Work

Phenomenological theory characterization of viscoelastic-plastic response of PA12 under indentation tests

Year: 2026

Type: article

Abstract: Nanoindentation is widely used to study the local time-dependent mechanical behavior of polymer materials. Usually, it can be considered that the indentation depth is the sum of elastic displacement, plastic displacement and time-dependent viscous displacement in the indentation process. In this paper, according to the mechanical model composed of a series of secondary mechanical elements, the viscoelastic-plastic characteristics of PA12 under indentation were extracted for different loading conditions. The results indicate that the model demonstrates a high degree of efficacy in predicting the loading segment of the experimental curve, irrespective of the variation in loading conditions. However, as the rate of loading decreases, the model's predictive capability appears to diminish. It is evident that this is related to the model's assumption that viscous displacement is an irreversible deformation. However, it has been demonstrated that the viscous displacement component, representing high elastic deformation caused by the continuous decrease in load during the unloading process, recovers with the increase of unloading time. The utilisation of the VEP model for the simulation of the compression loading and unloading process is appropriate for ideal elastic-plastic materials or materials exhibiting comparatively minor viscoelastic characteristics; however, it is not applicable to materials with pronounced viscoelastic characteristics. The attainment of a high viscosity coefficient under conditions of Continuous Stiffness Measurement signifies that the influence of viscosity release on the loading curve during the loading process is diminished in comparison to the constant load rate loading method. The impact of viscosity is amplified under conditions ranging from low to high , owing to an augmentation in loading time. Concurrently, the discrepancy between the experimental and predicted curves exhibits an escalation.

Source: Polymer Testing

DOI: 10.1016/j.polymertesting.2026.109187

Authors: Gesheng Xiao, Xin Hao, Yuhong Ma, Xuexia Yang, Erqiang Liu

Institutions: Taiyuan University of Technology, Taiyuan University of Science and Technology

Language: English

Topic: Metal and Thin Film Mechanics

Subfield: Mechanics of Materials

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,370

Funder: National Natural Science Foundation of China