Sensitivity of PMMA nanoindentation measurements to strain rate

Abstract

This study aims to investigate the effects of strain rate on polymethyl methacrylate (PMMA) nanoindentation measurements. Nanoindentation experiments were used to characterize the mechanical properties of PMMA. A wide range of strain rates were employed to examine strain rate sensitivity of PMMA. The test results indicate that the elastic modulus and hardness of PMMA are strain-rate-dependent. In addition, both the elastic modulus and hardness of PMMA exhibit increases with increasing strain rate. However, the elastic modulus became a stable value until strain-rate of 0.2 s 21 . Creep behavior of PMMA under the condition of high strain rate is more obvious than that experience a low strain rate. Moreover, the effects of strain rate on the PMMA nanomechanical properties are detailed analyzed by discussing each stage of the indentation process.

Quasi‐static and dynamic nanoindentation of particle‐reinforced soft composites

“…According to the above results, it is obviously found that the elastic modulus of the PRSC show a strong dependence on the loading and holding times because of the highly time‐dependent deformation nature. The elastic moduli will be inaccurate under the condition of loading time and holding time is too long or not, especially for soft materials . Therefore, it is essential to choose appropriate loading time and holding time.…”

“…They found an interphase region characterized by an abrupt change in the mechanical properties which is due to the elastic moduli of fillers having the same order of magnitude as matrix. To examine the effects of experimental variables on nanoindentation measurements, Jin et al . conducted nanoindentation tests on some polymethylmethacrylates and found that the mechanical properties of these materials increase with the loading rates, whereas decrease as the holding times.…”

Physical and Morphological Properties of Tough and Transparent PMMA-Based Blends Modified with Polyrotaxane

“…The surface hardness of each dumbbell-shaped specimen was measured using a G200 nanoindenter (MTS Nano Instruments Inc., Oak Ridge, TN, USA). The Berkovitch indenter had a triangular pyramidal shape, and hardness was determined by performing continuous stiffness measurements up to an indentation depth of 10 µm [23]. The reported surface hardness value was averaged over the indentation range from 500 to 1900 nm to eliminate the influences of surface roughness and indentation size.…”

Indentation Size Effect in Pressure-Sensitive Polymer Based on A Criterion for Description of Yield Differential Effects and Shear Transformation-Mediated Plasticity

“…Furthermore, each test was performed at room temperature (25 °C) and repeated three to four times to exclude uncertain experimental results. For CSM technique, the contact stiffness S is expressed as [8,33,34]:S=[1Famphampcosϕ−(Ks−mω2)−1Kf]−1 where F amp and h amp represent the amplitude of harmonic excitation force and the response displacement amplitude (~2 nm), respectively, ϕ is the phase shift that harmonic displacement lags behind the harmonic excitation force, ω=2πf is the angular frequency ( f = 45 Hz), K s is the spring constant in the vertical direction, K f is frame stiffness, m is the mass of compression bar connected to the indenter. A perfect Berkovich diamond indenter was used in this study, and the projected contact area Ac and contact depth hc can be respectively expressed as: Ac=24.56hc2 hc=h−εPS where ε=0.75 is a constant for the Berkovich indenter.…”

“…Therefore, the mechanical behaviour of PMMA is an important property that should be clarified prior to its usage. Many studies have been conducted to investigate the macroscopic [5,6] and mesoscopic [7,8] mechanical properties of PMMA such as compression, tension, and nanoindentation. The yield strength and modulus of PMMA were found to be sensitive to strain rate and both properties exhibit increases with strain rate.…”