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GB/T 37306.1-2019 English PDF (GBT37306.1-2019)

GB/T 37306.1-2019 English PDF (GBT37306.1-2019)

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GB/T 37306.1-2019: Metallic materials -- Fatigue testing -- Variable amplitude fatigue testing -- Part 1: General principles, test method and reporting requirements

GB/T 37306.1-2019
Metallic materials--Fatigue testing--Variable amplitude fatigue testing--Part 1. General principles, test method and reporting requirements ICS 77.040.10
H22
National Standards of People's Republic of China
Metal material fatigue test variable amplitude fatigue test
Part 1. General, test methods and reporting requirements
Part 1. Generalprinciples, testmethodandreportingrequirements
(ISO 12110-1.2013, IDT)
Published on.2019-03-25
2020-02-01 implementation
State market supervision and administration
China National Standardization Administration issued
Content
Foreword I
1 range 1
2 Normative references 1
3 Terms and Definitions 1
4 Test principle 3
4.1 Control signal generation 3
4.2 Test Method Overview 3
5 original load time history 5
5.1 General 5
5.2 Data Filtering 5
6 loading time history 5
6.1 General 5
6.2 Time History Sequence 5
6.3 Cycle Counting Method 6
7 program module 6
8 Conversion matrix and its control signal generation 9
8.1 Matrix establishment 9
8.2 Reconstruction of load signals 9
8.3 Control signal simplification 10
9 Variable amplitude fatigue test 10
10 Test report 11
10.1 General 11
10.2 Raw loading 11
10.3 Test conditions 11
10.4 Initial analysis of test data for individual and serial samples 12 Appendix A (informative) Standard loading time history 13
Appendix B (informative) Randomly extracted loading signal reconstruction example in the transformation matrix Appendix C (informative) Initial analysis of test data for individual samples 16 Reference 19
Foreword
GB/T 37306 "Metal material fatigue test variable amplitude fatigue test" is divided into two parts. --- Part 1. General, test methods and reporting requirements;
--- Part 2. Loop count and related data reduction methods.
This part is the first part of GB/T 37306.
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 12110-1.2013 "Metal material fatigue test variable amplitude fatigue test Part 1. General rules, test methods and reporting requirements.
The documents of our country that have a consistent correspondence with the international documents referenced in this part are as follows. ---GB/T 3075-2008 Metal material fatigue test axial force control method (ISO 1099.2006, MOD); ---GB/T 6398-2017 fatigue fatigue crack propagation method for metal materials (ISO 12108.2012, MOD); ---GB/T 24176-2009 Metal material fatigue test data statistical program and analysis method (ISO 12107.2003, IDT); ---GB/T 26077-2010 Metal material fatigue test axial strain control method (ISO 12106.2003, MOD); ---GB/T 34104-2017 Metallic material testing machine for testing the coaxiality of the test (ISO 23788.2012, MOD). This section has made the following editorial changes.
---Using the national standard GB/T 37306.2 "Metal materials fatigue test variable amplitude fatigue test Part 2. Cycle count and phase The Data Reduction Method replaces the international standard ISO 12110-2 (see 6.3, Chapter 9). This part was proposed by the China Iron and Steel Association.
This part is under the jurisdiction of the National Steel Standardization Technical Committee (SAC/TC183). This section drafted by. Guangzhou University, Shanghai University, Guangdong Entry-Exit Inspection and Quarantine Bureau Inspection and Quarantine Technology Center, Shanghai entry and exit inspection Quarantine Bureau Industrial Products and Raw Materials Testing Technology Center, Shenzhen Wan Testing Equipment Co., Ltd. Drafters of this section. Xu Zhonggen, Wu Yiwen, Wang Hongbin, Zhou Qi, Guo Xuan, Huang Xing. Metal material fatigue test variable amplitude fatigue test
Part 1. General, test methods and reporting requirements
1 Scope
This part of GB/T 37306 specifies the general rules for the cyclical fatigue test of laboratory samples for each cycle of amplitude variation. This section specifies and gives general rules for variable amplitude fatigue tests to generate for comparison when considering the typical dispersion of fatigue data. Consistent results.
This section is theoretically applicable to strain and force control or loading conditions for controlling fatigue crack growth rate, using this part of the loading Mode, not force - Appropriate protection should be taken when controlling the loading mode. This section applies to single actuator loading mode for single axis loading. The variable loading time history referred to in this section is deterministic, which is why this part deals with variable amplitude loading rather than random loading. The following items are outside the scope of this section.
--- Constant amplitude fatigue test with isolated overload or underload phenomenon; ---Experiment of large parts or structural parts;
--- Environmental impacts such as corrosion, temperature/time related creep leading to effects on frequency and waveforms; --- Multi-axis loading.
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. ISO 1099 metal material fatigue test axial force control method (Metalicmaterials-Fatiguetesting-Axial Force-controledmethod)
ISO 12106 Metal material fatigue test axial strain control method (Metalicmaterials-Fatiguetesting- Axial-strain-controledmethod)
ISO 12107 Metal material fatigue test data statistical program and analysis method Metalicmaterials-Fatigue testing-Statisticalplanningandanalysisofdata)
ISO 12108 metal material fatigue test fatigue crack growth method (Metalicmaterials-Fatiguetesting- Fatiguecrackgrowthmethod)
ISO 23788 Metallic material fatigue testing machine for testing the coaxiality (Metalicmaterials-Verification ofthe Alignmentoffatiguetestingmachines)
3 Terms and definitions
The following terms and definitions defined by ISO 1099, ISO 12106, ISO 12107 and ISO 12108 apply to this document. 3.1
Cumulative frequency diagram cumulativefrequencydiagram
A histogram representing the accumulation of each cycle since the start of the test. Note. The cumulative frequency map is also known as the cumulative spectrum or cumulative distribution. 3.2
Cycle cycle
Periodically repeated force-time/stress-time/strain-time under constant amplitude fatigue loading, or in some other signal applied to the specimen The smallest segment.
Note. In variable amplitude loading, the definition of the loop varies depending on the counting method used. 3.3
Loop counting method cyclecountingmethod
A method of calculating the number of load time history loops for a given length. 3.4
Loading loading
A general term for applying varying forces, strains, or other controlled quantities on the specimen. Note. This section mainly refers to the force control loading mode.
3.5
Load distribution loadingdistribution
A simple distribution or cumulative distribution of loads as a function of cycle. Note 1. The load distribution is the result of statistical processing of actual service loading records or a typical distribution unique to industrial fields (eg automotive, aerospace). Load distribution Suitable for force loading mode and strain loading mode or other loading modes. Note 2. The load distribution is often referred to as the “load spectrum”. Avoid using frequency domain loading. 3.6
Load histogram loadinghistogram
A simple histogram or cumulative histogram of the load as it changes with the cycle. Note 1. The loading time history is the result of statistical processing of actual service loading records or a typical distribution unique to industrial fields (eg automotive, aerospace). load Histograms are available for force loading mode and strain loading mode or other loading modes. Note 2. The term “force history” should have been used in the force-controlled loading mode, but this is not common in the field of variable amplitude fatigue. Whether the control variable is packaged or not In addition, always use the term "load time history."
3.7
Loading time history loadingtimehistory
A sequence of load cycles in which the load amplitude changes from one cycle to the next. Note 1. The loading time history is the result of statistical processing of actual service loading records or a typical distribution unique to industrial fields (eg automotive, aerospace). load The time history applies to force loading mode and strain loading mode or other loading modes. Note 2. The term “force history” should have been used in the force-controlled loading mode, but this is not common in the field of variable amplitude fatigue. Whether the control variable is packaged or not In addition, always use the term "load time history."
3.8
Load power spectrum loadingpowerspectrum
Energy density spectrum energydensityspectrum
The frequency domain description of the random loading time history.
Note. The power spectrum is the Fourier integral of the time signal correlation function. 3.9
Ignore omission
A cycle that removes non-damaging cycles or load amplitudes less than a threshold level is removed. 3.10
Ignore the level of the omissionlevel
The threshold level of the non-damaging cycle is removed.
3.11
Peak peak
The first derivative of the load time history changes from positive to negative. Note. For constant amplitude loading, the peak corresponds to the maximum load. For variable amplitude loading, the peak corresponds to the local maximum load in the loading time history. 3.12
Random randomdraw
A semi-cyclic sequence with different ranges and average values.
3.13
Valley valey
The first derivative of the loading time history changes from negative to positive. Note 1. The valley value is a relative minimum or "valley".
Note 2. The valley value is the minimum load point for constant amplitude loading. 3.14
Variable amplitude loading variableamplitudeloading
All loading modes where the peak loads are not equal or all valley loads are not equal or all peak and valley loads are not equal. Note 1. Also known as "irregular loading".
Note 2. “Spectrum loading” cannot replace variable amplitude loading because spectral loading is not a function of load and time. 4 Test principle
4.1 Control signal generation
It is difficult to obtain any number of cycles or failures from the original loading time history and thereby directly and effectively control the fatigue test, and The number of records of the actual load time history added to the sample does not represent the actual load, and the actual load can only be from the full load signal. It is calculated from the calculation that these statistical characteristics are obtained from a large number of actual loading measurements; therefore, the original loading time history usually needs to be simplified. Can be applied to the sample.
The simplification of the original load time history is usually done by loading the signal analysis onto two analog load control signals. These two The analog control signal is obtained by randomly extracting signals from a program module or a conversion matrix. If the testing machine and related electronic equipment can be simplified The original loading time history, which is not simplified, can be applied directly to the sample. Raw signal analysis was performed using the cycle counting method. The data obtained from the loop count is then used to build the cumulative frequency of the program module Rate map or randomly derived transformation matrix.
Note 1. The main advantage of the program module is that the control signal consists of a series of constant amplitude blocks, each of which has a different amplitude. Therefore, there is no need to pass calculations The machine generates complex digital control signals.
Note 2. Regardless of the complexity of the reconstruction control signal randomly selected from the transformation matrix, the control signal is still more than the actual loading for the actual loading. Program modules are more representative. In addition, due to the tremendous advances in digital electronics and computers, it has been generated by random extraction over the past few decades. Control signals have become easier and easier.
Signals should be filtered under the following conditions. Filtering should be carefully selected to avoid improper filtering and significant removal. Damage fatigue cycle. Average stress, residual stress, isolated high amplitude overload, etc. should be handled with caution. a) The raw signal obtained from direct measurement of loaded parts in service usually contains electronic noise or other non-fatigue vibrations. In use These interferences should be eliminated before the loop counting procedure processes the original signal; b) Since the non-damage cycle is usually the most (see 8.3.1), when the quick test is required, the slave program module can be removed. Or control signals obtained in random extraction to eliminate non-injury cycles (shortest cycles) to significantly reduce test duration. Note 3. These isolated high amplitude overloads actually increase the fatigue life due to the generation of favorable residual stresses when there is an isolated high amplitude overload in the load time history. 4.2 Overview of test methods
The variable amplitude fatigue test is applied to the sample using a cumulative frequency map (program module) or a control signal obtained by random extraction. The response of the sample is monitored by a load sensor or a force sensor or strain gauge given measurement and these output data are used for closed loop control. Note. The variable amplitude fatigue test usually uses hydraulic servo test equipment, but other actuators can be used in the case of closed loop control test. The test results are reported when the specimen breaks into two parts or when another failure criterion fails. Test results may include cycles of failure Number of times or sequence, crack spread measurement or any other sample damage process data. The specific test and test principle is shown in Figure 1. The detailed information of the main steps of the test is given in the subsequent part of this standard. Note. The dashed box is an optional step.
Figure 1 Flow chart for collecting variable amplitude loading data and converting it into laboratory variable amplitude fatigue test input data 5 original loading time history
5.1 General
There are two types of sources of load time history for an original component or structure. a) The first type of source is a direct measurement of the load condition of an in-service component or structural member, using a strain gage or other sensing device. Record and store the measurement results using a digital data acquisition system; Note. Automotive hubs, suspension systems, railway bogies, turbine blades, and aircraft wing beams are typical components that are subject to fatigue loading. b) The second type of source is the typical standard loading time history in the industrial sector, the meaning of which is usually the majority of the relevant industrial sectors. Recognized by personnel.
The original load time history is usually composed of a load sequence that completely repeats a given length (time or number of cycles). From a sequence Only very subtle changes can be observed by listing to the next sequence. When the original loading time history is obtained by directly measuring the in-service component load, filtering may be required to eliminate electrical or mechanical noise. sound. Filter parameters should be carefully selected when filtering to avoid removal of significant damage fatigue cycles. The average stress modulation filter can be used (see 8.3).
5.2 Data Filtering
5.2.1 General requirements
Efficient data filtering can greatly reduce the amount of data used to generate the variable amplitude fatigue control signal. Filtering typically contains a threshold or threshold for the set load or load amplitude. The choice of threshold or threshold should take into account the existing knowledge and experience of the fatigue process studied, and in particular to avoid ignoring parts or The true damage cycle that plays a major role in the fatigue damage process of the component. 5.2.2 Noise Filtering
High-frequency low-amplitude peaks superimposed on the fatigue loading signal that do not contribute to fatigue are usually ignored, as by data recording systems (strain gauges) The resulting electronic noise shall be indicated in the test report for each individual sample. 6 loading time history
6.1 General
The load time history can be described in any of the following three ways. ---Time history sequence;
--- Cycle count;
--- Power or energy density spectrum.
6.2 Time history sequence
Variable amplitude loading can be divided into discontinuous or partially continuous random processes. These stochastic processes can be calculated by in-service measurements or time step calculations. determine.
The short range can be represented by a continuous force-time signal, and the long range needs to be represented by a series of consecutive short ranges (see Figure 2), where each short range Generally continuous. The long distance is obtained by connecting the short distances in the correct order. Description.
X --- time;
Y --- load;
1 --- Load order.
Figure 2 Load-time history
6.3 Cycle counting method
The load time history can be represented by a series of loop numbers. In this case, the order in which the loop occurs is lost. The raw load time history is processed by a loop counting program that defines the number of cycles and cycles by any time of fatigue life. To describe the original signal. This program allows the number of fail cycles for a component to be defined in the same way as a constant-load condition. Different cycle counting methods are available. All methods are to divide the entire load range (between the minimum and maximum values) or level. The 32 loading levels are basically sufficient (see Figure 2). Refer to GB/T 37306.2 for the counting method. Note 1. General industrial practice uses 64 loading levels.
Note 2. The most common cycle counting methods are.
--- Cross level counting;
--- Peak count;
--- Simple range count;
--- Range pairs count;
--- "Rain flow" count.
When the original load time history is completely processed by the correlation counting method, it is performed in one of two ways. a) determine the cumulative frequency map and establish the program module; b) Determine the transformation matrix by random extraction and reconstruct the load time history. The fatigue life of the sequence of program modules is sometimes quite different from the fatigue life under random loading sequences and should be avoided as much as possible. 7 program module
The program module is derived from a cumulative frequency map corresponding to the cumulative probability expressed by the relationship between the loaded excess and the number of cycles. It is a smooth continuous curve (see Figure 3).
Description.
1---Gauss normal distribution;
X---loop;
Y---normalized stress range.
Figure 3 Example of cumulative load graph
Simplify the cumulative frequency map into discrete box plots. Load division should be carried out in the form of equivalent damage. The first box is the largest discrete load level Box diagr...

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