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GB/T 1043.2-2018: Plastics -- Determination of Charpy impact properties -- Part 2: Instrumented impact test
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Plastics -- Determination of Charpy impact properties -- Part 2: Instrumented impact test
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GB/T 1043.2-2018
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Basic data | Standard ID | GB/T 1043.2-2018 (GB/T1043.2-2018) | | Description (Translated English) | Plastics -- Determination of Charpy impact properties -- Part 2: Instrumented impact test | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | G31 | | Classification of International Standard | 83.080.01 | | Word Count Estimation | 22,289 | | Date of Issue | 2018-03-15 | | Date of Implementation | 2018-10-01 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | GB/T 1043.2-2018: Plastics -- Determination of Charpy impact properties -- Part 2: Instrumented impact test
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Plastics--Determination of charpy impact properties--Part 2. Instrumented impact test
ICS 83.080.01
G31
National Standards of People's Republic of China
Determination of impact properties of plastic simply supported beams
Part 2. Instrumented impact test
Part 2. Instrumentedimpacttest
(ISO 179-2.1997, IDT)
Published on.2018-03-15
2018-10-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
China National Standardization Administration issued
Content
Foreword III
1 Scope 1
2 Normative references 1
3 Terms and Definitions 1
4 Principle 4
5 Instrument 5
6 sample 7
7 Test step 7
8 Calculation and representation of results 8
9 precision 9
10 Test report 9
Appendix A (informative appendix) Inertia Peak 11
Appendix B (informative) Rack quality 14
Appendix C (informative) Precision data 15
Reference 17
Foreword
GB/T 1043 "Determination of impact properties of plastic simply supported beams" is divided into two parts.
--- Part 1. Non-instrumental impact test;
--- Part 2. Instrumented impact test.
This part is the second part of GB/T 1043.
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
This part uses the translation method equivalent to ISO 179-2.1997 "Determination of impact properties of plastic simply supported beams - Part 2. Instrumentation
Determination of impact properties of plastic simply supported beams - Part 2. Instrumentation impact test - 1988 - Am.
Precision.
This part was proposed by the China Petroleum and Chemical Industry Federation.
This part is under the jurisdiction of the National Plastics Standardization Technical Committee General Method and Product Subcommittee (SAC/TC15/SC4).
This section is responsible for drafting units. China Petroleum and Chemical Corporation, Beijing Beihua Institute Yanshan Branch, Zhonglan Chenguang Chengdu detection technology
Limited company, Dalian University of Technology.
The main drafters of this section. Wang Chaoxian, Deng Yanxia, Zhang Youwen, Guo Wei, Chen Minjian, Wang Yanse.
Determination of impact properties of plastic simply supported beams
Part 2. Instrumented impact test
1 Scope
1.1 This part of GB/T 1043 specifies a test method for determining the impact properties of plastic simply supported beams using force-deflection curves. follow
Several different types of specimens and tests specified in GB/T 1043.1-2008, and according to different material types, specimen types and gaps
Type and specified test parameters.
Describes dynamic effects such as resonance of the sensor-impact knife system, sample resonance, and the relationship between initial contact and inertia peaks (see
See curve b and Appendix A) in Figure 1.
1.2 For a comparison between the test methods of simply supported beams and cantilever beams, see Chapter 1 of GB/T 1043.1-2008.
GB/T 1043.1-2008 is applicable to the impact behavior only by impact strength, and the potential energy of the impact tester is to be compared with the sample to be tested.
The fracture energy is approximately matched (see ISO 13802.1999, Appendix C). This section applies to the use of force-deflection curve or force-time curve detailed table
The impact behavior, as well as the development of automated impact instruments that avoid the energy matching requirements mentioned above.
1.3 For the scope of materials applicable in this section, refer to Chapter 1 of GB/T 1043.1-2008.
1.4 For the general requirements for guaranteeing the test results, refer to Chapter 1 of GB/T 1043.1-2008.
1.5 The test data obtained in this section does not apply to the design calculation of components, and the use of test data is not discussed in this section.
Content. When applying the data obtained by this method, it must be marked with reference to this part or negotiate with relevant parties.
Materials can be obtained by changing the test environment temperature, the notch radius of the sample, the thickness of the sample, and the preparation of samples using different conditions.
Information on the behavior of the break.
This part does not involve the formation mechanism of each point on the analytical force-deflection curve. The analytical method for this mechanism is still in the research stage.
1.6 The results of the measurements are comparable only when the sample preparation conditions and test conditions are the same. Comprehensive evaluation of impact stress on specimens
In response, it is necessary to determine the deformation rate and the effect of temperature on material parameters such as crystallinity and moisture content. Therefore, you cannot use this part.
The impact fracture behavior of the product is directly predicted, but this section can be used to measure the sample taken from the product.
1.7 If the comparability of this part and GB/T 1043.1-2008 is established through preliminary tests, the impact strength can be determined by this part.
the result of.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
GB/T 1043.1-2008 Determination of impact properties of simply supported beams - Part 1. Non-instrumental impact (ISO 179-1.2000,
IDT)
ISO 13802.1999 Plastic pendulum impact tester for pendulum impact test, Izod impact test and tensile impact
Test (Plastics-Verification of pendulumimpact-testingmachines-Charpy, Izodandtensileimpact-
Testing)
3 Terms and definitions
The following terms and definitions as defined in GB/T 1043.1-2008 apply to this document.
3.1
Impact speed impactvelocity
V0
The speed at which the impact knife is relative to the sample holder when an impact occurs. Expressed in meters per second (m/s).
3.2
Inertia peak
After the first time the impact knife contacts the sample, the sample is accelerated, and the force of the inertia of the contact portion is changed to form force-time or force-deflection.
The first peak on the curve. (See curve b in Figure 1, and Appendix A).
3.3
Impact force
The force exerted by the impact blade on the specimen in the direction of impact. Expressed in Newtons (N).
3.4
Deflection
The displacement of the impact knife relative to the sample holder during the impact is based on the position at which the impact knife and the sample first contact. In millimeters
(mm) indicates.
3.5
Impact energy impactenergy
The energy consumed to accelerate, deform, and fracture the specimen at deflection s. Expressed in joules (J).
The measurement method is to calculate the integral area from the initial point of the impact to the deflection s below the force-deflection curve.
3.6
Maximum impact maximumimpactforce
FM
The force value at the maximum impact force on the force-time or force-deflection curve (see Figure 1). Expressed in Newtons (N).
3.7
Maximum impact deflection deflection atmaximumimpactforce
sM
Deflection at maximum impact force FM (see Figure 1). Expressed in millimeters (mm).
Figure 1 Force-deflection (N and t) and force-time (b) curves
Time/ms
Figure 1 (continued)
(The damage curve is shown in Figure 2)
In the picture.
N---non-fracture. plastic deformation after yielding continues to the ultimate deflection sL;
P---partial fracture. the crack propagates stably after the sample yields, and the impact force when the ultimate deflection sL is reached is greater than 5% of the maximum impact force;
t --- ductile fracture. the crack propagates stably after the yield of the specimen, and the impact force when the ultimate deflection sL is reached is less than or equal to 5% of the maximum impact force;
b --- brittle fracture. unstable crack propagation after yielding;
s --- broken fracture. unstable crack propagation before yielding;
sL=limit deflection; drag start.
Note. Due to the different deformation modes of the specimen, the force-deformation curve obtained with this section differs from the curve obtained with ISO 6603-2. The difference is in instrumentation
After the first failure in the drop weight test, the force suddenly has a slight decrease (crack generation), followed by a gradual increase in force. Instrumented three-point bending shock
In the test, the increase in force after crack generation was never observed. In addition, there is no inertial effect of the bending shock in the drop impact test of the flat plate (see Appendix A).
Fig. 2 Typical force-deflection curve of different fracture modes when the specimen of type 1 is subjected to lateral impact
3.8
Maximum impact energy energytomaximumimpactforce
WM
The energy consumed to reach maximum impact. Expressed in joules (J).
3.9
Fracture deflection
sB
Deflection when the impact force is reduced to less than or equal to 5% of the maximum impact force FM (see Figure 1). Expressed in millimeters (mm).
The difference between the fracture deflection sB of the specimen at the fracture and the ultimate deflection sL of the specimen at the start of the drag (see Figure 1, curve N) can be tested.
The length l, width b and span L are judged. For type 1 specimens with lateral impact, sL ranges from 32 mm to 34 mm.
Note. When the type 1 specimen is impacted laterally, the suspected deflection limit is sometimes observed, that is, the deflection value is unusually low when the impact force drops to zero (low to only
20mm), however the sample did not break at this time. When the test speed is lowered, it will be found that this behavior is affected by the combined effects of bending and distortion.
The sample is flipped from the side to a more stable layer position. This behavior can be confirmed by examining the test specimen, at which point the bending axis on the specimen is not
Parallel is inclined to the width direction of the sample.
The reason for this is that the sample has a high bending stiffness ratio between the lateral direction and the direction of the impact of the layer, and there is a microscopic such as a draft angle.
Small asymmetry can trigger this behavior.
The elimination method is to install the guide member in front of the blade of the instrumented impact knives, so as to avoid large distortion in the middle of the sample. But the orientation
Parts cannot be mounted on the blade of the impact knife.
3.10
Impact break energy impactenergyatbreak
WB
The energy consumed to reach the fracture deflection sB. Expressed in joules (J).
3.11
Simply supported beam without gap (notch) impact strength Charpy (notched) impactstrength
acU(acN)
Impact fracture energy per unit of original cross-sectional area A (AN) relative to the unnotched (notched) specimen (see 8.4 and GB/T 1043.1-
3.1 and 3.2 of.2008). Expressed in kilojoules per square meter (kJ/m2).
3.12
Destruction type typeoffailure
The type of deformation behavior of the material during the test (see Figure 2). Types include no damage (N), partial damage (P), ductile damage (t), brittleness
Destruction (b) and fragmentation (s).
Types t, b, and s are subclasses of Complete Destruction (C) and Hinge Destruction (H) as defined in GB/T 1043.1-2008. These damages
The type of impact fracture energy value WB and the simply supported beam impact strength can be expressed as the average of the corresponding test results.
For partially damaged (P) specimens and materials with interlaminar shear cracking, see 7.6 of GB/T 1043.1-2008. If a group of samples
There is more than one type of damage, see 7.7 of GB/T 1043.1-2008.
Note. As can be seen in Figure 2, for broken damage (see curve s) and brittle failure (see curve b), deflection and impact energy at break and deflection at maximum impact force
The degree is the same as the impact energy, and crack instability propagates at the maximum impact force.
4 Principle
The two strips support the strip-shaped specimen near the two ends to form a horizontal beam, the impact line is in the middle of the support, and the sample is subjected to
Vertical impact and high speed bending at a constant nominal speed. The geometry of the impact test is given in Chapter 5 of ISO 13802.1999. In the rush
The impact is recorded during the strike. Depending on the method of measurement, the deflection of the specimen can be measured directly with suitable measuring equipment, or it can be carried
In the case where the body can apply a frictionless impact, the deflection is calculated as a function of initial velocity, force, and time. Obtained by the above test
The force-deflection curve can describe the impact behavior of the specimen at high bending rates to infer some properties of the material.
5 instruments
5.1 Testing machine
5.1.1 Basic components
The energy carrier, the impact knives and the frame with the sample holder are the basic components of the test machine. The energy carrier can be inertial (such as a pendulum or
Free darts can also be used in the form of impacts such as springs or pneumatic aids, or hydraulic.
The test machine shall be capable of ensuring that the specimen is bent by impact at a nominal constant velocity perpendicular to the length of the specimen. Can be measured on the sample
The force can simultaneously calculate or measure the deflection of the specimen in the direction of impact.
5.1.2 Energy carrier
The impact velocity v0 of the low energy pendulum specified in GB/T 1043.1-2008 (see also ISO 12.802.1999, 4.2.4) is
2.90 m/s ± 0.15 m/s, the speed of the high energy pendulum is 3.8 m/s ± 0.2 m/s. Although it can also be used v0=3.8m/s±0.2m/s
Speed, but in order to make the data comparable to the data measured according to GB/T 1043.1-2008, the impact of this part of GB/T 1043
The speed should be 2.90m/s ± 0.15m/s (see Note 1 and Note 2 below).
In order to avoid the viscoelastic behavior of the material during the test, the measured data is not comparable, and the speed reduction during the impact cannot be
More than 10% (see note 3 below).
The hydraulic carrier is a high-speed impact tester with suitable accessories. Need to check the impact knife during the impact process relative to the sample support speed
Any error in degree, such as the method of checking the slope of the deflection-time curve.
When using a gravity-accelerated energy carrier, the above-mentioned impact speeds correspond to heights of 43 cm ± 5 cm and 74 cm ± 7 cm, respectively.
The same energy carrier uses two different speeds, the latter's impact kinetic energy E is increased by 1.54 times.
The allowable speed reduction of up to 10% during the impact process described above means that the kinetic energy E (expressed in joules) during impact should satisfy the following
condition.
E/W * ≥5 (1)
In the formula.
E --- kinetic energy of the energy carrier, the unit is Joule (J);
W *---Maximum impact energy to be measured, in joules (J).
The mass mC of the energy carrier should satisfy the requirements of equations (2) and (3).
mC ≥10W */v20 (2)
mC ≥1.2W *(when v0=2.9m/s) (3)
In the formula.
mC---the mass of the energy carrier, in kilograms (kg);
V0 --- impact speed in meters per second (m/s);
W *---Maximum impact energy to be measured, in joules (J).
For example, when W*=10J, mC≥12kg.
Note 1. As the impact velocity increases, the height of the inertia peak F1 (see Figure 1, curve b) and the amplitude of subsequent sample vibrations increase. About these vibrations
See Appendix A and references [1] and [2] for basic knowledge. See Appendix A for details of inertia peaks and damped vibrations.
Note 2. For some specific applications, such as obtaining impact performance data for pre-cracked specimens, use a lower impact velocity (eg 1 m/s ± 0.05 m/s)
It can help to reduce the vibration mentioned in Note 1.
Note 3. This standard complies with the test conditions required by 7.3 of GB/T 1043.1-2008. It ensures that the change in speed during impact is equivalent to conventional
Impact test, and the impact strength value is comparable. The importance of plastics is that the plastic is a bending rate sensitive material, especially when the temperature is close to the transition temperature.
5.1.3 Impact blade
See 5.8.1 and Table 3 of ISO 13802.1999.
The material that can be used for the impact edge is any wear-resistant, high-strength, non-deformable, and can transmit the force applied to the specimen to the force measurement system.
material.
Note. Experience has shown that steel is generally suitable for impact blades. Low-density materials like titanium can be used to increase the natural frequency of force measuring devices.
5.1.4 Pendulum
The pendulum shall comply with the requirements of 5.2 and Table 3 of ISO 13802.1999.
5.1.5 Sample support
The sample holder shall comply with the requirements of 5.7.1 of ISO 13802.1999.
5.1.6 Rack
The frame of the test machine can be adjusted horizontally, and the impact knives and sample holders meet the requirements of 5.1.3 and 5.1.5.
When the deflection is calculated using the kinetic energy of the energy carrier, the mass ratio of the frame to the energy carrier mF/mC shall be not less than 10 (see Appendix B and below).
Note 1 and Note 2). When the deflection can be measured directly, this ratio is only recommended. Impact testing machines are often susceptible to vibration, so
The center of gravity of the rack should fall on the impact projection line.
Note 1. The ratio of rack mass to pendulum mass in ISO 3.802.1999 5.3.3 is 40, which minimizes the energy delivered to the rack. however
What is measured in the method is the force applied to the specimen and the deflection of the specimen, so any energy delivered to the frame does not affect the test results.
Note 2. The ratio of mF/mC to 10 is to prevent the frame from being accelerated to more than 1% of the impact speed in the later stages of the test (see Appendix B).
5.1.7 Friction loss
When the deflection is not measured, when using a friction-free impact carrier such as a dart or a pendulum, the deviation of the impact velocity cannot exceed the calculation.
1% of the value. That is, the friction loss Wf should be less than 2% of the nominal energy E during the first quarter swing period, and should be within the complete swing period.
Less than 8% (see 5.6 of ISO 13802.1999).
Note. If the deflection is directly measured, when the impact velocity is within the specified range, the energy loss of the energy carrier caused by friction will not affect the test results.
5.2 Measuring device for force and deflection
5.2.1 Measurement of force
The force applied to the specimen is measured by mounting a strain gauge or a piezoelectric sensor on the impact knives, and the installation site is close to the impact.
Blades can also be used in other suitable ways. The measurement accuracy of the force measurement system shall not be less than 1% of the maximum force measured.
The assembled force measurement system is calibrated and can be calibrated using static methods (such as applying a known load on the impact knives) or dynamic methods.
The measurement error should be less than ±2% after calibration.
The force measurement system of the impact test has a natural frequency fn that is more than three times higher than the resonance frequency fs of the sample after impact (see below).
Note 1).
When designing the force measurement system, consider reducing the negative force behind the inertia peak to ensure that the force measurement system can measure quickly and accurately.
The force that deflects the specimen (see Notes 2 and 3). The negative force after the inertia peak should not exceed 20% of the inertia peak (see Figure A.2).
The bandwidth limit of the selected DC or carrier amplifier should cover the response frequency of the test equipment.
If the filtering process after impact is implemented, the type of filter and its basic characteristics should be given in the test report (see Chapter 10).
m item).
Note 1. The resonance frequency fs of the plastic sample is between 2 kHz and 10 kHz. A force measurement system with a natural frequency fn of 30 kHz is generally suitable for plastic testing.
The greater the difference between fs and fn, the easier it is to detect the onset and expansion of the crack.
In addition, if the above requirements are met, it is possible to vibrate the specimen during the test (see Figure 1, curve b, the recording line to the left of point tB) and the force measurement system.
The vibration (the recording line to the right of the tB point) is distinguished.
Note 2. After the impact, the force measurement system will be excited by the vibration of the natural frequency. The design of the mass and stiffness of the system determines the amplitude of the vibration. After the inertia peak
During the period when the impact blade and the sample are out of contact, if the amplitude of the excited vibration is large and the effective mass will “pull” the force measuring element, it may be observed.
A negative force that is unrelated to the deflection of the specimen.
Note 3. The vibration of the specimen (see curve b in Figure 1) and the noise on the impact curve will affect the determination of the maximum impact force, but the maximum impact energy or fracture
The determination of energy has almost no effect.
The duration t1 of the inertia peak (see Figure 1, curve b) is generally 0.1ms, and the accompanying vibration frequency depends on the modulus of the sample at 2kHz~
Within 10 kHz. In order to completely record the inertia peak, the sampling frequency of the force measuring system (transient recorder) should be no less than 100 kHz (see below).
Note 4).
The sampling frequency (≥100 kHz) used and the break time tB (≤13 ms) determine the size used for data storage capacity.
Note 4. The impact is a fast process with a speed of 2.9 m/s and a maximum duration of approximately 13 ms. If applicable, it is necessary to store the sample in a transient recorder
Data on force and deflection (if the deflection is a measured value). Approximately 50% of the storage space is available for storing actual test data.
The higher the sampling frequency, the better the time resolution. Increasing the sampling frequency helps to evaluate the impact of brittle materials with a short fracture time tB.
test.
5.2.2 Measurement of deflection
The deflection of the specimen is a function of time, which can be calculated either by quadratic integration of the force-time curve or directly.
If the deflection is measured directly, the sampling frequency used should be the same as the frequency at which the impact force is measured. Time and resolution of deflection measurement
Match each other.
In most cases, instruments used to measure force and deflection will have different signal transmission times, resulting in a bias in the force-deflection curve.
shift. This offset is proportional to the impact speed. Time shifting should be performed according to the difference in transmission time to achieve synchronization of the time recording line.
5.3 Micrometers and gauges
The micrometer and gauge should meet the requirements of 5.2 of GB/T 1043.1-2008.
6 sample
The sample shall comply with the requirements of Chapter 6 of GB/T 1043.1-2008.
7 Test procedure
7.1 Perform tests in an environment where the condition of the sample is adjusted, or ensure that the sample is transferred from the state-regulated environment to the test environment for a sufficient period of time.
Short to prevent changes in the state of the sample and changes in mechanical properties.
When the cryostated sample is tested at room temperature, the test can be carried out within 10 s after conditioning. Condition adjustment and wetness between test environments
The difference in degree has little effect on the sample. For example, after the sample transfer time of the polyamide reaches 30 minutes, there is no obvious difference in the impact behavior.
7.2 Determine the width and thickness of the specimen in accordance with the requirements of 7.1 of GB/T 1043.1-2008.
7.3 Verify the impact speed of the test machine according to the provisions of 5.1.2, and use a low-energy inertial type energy carrier according to the standard requirements. Impact speed
Accurate to ±1%.
7.4 Place the energy carrier in the starting position. Place the specimen on the specimen holder so that the impact blade hits the center of the specimen. Placement gap test
In this case, the center of the notch should be located just on the impact plane (see the left figure in Figure 1 of GB/T 1043.1-2008).
7.5 Release the energy carrier and record the change in force over time during the impact. If there is a displace...
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