Equivalent simplified test method for load of movable arm and bucket rod of excavator

Abstract

The invention discloses an equivalent simplified test method for the load of a movable arm bucket rod of an excavator, and belongs to the technical field of excavator test, and the method comprises the steps: obtaining strain data measured at a set measuring point of the movable arm bucket rod of the excavator; calculating normal stress and shear stress of the measuring points; according to the normal stress and the shear stress, six load components of the box type section of the bucket rod of the movable arm of the excavator are calculated when the strain data reach an extreme point; six load components are loaded on the pre-simplified box-shaped section of the bucket rod of the movable arm of the excavator, and the stress of the cracking hot spot position is calculated; establishing an incidence matrix of the relationship between the six load components and the cracking hot spot position stress; 6 load components of other working conditions are tested, and the stress of the cracking hot spot position under all working conditions is calculated based on the incidence matrix; according to the invention, the box type structure of the movable arm bucket rod is simplified, the equivalent six-component decomposition of the box type section load is realized, and the strain is tested at the cracking hot spot position, so that a relatively accurate box body inner wall cracking risk point stress-strain measurement scheme is provided.

Description

Technical Field

[0001] The invention relates to a simplified test method for equivalent load of a boom arm of an excavator, and belongs to the technical field of excavator testing. Background Art

[0002] The boom and dipper arm are the main components of the excavator's working device. Their service reliability is particularly important to the excavator's market reputation. Therefore, it is very important to fully verify the excavator's working device before leaving the factory.

[0003] Most of the market failures of booms and dipper arms are weld cracks, which are mainly divided into weld manufacturing defects and insufficient joint strength design. Limited to the box-type closed structure of booms and dipper arms, it is impossible to directly measure the stress and strain values ​​of welds with the crack initiation point inside the box during operation. On the other hand, in crack risk areas such as weld toes and weld roots, the structural transition is not smooth, the stress gradient is large, and the slight difference in the position of the strain rosette when pasting causes large measurement errors.

[0004] The existing technical solutions are as follows:

[0005] (1) An existing technical solution is the stress fatigue test of the working device. The entire working device is fixed on the tooling, and a two-force rod is used instead of the oil cylinder to load the axial force and lateral force on the tooth seat of the bucket to simulate the bucket excavation and turntable rotation conditions. While loading, strain gauges are pasted on the hot spots on the outer surface of the working device to monitor the impact of the loading load on the structure, and sensors are installed on the pins to monitor the wear of the pins. In addition, the fatigue resistance of the working device is studied by continuously loading axial force and lateral force until the working device fails.

[0006] (2) Another existing technical solution is the whole vehicle stress fatigue test, which directly performs various working conditions on the whole vehicle. While the operation is in progress, the dynamic response of the strain rosette at the hot spot position on the outer surface of the device is monitored. At the same time, other signals such as pin force, cylinder pressure, displacement, and whole vehicle vibration are monitored. After a certain period of operation, the vehicle is stopped to check the conditions at various locations, and the test is continued after the fault is repaired.

[0007] The disadvantages of the prior art are as follows:

[0008] (1) The existing technical solutions, due to the complex working conditions and the influence of various components, not only have structural cracks, but also abnormal wear of the pin shaft and other faults. In addition, the faults are highly random, and often several locations fail at the same time, and the order of failure cannot be determined. It is very accidental. If only the service condition of the boom or dipper arm weld is examined, it seems to be a waste of resources.

[0009] (2) The existing technical solution has a relatively complex cracking structure for the working device, long and dense welds, uncontrollable weld manufacturing defects, and weld defects often lead to cracking. The occurrence of weld defects is relatively random, which is inconsistent with the original intention of testing the fatigue strength of the structure;

[0010] (3) The existing technical solutions cannot directly measure stress and strain inside the boom and arm boxes. The areas near the internal pads of the joints, the roots of the fillet welds at the grooves between the side plates and the cover plates, and the T-shaped fillet welds between the inner partition and the side wall are all hot spots for cracking, but they cannot be directly measured because they are inside the boxes.

[0011] (4) In the existing technical solution, when the measuring point is near the weld, the strain rosette is closely attached to the crack risk areas such as the weld toe and weld root. Due to the uneven transition of the weld structure and the large stress gradient, the slight difference in the position of the strain rosette when it is attached causes a large measurement error. Summary of the invention

[0012] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a simplified test method for the equivalent load of an excavator boom arm. By simplifying the box-type structure of the boom arm, the box-type section load is equivalent to six-component decomposition, and the strain is tested at the cracking hotspot position, a more accurate stress-strain measurement scheme for the cracking risk point on the inner wall of the box is provided.

[0013] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0014] In a first aspect, the present invention provides a simplified test method for equivalent load of a boom arm of an excavator, wherein the excavator is started to perform a complete cycle of a predetermined excavation condition, and the method comprises:

[0015] Acquire strain data measured at a set measuring point of the excavator boom;

[0016] Calculate the normal stress and shear stress of the measuring point based on the strain data;

[0017] According to the normal stress and shear stress, the six load components of the box-shaped section of the excavator boom are calculated when the strain data reaches the extreme point;

[0018] Six load components are applied to the simplified box-shaped section of the excavator boom, and the stress at the cracking hotspot is calculated based on the strain at the cracking hotspot measured in advance.

[0019] Through the stress at the crack hotspot, the correlation matrix between the six load components and the stress at the crack hotspot is established;

[0020] The six load components of other working conditions were tested, and the stress at the cracking hotspot under all working conditions was calculated based on the correlation matrix.

[0021] Furthermore, the normal stress and shear stress of the measuring point are calculated according to the strain data, and the formula is as follows: ; ; in, is the measuring point number, i=1,2,3, For the The normal stress at each measuring point, For the The shear stress at each measuring point, For the The strain value of each measuring point in the 0° direction is: For the The strain value of each measuring point in the 45° direction, For the The strain value of each measuring point in the 90° direction, E is Young's modulus and μ is Poisson's ratio.

[0022] The simplified test method for equivalent load of an excavator boom arm according to claim 2 is characterized in that, according to the normal stress and the shear stress, six load components of the box-type section of the excavator boom arm are calculated when the strain data reaches the extreme point, and the formula is as follows: ; ; ; ; ; ; ; ; ; ; ; Among them, F x , F y , F z , M x , M y , M z There are 6 load components, A is the effective area of ​​the section; A0 is the area enclosed by the midline of each plate thickness of the section; Iz is the moment of inertia of the section about the z-axis; Iy is the moment of inertia of the section about the y-axis; y1 is the z-axis distance from the No. 1 measuring point to the neutral axis; y2 is the z-axis distance from the No. 2 measuring point to the neutral axis; z3 is the y-axis distance from the No. 3 measuring point to the neutral axis; δ i is the wall thickness at the i-th measuring point; c i For the The sum of the widths of the webs of the section at measuring point No. is the static moment of the partial cross section on one side of the neutral axis y-axis about the neutral axis y-axis; It is the static moment of the partial cross section on one side of the neutral axis z-axis about the neutral axis z-axis.

[0023] The simplified test method for equivalent load of an excavator boom arm according to claim 3 is characterized in that the simplified method for the box section of the excavator boom arm comprises: Simplify the box-type section of the excavator boom and bucket arm into a box-type structure, in which the wall thickness and box section of the box-type structure are equal to the original boom or bucket arm, and the weld form and size are also equal; A strain rosette is pasted at the cracking hotspot of the simplified box-type structure, where the direction of the strain rosette is perpendicular to the direction of the weld.

[0024] The simplified test method for excavator boom load equivalence according to claim 4 is characterized in that the cracking hotspot positions include three adjacent hotspots P, A, and B on the weld root of the groove fillet weld of the box-type structure; three adjacent hotspots Q, M, and N on both sides of the pad of the groove butt joint and three adjacent hotspots R, U, and V on the T-shaped fillet weld of the inner partition, wherein P, Q, and R are hotspots close to one side of the weld, respectively.

[0025] The excavator boom load equivalent simplified test method according to claim 5 is characterized in that the stress at the cracking hotspot position is calculated based on the strain at the cracking hotspot position measured in advance, comprising: Measure the strains of the hot spots A and B at the root of the groove fillet weld, the hot spots M and N on both sides of the backing plate of the groove butt joint, and the hot spots U and V at the inner partition T-shaped fillet weld; According to the linear superposition principle, the stress at the three cracking hotspots P, Q, and R is calculated and recorded as σ P , σ Q , σ R The calculation formula is as follows: ; ; ; Among them, S1 is the distance between the strain rosettes on hot spots P and A, S2 is the distance between the strain rosettes on hot spots A and B, L1 is the distance between the strain rosettes on hot spots Q and M, L2 is the distance between the strain rosettes on hot spots M and N, D1 is the distance between the strain rosettes on hot spots R and U, D2 is the distance between the strain rosettes on hot spots U and V, σ A , σ B , σ M , σ N , σ U , σ V They represent the stresses at positions A, B, M, N, U, and V, respectively, and are calculated from the measured strains.

[0026] Furthermore, the calculation formulas of S1, S2, L1, L2, D1, and D2 are as follows:

[0027] ; ; ; ; ; ;

[0028] Where, t is the plate thickness at the root of the groove fillet weld, is the plate thickness on both sides of the pad of the groove joint, is the plate thickness at the T-shaped fillet weld of the inner partition, k A , k B , k M , k N , k U , k V They are respectively the proportional relationship with the plate thickness at the corresponding positions.

[0029] Furthermore, the σ A , σ B , σ M , σ N , σ U , σ V The calculation formula is as follows:

[0030] , j = A, B, M, N, U, V;

[0031] in, Represents the strain numbered j.

[0032] Furthermore, the stress at the cracking hotspot position is used to establish a correlation matrix of the relationship between the six load components and the stress at the cracking hotspot position, and the formula is as follows:

[0033] ;

[0034] in: is the incidence matrix, σ P n ,σ Q n ,σ R n When n components are loaded separately, the stress values ​​at the corresponding hot spots P, Q, and R are n=F x , F y , F z , M x , M y , M z .

[0035] Furthermore, the stress at the cracking hotspot under all working conditions is calculated based on the correlation matrix for the six load components of other working conditions, and the formula is as follows:

[0036] ;

[0037] ;

[0038] ;

[0039] Where: P t ,σ Q T ,σ R d There are 6 components F x , F y , F z , M x , M y , M z Total stress values ​​at hot spots P, Q, and R after loading in sequence.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The present invention provides a simplified test method for the equivalent load of an excavator boom arm. By simplifying the box-type structure of the boom arm, the box-type cross-section load is equivalent to six components, and the strain is tested at the cracking hotspot position, a relatively accurate stress-strain measurement scheme for the cracking risk point on the inner wall of the box body is provided, which provides a powerful tool for the structural optimization design, fatigue life evaluation, and performance prediction of the excavator.

[0042] (2) The simplified test method and device for equivalent load of the excavator boom arm simplify the box-type welded structure, greatly reducing the number and length of welds compared with the original structure. The method is simple to manufacture, weld defects are easy to control, and manufacturing problems are relatively easy to eliminate. Only the design strength of the welded structure can be tested without other uncertain faults. The method has high cost performance and specificity.

[0043] (3) In the simplified box-type welding structure design, holes are opened at the upper and lower ends to facilitate manual pasting of strain gauge rosettes, and holes are opened on the side walls to facilitate the entry and exit of strain gauge wire harnesses, thus solving the problem of direct stress and strain measurement inside the boom box, which cannot be achieved in stress fatigue bench tests of working devices and vehicle tests.

[0044] (4) The simplified test method and device for equivalent load on the boom of an excavator, at the cracking hotspot, obtains the stress value by linear recursion of the nearby double strain rosette, providing a more accurate stress-strain measurement scheme for the cracking risk point on the inner wall of the box, solving the problem of uneven transition and large stress gradient in the cracking risk areas such as the weld toe and weld root, and large measurement errors caused by slight differences in the position of the strain rosette when it is pasted.

[0045] (5) The load equivalent simplified test method can be used repeatedly when the simplified box-type welding structure is the same. It only needs to test the six components of the load once to obtain the correlation matrix HPQR. The stress level calculation of the hot spot cracking position under other working conditions can also be obtained through the corresponding six components of the load and the correlation matrix HPQR. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Schematic diagram of the angle of the hinge point of a specific posture of the excavator working device provided by an embodiment of the present invention;

[0047] Figure 2 It is a schematic diagram of the sticking position of the boom and the boom box-section strain rosette provided by an embodiment of the present invention;

[0048] Figure 3 It is a schematic diagram of a simplified box-type welding structure provided by an embodiment of the present invention;

[0049] Figure 4 is a three-dimensional schematic diagram of a stretching tool provided in an embodiment of the present invention;

[0050] Figure 5 It is a schematic diagram of the assembly of the stretching tooling and the actuator provided by an embodiment of the present invention;

[0051] Figure 6 is a schematic diagram of a three-dimensional model of a bending tool provided in an embodiment of the present invention;

[0052] Figure 7 It is a stereogram of the assembly of the bending tool and the actuator provided by the embodiment of the present invention;

[0053] Figure 8 It is a plan view of the assembly of the bending tool and the actuator provided by an embodiment of the present invention;

[0054] Fig. 9 is a schematic diagram of a three-dimensional model of a torsion tooling provided in an embodiment of the present invention;

[0055] Fig.10 It is a stereoscopic diagram of the assembly of the torsion tooling and the actuator provided by an embodiment of the present invention;

[0056] Fig.11 It is a plan view of the assembly of the torsion tooling and the actuator provided by an embodiment of the present invention;

[0057] Fig.12 Schematic diagram of the attachment position of the strain rosette at the root of the groove fillet weld provided by the embodiment of the present invention;

[0058] Fig.13 It is a schematic diagram of the sticking positions of the strain rosettes on both sides of the pad of the groove butt joint provided by an embodiment of the present invention;

[0059] Fig.14Schematic diagram of the sticking position of the strain rosette of the T-shaped fillet weld of the inner partition provided by an embodiment of the present invention;

[0060] Fig.15 This is a schematic diagram of the cross-sectional component load Fx provided in an embodiment of the present invention. Figure 1 ;

[0061] Fig.16 This is a schematic diagram of the cross-sectional component load Fx provided in an embodiment of the present invention. Figure 2 ;

[0062] Fig.17 This is a schematic diagram of the cross-sectional component load Fy provided in an embodiment of the present invention. Figure 1 ;

[0063] Fig.18 This is a schematic diagram of the cross-sectional component load Fy provided in an embodiment of the present invention. Figure 2 ;

[0064] Fig.19 This is a schematic diagram of the cross-sectional component load Fz provided in an embodiment of the present invention. Figure 1 ;

[0065] Fig. 20 This is a schematic diagram of the cross-sectional component load Fz provided in an embodiment of the present invention. Figure 2 ;

[0066] Fig.21 This is a schematic diagram of the cross-sectional component load Mx provided in an embodiment of the present invention. Figure 1 ;

[0067] Fig. 22 This is a schematic diagram of the cross-sectional component load Mx provided in an embodiment of the present invention. Figure 2 ;

[0068] Fig.23 This is a schematic diagram of the cross-sectional component load Mx provided in an embodiment of the present invention. Figure 3 ;

[0069] Fig.24 This is a schematic diagram of the loading of the cross-sectional component load My provided in an embodiment of the present invention. Figure 1 ;

[0070] Fig.25 This is a schematic diagram of the loading of the cross-sectional component load My provided in an embodiment of the present invention. Figure 2 ;

[0071] Fig.26 This is a schematic diagram of the cross-sectional component load Mz provided in an embodiment of the present invention. Figure 1 ;

[0072] Fig. 27 This is a schematic diagram of the cross-sectional component load Mz provided in an embodiment of the present invention. Figure 2 ;

[0073] Fig.28 It is a flow chart of a simplified test method for excavator boom load equivalence provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0074] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0075] Example 1: This example introduces a simplified test method for equivalent load of an excavator boom arm. The excavator is started to perform a complete cycle of a predetermined excavation condition. The method includes:

[0076] Acquire strain data measured at a set measuring point of the excavator boom;

[0077] Calculate the normal stress and shear stress of the measuring point based on the strain data;

[0078] According to the normal stress and shear stress, the six load components of the box-shaped section of the excavator boom are calculated when the strain data reaches the extreme point;

[0079] Six load components are applied to the simplified box-shaped section of the excavator boom, and the stress at the cracking hotspot is calculated based on the strain at the cracking hotspot measured in advance.

[0080] Through the stress at the crack hotspot, the correlation matrix between the six load components and the stress at the crack hotspot is established;

[0081] The six load components of other working conditions were tested, and the stress at the cracking hotspot under all working conditions was calculated based on the correlation matrix.

[0082] like Fig.28 As shown, the simplified test method for equivalent load of an excavator boom arm provided in this embodiment specifically involves the following steps in its application process:

[0083] (1) This scheme simplifies the box-type structure of the excavator boom, decomposes the six components of the box-type section load into an equivalent structure, tests each component load separately, and uses double strain rosette linear recursion at the cracking hotspot inside the box, providing a more feasible strain measurement scheme for the risk points on the inner wall of the box.

[0084] (2) Adjust the working device of the excavator and measure the initial angles θ1 / θ2 / θ3 of the boom, arm and bucket. Figure 1 , install the cylinder displacement sensor;

[0085] (3) There are three measuring points, 1, 2, and 3, at the intersection of the main inertia axis of the boom and the arm and the outer surface. Paste the three-dimensional strain rosette, see Figure 2 , establish a local coordinate system in the measuring point area, the x-axis is the length direction of the working device, the y-axis is the left and right direction of the excavator, and the z-axis is perpendicular to the upper and lower sealing plates. When the strain rosette is pasted, its 0° direction is consistent with the x-axis;

[0086] (4) The excavator performs a complete cycle of a certain excavation condition, records the displacement change of the cylinder of the working device and the dynamic change of strain at the three measuring points, and obtains the normal stress and shear stress at the three measuring points at a certain moment, recorded as σ 1、 τ 1、 σ 2、 τ 2、 σ 3、 τ3;

[0087] (where i=1,2,3);

[0088] (where i=1,2,3);

[0089] Where: ε i-0° , ε i-45° , ε i-90° The strain values ​​of the i-th strain rosette in the directions of 0°, 45°, and 90° respectively; E is Young's modulus; μ is Poisson's ratio.

[0090] (5) Identify the strain extreme point within the cycle and convert the cylinder displacement at this time into the hinge angle θ 1m / θ 2m / θ 3m , and calculate the six load components of the box section at this time. The six load components are F x、 F y、 F z、 M x、 M y、 M z , obtained by the following calculation formula;

[0091] ;

[0092] ;

[0093] In the above formula:

[0094] A——Effective area of ​​the cross section; A0——Area enclosed by the midline of each plate thickness of the cross section; Iz——Moment of inertia of the cross section about the z-axis;

[0095] Iy——moment of inertia of the cross section about the y-axis; y1——distance from measuring point 1 to the neutral axis on the z-axis; y2——distance from measuring point 2 to the neutral axis on the z-axis; z3——distance from measuring point 3 to the neutral axis on the y-axis; δ i ——the wall thickness at the i-th measuring point; c i——The sum of the widths of the webs of the cross section at the i-th measuring point; ——static moment of the partial cross section on one side of the neutral axis y-axis about the neutral axis y-axis; ——Static moment of the partial cross section on one side of the neutral axis z-axis about the neutral axis z-axis.

[0096] (6) Simplify the cross section of the boom or dipper arm measuring point into a box-type structure. The wall thickness and cross section of the box-type structure are equal to those of the original boom or dipper arm. The weld form and size are also equal. Design a box-type welding structure and three sets of loading tooling (tensile, bending, torsion). Reserve a strain gauge wire harness hole on the side wall. Figure 3~Figure 11 , then cut materials, assemble points and weld;

[0097] (7) Paste unidirectional strain gauges on the inner wall, weld toe, weld root and other hot spots of the simplified box welding structure. The strain gauge direction is perpendicular to the weld direction and the pasting position requirements are as shown in Figure 12~Figure 14 , the distances between the strain rosettes S1 and S2, L1 and L2, D1 and D2, and their proportional relationship with the plate thickness k A , k B , k M , k N , k U , k V , see the solution formula below;

[0098] ;

[0099] In the above formula: t is Fig.12 The corresponding plate thickness.

[0100] ;

[0101] In the above formula: T is Fig.13 The corresponding plate thickness.

[0102] ;

[0103] In the above formula: d is Fig.14 The corresponding plate thickness.

[0104] ( j = A, B, M, N, U, V);

[0105] (8) The actuator is equipped with a special tool to load six load components on the simplified box structure. Figure 15~Figure 27 , and measure the strain at the hot spot position, and calculate the stress at the three positions P / Q / R according to the linear superposition principle, which is recorded as σ P、 σ Q、 σ R , the calculation formula is as follows;

[0106] ;

[0107] ;

[0108] ;

[0109] (9) Through the hot spot position stress, the relationship between the six component loads and the hot spot position stress is established, and the correlation matrix HPQR is solved;

[0110] ;

[0111] In the above formula: P i ,σ Q i ,σ R i (i=F x , F y , F z , M x , M y , M z ) are the stress values ​​at the corresponding hot spots P, Q, and R when the i component is loaded separately.

[0112] (10) Remeasure the six load components of other working conditions and use the correlation matrix , recalculate the stress at the hot spot position under this working condition.

[0113] ;

[0114] ;

[0115] ;

[0116] In the above formula: P t ,σ Q T ,σ R d There are 6 components (F x , F y , F z , M x , M y , M z ) The total stress value at hot spots P, Q, and R after loading in sequence.

[0117] The beneficial effects brought by this embodiment are as follows:

[0118] (1) The present invention provides a simplified test method for the equivalent load of an excavator boom arm. By simplifying the box-type structure of the boom arm, the box-type cross-section load is equivalent to six components, and the strain is tested at the cracking hotspot position, a relatively accurate stress-strain measurement scheme for the cracking risk point on the inner wall of the box body is provided, which provides a powerful tool for the structural optimization design, fatigue life evaluation, and performance prediction of the excavator.

[0119] (2) The simplified test method and device for equivalent load of the excavator boom arm simplify the box-type welded structure, greatly reducing the number and length of welds compared with the original structure. The method is simple to manufacture, weld defects are easy to control, and manufacturing problems are relatively easy to eliminate. Only the design strength of the welded structure can be tested without other uncertain faults. The method has high cost performance and specificity.

[0120] (3) In the simplified box-type welding structure design, holes are opened at the upper and lower ends to facilitate manual pasting of strain gauge rosettes, and holes are opened on the side walls to facilitate the entry and exit of strain gauge wire harnesses, thus solving the problem of direct stress and strain measurement inside the boom box, which cannot be achieved in stress fatigue bench tests of working devices and vehicle tests.

[0121] (4) The simplified test method and device for equivalent load on the boom of an excavator, at the cracking hotspot, obtains the stress value by linear recursion of the nearby double strain rosette, providing a more accurate stress-strain measurement scheme for the cracking risk point on the inner wall of the box, solving the problem of uneven transition and large stress gradient in the cracking risk areas such as the weld toe and weld root, and large measurement errors caused by slight differences in the position of the strain rosette when it is pasted.

[0122] (5) The load equivalent simplified test method can be used repeatedly when the simplified box-type welding structure is the same. It only needs to test the six components of the load once to obtain the correlation matrix , the stress level calculation of the hot spot cracking position under other working conditions is carried out through the corresponding six-component load and the correlation matrix It can also be obtained.

[0123] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A simplified test method for equivalent load of an excavator boom, characterized in that: Start the excavator to perform a complete cycle of the intended excavation conditions by: Acquire strain data measured at a set measuring point of the excavator boom; Calculate the normal stress and shear stress of the measuring point based on the strain data; According to the normal stress and shear stress, the six load components of the box-shaped section of the excavator boom are calculated when the strain data reaches the extreme point; Six load components are applied to the simplified box-shaped section of the excavator boom, and the stress at the cracking hotspot is calculated based on the strain at the cracking hotspot measured in advance. Through the stress at the crack hotspot, the correlation matrix between the six load components and the stress at the crack hotspot is established; The six load components of other working conditions were tested, and the stress at the cracking hotspot under all working conditions was calculated based on the correlation matrix.

2. The simplified test method for excavator boom load equivalence according to claim 1 is characterized in that: The normal stress and shear stress of the measuring point are calculated according to the strain data, and the formula is as follows: ； ； in, is the measuring point number, i=1,2,3, For the The normal stress at each measuring point, For the The shear stress at each measuring point, For the The strain value of each measuring point in the 0° direction is: For the The strain value of each measuring point in the 45° direction is: For the The strain value of each measuring point in the 90° direction, E is Young's modulus and μ is Poisson's ratio.

3. The simplified test method for equivalent load of an excavator boom arm according to claim 2, characterized in that: According to the normal stress and shear stress, the six load components of the box-type section of the excavator boom arm are calculated when the strain data reaches the extreme point. The formula is as follows: ； ； ； ； ； ； ； ； ； ； ； Among them, F x , F y , F z , M x , M y , M z There are 6 load components, A is the effective area of ​​the section; A0 is the area enclosed by the midline of each plate thickness of the section; Iz is the moment of inertia of the section about the z-axis; Iy is the moment of inertia of the section about the y-axis; y1 is the z-axis distance from the No. 1 measuring point to the neutral axis; y2 is the z-axis distance from the No. 2 measuring point to the neutral axis; z3 is the y-axis distance from the No. 3 measuring point to the neutral axis; δ i is the wall thickness at the i-th measuring point; c i For the The sum of the widths of the webs of the section at measuring point No. is the static moment of the partial cross section on one side of the neutral axis y-axis about the neutral axis y-axis; It is the static moment of the partial cross section on one side of the neutral axis z-axis about the neutral axis z-axis.

4. The simplified test method for equivalent load of an excavator boom arm according to claim 3, characterized in that: The method for simplifying the box-shaped cross section of the excavator boom arm comprises: Simplify the box-type section of the excavator boom and bucket arm into a box-type structure, in which the wall thickness and box section of the box-type structure are equal to the original boom or bucket arm, and the weld form and size are also equal; A strain rosette is pasted at the cracking hotspot of the simplified box-type structure, where the direction of the strain rosette is perpendicular to the direction of the weld.

5. The simplified test method for equivalent load of an excavator boom arm according to claim 4, characterized in that: The cracking hotspot positions include three adjacent hotspots P, A, and B on the weld root of the groove fillet weld of the box-type structure; three adjacent hotspots Q, M, and N on both sides of the pad of the groove butt joint, and three adjacent hotspots R, U, and V on the T-shaped fillet weld of the inner partition, among which P, Q, and R are the hotspots close to one side of the weld respectively.

6. The simplified test method for equivalent load of an excavator boom arm according to claim 5, characterized in that: The step of calculating the stress at the cracking hotspot location according to the strain at the cracking hotspot location measured in advance comprises: Measure the strains of the hot spots A and B at the root of the groove fillet weld, the hot spots M and N on both sides of the backing plate of the groove butt joint, and the hot spots U and V at the inner partition T-shaped fillet weld; According to the linear superposition principle, the stress at the three cracking hotspots P, Q, and R is calculated and recorded as σ P , σ Q , σ R The calculation formula is as follows: ； ； ； Among them, S1 is the distance between the strain rosettes on hot spots P and A, S2 is the distance between the strain rosettes on hot spots A and B, L1 is the distance between the strain rosettes on hot spots Q and M, L2 is the distance between the strain rosettes on hot spots M and N, D1 is the distance between the strain rosettes on hot spots R and U, D2 is the distance between the strain rosettes on hot spots U and V, σ A , σ B , σ M , σ N , σ U , σ V They represent the stresses at positions A, B, M, N, U, and V, respectively, and are calculated from the measured strains.

7. The simplified test method for equivalent load of an excavator boom arm according to claim 6, characterized in that: The calculation formulas of S1, S2, L1, L2, D1 and D2 are as follows: ； ； ； ； ； ； Where, t is the plate thickness at the root of the groove fillet weld, is the plate thickness on both sides of the backing plate of the groove joint, is the plate thickness at the T-shaped fillet weld of the inner partition, k A , k B , k M , k N , k U , k V They are respectively the proportional relationship with the plate thickness at the corresponding positions.

8. The simplified test method for equivalent load of an excavator boom arm according to claim 7, characterized in that: The σ A , σ B , σ M , σ N , σ U , σ V The calculation formula is as follows: ,j=A,B,M,N,U,V; in, Represents the strain numbered j.

9. The simplified test method for equivalent load of an excavator boom arm according to claim 8, characterized in that: The stress at the cracking hotspot position is used to establish a correlation matrix between the six load components and the stress at the cracking hotspot position. The formula is as follows: ； in: is the incidence matrix, σ P n ,σ Q n ,σ R n When n components are loaded separately, the stress values ​​at the corresponding hot spots P, Q, and R are n=F x , F y , F z , M x , M y , M z .

10. The simplified test method for equivalent load of an excavator boom arm according to claim 9, characterized in that: The six load components of other working conditions in the test are used to calculate the stress at the cracking hotspot under all working conditions based on the correlation matrix. The formula is as follows: ； ； ； Where: P t ,σ Q T ,σ R d There are 6 components F x , F y , F z , M x , M y , M z Total stress values ​​at hot spots P, Q, and R after loading in sequence.

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