Determination of the mechanical properties of amorphous materials through instrumented nanoindentation

Abstract

A novel methodology based on instrumented indentation is developed to determine the mechanical properties of amorphous materials which present cohesive-frictional behaviour. The approach is based on the concept of a universal hardness equation, which results from the assumption of a characteristic indentation pressure proportional to the hardness. The actual universal hardness equation is obtained from a detailed finite element analysis of the process of sharp indentation for a very wide range of material properties, and the inverse problem (i.e. how to extract the elastic modulus, the compressive yield strength and the friction angle) from instrumented indentation is solved. The applicability and limitations of the novel approach are highlighted. Finally, the model is validated against experimental data in metallic and ceramic glasses as well as polymers, covering a wide range of amorphous materials in terms of elastic modulus, yield strength and friction angle.

High temperature micropillar compression of Al/SiC nanolaminates

“…Recent progress in instrumented nanoindentation has opened the possibility of carrying out nanoindentation tests at high temperatures [15]. Nevertheless, it is not easy to obtain the constitutive mechanical properties from nanoindentation tests because of the complex stress state below the indenter, despite the large body of literature on the so-called inverse problem of instrumented indentation [16][17][18]. As a result, current knowledge about the effect of temperature on the mechanical properties of nanoscale multilayers is scarce [15,[19][20][21], This information is not only important from the engineering viewpoint, but also from the fundamental perspective, as the dominant mechanisms controlling the deformation and fracture of nanoscale multilayers (interface strength, dislocation plasticity) are often thermally activated.…”

Multiscale Characterization of Nanoengineered Fiber-Reinforced Composites: Effect of Carbon Nanotubes on the Out-of-Plane Mechanical Behavior

“…Based on the hardness-compression strength factor established by Rodríguez et al [28], the results indicate an increase in the compression strength of the nanocomposite. Moreover, the compression modulus also shows an increase of 11%, with the incorporation of CNTs ( Table 2).…”

Nanoindentation of Functionally Graded Polymer Nanocomposites: Assessment of the Strengthening Parameters through Experiments and Modeling

“…Despite the approximations given by the utilized approach (Oliver and Pharr, 1992), experimental results have been successfully reproduced by material point method (MPM) simulations. Unlike previous publications that mostly deal either with the nanoindentation of homogeneous amorphous materials (Rodríguez et al, 2012) or with the effect of the substrate during the tests (Nunes and Piedade, 2013), the present work clarifies the relationship between the mechanical properties obtained by indentation and the morphology of graded polymer composites, constituting a useful tool for a smarter design of functionally graded nanocomposites FIGURE 1 | For a given average particle volume fraction ϕ ϕ ϕ and a given indentation load (micro and nano), which composite (homogeneous particle fraction, H, or graded particle fraction, G) is the hardest?…”

“…Although challenging, the extraction of material properties by this method has been successfully carried out for macroscopically homogeneous samples, such as polycrystalline solids (Dao et al, 2001), amorphous solids (Rodríguez et al, 2012), and even nanocomposite structures (Penumadu et al, 2011;Díez-Pascual et al, 2015). On the contrary, less attention has been paid to the analysis of graded structures.…”