GB/T 15777-2017Method for determination of the modulus of elasticity in compression parallel to grain of wood (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard replaces GB/T 15777-1995 "Determination of compressive modulus of elasticity of wood grain", in addition to editorial changes outside the main technology The content changes as follows.

--- Increased the load on the testing machine and measuring the accuracy of the deformation device, increase the method of measuring the deformation of the paste strain gauge, and increase the deformation gauge Range, but also to increase the measurement of sample size measurement and measurement accuracy (see 4.1, 4.2, 4.3, 6.1, 1995 edition 4.1,4.3,4.2, 6.2);

--- Increase the secondary section of the sample for the determination of density and ring width, "when the test material is sufficient, take the main section of the sample 60mm (h) × 20mm (a) × 20mm (a) 20mm (h) × 20mm (a) × 20mm (a) Used to determine the density and ring width. In the test material is not enough, only take the main section of the sample, intercept the sample after the test Water rate specimens and simultaneous determination of density and ring width (see 5.2, 1995 version 5.2) ";

--- Increase the loading rate of the provisions of "a constant load rate of 0.50mm/min load to the lower limit load, load speed range ± 25% (see 6.3, 1995 version 6.4);

--- Increase the paste strain gauge deformation measurement method, "for the measurement of the deformation of wood paste deformation deformation of the case, each time you uninstall, should be slightly Below the lower limit load, and then directly loaded to slightly exceed the upper limit load, load the maximum load does not exceed the proportion of the sample limit load and Can not make the sample appear compression damage (see 6.3, 1995 edition of 6.4) ";

--- After the end of the test to increase the test density and the width of the ring, "when the test material is sufficient, according to the provisions of 5.2 to determine the secondary test sample density and the growth ring Width, the lack of test materials available interception of the moisture content of the sample determination of density and ring width (see 6.5, 1995 edition of 6.6) ", which Like sample can better characterize the parallel grain compression performance and its influencing factors;

--- Corrigendum to the original standard 7.3 Water content adjustment formula a typo (see 7.3, 1995 version 7.3);

--- Increase the test report specific content (see Chapter 8, 1995 edition of Chapter 8).

1 Scope

This standard specifies the testing equipment, samples, test procedures and results of the calculation of compressive elastic modulus of wood along the grain.

This standard applies to non-defective small sample of wood grain compression modulus of elasticity.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version applies to this document. For undated references, the latest edition (including all amendments) applies to this document.

General principles of wood physical and mechanical test methods

Wood mechanics test sawing and sample intercepting method GB/T 1929-2009

Determination of moisture content of wood GB/T 1931-2009

Determination of density of wood GB/T 1933-2009

3 Principle

In parallel compression of wood, the compressive elastic modulus of wood along the grain is obtained from the ratio of stress to strain within the proportional ultimate stress.

4 Test equipment

4.1 test machine, should be in accordance with the national standards of measurement procedures regularly calibrated test machine load indication error must not exceed ± 1%, and at least Has a spherical sliding platen (or stand).

4.2 measuring deformation device for the strain gauge or holding extensometer, an example shown in Figure 1, the initial gauge 10mm ~ 40mm, the sample from the upper and lower Compression head more than 10mm, compression deformation measurement error is not greater than ± 1%, or other measurement accuracy and deformation of the device. […]