Topic
Indentation
About: Indentation is a research topic. Over the lifetime, 13002 publications have been published within this topic receiving 340476 citations.
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TL;DR: In this article, the hardness and elastic modulus of solid and hollow cuprous oxide (Cu2O) nanocubes were measured and compared with the values of bulk Cu2O.
Abstract: Nanoindentation tests were performed directly on solid and hollow cuprous oxide (Cu2O) nanocubes. The hardness and elastic modulus of solid Cu2O nanocubes were measured and compared with the values of bulk Cu2O. It is found that the hollow cube top wall acts as a membrane that bends under an indentation load. The Cu2O nanocubes are more ductile rather than brittle. Deformation behavior and fracture mechanics are discussed in conjunction with the structure of the Cu2O nanocube.
164 citations
TL;DR: In this article, a relatively simple numerical algorithm based on an exact integral formulation of the elastic contact of an axisymmetric indenter to a coated substrate is detailed. But, if the indenter is not flat-ended, the simple relation between contact radius and penetration valid for homogeneous substrates breaks down.
Abstract: A new approach to the contact to coated elastic materials is presented. A relatively simple numerical algorithm based on an exact integral formulation of the elastic contact of an axisymmetric indenter to a coated substrate is detailed. It provides contact force and penetration as a function of the contact radius. Computations were carried out for substrate to layer moduli ratios ranging from 10−2 to 102 and various indenter shapes. Computed equivalent moduli showed good agreement with the Gao model for mismatch ratios ranging from 0.5 to 2. Beyond this range, substantial effects of inhomogeneous strain distribution are evidenced. An empirical function is proposed to fit the equivalent modulus. More importantly, if the indenter is not flat-ended, the simple relation between contact radius and penetration valid for homogeneous substrates breaks down. If neglected, this phenomenon leads to significant errors in the evaluation of the contact radius in depth-sensing indentation on coated substrates with large elastic modulus mismatch.
164 citations
TL;DR: In this article, the Vickers indentation technique was used to detect cracks in a piezoelectric lead-zirconium-titanate (PZT) material under simultaneous mechanical loading and applied electric fields.
Abstract: Crack propagation in a piezoelectric lead–zirconium–titanate (PZT) material under simultaneous mechanical loading and applied electric fields is studied using the Vickers indentation technique. It is demonstrated experimentally that electric fields can inhibit or enhance crack propagation in piezoelectric materials. Cracks introduced by indentation are observed to propagate less under a positive applied electric field (the polarity of the field was the same as that for poling), whereas under a negative applied electric field, crack propagation is enhanced. Such an effect is observed to be more profound with increasing electric-field strength and decreasing mechanical loading. Attempts are made to compare these experimental observations with the results of various theoretical analyses. A mechanism for the change in crack propagation behavior of the piezoelectric PZT material under applied electric fields is presented.
163 citations
TL;DR: In this paper, the authors used rate effects to study low temperature deformation mechanisms using nanoindentation creep and load relaxation and found that the rate effects are conspicuous in terms of the rate sensitivity of the hardness, ∂H / ∂ ln e eff, and calculated the activation volume, V ∗, and compared data from indentation creep with data from uniaxial loading.
163 citations
TL;DR: In this article, the anisotropic indentation response of α-titanium was characterized by electron backscatter diffraction, which was performed for a number of different crystallographic orientations.
Abstract: This study reports on the anisotropic indentation response of α-titanium. Coarse-grained titanium was characterized by electron backscatter diffraction. Sphero-conical nanoindentation was performed for a number of different crystallographic orientations. The grain size was much larger than the size of the indents to ensure quasi-single-crystal indentation. The hexagonal c-axis was determined to be the hardest direction. Surface topographies of several indents were measured by atomic force microscopy. Analysis of the indent surfaces, following Zambaldi and Raabe (Acta Mater. 58(9), 3516–3530), revealed the orientation-dependent pileup behavior of α-titanium during axisymmetric indentation. Corresponding crystal plasticity finite element (CPFE) simulations predicted the pileup patterns with good accuracy. The constitutive parameters of the CPFE model were identified by a nonlinear optimization procedure, and reproducibly converged toward easy activation of prismatic glide systems. The calculated critical resolved shear stresses were 150 ± 4, 349 ± 10, and 1107 ± 39 MPa for prismatic and basal 〈a〉-glide and pyramidal〈c + a〉-glide, respectively.
163 citations