This standard specifies the method of measuring the impact toughness of materials by applying a single impact bending load to the specimen using a simply supported beam pendulum impact tester to cause the specimen to fail, and using the energy absorbed per unit area when the specimen fails. This standard applies to castings of resins for fiber reinforced plastics and special casting resins. GB/T 2571-1995 Impact test method for resin castings GB/T2571-1995 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test method for impact resistance of resin casting body
1 Subject and scope of application
GB/T2571—1995
Replaces GB 2571—81
This standard specifies the method of using a simply supported beam pendulum impact tester to apply a single impact bending load to the specimen to cause the specimen to fail, and uses the energy absorbed per unit area when the specimen fails to measure the impact toughness of the material. This standard applies to castings of resins for fiber-reinforced plastics and special casting resins. 2 Test specimens
2.1 See Figure 1 and Table 1 for the shape and size of the test specimen. Unit: mm
: 45°±1°
r 0. 25 ±0. 05
Figure 1 Impact specimen
Type I-V-notched specimen, Type I-unnotched specimenTable 1 Specimen type, size, span
V-notched specimen
Unnotched specimen
Small V-notched specimen
Small unnotched specimen
120±2
120±2
Note: The notch of the specimen is made by machining.
Approved by the State Administration of Technical Supervision on December 20, 1995 Thickness
Thickness under the notch
Radius of the arc at the bottom of the notch
0.25±0.05
0.25±0.05
Implemented on August 1, 1996
GB/T2571--1995
2.2 The number of 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 A simply supported beam pendulum impact tester is used. The geometric dimensions and relative positions of the pendulum blade, specimen and support are shown in Figure 2. Unit: mm
Figure 2 Schematic diagram of simply supported beam impact
1-Support, 2-Specimen, 3-Pendulum blade
3.3 The impact velocity of the pendulum when impacting the center of the specimen is 2.9m/s, and the limit deviation is ±10%. 4 Test steps
4.1 Sample preparation shall be in accordance with Chapter 2 of GB/T2567-1995. 4.2 Specimen appearance inspection shall be in accordance with Chapter 3 of GB/T2567-1995. 4.3 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 the middle of the specimen for the unnotched specimen, measure the width under the notch for the notched specimen, and measure the thickness on both sides under the notch and take the average value. The measurement accuracy shall be in accordance with Chapter 6 of GB/T2567-1995. 4.5 Select the pendulum according to the energy required for the specimen to be destroyed, so that the energy consumed is within the range of 10%~85% of the pendulum energy. 4.6 Use the standard span template to adjust the distance of the support. 4.7
Before the test, check the energy consumed by the test machine when it is not loaded, so that the pointer points to zero after the no-load impact. Lift and lock the pendulum, press the entire width of the specimen against the support, and align the impact center with the center of the specimen or the back of the notch center. 4.8Www.bzxZ.net
Release the pendulum steadily, and read the energy consumed by the specimen from the dial. 752
GB/T2571-1995
4.10 Specimens that are broken at non-notch locations should be discarded, and other specimens should be taken as supplements. Specimens without notches are calculated as having one fracture. No value should be taken for specimens that are not broken. When there are less than 5 valid specimens in the same batch, the test should be repeated. 5 Calculation
5.1 Impact strength is calculated according to formula (1)
Where: α impact strength, kJ/m;
A—-~ The energy consumed by breaking the specimen, mJ; b width of the specimen under the notch or the width of the middle of the unnotched specimen, mm; h thickness of the specimen under the notch or the thickness of the middle of the unnotched specimen, mm6 Test results
The test results are in accordance with Chapter 8 of GB/T2567--1995. The test results of various types of specimens are not comparable. The test results of each group of specimens must indicate the type of specimen.
7 Test report
The test report is in accordance with Chapter 9 of GB/T2567-1995. Additional notes:
This standard is proposed by the State Administration of Building Materials Industry. It is under the jurisdiction of the National Technical Committee for the Promotion of Fiber Reinforced Plastics Standards. This standard was drafted by Tianma Group Corporation.
The main drafters of this standard are Wang Yufen and Liang Liusheng. This standard was first published in 1981.
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