GB/T 41061-2021Test methods for creep properties of fiber reinforced plastics (English PDF)

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.

6.1 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.

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. […]

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);

(deltaL)t,T - the amount of elongation at time t, in millimeters (mm). […]