GB/T 1927.3-2021Test methods for physical and mechanical properties of small clear wood specimens—Part 3: Determination of the growth rings width and latewood rate of wood (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 3 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 12. Determination of transverse grain compressive strength;

--- Part 17. Determination of impact toughness;

--- Part 18. Determination of impact indentation;

--- Part 19. Determination of hardness;

--- Part 20. Determination of splitting resistance.

This document replaces GB/T 1930-2009 "Determination Method of Timber Annual Ring Width and Latewood Rate", compared with GB/T 1930-2009, except In addition to structural adjustments and editorial changes, the main technical changes are as follows:

a) Changed "Annual Rings" to "Growth Rings" throughout the text;

b) Added the terms and definitions of growth rings, growth ring width, latewood and latewood rate (see Chapter 3).

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 methods 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 measurement.

--- 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 equipment, test specimens, test procedures, calculation results and test records, etc.

This document is applicable to the width of the growth ring with a clear growth ring boundary on the cross section of the wood sample without defects and the wood growth ring with a clear difference between the early and late wood. Determination of latewood percentage in long rounds.

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 documents, only the version corresponding to that date 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 physical and mechanical properties of wood with small unblemished samples - Part 2. Sampling methods and general requirements

LY/T 1788-2008 Terms of wood properties

3 Terms and Definitions

The terms and definitions defined in LY/T 1788-2008 and the following terms and definitions apply to this document.

4 Principles

Measure the width, number and total latewood width of all whole growth rings of the sample, and determine the average width of growth rings and latewood ratio. END. Draft Version (GB/T 1927.3-2021)