An Investigation of Nanomechanical Properties of Materials using Nanoindentation and Artificial Neural Network

Abstract

Mechanical properties of materials can be derived from the force-displacement relationship through instrumented indentation tests. Complications arise when establishing the full elastic-plastic stress-strain relationship as the accuracy depends on how the material’s and indenter’s parameters are incorporated. For instance, the effect of the material work-hardening phenomenon such as the pile-up and sink-in effect cannot be accounted for with simplified analytical indentation solutions. Due to this limitation, this paper proposes a new inverse analysis approach based on dimensional functions analysis and artificial neural networks (ANNs). A database of the dimensional functions relating stress and strain parameters of materials has been developed. The database covers a wide range of engineering materials that have the yield strength-to-modulus ratio (σy/E) between 0.001 to 0.5, the work-hardening power (n) between 0–0.5, Poisson’s ratio (v) between 0.15–0.45, and the indentation angle (θ) between 65–80 degrees. The proposed algorithm enables determining the nanomechanical stress-strain parameters using the indentation force-displacement relationship, and is applicable to any materials that the properties are within the database range. The obtained results are validated with the conventional test results of steel and aluminum samples. To further demonstrate the application of the proposed algorithm, the nanomechanical stress-strain parameters of ordinary Portland cement phases were determined.

Наноиндентирование И Механические Свойства Материалов В Субмикро- И Наношкале. Недавние Результаты И Достижения (О Б З О Р)

“…Различным аспектам наномеханического поведения твердых тел и способам их исследования методами NI и SSMT посвящено большое число книг [13][14][15][16][17][18][19] и обзоров [20][21][22][23][24][25][26], опубликованных в последнее десятилетие. Поэтому концептуальные основы техники исследования наномеханических свойств материалов классическими методами NI описаны в настоящем обзоре кратко, в порядке введения к основному материалу.…”

Transversely isotropic elastic-plastic properties in thermal arc sprayed Al–Zn coating: a microporomechanics approach

“…Existing researches 5,21 showed that indentation measurement has implicit response parameters derived from the load and unload curve from nanoindentation which can be inter-related using the dimensional function approach based on the work by Cheng and Cheng 22 . Conventionally, the indentation modulus (M) and hardness (H) results are calculated from this force and displacement response using the popular Oliver-Pharr method 23,24 .…”

Cohesive-strength homogenisation model of porous and non-porous materials using linear comparison composites and application

“…Firstly, the cohesive-strength homogenisation model in Level I is applied for the continuum discretisation of instrumented indentation solution. The instrumented indentation is a well-known technique that has emerged for determining mechanical properties 17,18 . Recently, the instrumented indentation makes it possible to test the structure of porous materials with the characteristic size of porosity much smaller than the maximum indentation depth 19 .…”

“…Nanoindentation test was conducted on the three sets of cube specimens with XP BASIC testing mode with Keysight Nanoindentation G200; each set was specified around 300 indentation points on the cementitious matrix, fine sand and coarse aggregate using the Berkovich indenter. The hardness values of each indentation point then determined using our inverse algorithm 18 695 GPa, respectively. he present results show that even though M1 and M2 matrices have the same mix design, Level 0 (solid) properties are not consistent to each other.…”

“…he present results show that even though M1 and M2 matrices have the same mix design, Level 0 (solid) properties are not consistent to each other. It is believed that the development of calcium silicate hydrated (CSH) which is one of major hydration products of cementitious matrix contributing to the primary source of nanometre-scale elastic modulus degradation 13,18 . In fact that the nanostructure of CSH is still not known, forms poorly crystalline during the hydration of the cementitious matrix and characterised by extensive atomic imperfection and structural variations at…”