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A gas pycnometer is a laboratory device used for measuring the density—or, more accurately, the volume—of solids, be they regularly shaped, porous or non-porous, monolithic, powdered, granular or in some way comminuted, employing some method of gas displacement and the volume:pressure relationship known as Boyle's law.
If the material is linearly elastic, the computation of its energy release rate can be much simplified. In this case, the Load vs. Load-point Displacement curve is linear with a positive slope, and the displacement per unit force applied is defined as the compliance, [3] =.
Indentation plastometry is the idea of using an indentation-based procedure to obtain (bulk) mechanical properties (of metals) in the form of stress-strain relationships in the plastic regime (as opposed to hardness testing, which gives numbers that are only semi-quantitative indicators of the resistance to plastic deformation).
The J-integral represents a way to calculate the strain energy release rate, or work per unit fracture surface area, in a material. [1] The theoretical concept of J-integral was developed in 1967 by G. P. Cherepanov [2] and independently in 1968 by James R. Rice, [3] who showed that an energetic contour path integral (called J) was independent of the path around a crack.
A schematic depicting how a material's rising R-curve leads to added crack stability. Two different crack driving force curves are applied to the material, () and ().Even though both are initially unstable, due to their different slopes () will unstably propagate the crack while () will arrest the crack after propagating it a short distance .
In the Knoop test, only the longer diagonal is measured, and the Knoop hardness is calculated based on the projected area of the indent divided by the applied force, also giving test units in kgf/mm 2. The Vickers microindentation test is carried out in a similar manner welling to the Vickers macroindentation tests, using the same pyramid.
Displacement measurement is the measurement of changes in directed distance (displacement). Devices measuring displacement are based on displacement sensors, which can be contacting or non-contacting. [1] Some displacement sensors are based on displacement transducers, [2] devices which convert displacement into another form of energy. [3]
The particle deformation can be measured by the deflection of the cantilever tip over the sample. The resulting force-displacement curves can be used to calculate elastic modulus. [75] However, it is unclear whether particle size and indentation depth affect the measured elastic modulus of nanoparticles by AFM. [75]