This standard specifies the test method for applying static tensile load to the specimen to determine the tensile strength, tensile elastic modulus, maximum load elongation and elongation at break and tensile stress-strain curve. This standard is applicable to castings of resins for fiber reinforced plastics and special casting resins. GB/T 2568-1995 Test method for tensile properties of resin castings GB/T2568-1995 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test method for tensile properties of resin casting body
1 Subject content and scope of application
GB/T 2568-1995
Replaces GB2568-81
This standard specifies the test method for determining tensile strength, tensile elastic modulus, maximum load elongation and breaking elongation and tensile stress-strain curve by applying static tensile load to the specimen. This standard is applicable to the casting body of resin for fiber reinforced plastics and special casting resin. 2 Test specimen
2.1 The shape and size of the test specimen are shown in Figure 1.
Unit: mm
Note: The thickness tolerance of each set of test specimens is ±0.2mm. Figure 1 Tensile test specimen diagram
2.2 The number of test specimens shall be in accordance with Chapter 3 of GB/T2567-1995. 3 Test conditions
3.1 Test environment conditions shall be in accordance with Chapter 4 of GB/T2567-1995, 3.2 Test equipment shall be in accordance with Chapter 7 of GB/T2567--1995. 2
3.3 When measuring tensile strength, the conventional test speed is 2~10mm/min, the arbitration test speed is 2mm/min, and when measuring elastic modulus and stress-strain curve, 2mm/min is used.
Approved by the State Administration of Technical Supervision on December 20, 1995 742
Implemented on August 1, 1996
4 Test steps
GB/T 2568-1995
4.1 Sample preparation shall be in accordance with Chapter 2 of GB/T2567--1995. 4.2 Sample appearance inspection shall be in accordance with Chapter 3 of GB/T2567-1995. 4.3 The specimen state adjustment shall be in accordance with Chapter 5 of GB/T2567--1995. 4.4 Number the specimens, measure the width and thickness of any three points within the specimen gauge length (50±0.5 section in Figure 1), and take the arithmetic mean. The measurement accuracy shall be in accordance with Chapter 6 of GB/T2567-1995.
4.5 Clamp the specimen so that the central axis of the specimen is consistent with the alignment center line of the upper and lower clamps, and load evenly and continuously at the specified speed until it is destroyed, and read the destruction load value.
4.6 When measuring the tensile elastic modulus, install an instrument for measuring deformation in the working section, apply the initial load (about 5% of the destruction load), check and adjust the instrument. Then apply the load at a certain interval, record the load and the corresponding deformation value, and load at least in five levels. The applied load should not exceed 40% of the destruction load. If there is an automatic recording device, continuous loading can be performed. 4.7 When measuring the elongation at failure and the stress-strain curve, there should be a device for automatically recording the load and deformation. 4.8 If the specimen breaks in the fixture or at the rounded part, the specimen shall be discarded and another specimen shall be taken to supplement it. If there are less than 5 valid specimens in the same batch, the test shall be repeated. 5 Calculation
5.1 The tensile strength shall be calculated according to formula (1)
where: a,—tensile strength, MPa;
P breaking load (or maximum load), N;
b—specimen width, mm;
specimen thickness, mm.
5.2 The tensile elastic modulus shall be calculated according to formula (2)
L. ·AP
where: E,
tensile elastic modulus, MPa;
L. 一—measurement gauge length, mm;
△P load increment of the initial straight line segment on the load-deformation curve, N; AL
deformation increment within the gauge length L corresponding to the load increment △P, mm. The rest is the same as (1).bZxz.net
5.3 The elongation of the specimen at the time of tensile failure or at the maximum load is calculated according to formula (3): AL×100
Where: E, —
The elongation of the specimen at the time of tensile failure or at the maximum load, %; △ Lb The elongation within the gauge length L at the time of specimen failure or at the maximum load, mm; L. ~--Same as (2).
5.4 Draw the tensile stress-strain curve.
6 Test results
The test results are in accordance with Chapter 8 of GB/T2567-1995. (1)
（2）
Test report
GB/T2568-1995
The test report is in accordance with Chapter 9 of GB/T2567-1995. Additional remarks:
This standard is proposed by the State Administration of Building Materials Industry and is under the jurisdiction of the National Technical Committee for Standardization of Fiber Reinforced Plastics. This standard was drafted by Tianma Group.
The main drafters of this standard are Zhu Yufen and Liang Liusheng. This standard was first issued in 1981.
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