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GB/T 40388-2021 (GBT40388-2021)

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BASIC DATA
Standard ID GB/T 40388-2021 (GB/T40388-2021)
Description (Translated English) Test method for shear strength of C/C composites
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard Q23
Classification of International Standard 83.120
Word Count Estimation 10,111
Date of Issue 2021-08-20
Date of Implementation 2022-03-01
Drafting Organization Hunan Boyun New Materials Co., Ltd., Central South University, China Aircraft Strength Institute
Administrative Organization National Fiber Reinforced Plastics Standardization Technical Committee (SAC/TC 39)
Proposing organization China Building Materials Federation
Issuing agency(ies) State Administration for Market Regulation, National Standardization Administration

Standards related to: GB/T 40388-2021

GB/T 40388-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.120
CCS Q 23
Test method for shear strength of C/C composites
ISSUED ON: AUGUST 20, 2021
IMPLEMENTED ON: MARCH 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 4 
4 Method principle ... 5 
5 Test equipment ... 5 
6 Test pieces ... 5 
7 Test conditions ... 7 
8 Test procedures ... 7 
9 Calculation ... 8 
10 Test report ... 9 
Appendix A (Informative) Diagram of shearing fixture and main components ... 10 
Test method for shear strength of C/C composites
1 Scope
This document specifies the method principle, test equipment, test pieces, test
conditions, test procedures, calculations and test report of the test method for shear
strength of C/C composites at room temperature.
This document applies to the determination of the shear strength of C/C composites
by the method of punching and shearing.
2 Normative references
The following documents are normatively referenced in this document and are
indispensable for its application. For dated references, only the version
corresponding to that date is applicable to this document; for undated references, the
latest version (including all amendments) is applicable to this document.
GB/T 1446, Fiber-reinforced plastics composites - The generals
GB/T 33501-2017, Test method for tensile property of C/C composites
3 Terms and definitions
Terms and definitions determined by GB/T 33501-2017 are applicable to this
document.
3.1 C/C composites
Carbon fiber-reinforced carbon matrix composites.
[Source: GB/T 33501-2017, 3.1]
3.2 The XY direction
Direction of no weft or continuous long fiber tiling planes in C/C composites (3.1).
[Source: GB/T 33501-2017, 3.6]
3.3 The Z direction
Direction vertical to the XY direction (3.2) in the C/C composites (3.1).
[Source: GB/T 33501-2017, 3.7]
Valid samples in each group shall be no less than 5.
7 Test conditions
7.1 Test environment
The test environment shall meet the laboratory standard environment specified in
GB/T 1446.
7.2 Sample state adjustment
Before the test, the sample shall be placed at least 24 h under the condition of
laboratory standard environment.
8 Test procedures
8.1 Check the appearance of the sample according to the provisions of GB/T 1446;
check the number and direction of each sample.
8.2 Adjust the state of the sample according to the provisions of 7.2.
8.3 After the sample state adjustment, measure the sample thickness h at four
positions in the direction of 90° to each other, at the diameter of 25 mm of the
sample, accurate to 0.01 mm; take the arithmetic mean of the four measurement
results. Measure the diameter d at any two positions of the inner ring clamping block
on the fixture, accurate to 0.02 mm; take the arithmetic mean of the two
measurement results. The schematic diagram of the shearing fixture assembly is
shown in Figure 3.
8.4 Fix the pin shaft on the force acting platform; respectively insert the upper inner
ring clamping block, upper outer ring, sample and lower inner ring clamping block
into the pin shaft in sequence; use the gasket and the sample clamping nut to fasten
the sample in the upper and lower inner ring clamping blocks. The tightening torque
is 1 N·m [see Figure 3a)].
8.5 Put the combination of the upper and lower inner ring clamping blocks of the
sample into the lower outer ring of the test fixture, where the upper outer ring is
connected to the lower outer ring through the clamp screw [see Figure 3b)], and the
tightening torque of the screw is 1 N·m. The sample installation is then completed
[see Figure 3c)].
8.6 Center the test fixture on the compression platform of the testing machine;
continuously apply a compressive load to the sample at a loading rate of 2 mm/min
until the sample fails or the load drops to 30% of the maximum load; continuously
measure the load-displacement data; record the maximum load.
Pmax – maximum load before failure, in Newtons (N);
d – diameter of the upper inner ring clamping block of the fixture, in millimeters
(mm);
h – sample thickness, in millimeters (mm).
9.2 Calculate the arithmetic mean, standard deviation and dispersion coefficient
according to GB/T 1446.
10 Test report
The test report generally includes the following contents:
a) name of the test item and number of this document;
b) test time, place and test environmental conditions;
c) sample source, material variety and specification;
d) sample number, size, sample direction and quantity;
e) types and specifications of test equipment and instruments;
f) loading rate;
g) load-displacement curve for each sample;
h) the measured value of each sample, the mean, standard deviation and
dispersion coefficient of each group of samples;
i) test personnel, date and others.
...