GB/T 1927.13-2022Test methods for physical and mechanical properties of small clear wood specimens—Part 13:Determination of the modulus of elasticity in compression perpendicular to grain (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for Standardization Work Part 1: Structure and Drafting Rules of Standardization Documents" drafted.

This document is part 13 of GB/T 1927 "Test Methods for Physical and Mechanical Properties of Small Specimens of Wood without Defects". GB/T 1927 has been issued The following parts are distributed.

--- Part 1: Collection of test materials;

--- Part 2: Sampling methods and general requirements;

--- Part 3: Determination of growth ring width and latewood rate;

--- Part 4: Determination of moisture content;

--- Part 5: Density determination;

--- Part 6: Determination of dry shrinkage;

--- Part 7: Determination of water absorption;

--- Part 8: Determination of swelling properties;

--- Part 9: Determination of flexural strength;

--- Part 10: Determination of flexural modulus of elasticity;

--- Part 11: Determination of compressive strength along grain;

--- Part 12: Determination of transverse grain compressive strength;

--- Part 13: Determination of compressive elastic modulus of transverse grains;

--- Part 14: Determination of tensile strength along grain;

--- Part 15: Determination of transverse grain tensile strength;

--- Part 16: Determination of shear strength along grain;

--- Part 17: Determination of impact toughness;

--- Part 18: Determination of impact indentation;

--- Part 19: Determination of hardness;

--- Part 20: Determination of splitting resistance;

--- Part 21: Determination of nail holding force.

This document replaces GB/T 1943-2009 "Determination of compressive elastic modulus of wood transverse grain", compared with GB/T 1943-2009, except In addition to structural adjustments and editorial changes, the main technical changes are as follows.

--- Added "Terms and Definitions" (see Chapter 3);

--- Changed the provisions for measuring the gauge length of deformation (see 5.2, 4.2 of the 2009 edition);

--- Changed the provisions of the sample size (see 6.2, 5.2 of the 2009 edition);

--- Added wood in green state or air-dried state (see 6.5);

--- Increase the provisions for the measurement of sample density (see 7.1);

--- Changed the provisions for measuring the position of the deformation gauge length of the sample, from 20mm from both ends to more than 10mm (see 7.2, 2009 version 6.2);

--- Changed the provisions on loading and unloading, and changed it to six times of loading and unloading, and took the average value of the deformation measured in the last three tests as the calculation Deformation mean (see 7.4 and 7.5, 6.3 and 6.4 of the 2009 edition);

--- Changed the water content adjustment range and expression method (see 8.2, 7.2 of the 2009 edition).

Introduction

The standard of test methods for physical and mechanical properties of wood is used in wood scientific research, teaching, wood inspection, wood structure design, wood processing and production, etc.

It is widely used and is an important basic standard in the wood industry. In 1980, my country issued the first edition of the test methods for physical and mechanical properties of wood.

The domestic standard (GB/T 1927~GB/T 1943) was revised twice in 1991 and 2009 respectively. In recent years, with the development of wood science and technology The development of technology, ISO 3129:2012 "Sampling methods for wood physical and mechanical tests of small samples of wood without defects and "General Requirements" has been revised, ISO 3130:1975 "Determination of moisture content by physical and mechanical tests of wood", ISO 3131:1975 "Wood 15 international standards for test methods such as "Determination of Density in Physical and Mechanical Tests" have been integrated and revised. Based on this, in order to be in line with international standards, this time The third revision was made to the national standard for test methods for physical and mechanical properties of wood in my country, and the 22 scattered test method standards were integrated and adjusted to The sub-part document of GB/T 1927 adopts the latest version of the international standard in the revision.

GB/T 1927 aims to establish a test method for the physical and mechanical properties of small sample wood without flaws, and is intended to be composed of 21 parts.

--- Part 1: Collection of test materials. The purpose is to describe the sample collection method for testing the physical and mechanical properties of wood with small samples without defects.

--- Part 2: Sampling methods and general requirements. The purpose is to establish a suitable test for the physical and mechanical properties of small wood samples without defects.

Specimen sawing, interception methods and general requirements to be observed when testing methods.

--- Part 3: Determination of growth ring width and latewood rate. The purpose is to characterize the growth ring width and latewood rate of small samples of clear wood method of determination.

--- Part 4: Determination of moisture content. The purpose is to describe a method for the determination of the moisture content of small wood samples without defects.

--- Part 5: Density determination. The purpose is to describe the density, air-dry density, absolute dry Methods for the determination of density and basic density.

--- Part 6: Determination of dry shrinkage. The purpose is to describe the measurement of radial, chordwise and volume drying shrinkage of unblemished small sample wood. determined method.

--- Part 7: Determination of water absorption. The purpose is to describe the determination method of 6h, 24h and the maximum water absorption rate of small sample wood without defect.

--- Part 8: Determination of swelling. The purpose is to describe the measurement of radial, chordwise and volumetric swell of unblemished small wood samples. determined method.

--- Part 9: Determination of flexural strength. The purpose is to describe a method for the determination of the flexural strength of small wood samples without defects.

--- Part 10: Determination of flexural modulus of elasticity. The purpose is to describe a method for the determination of the flexural modulus of elasticity of small wood samples without defects.

--- Part 11: Determination of compressive strength along grain. The purpose is to describe a method for the determination of the compressive strength along the grain of small wood samples without defects.

--- Part 12: Determination of transverse grain compressive strength. The purpose is to describe the transverse grain compressive proportional ultimate strength of small unblemished wood samples, including Methods for the determination of the total compressive proportional ultimate strength of the horizontal grain and the partial compressive proportional ultimate strength of the horizontal grain.

--- Part 13: Determination of compressive elastic modulus of transverse grains. The purpose is to describe the measurement of the transverse-grain compressive elastic modulus of unblemished small samples of wood. determined method.

--- Part 14: Determination of tensile strength along grain. The purpose is to describe a method for the determination of the along-grain tensile strength of unblemished small samples of wood.

--- Part 15: Determination of transverse grain tensile strength. The purpose is to describe a method for the determination of the transverse grain tensile strength of small wood samples without defects.

--- Part 16: Determination of shear strength along grain. The purpose is to describe a method for the determination of the shear strength along the grain of small wood samples without defects.

--- Part 17: Determination of impact toughness. The purpose is to describe a method for the determination of the chordwise impact toughness of small unblemished wood samples.

--- Part 18: Determination of impact indentation. The purpose is to describe a method for the determination of the impact indentation resistance of unblemished small samples of wood.

--- Part 19: Determination of hardness. The purpose is to describe a method for the determination of radial, chord, and longitudinal hardness of small, unblemished wood samples.

--- Part 20: Determination of splitting resistance. The purpose is to describe the method for the determination of the splitting resistance on the radial and chord surfaces of small wood samples without defects.

--- Part 21: Determination of nail holding force. The purpose is to describe a method for the determination of the nail-holding force of small samples of wood without defects.

1 Scope

This document describes the test principle, equipment, specimens, test procedures, result calculation and test report for determining the transverse grain compressive elastic modulus of wood. Announcement and so on.

This document is applicable to the determination of the compressive elastic modulus of all transverse grains of wood in the green state or in the air-dried state without any defects.

2 Normative references

The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, dated citations For documents, only the dated version applies to this document; for undated references, the latest edition (including all amendments) applies to this document.

GB/T 1927.2-2021 Test methods for the physical and mechanical properties of wood with small unblemished samples - Part 2: Sampling methods and general rules

GB/T 1927.4 Test methods for physical and mechanical properties of wood with small samples without flaws - Part 4: Determination of moisture content

GB/T 1927.5 Test methods for the physical and mechanical properties of wood with small samples without defects - Part 5: Density determination

LY/T 1788 Terms for wood properties

3 Terms and Definitions

Terms and definitions defined in LY/T 1788 apply to this document.

4 Principles

When the transverse grain of wood is compressed, the compressive elastic modulus of the transverse grain of wood is determined by the ratio of stress to strain within the proportional limit stress.

5 Test equipment

5.1 The testing machine should be calibrated regularly in accordance with the standard procedures of the national metrology department. The error of the displayed value of the testing machine should not exceed ±1%, and it should have at least A spherical sliding platen (or support).

5.2 The gauge length of the strain gauge for measuring the strain of the specimen shall not be less than 5mm, and the dispersion of the sensitivity coefficient shall be less than ±1%, or other gauge length deformation indications shall be For devices with an error within ±1%.

5.3 Test measuring tool, the measurement size should be accurate to 0.1mm.

5.4 The test equipment specified in GB/T 1927.4 shall be used for the determination of moisture content.

6 Samples

6.1 The sawing of the test material and the interception of the sample shall be carried out according to the provisions of GB/T 1927.2.

6.2 The sample is a cuboid, each side is square or rectangle, and the size of the sample is shown in Figure 1. Height (h) × width (b) × thickness (t), where the height