GB/T 41061-2021 English PDF (GBT41061-2021)

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GB/T 41061-2021: Test methods for creep properties of fiber reinforced plastics
GB/T 41061-2021
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 83.120
CCS Q 23
Test Methods for Creep Properties of Fiber Reinforced Plastics
ISSUED ON: DECEMBER 31, 2021
IMPLEMENTED ON: JULY 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 Test Principle ... 5
5 Test Equipment ... 6
6 Specimen ... 7
7 Conditioning ... 7
8 Test Conditions ... 7
9 Test Steps ... 8
10 Test Results ... 9
11 Test Report ... 12
Bibliography ... 14
Test Methods for Creep Properties of Fiber Reinforced Plastics
1 Scope
This Document specifies the test principles, test equipment, samples, state adjustment, test
conditions, test procedures, test results and test reports of the test method for creep properties
of fiber reinforced plastics.
This Document applies to the determination of tensile creep properties, compressive creep
properties, flexural creep properties and creep rupture stress of fiber reinforced plastics under
specified conditions.
2 Normative References
The provisions in following documents become the essential provisions of this Document
through reference in this Document. For the dated documents, only the versions with the dates
indicated are applicable to this Document; for the undated documents, only the latest version
(including all the amendments) is applicable to this Document.
GB/T 1446 The Generals of Test Methods for Properties of Fiber-Reinforced Plastics
GB/T 1447 Test Method for Tensile Properties of Glass Fiber-Reinforced Plastics
GB/T 1448 Fiber-Reinforced Plastics Composites - Determination of Compressive
Properties
GB/T 1449 Test Method for Flexural Properties of Glass Fiber-Reinforced Plastics
GB/T 3961 Terms for Fiber Reinforced Plastics
GB/T 9979 Rule of Test for Mechanical Properties of Fiber - Reinforced Plastics at
Elevated and Reduced Temperatures
GB/T 16825.2-2018 Verification of Static Uniaxial Testing Machines - Part 2: Tension
Creep Testing Machines - Verification of the Applied Force
3 Terms and Definitions
For the purposes of this Document, the terms and definitions given n GB/T 3961 and the
5 Test Equipment
5.1 Loading system
5.1.1 The electronic testing machine shall comply with the provisions of the Class-1 testing
machine in GB/T 16825.2-2018, the relative error of the load shall not exceed ±1%, and the
repeatability error shall not exceed 1%.
5.1.2 The relative error of the load provided by the weight test device shall not exceed ±1%.
5.1.3 The loading system shall have a buffer device, and shall be kept away from external
vibration and shock during installation.
5.1.4 The loading system shall ensure that the load can be applied smoothly without
instantaneous overload, and the applied load shall be within ±1% of the required load.
5.1.5 During the test, the loading device shall be able to provide a constant load. In the creep
rupture test, measures shall be taken to prevent the vibration generated when the specimen
ruptures from being transmitted to the adjacent loading system.
5.2 Clamp
5.2.1 The tensile creep test fixture should ensure that the loading axis is consistent with the
longitudinal axis of the sample as much as possible. It is recommended to use a fixture that can
center and fix the sample before loading.
5.2.2 The compressive creep test fixture shall comply with the provisions of GB/T 1448.
5.2.3 The bending creep test fixture shall comply with the provisions of GB/T 1449.
5.3 Deformation measuring device
5.3.1 The deformation measuring device consists of a device capable of measuring the
elongation, compression or deflection of the specimen under load. This device shall not
influence the specimen through mechanical effects (deformation, indentation, etc.), physical
effects (heating the specimen, etc.) and chemical effects on the sample.
5.3.2 The accuracy of the deformation measuring device is 0.001mm.
5.3.3 The deformation measuring device shall be fixed and shall not slip.
5.4 Dimension measuring tool
The accuracy is 0.01mm.
5.5 Time measuring device
The accuracy is 1min.
5.6 Automatic temperature control device
The error shall not exceed ±2°C.
6 Specimen
6.1 Shape and size of specimen
6.1.1 The specimen for tensile creep test shall comply with provisions of GB/T 1447.
6.1.2 The specimen for compression creep test shall comply with the provisions of GB/T 1448.
6.1.3 The specimen for bending creep test shall comply with the provisions of GB/T 1449.
6.2 Number of specimens
6.2.1 The number of valid specimens at each test temperature and each stress level shall at least
meet the following requirements:
--- 2 pieces for no less than 4 stress levels;
--- 3 pieces if there are less than 4 stress levels.
6.2.2 When testing creep rupture, test at least 2 specimens at each test temperature and each
stress level.
6.2.3 When it is known that the size of the material shall change significantly under the
influence of temperature, a comparison sample shall be added. At least 3 comparison specimens
are tested at each test temperature.
7 Conditioning
Except for special provisions, the conditioning of the sample shall be according to the
provisions of GB/T 1446.
8 Test Conditions
8.1 Test temperature
The choice of the test temperature depends on the purpose of the test, and is selected with
reference to the following provisions.
temperature and initial stress.
9.6 According to the provisions of GB/T 9979, preserve the heat of specimen. After the heat
preservation, it shall be quickly and smoothly loaded to the test load, and the loading process
should be completed within 10s. A series of tests of the same material shall use the same loading
speed. Start timing when the test load is loaded.
9.7 Measure the elongation, compression or deflection of the specimen (and the comparison
specimen). If the deformation measurement is not automatically and continuously recorded;
measure the strain at the following time intervals: 1min, 6min, 12min, 30min, 1h, 2h, 5h, 20h,
50h, 100h, 200h, 500h, 700h and 1000h, etc. If the creep strain curve is discontinuous or
interrupted with time, the reading frequency shall be increased.
9.8 Measure and record the test temperature, test environment temperature and humidity. If the
temperature and humidity measurement is not automatically recorded, it shall be recorded when
the deformation is measured.
9.9 When performing the stress test of 1% strain for 1000h, measure the strain generated for
1000h under at least 3 stress levels, then draw the isochronous stress-strain curve for 1000h;
and obtain the stress value of 1% strain by interpolation method.
9.10 When performing the creep rupture test, measure the rupture time of the material; for
materials with obvious yield characteristics before rupture, the rupture time is the starting time
of the above yield characteristics. For creep rupture test the tensile method is recommended.
10 Test Results
10.1 Creep modulus
10.1.1 The tensile creep modulus shall be calculated as per Formula (1):
Where:
Et,T - tensile creep modulus at time t, in megapascals (MPa);
P - load, in Newtons (N);
A - initial cross-sectional area, in square millimeters (mm2);
L0,T - initial gauge length, in millimeters (mm);
(ΔL)t,T - the amount of elongati...