. The designed architecture of the device is described in details alongside the procedure adopted for testing polymers, the corresponding signal processing procedure for the identification of materials stiffness and damping parameters is also described. For the scope of this paper the aforementioned procedure was tested on two different rubber compounds. Finally, the storage and loss moduli are calculated based on the linear viscoelasticity theory and the results are compared to the ones obtained with the standard Dynamic Mechanical Analysis technique (DMA): both these approaches show the same relative ranking between the compounds and a different trend in temperature due to the reached indentation depth. To overcome this limitation of linear viscoelasticity theory, normally valid for low indentation depths, a generalized formulation is proposed that takes into account the indentation depth on the moduli estimation. The results obtained with the generalized formulation show that this approach allows to evaluate accurately the trends and rankings of viscoelastic moduli, giving reliable results.

中文翻译：

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用于聚合物粘弹性特性的非破坏性表征的便携式仪器的开发

摘要 固体材料力学性能的非破坏性量化是许多应用中日益增长的研究课题。它可用于在组件的整个生命周期内监测材料性能，用于采样有限或不可能的情况，或者用于需要样品识别的应用。在本文中，提出了一种基于仪器压痕的聚合物非破坏性粘弹性表征便携式仪器，其目的是允许直接原位实时评估粘弹性储存和损失模量（E' 和 E”） . 该装置的设计架构与用于测试聚合物的程序一起详细描述，还描述了用于识别材料刚度和阻尼参数的相应信号处理程序。对于本文的范围，上述程序在两种不同的橡胶化合物上进行了测试。最后，基于线性粘弹性理论计算存储模量和损耗模量，并将结果与​​使用标准动态机械分析技术 (DMA) 获得的结果进行比较：这两种方法在化合物之间显示出相同的相对排名和不同的趋势由于达到压痕深度而导致温度升高。为了克服线性粘弹性理论的这种限制，通常适用于低压痕深度，提出了一种广义公式，该公式考虑了模量估计的压痕深度。用广义公式获得的结果表明，这种方法可以准确评估粘弹性模量的趋势和排名，给出可靠的结果。