Using the ratio: maximum load over unload stiffness squared, Pm/Su², on the evaluation of machine stiffness and area function of blunt indenters on depth-sensing indentation equipment

Abstract

Depth sensing indentation study was conducted in a Fischerscope H100V machine, equipped with a Vickers indenter with a tip roundness of approximately 1330 nm. Tests were carried out on soda-lime glass, fused silica, sapphire, aluminum (1100 alloy), high alloyed steel, titanium and copper. The widely used iterative method of Oliver and Pharr was unsuccessful in the attempts to analyze machine compliance and indenter area function. Therefore, an alternative procedure was adopted. The alternative procedure is based on the ratio between maximum load and unload stiffness squared, Pm/Su². It was found that this procedure, which is not iterative, gives good results. A careful study of the Pm/Su² ratio, lead us to conclude that the Fischercope machine has a low compliance which depends on the sample mounting. This low compliance in conjunction with the recent discovery of the dependence of beta factor on the tip roundness/maximum depth ratio, which appears in the relation between contact stiffness and contact area, explains why the iterative method does not converge. However, variations in beta and machine compliance produces deviation on the hardness and elastic modulus lower that 6% with respect to expected values for the materials and the machine studied in this work

Deconvolution of design parameters from elasto-plastic energy data acquired by nanoindentation in ceramic coatings

“…The nano-indentation test was carried out in a Fisher H100V equipment; a Vickers indenter with an area function previously calibrated was used [7]. To obtain the hardness and elastic modulus, the data was post-processed according to the Oliver and Pharr method [8].…”

Analysis of the effects of conical indentation variables on the indentation response of elastic–plastic materials through factorial design of experiment

“…At least 15 indentation tests were conducted in each specimen for each value of peak load and only those curves within two standard deviations from the average P m /S 2 u ratio were used in the analysis of indentation data. 39 When true replicates are made under a given set of experimental conditions, the variation between their associated observations may be used to estimate the standard deviation of a single experimental condition. In this case, the statistical significance of the effects may be judged from an estimate of variance obtained by genuine replication.…”

Interfaz gráfica de usuario para la simulación por dinámica molecular de películas delgadas

“…Para calcular la dureza del material mediante la interfaz gráfica de usuario, se examina la curva de carga-descarga en el régimen elástico [29]. Se pueden obtener dos valores a partir de estas curvas: la penetración bajo carga máxima (hT) y la penetración final (hR) que se mide cuando el indentador está fuera de contacto con la muestra o material analizado.…”