Method for testing mechanical performances of calcified bone based on nano-indentation and nano-scratch

Abstract

The invention discloses a method for testing the mechanical performances of a calcified bone based on nano-indentation and nano-scratch, and belongs to a method for testing micro-nano mechanics of biological materials. The method comprises the following steps: placing a bone cartilage in a metal sample cup, and obtaining the starting point position and the end point position of every scratch transition area according to a contact mechanics judgment criterion; establishing a rectangular coordinate system including all scratch with the summit of the left bottom of a rectangular area as the zeropoint, and sequentially connecting the start points and the end points of the transition areas to form a line; and summing up the calculated structural flexibility and the structural flexibility of aninstrument frame to obtain a corrected frame flexibility, and afresh calculating a bone and calcified bone elastic modulus to obtain the corrected bone and calcified bone elastic modulus. The bone-calcified bone interface influence area is effectively judged at a certain depth, and the pressed depth is smaller than the scratch depth, the indentation is effectively prevented from being pressed inthe bone-calcified bone composite phase, and the mechanical performances of the nano-indentation of the calcified bone are obtained.

Description

technical field [0001] The invention belongs to a micro-nano mechanical testing method of biological materials, in particular a method for conducting experiments through nano-indentation and nano-scratch. Background technique [0002] Mature articular cartilage can be divided into four layers: superficial layer, transition layer, radiation layer and calcified bone from the deep part of the joint. Immature articular cartilage has only areas of chondrocyte proliferation for growth. Among them, the superficial proliferative area of ​​the articular surface expands the range of articular cartilage, while the deep proliferative area forms subchondral bone in an osteogenic manner. At this time, the deposition and absorption of calcium salts in the cartilage are in balance, making the bone continue to grow thick and long. After the bone matures, that is, after the age of 17, the growth of endochondral ossification stops. At this time, the calcium salt deposited in the matrix is ​​n...

AI Technical Summary

Problems solved by technology

[0006] First, the conventional contact scanning method (atomic force microscope or nanoindentation instrument) can obtain the contact stiffness or contact force according to the scanning, and then calculate the elastic modulus of the bone-calcified bone area, but the measured results will be affected by the surface properties. And it is not possible to accurately distinguish between bone and calcified bone test results in a certain area

[0007] Second, the conventional method of obtaining the mechanical properties of calcified bone is to observe the bone-calcified bone interface through an optical microscope, and then perform positioning indentation in the calcified bone area. This method cannot determine whether it is calcified bone or bone at a certain depth, and the measured results are not acceptable Determined Basal Effects

When observing, the indentation is often inaccurate, and it is necessary to repeatedly compare multiple dyed images for one indentation, which is difficult to analyze and the test efficiency is very low

[0009] Fourth, the conventional scratching method through the nanoindenter controls the scratching process through the change of the normal phase force, which makes the scratching depth different on different materials, that is, the relative position of the indenter and the sample when scratching on different phases are different, which makes it impossible to obtain the width of the interface influence zone by the contact mechanics judgment criterion

[0010] Fifth, the effects of the conventional scratch method performed by the nanoindenter such as substrate effect and peripheral effect, sample roughness, subsurface damage caused by grinding and polishing, surface viscosity, protrusions or depressions are not constant, and through non-constant depth The affected area measured by scratches is difficult to analyze, and quantitative conclusions cannot be obtained

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