Method for testing bending strength of fragile wooden cultural relic in micro-damage manner

A technology for flexural strength and wood, which is applied in the field of micro-damage testing of the flexural strength of fragile wooden cultural relics, which can solve the problems that it is difficult to apply decayed archaeological wood, the load of the test instrument is large, and the sample volume is large, so as to achieve high sensitivity and accuracy , Simple sample preparation, high precision effect

Active Publication Date: 2021-12-14
UNIV OF SCI & TECH BEIJING +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In order to solve the problems that the existing testing methods for mechanical properties of wood require large sample size and sample volume, large test instrument load, low precision, and difficulty in applying to decayed archaeological wood, the present invention provides a micro-damage testing method for bending resistance of fragile wooden cultural relics. The strength method, that is, using a static thermomechanical analyzer, only a small amount of thin slice samples can effectively test the flexural strength of most archaeological wooden cultural relics in different preservation conditions. It has a wide range of applications, high precision and good repeatability of test results

Method used

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  • Method for testing bending strength of fragile wooden cultural relic in micro-damage manner
  • Method for testing bending strength of fragile wooden cultural relic in micro-damage manner

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Embodiment 1

[0052] The flexural strength of the "Nanhai No. 1" shipwreck loose wood samples was tested by bending experiments. The wood species is fir, which is mildly and moderately degraded, and the maximum moisture content is 331%. The samples were cut into standard strips (8mm×2mm×0.3mm) and dried naturally. The span L of the fixture is measured to be 5mm, the width b of the sample is 2.299mm, and the thickness d is 0.244mm; the wooden bar is placed on the three-point bending fixture, and the position is as follows figure 2 shown. Start the test at room temperature, lower the probe, set the initial load to 5mN, and increase it uniformly at 5mN / min. After 30 minutes, the sample breaks, and record the change curve of displacement and load with time; process the data obtained from the experiment, and set the span of the fixture L, sample width b, thickness d, real-time displacement D, real-time load P into the formula The stress σ of the sample is obtained f , Specimen strain ε f...

Embodiment 2

[0054] The flexural strength of the bulkhead of the "Nanhai No. 1" sunken ship was tested by bending experiments. The wood species is hardwood pine, which is moderately degraded and has a moisture content of 452%. Samples were cut into standard strips (8 mm x 2 mm x 0.3 mm) and dried slowly. The span L of the fixture is measured to be 5mm, the width b of the sample is 1.885mm, and the thickness d is 0.172mm; place the wooden bar on the three-point bending fixture, start the test at room temperature, lower the probe, set the initial load 2mN, and Increase uniformly at 5mN / min, the sample breaks after 10min, and record the change curve of displacement and load with time, such as Figure 5 Shown; process the data obtained from the experiment, and substitute the fixture span L, sample width b, thickness d, real-time displacement D, and real-time load P into the formula The stress σ of the sample is obtained f , Specimen strain ε f , to make the stress-strain curve of the sampl...

Embodiment 3

[0056] The flexural strength of the wooden components of the "Nanhai I" shipwreck was tested by bending experiments. The wood species is sweetgum, which is moderately to severely degraded, with a maximum moisture content of 472%. Cut the sample into standard splines (8mm×2mm×0.3mm) and dry them slowly. Measure the clamp span L to be 5mm, sample width b and thickness d; place the strip on the three-point bending fixture, and Start the test under normal temperature conditions, lower the probe, set the initial load of 1mN, and increase it uniformly at 2mN / min. After 12 minutes, the sample breaks, and record the change curve of displacement and load with time; process the data obtained from the experiment, and set the fixture span L , sample width b, thickness d, real-time displacement D, real-time load P into the formula The stress σ of the sample is obtained f , Specimen strain ε f , make a stress-strain curve; the instantaneous stress of the sample fracture is the bending st...

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Abstract

The invention relates to the field of detection of wooden cultural relics, and discloses a method for testing the bending strength of a fragile wooden cultural relic in a micro-damage manner. The method comprises the following steps of cutting a sample into standard sample strips, measuring the span between the clamps and the width and the thickness of the standard sample strip, and reading and recording numerical values, placing the standard sample strip on a clamp to start a test, applying a uniformly increasing load to the standard sample strip until the standard sample strip is pressed to be broken, measuring the relationship between the displacement and the pressure of the standard sample strip, and recording a curve of the displacement and the load changing along with time, according to the clamp span, the width, the thickness, the real-time displacement and the real-time load of the standard sample strip, acquiring the stress and the strain of the standard sample strip, and drawing a stress-strain curve. The instantaneous stress of the fracture of the standard sample strip is the bending strength of the standard sample strip. The bending strength of most archaeological wood cultural relics under different preservation conditions can be effectively tested only by a small number of sheet samples, the application range is wide, the test result precision is high, and the repeatability is good.

Description

technical field [0001] The invention relates to the technical field of cultural relics testing, in particular to a method for testing the flexural strength of fragile wooden cultural relics with minimal damage. Background technique [0002] Wooden cultural relics are an important part of my country's splendid cultural heritage, and are precious material materials for studying ancient technology, art and culture. In the protection research of large water-saturated wooden cultural relics such as shipwrecks, coffins, wood carvings, etc., accurate characterization of their mechanical properties is of great significance, and it is an important basis for the evaluation of cultural relics preservation status, disease degree classification and protection plan formulation. However, after a long period of underground / underwater burial and microbial degradation, the cellulose and hemicellulose in the wood cell wall were partially degraded, resulting in a loose and porous cell wall and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/20
CPCG01N3/20G01N2203/0023G01N2203/0012G01N2203/0067G01N2203/0676G01N2203/0682
Inventor 韩向娜韩刘杨秦振芳吴梦若席光兰张治国
Owner UNIV OF SCI & TECH BEIJING
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