Single-crystal sapphire (α-Al2O3) is a hard and brittle material. Due to its highly crystalline nature, the fracture behavior of sapphire is strongly related to its crystal structure, and understanding the effects of crystal structure on the crack propagation of sapphire is essential for the successful application of this important material (e.g., as wafers in the electronics industry). In the ...

The main goal of this work is to determine values of elastic constants of orthotropic, transversely isotropic and cubic materials through indentation tests on thin layers bonded to rigid substrates. Accordingly, we first use the Stroh formalism to provide an analytical solution for generalized plane strain deformations of a linear elastic anisotropic layer bonded to a rigid substrate, and inden...

Nix and Gao established an important relation between microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments (indentation depths in the micrometer range), but it does not always hold in nanoindentation experiments (indentation depths approaching the nanometer range). We have developed a unified computational model for both microan...

In this paper, Berkovich depth-sensing indentation has been used to study the effects of temperature-dependent quasi-static mechanical properties and creep deformation heat-treated wood at temperatures from 20 °C 180 °C. The characteristics load–depth curve, strain rate, compliance, stress exponent are evaluated. results showed that high temperature heat treatment improved hardness cell walls r...

Silicon carbide (SiC) is an important orthopedic material due to its inert nature and superior mechanical and tribological properties. Some of the potential applications of silicon carbide include coating for stents to enhance hemocompatibility, coating for prosthetic-bearing surfaces and uncemented joint prosthetics. This study is the first to explore nanomechanical response of single crystal ...

A physical deduction of the FN = kh 3/2 relation (where FN is normal force, k penetration resistance and h penetration depth) for conical/pyramidal indentation loading curves has been achieved on the basis of elementary mathematics. The indentation process couples the productions of volume and pressure to the displaced material that often partly plasticizes due to such pressure. As the pressure...

We have developed a tool for performing surgical operations on living cells at nanoscale resolution using atomic force microscopy (AFM) and a modified AFM tip. The AFM tips are sharpened to ultrathin needles of 200-300 nm in diameter using focused ion beam etching. Force-distance curves obtained by AFM using the needles indicated that the needles penetrated the cell membrane following indentati...

INSTRUMENTED INDENTATION TESTING (IIT), also known as depth-sensing indentation, continuous-recording indentation, ultra-low-load indentation, and nanoindentation, is a relatively new form of mechanical testing that significantly expands on the capabilities of traditional hardness testing. Developed largely over the past two decades, IIT employs high-resolution instrumentation to continuously c...