Fatigue test method and system for main stress structural member of crane

Abstract

The invention discloses a fatigue test method and system for a main stress structural member of a crane, and the method comprises the steps: 1), determining a test target position of the main stress structural member of the crane through finite element simulation; 2) acquiring feature data of the structural member at each target position in the crane operation process, and determining test parameter setting of each target position in the structural member fatigue test process according to the acquired feature data of each target position; 3) testing each target position of the structural member according to the determined parameter setting, and acquiring fatigue crack size data at each target position of the structural member in real time; and 4) circularly executing the test until a preset test termination condition is met, and estimating the fatigue life of the main stress structural member of the crane according to the test result of the structural member. The fatigue life of the main stressed structural member of the crane can be effectively estimated through reasonable design of the test, and the method has great significance in guaranteeing safe production of the crane.

Description

Technical Field

[0001] The invention relates to the technical field of structural component fatigue testing, and in particular to a fatigue testing method and system for a main load-bearing structural component of a crane. Background Art

[0002] Ports are key logistics hubs for modern transportation systems to achieve transit transportation. Cranes, as one of the main port machinery, are important equipment for ports to complete loading and unloading operations and transshipment transportation. Cranes work in harsh environments and complex conditions. Fatigue damage is inevitable in the process of bearing their own weight, alternating workloads and environmental loads for a long time. When fatigue damage accumulates to a certain extent, fatigue cracks will appear, and then cracks will expand under the action of external loads, eventually leading to structural damage, resulting in serious consequences. Therefore, it is very important to perform fatigue tests on the main load-bearing structural parts of cranes to test their performance. Summary of the invention

[0003] To solve the above problems, the present invention provides a fatigue test method and system for the main load-bearing structural parts of a crane, which can achieve effective prediction of the fatigue life of the structural parts through reasonable design of the test, and is of great significance for ensuring the safe production of the crane.

[0004] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0005] The present invention provides a fatigue test method for a main load-bearing structural member of a crane, comprising:

[0006] Step 1): Determine the target position of the main load-bearing structural parts of the crane for testing through finite element simulation;

[0007] Step 2): acquiring characteristic data of the main load-bearing structural parts of the crane at each target position during the crane operation, and determining the test parameter settings of each target position during the fatigue test of the main load-bearing structural parts of the crane according to the acquired characteristic data of each target position;

[0008] Step 3): testing each target position of the main load-bearing structural member of the crane according to the determined parameter settings, and obtaining fatigue crack size data at each target position of the main load-bearing structural member of the crane in real time;

[0009] Step 4): The test is executed cyclically until the preset test termination condition is met, and the fatigue life of the main load-bearing structural parts of the crane is estimated based on the test results of the main load-bearing structural parts of the crane.

[0010] As a possible implementation, further, in step 1), the target position of the main load-bearing structural parts of the crane for testing is determined by finite element simulation, which specifically includes the following steps:

[0011] Step 1.1): Establish a finite element model of the main load-bearing structural components of the crane;

[0012] Step 1.2): Load the load spectrum at the constraint of the model to perform random vibration fatigue simulation analysis;

[0013] Step 1.3): Obtain fatigue damage values ​​of different test positions of the structural component within a preset time of the loading load spectrum;

[0014] Step 1.4): Sort the damage values ​​of different test positions from large to small, and select the test positions corresponding to the first x largest fatigue damage values ​​as the target positions.

[0015] As a possible implementation, further, the characteristic data in step 2) includes stress and strain data of target positions of main load-bearing structural parts of the crane at each moment.

[0016] As a possible implementation, further, in step 2), determining the test parameter settings of each target position during the fatigue test of the main load-bearing structural parts of the crane according to the acquired characteristic data of each target position specifically includes the following steps:

[0017] Step 2.1): Count the duration of each stress at each target position of the main load-bearing structural parts of the crane according to the acquired characteristic data;

[0018] Step 2.2): sort the stresses at each target position according to the action duration from large to small, and select the first n stresses with longer action duration as the stress parameter setting of the corresponding target position; wherein the sum of the action durations corresponding to the first n stresses screened out at the same target position accounts for no less than 80% of the total action duration of the stress at the target position;

[0019] Step 2.3): Set the duration Tx of each stress in a single load cycle at the target position according to the ratio of the duration of each stress in the first n order. i ;

[0020] Among them, Tx i The expression is as follows:

[0021]

[0022] Among them, Tx i represents the duration of action of the i-th stress among the top n stresses at the x-th target position during a single load cycle; t xi Indicates the duration of action corresponding to the i-th stress among the first n stresses at the x-th target position in the characteristic data, t xnIt represents the action duration corresponding to the nth stress among the first n stresses in the order at the xth target position in the characteristic data; A represents the duration of a single load cycle.

[0023] As a preferred implementation mode, preferably, during each load cycle, n stresses selected from each target position are applied to the corresponding target position in a random order to test the main load-bearing structural parts of the crane.

[0024] As a possible implementation, further, in step 3), each target position of the main load-bearing structural member of the crane is tested according to the determined parameter settings, and fatigue crack size data at each target position of the main load-bearing structural member of the crane is obtained in real time. The specific steps are as follows:

[0025] According to the first n selected stresses and the duration of the first n stresses in a single load cycle, the fatigue test parameters at the corresponding target positions in the main load-bearing structural parts of the crane are set;

[0026] The main load-bearing structural parts of the crane are tested, and the fatigue crack size data at each target position of the main load-bearing structural parts of the crane are obtained in real time during the test.

[0027] As a possible implementation mode, further, in step 4), the test is cyclically executed until a preset test termination condition is met, and the fatigue life of the main load-bearing structural parts of the crane is estimated based on the test results of the main load-bearing structural parts of the crane. The specific steps are as follows:

[0028] Step 4.1): When there is a crack exceeding the critical crack length in the obtained fatigue crack size data, or when the number of load cycles reaches a preset number of cycles, the test is terminated; wherein the preset number of cycles should be greater than the number of cycles corresponding to the occurrence of fatigue cracks in the main load-bearing structural parts of the crane;

[0029] Step 4.2): When there is a crack exceeding the critical crack length in the obtained fatigue crack size data, the number of cycles corresponding to the moment when the fatigue crack size data exceeds the critical crack length is used as the fatigue life of the main load-bearing structural parts of the crane;

[0030] When the number of load cycles reaches the preset number of cycles, the fatigue life of the main load-bearing structural parts of the crane is estimated based on the obtained fatigue crack size data, the number of cycles and the fatigue test parameter settings.

[0031] As a possible implementation method, further, based on the acquired fatigue crack size data, the number of cycles and the fatigue test parameter settings, the fatigue life of the main load-bearing structural parts of the crane is estimated in the following specific manner:

[0032] S1: Based on the obtained fatigue crack size data, number of cycles and fatigue test parameter settings, estimate the fatigue life N corresponding to the target location of each crack in the main load-bearing structural parts of the crane xf , where N xf The expression is as follows:

[0033]

[0034] Among them, N xf represents the fatigue life corresponding to the xth target position; N x0 Indicates the number of cycles corresponding to the occurrence of fatigue cracks in the main load-bearing structural parts of the crane at the xth target position; a f represents the critical crack length; a x0 It represents the initial crack length when fatigue crack appears at the xth target position of the main load-bearing structural member of the crane; a x represents the crack length at the xth target position; Δσ x represents the stress increase at the xth target position; Δσ x =σ xmax -σ xmin , σ xmax represents the maximum stress during the load cycle at the xth target position, σ xmin represents the minimum stress during the load cycle at the xth target position; C and m are material constants and the same as C and m in the Pais formula (measured by experiments); q represents the correction factor related to the crack length as a constant, usually set between 0.5 and 2; a 0 is the reference crack length, a 0 The expression is as follows:

[0035]

[0036] Among them, K IC represents fracture toughness; k is an empirical constant, usually set between 0.2 and 0.5; σ a is the alternating stress increase, σ a The expression is as follows:

[0037]

[0038] Where σ xmax represents the maximum stress during the load cycle at the xth target position, σ xmin represents the minimum stress during the load cycle at the xth target position;

[0039] S2: From the fatigue lives corresponding to the estimated target locations where cracks occur, the shortest fatigue life is selected, and the shortest fatigue life is used as the fatigue life of the main load-bearing structural parts of the crane.

[0040] The present invention also provides a fatigue test system for a main load-bearing structural component of a crane, which uses the fatigue test method for the main load-bearing structural component of a crane, and the system comprises:

[0041] The finite element simulation module is used to determine the target position of the main load-bearing structural parts of the crane for testing through finite element simulation;

[0042] A data acquisition module is used to acquire characteristic data of the main load-bearing structural parts of the crane at each target position during the operation of the crane;

[0043] A data processing module, used to determine the test parameter settings of each target position during the fatigue test of the main load-bearing structural parts of the crane according to the acquired characteristic data of each target position;

[0044] A parameter setting module is used to set the test module accordingly according to the determined fatigue test parameters and the preset test termination conditions;

[0045] A test module, used to apply corresponding stress to each target position of the main load-bearing structural member of the crane according to the settings, and cyclically perform the test on the main load-bearing structural member of the crane until the preset test termination condition is met;

[0046] Image recognition module, used to obtain fatigue crack size data at each target position of the main load-bearing structural parts of the crane in real time;

[0047] The structural component life estimation module is used to estimate the fatigue life of the main load-bearing structural components of the crane based on the test results of the main load-bearing structural components of the crane.

[0048] The present invention also provides a computer-readable storage medium, in which at least one instruction, at least one program, code set or instruction set is stored. The at least one instruction, at least one program, code set or instruction set is loaded and executed by a processor to implement the fatigue test method for the main load-bearing structural parts of the crane.

[0049] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0050] The present invention can achieve accurate prediction of the fatigue life of structural parts through reasonable design of experiments. During the experiment, the positions prone to fatigue damage in the main load-bearing structural parts of the crane are first determined according to finite element simulation, and then relevant test parameters are set according to characteristic data obtained during the actual operation of the main load-bearing structural parts of the crane. This allows the test process to be closer to the stress conditions of the structural parts in actual operation, thereby improving the accuracy of fatigue life estimation of the main load-bearing structural parts of the crane, which is of great significance for ensuring the safe production of the crane. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 It is a brief flow chart of a fatigue test method for a main load-bearing structural component of a crane provided by an embodiment of the present invention;

[0053] Figure 2 It is a schematic diagram of a system implementation structure of a fatigue test method for a main load-bearing structural component of a crane corresponding to the solution of the present invention;

[0054] Figure 3 It is a schematic diagram of a computer-readable storage medium provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0056] Embodiment 1

[0057] See attached Figure 1 As shown, this embodiment provides a fatigue test method for the main load-bearing structural parts of a crane, comprising the following steps:

[0058] Step 1): Determine the target position of the main load-bearing structural parts of the crane for testing through finite element simulation, which specifically includes the following steps:

[0059] Step 1.1): Establish a finite element model of the main load-bearing structural components of the crane;

[0060] Step 1.2): Load the load spectrum at the constraint of the model to perform random vibration fatigue simulation analysis;

[0061] Step 1.3): Obtain fatigue damage values ​​of different test positions of the structural component within a preset time of the loading load spectrum;

[0062] Step 1.4): Sort the damage values ​​of different test positions from large to small, and select the test positions corresponding to the first x largest fatigue damage values ​​as target positions, that is, select x target positions in total.

[0063] Step 2): Acquire the characteristic data of the main load-bearing structural parts of the crane at each target position during the crane operation process, including the stress, strain and other data of the target position of the main load-bearing structural parts of the crane at each moment, and determine the test parameter settings of each target position during the fatigue test of the main load-bearing structural parts of the crane according to the acquired characteristic data of each target position, specifically including the following steps:

[0064] Step 2.1): Count the duration of each stress at each target position of the main load-bearing structural parts of the crane according to the acquired characteristic data;

[0065] Step 2.2): Sort the stresses at each target position according to the duration of action from large to small, and select the first n stresses with longer duration of action as the stress parameter settings of the target position; wherein, the sum of the durations of action corresponding to the first n stresses screened out at the same target position accounts for no less than 80% of the total duration of stress action at the target position. In actual operation, the proportion is usually set between 80% and 90%.

[0066] For ease of understanding, an example is given here to illustrate. For example, after finite element simulation, the test positions corresponding to the first three largest fatigue damage values ​​of the main load-bearing structural parts of the crane are selected as the target positions, that is, a total of three target positions are selected. The stresses to which the first target position is subjected during the actual operation of the crane include: 11 , σ 12 , σ 13 , σ 14 , the duration of action of each stress is t 11 ,t 12 ,t 13 ,t 14 (where t 11 <t 13 <t 12 <t 14 ); select the top n stresses at the first target position in order, and the sum of the action durations corresponding to the top n stresses selected in order accounts for no less than 80% of the total action duration of the stresses at the first target position; for example, select the top two stresses σ at the first target position 14 , σ 12 , where σ 14 , σ 12 The sum of the corresponding action duration (t 12 +t 14 ) in the total stress duration (t 11 +t 12 +t 13 +t 14 ) accounts for no less than 80%, that is, (t 12+t 14 ) / (t 11 +t 12 +t 13 +t 14 )≥80%; for example, if the sum of the action durations corresponding to the current two stresses is less than 80% of the total action duration of the stresses, the first three stresses are screened out, that is, this step must ensure that the sum of the action durations corresponding to the first n stresses screened out is not less than 80% of the total action duration of the stresses at the target position.

[0067] Step 2.3): Set the duration Tx of each stress in a single load cycle at the target position according to the ratio of the duration of each stress in the first n order. i ;

[0068] Among them, Tx i The expression is as follows:

[0069]

[0070] Among them, Tx i Tx represents the duration of action of the i-th stress among the top n stresses at the x-th target position during a single load cycle; i Indicates the duration of action corresponding to the i-th stress among the first n stresses at the x-th target position in the characteristic data, t xn It represents the action duration corresponding to the nth stress among the first n stresses in the order at the xth target position in the characteristic data; A represents the duration of a single load cycle.

[0071] For ease of understanding, an example is given here to illustrate. In the same example as above: the first two stresses σ are selected at the first target position. 14 , σ 12 , and σ 14 , σ 12 The corresponding action duration satisfies (t 12 +t 14 ) / (t 11 +t 12 +t 13 +t 14 )≥80%; then the stress σ of the first two sorted ones selected at the first target position 14 , σ 12 The first stress σ 14 The duration of a single load cycle at the first target position is: T 11 =A×t 14 / (t 12 +t 14 ); the second stress σ 12 The duration of a single load cycle at the first target position is: T12 =A×t 12 / (t 14 +t 12 ).

[0072] During the test, the n stresses selected from each target position in each load cycle act on the target position in a random order, and the main load-bearing structural parts of the crane are tested. For ease of understanding, an example is given here to illustrate. In the same example as above: the first two stresses σ selected at the first target position 14 , σ 12 When the load cycle test is performed on the first target position of the main load-bearing structural member of the crane, the stress action sequence of the first load cycle can be σ 14 , σ 12 , or σ 12 , σ 14 ; During the second load cycle, the stress action sequence can be σ 14 , σ 12 , or σ 12 , σ 14 ; That is, in each load cycle σ 12 , σ 14 The order of applying to the first target position is random.

[0073] Step 3): Test each target position of the main load-bearing structural member of the crane according to the determined parameter settings, and obtain fatigue crack size data at each target position of the main load-bearing structural member of the crane in real time. The specific steps are as follows:

[0074] According to the first n stresses screened out and the duration of the first n stresses in a single load cycle, the fatigue test parameters at the corresponding target positions in the main load-bearing structural parts of the crane are set;

[0075] After setting the fatigue test parameters of x target positions, the main load-bearing structural parts of the crane are tested. During the test, the fatigue crack size data at each target position of the main load-bearing structural parts of the crane are obtained in real time.

[0076] In the above steps, the locations prone to fatigue damage in the main load-bearing structural parts of the crane are first determined based on finite element simulation, and then the relevant test parameters are set according to the characteristic data obtained during the actual operation of the main load-bearing structural parts of the crane. This makes the test process closer to the stress conditions of the structural parts in actual operation, which can effectively improve the accuracy of fatigue life estimation of the main load-bearing structural parts of the crane.

[0077] Step 4): Execute the test repeatedly until the preset test termination condition is met, and estimate the fatigue life of the main load-bearing structural parts of the crane based on the test results of the main load-bearing structural parts of the crane. The specific steps are as follows:

[0078] Step 4.1): When the fatigue crack size data obtained contains a value exceeding the critical crack length (critical crack length a f The test is terminated when a crack (preset value) occurs, or when the number of load cycles reaches a preset number of cycles; wherein the preset number of cycles should be greater than the number of cycles corresponding to the occurrence of fatigue cracks in the main load-bearing structural parts of the crane.

[0079] Step 4.2): When there is a crack exceeding the critical crack length in the obtained fatigue crack size data, the number of cycles corresponding to the moment when the fatigue crack size data exceeds the critical crack length is used as the fatigue life of the main load-bearing structural parts of the crane. For ease of understanding, an example is given here to illustrate. In the same example as above: after finite element simulation, the test positions corresponding to the first three largest fatigue damage values ​​of the main load-bearing structural parts of the crane are selected as target positions, that is, a total of three target positions are selected. During the test, the fatigue crack size data at the three target positions of the main load-bearing structural parts of the crane are obtained in real time. When there is a crack exceeding the critical crack length in the three target positions, the number of cycles corresponding to the moment when the fatigue crack size data exceeds the critical crack length is used as the fatigue life of the main load-bearing structural parts of the crane. For example: After 90,000 load cycles, the first target position among the three target positions has a crack length exceeding the critical crack length a. f In this case, the fatigue life of the main load-bearing structural parts of the crane is 90,000 times.

[0080] When the number of load cycles reaches the preset number of cycles, the fatigue life of the main load-bearing structural parts of the crane is estimated based on the obtained fatigue crack size data, the number of cycles and the fatigue test parameter settings. The specific method is as follows:

[0081] S1: Based on the obtained fatigue crack size data, number of cycles and fatigue test parameter settings, estimate the fatigue life N corresponding to the target location of each crack in the main load-bearing structural parts of the crane xf , where N xf (Based on the pairs formula for fatigue life prediction) The expression is as follows:

[0082]

[0083] Among them, N xf represents the fatigue life corresponding to the xth target position; N x0 Indicates the number of cycles corresponding to the occurrence of fatigue cracks in the main load-bearing structural parts of the crane at the xth target position; a f Indicates the critical crack length. In this embodiment, a f It can be set to the same value or set separately according to different target positions; ax0 It represents the initial crack length when fatigue crack appears at the xth target position of the main load-bearing structural member of the crane; a x represents the crack length at the xth target position; Δσ x represents the stress increase at the xth target position; Δσ x =σ xmax -σx min ,σx max represents the maximum stress during the load cycle at the xth target position, σ xmin It represents the minimum stress value during the load cycle at the x-th target position. Since the stress used in each load cycle at the same target position is the first n stresses screened out, the maximum and minimum stress values ​​are fixed. Therefore, the same target position has a constant Δσ in each load cycle. x The values ​​are the same. C and m are material constants, the same as C and m in the Pais formula (measured by experiments, the determination method of C and m in the Pais formula is the existing technology and will not be repeated here); q represents the correction factor related to the crack length as a constant, usually set between 0.5 and 2; a 0 is the reference crack length, a 0 The expression is as follows:

[0084]

[0085] Among them, K IC represents fracture toughness; k is an empirical constant, usually set between 0.2 and 0.5; σ a is the alternating stress increase, σ a The expression is as follows:

[0086]

[0087] Where σ xmax represents the maximum stress during the load cycle at the xth target position, σ xmin Represents the minimum stress during the load cycle at the xth target position.

[0088] For ease of understanding, an example is given here to illustrate the above example. For example, among the first three target positions selected, only the second and third target positions have cracks, and the first target position has no cracks. Then only the fatigue life N of the second and third target positions is calculated. 2f 、N 3f .

[0089] To calculate the fatigue life N of the second target position 2f For example, N 2f The expression is as follows:

[0090]

[0091] Among them, N 20 Indicates the number of cycles corresponding to the occurrence of fatigue cracks in the main load-bearing structural parts of the crane at the second target position; a 20 It indicates the initial crack length when fatigue crack appears in the main load-bearing structural member of the crane at the second target position; a 2 represents the crack length at the second target position; Δσ 2 represents the stress increase at the second target position; Δσ 2 =σ 2max -σ 2min , σ 2max represents the maximum stress during the load cycle at the second target position, σ 2min Indicates the minimum stress during the load cycle at the second target position. Reference crack length a 0 The expression is as follows:

[0092]

[0093] Among them, K IC represents fracture toughness; k is an empirical constant, usually set between 0.2 and 0.5; σ a is the alternating stress increase, σ a The expression is as follows:

[0094]

[0095] Where σ 2max represents the maximum stress during the load cycle at the second target position, σ 2min Indicates the minimum stress during the load cycle at the second target position. Similarly, calculate the fatigue life N of the third target position where the crack appears. 3f .

[0096] S2: From the fatigue lives corresponding to the estimated target positions where cracks appear, select the shortest fatigue life, and use the shortest fatigue life as the fatigue life of the main load-bearing structural parts of the crane. For ease of understanding, take the above example as an example: calculate the fatigue life N of the second target position and the third target position 2f and N 3f After that, compare N 2f 、N 3f The smaller fatigue life is used as the fatigue life of the main load-bearing structural parts of the crane, for example: N 2f <N 3f , then N 2f The fatigue life of the main load-bearing structural components of the crane.

[0097] As a further improvement, the above k and q can be determined by measuring the crack growth rate under different stress load conditions and by using the least squares fitting method to further improve the accuracy of fatigue life estimation of the main load-bearing structural parts of the crane.

[0098] Embodiment 2

[0099] See attached Figure 2 As shown, this embodiment provides a fatigue test system for the main load-bearing structural parts of a crane, which applies the fatigue test method for the main load-bearing structural parts of a crane in the first embodiment. The system includes:

[0100] The finite element simulation module is used to determine the target position of the main load-bearing structural parts of the crane for testing through finite element simulation;

[0101] A data acquisition module is used to acquire characteristic data of the main load-bearing structural parts of the crane at each target position during the operation of the crane;

[0102] A data processing module, used to determine the test parameter settings of each target position during the fatigue test of the main load-bearing structural parts of the crane according to the acquired characteristic data of each target position;

[0103] A parameter setting module is used to set the test module accordingly according to the determined fatigue test parameters and the preset test termination conditions;

[0104] A test module, used to apply corresponding stress to each target position of the main load-bearing structural member of the crane according to the settings, and cyclically perform the test on the main load-bearing structural member of the crane until the preset test termination condition is met;

[0105] Image recognition module, used to obtain fatigue crack size data at each target position of the main load-bearing structural parts of the crane in real time;

[0106] The structural component life estimation module is used to estimate the fatigue life of the main load-bearing structural components of the crane based on the test results of the main load-bearing structural components of the crane.

[0107] Embodiment 3

[0108] See attached Figure 3 As shown, based on the same inventive concept, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions. When the computer instructions are executed on a computer, the computer executes the fatigue test method for the main load-bearing structural parts of the crane as described in Embodiment 1.

[0109] In the specific implementation process, computer-readable storage media include: Universal Serial Bus flash drive (USB), mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, and other storage media that can store program codes.

[0110] The device embodiments described above are merely illustrative, wherein the units / modules described as separate components may or may not be physically separated, and the components displayed as units / modules may or may not be physical units / modules, i.e., they may be located in one place, or they may be distributed over multiple network units / modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Those of ordinary skill in the art may understand and implement it without creative effort.

[0111] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0112] The above descriptions are only some embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A fatigue test method for main load-bearing structural parts of a crane, characterized in that: include: Step 1): Determine the target position of the main load-bearing structural parts of the crane for testing through finite element simulation; Step 2): acquiring characteristic data of the main load-bearing structural parts of the crane at each target position during the crane operation, and determining the test parameter settings of each target position during the fatigue test of the main load-bearing structural parts of the crane according to the acquired characteristic data of each target position; Step 3): testing each target position of the main load-bearing structural member of the crane according to the determined parameter settings, and obtaining fatigue crack size data at each target position of the main load-bearing structural member of the crane in real time; Step 4): The test is executed cyclically until the preset test termination condition is met, and the fatigue life of the main load-bearing structural parts of the crane is estimated based on the test results of the main load-bearing structural parts of the crane.

2. The fatigue test method for the main load-bearing structural parts of a crane according to claim 1 is characterized in that: In step 1), the target position of the main load-bearing structural parts of the crane for testing is determined by finite element simulation, which specifically includes the following steps: Step 1.1): Establish a finite element model of the main load-bearing structural components of the crane; Step 1.2): Load the load spectrum at the constraint of the model to perform random vibration fatigue simulation analysis; Step 1.3): Obtain fatigue damage values ​​of different test positions of the structural component within a preset time of the loading load spectrum; Step 1.4): Sort the damage values ​​of different test positions from large to small, and select the test positions corresponding to the first x largest fatigue damage values ​​as the target positions.

3. The fatigue test method for the main load-bearing structural parts of a crane according to claim 2 is characterized in that: The characteristic data in step 2) include stress and strain data of the target positions of the main load-bearing structural parts of the crane at each moment.

4. The fatigue test method for the main load-bearing structural parts of a crane according to claim 3 is characterized in that: In step 2), the test parameter settings of each target position during the fatigue test of the main load-bearing structural parts of the crane are determined according to the characteristic data of each target position obtained, which specifically includes the following steps: Step 2.1): Count the duration of each stress at each target position of the main load-bearing structural parts of the crane according to the acquired characteristic data; Step 2.2): sort the stresses at each target position according to the action duration from large to small, and select the first n stresses with longer action duration as the stress parameter setting of the corresponding target position; wherein the sum of the action durations corresponding to the first n stresses screened out at the same target position accounts for no less than 80% of the total action duration of the stress at the target position; Step 2.3): Set the duration Tx of each stress in a single load cycle at the target position according to the ratio of the duration of each stress in the first n order. i ; Among them, Tx i The expression is as follows: Among them, Tx i represents the duration of action of the i-th stress among the top n stresses at the x-th target position during a single load cycle; t xi Indicates the duration of action corresponding to the i-th stress among the first n stresses at the x-th target position in the characteristic data, t xn It represents the action duration corresponding to the nth stress among the first n stresses in the order at the xth target position in the characteristic data; A represents the duration of a single load cycle.

5. The fatigue test method for the main load-bearing structural parts of a crane according to claim 4 is characterized in that: During each load cycle, n stresses selected from each target position act on the corresponding target position in a random order to test the main load-bearing structural components of the crane.

6. The fatigue test method for the main load-bearing structural parts of a crane according to claim 4 is characterized in that: In step 3), each target position of the main load-bearing structural member of the crane is tested according to the determined parameter settings, and fatigue crack size data at each target position of the main load-bearing structural member of the crane is obtained in real time. The specific steps are as follows: According to the first n selected stresses and the duration of the first n stresses in a single load cycle, the fatigue test parameters at the corresponding target positions in the main load-bearing structural parts of the crane are set; The main load-bearing structural parts of the crane are tested, and the fatigue crack size data at each target position of the main load-bearing structural parts of the crane are obtained in real time during the test.

7. The fatigue test method for main load-bearing structural parts of a crane according to claim 4 is characterized in that: In step 4), the test is executed cyclically until the preset test termination condition is met, and the fatigue life of the main load-bearing structural parts of the crane is estimated based on the test results of the main load-bearing structural parts of the crane. The specific steps are as follows: Step 4.1): When there is a crack exceeding the critical crack length in the obtained fatigue crack size data, or when the number of load cycles reaches a preset number of cycles, the test is terminated; wherein the preset number of cycles should be greater than the number of cycles corresponding to the occurrence of fatigue cracks in the main load-bearing structural parts of the crane; Step 4.2): When there is a crack exceeding the critical crack length in the obtained fatigue crack size data, the number of cycles corresponding to the moment when the fatigue crack size data exceeds the critical crack length is used as the fatigue life of the main load-bearing structural parts of the crane; When the number of load cycles reaches the preset number of cycles, the fatigue life of the main load-bearing structural parts of the crane is estimated based on the obtained fatigue crack size data, the number of cycles and the fatigue test parameter settings.

8. The fatigue test method for main load-bearing structural parts of a crane according to claim 7 is characterized in that: According to the obtained fatigue crack size data, number of cycles and fatigue test parameter settings, the fatigue life of the main load-bearing structural parts of the crane is estimated as follows: S1: Based on the obtained fatigue crack size data, number of cycles and fatigue test parameter settings, estimate the fatigue life T corresponding to the target location of each crack in the main load-bearing structural parts of the crane xf , where T xf The expression is as follows: Among them, N xf represents the fatigue life corresponding to the xth target position; N x0 Indicates the number of cycles corresponding to the occurrence of fatigue cracks in the main load-bearing structural parts of the crane at the xth target position; a f represents the critical crack length; a x0 It represents the initial crack length when fatigue crack appears at the xth target position of the main load-bearing structural member of the crane; a x represents the crack length at the xth target position; Δσ x represents the stress increase at the xth target position; Δσ x =σ xmax -σ xmin , σ xmax represents the maximum stress during the load cycle at the xth target position, σ xmin represents the minimum stress during the load cycle at the xth target position; C and m are material constants and the same as C and m in the Pais formula (measured by experiment); q represents the correction factor related to the crack length as a constant, usually set between 0.5 and 2; a0 is the reference crack length, and the expression of a0 is as follows: Among them, K IC represents fracture toughness; k is an empirical constant, usually set between 0.2 and 0.5; σ a is the alternating stress increase, σ a The expression is as follows: Where σ xmax represents the maximum stress during the load cycle at the xth target position, σ xmin represents the minimum stress during the load cycle at the xth target position; S2: From the fatigue lives corresponding to the estimated target locations where cracks occur, the shortest fatigue life is selected, and the shortest fatigue life is used as the fatigue life of the main load-bearing structural parts of the crane.

9. A fatigue test system for main load-bearing structural parts of a crane, characterized in that: The fatigue test method for the main load-bearing structural parts of a crane according to any one of claims 1 to 8 is applied, and the system comprises: The finite element simulation module is used to determine the target position of the main load-bearing structural parts of the crane for testing through finite element simulation; A data acquisition module is used to acquire characteristic data of the main load-bearing structural parts of the crane at each target position during the operation of the crane; A data processing module, used to determine the test parameter settings of each target position during the fatigue test of the main load-bearing structural parts of the crane according to the acquired characteristic data of each target position; A parameter setting module is used to set the test module accordingly according to the determined fatigue test parameters and the preset test termination conditions; A test module, used to apply corresponding stress to each target position of the main load-bearing structural member of the crane according to the settings, and cyclically perform the test on the main load-bearing structural member of the crane until the preset test termination condition is met; Image recognition module, used to obtain fatigue crack size data at each target position of the main load-bearing structural parts of the crane in real time; The structural component life estimation module is used to estimate the fatigue life of the main load-bearing structural components of the crane based on the test results of the main load-bearing structural components of the crane.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the fatigue test method for the main load-bearing structural parts of a crane according to any one of claims 1 to 8 is implemented.

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