Airport runway base fatigue performance loading test base

Abstract

A fatigue performance loading test base for airport runway base layers includes a bottom plate with a fixing rod fixed to its center area for securing it to a testing machine. Bolt fixing fittings are provided at both ends of the bottom plate for fixing with bolts. An adjustment block is provided on each of the two upper edges of the bottom plate: a left adjustment block and a right adjustment block. The left and right adjustment blocks have the same structure and are symmetrically arranged. A bolt passes through the bottom of the right adjustment block, and the adjustment block is fixed to the bottom plate through the engagement of the bolt and the bolt fixing fitting. Compared to existing technologies, the technical advantage of this invention is that it features a strip-shaped hole, facilitating adjustment of the distance between the two supports, and making testing convenient even for large semi-circular specimens.

Description

Technical Field

[0001] This utility model belongs to the technical field of road engineering structural materials, specifically relating to a fatigue performance loading test base for airport runway base courses. Background Technology

[0002] In the fields of road engineering, aerospace, railway tracks, and structural materials, fatigue performance evaluation of materials is a crucial step in ensuring structural safety and durability. Especially for asphalt mixtures, metallic materials, or composite materials, repeated loading-unloading cyclic tests are necessary to obtain parameters such as fatigue life and fatigue modulus to guide material formulation optimization and structural design. Fatigue testing equipment can be categorized by loading method: universal testing machines (screw or hydraulically driven), electro-hydraulic servo testing machines, and specialized fatigue testing machines. Among these, electro-hydraulic servo testing machines are widely used in micro-deformation and high-cycle fatigue testing due to their high loading accuracy, flexible control, and ability to customize fixtures according to different materials and workpiece shapes.

[0003] Traditional fatigue testing methods typically include uniaxial tension, compression, or torsional loading, but the three-point bending test, as a standard mechanical testing method, has unique advantages in evaluating the bending properties, crack propagation, and fatigue life of materials. The three-point bending test has been widely used in the mechanical property evaluation of metals, plastics, and composite materials.

[0004] In fatigue studies of brittle materials such as concrete, asphalt mixtures, rocks, and concrete base materials, the semi-circular bending specimen (SCB) test has become an important standard specimen type for studying fracture and fatigue behavior due to its convenient sampling, clear crack guidance, and good geometric symmetry. Among these, the three-point bending loading method is the most commonly used loading form in SCB fatigue testing because of its clear stress distribution. This method has been adopted in standards such as ASTM D8044-16 and AASHTO TP105-13 due to its simple specimen preparation and clear loading form.

[0005] Although the SCB semicircular bending test has significant advantages in both theory and practice, existing experimental equipment still has some shortcomings. Traditional SCB experimental equipment typically uses basic static loading devices, which struggle to provide accurate dynamic loading, especially in fatigue tests simulating long-term repeated loading, where the loading accuracy and control stability of existing equipment are insufficient.

[0006] Furthermore, traditional SCB testing equipment generally lacks an integrated servo control system, resulting in significant stress fluctuations during the loading process and affecting the accuracy of experimental data. This often necessitates more manual intervention when conducting fatigue tests requiring high-precision control, making the experimental process cumbersome and inefficient.

[0007] Technical issues: Limited specimen size: Many foreign equipment (such as the SCB test rack launched by some scientific research equipment companies in Germany and the United States) are designed for small specimens. Due to the limitations of the rigidity of the clamps and the stroke of the loading head, they can only test small semi-circular specimens with a diameter ≤150mm and a thickness ≤50mm. They are not suitable for large or irregularly shaped specimens, such as concrete for airport runway base courses and layered specimens of composite structures, and it is difficult to provide stable loading support. Utility Model Content

[0008] The technical problem to be solved by this utility model is: how to design a fatigue performance loading test base for airport runway base that is suitable for large or irregularly shaped specimens.

[0009] The specific technical solution of this utility model is as follows:

[0010] A fatigue performance loading test base for airport runway base includes a bottom plate with a fixing rod fixed to the center of the bottom of the bottom plate for fixing to a testing machine. Bolt fixing fittings are provided at both ends of the bottom plate for fixing with bolts. An adjustment block is provided on each of the two upper edges of the bottom plate: a left adjustment block and a right adjustment block. The left and right adjustment blocks have the same structure and are symmetrically arranged. A bolt passes through the bottom of the right adjustment block, and the adjustment block is fixed to the bottom plate through the engagement of the bolt and the bolt fixing fitting. Supports are fixed to the upper inner edges of the left and right adjustment blocks for supporting the lower edge of the test specimen.

[0011] The bolt fixing fitting is a first strip hole or a screw hole set along the axial direction of the bottom plate. When the bolt fixing fitting is a first strip hole set along the axial direction of the bottom plate, the bolt passes through the entire first strip hole, and the lower end of the bolt is threaded to a nut. The "adjusting block is fixed together with the bottom plate" is completed by tightening the nut. When the bolt fixing fitting is a screw hole, the bolt is screwed into the screw hole. The "adjusting block is fixed together with the bottom plate" is completed by "tightening the bolt in the screw hole".

[0012] When the bolt fixing fitting is a first strip hole or screw hole set along the axial direction of the bottom plate, two alignment lines are provided on the bottom of the right adjusting block for easy alignment. The part between the two alignment lines is an alignment band. The width of the alignment band is the same as the width of the first strip hole, and the alignment band extends to both ends of the right adjusting block.

[0013] The support is cylindrical.

[0014] The adjustment block has an alloy steel frame.

[0015] Compared with the prior art, the technical advantage of this utility model is that it has a strip hole, which makes it easy to adjust the distance between the two supports, and it is convenient to test even if the size of the semicircular specimen is large. Attached Figure Description

[0016] Figure 1 This is a three-dimensional schematic diagram of the present invention.

[0017] Figure 2 This is a front view schematic diagram of the present invention.

[0018] Figure 3 This is a side view of the present invention.

[0019] Figure 4 This is a top view of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1-4 A fatigue performance loading test base for airport runway base layer, which is also the lower fixture in the fixture, includes a bottom plate 10. A fixing rod 11 is fixed in the bottom center area of ​​the bottom plate 10. The fixing rod 11 is used to "insert into the testing machine" and is fixed to the testing machine.

[0022] like Figure 1 Both ends of the bottom plate 10 are provided with bolt fixing fittings, which are used to fix the bolts.

[0023] like Figure 1 The bottom plate 10 has two adjustment blocks on its upper edges: a left adjustment block 20 and a right adjustment block 30. The left adjustment block 20 and the right adjustment block 30 have the same structure and are symmetrically arranged. A bolt 32 is inserted through the bottom of the right adjustment block 30. The adjustment block is fixed to the bottom plate 10 by the cooperation of the bolt 32 and the bolt fixing fitting.

[0024] Supports 40 are fixed to the upper inner edges of the left adjustment block 20 and the right adjustment block 30. The supports 40 are used to support the lower edge of the sample 90.

[0025] The bolt fixing fitting is either a first strip hole 12 or a screw hole (not shown in the figure) set along the axial direction of the bottom plate 10. When the bolt fixing fitting is the first strip hole 12 set along the axial direction of the bottom plate 10, the bolt 32 passes through the entire first strip hole 12, and the lower end of the bolt 32 is threaded to a nut. The "adjusting block is fixed together with the bottom plate 10" is completed by tightening the nut. When the bolt fixing fitting is a screw hole, the bolt 32 is screwed into the screw hole. The "adjusting block is fixed together with the bottom plate 10" is completed by "tightening the bolt 32 in the screw hole".

[0026] Advantages and disadvantages of both:

[0027] First strip hole: Advantages: Convenient for alignment and adjustment; Disadvantages: The lower end of the nut or bolt 32 is exposed below the bottom plate 10, which may affect the fixing of the nut or bolt 32.

[0028] Screw hole: Advantages: The screw hole can be a blind hole, and the lower end of the bolt 32 will not be exposed below the bottom plate 10; Disadvantages: It is inconvenient to align.

[0029] When the bolt fixing fitting is a first strip hole 12 or a screw hole (not shown in the figure) set along the axial direction of the bottom plate 10, two alignment lines are provided at the bottom of the right adjustment block 30 for easy alignment. The part between the two alignment lines is an alignment band 31. The width of the alignment band 31 is the same as the width of the first strip hole 12, and the alignment band 31 extends to both ends of the right adjustment block 30.

[0030] To prevent lateral friction from affecting the test, the support 40 is cylindrical.

[0031] To increase support performance, the adjustment block is made of alloy steel frame.

[0032] Its working principle is as follows:

[0033] like Figure 1-4 It includes the following steps:

[0034] S1. Installation: Insert the fixing rod 11 into the testing machine to complete the fixing of this test base to the testing machine.

[0035] S2. Adjusting the spacing: Loosen the two bolts 32, and set the positions of the two supports 40 according to the size of the sample 90, so that the two edges of the sample 90 are just pressed on the supports 40. At this time, tighten the bolts 32 to fix the two adjusting blocks together with the bottom plate 10.

[0036] S3. Testing: The load application device 90 of the testing machine is located directly above the center of the specimen 90. The fatigue performance loading test is completed by gradually pressing down on the load application device 90. This step is existing technology and will not be described in detail.

[0037] S4. End: The load application device 90 of the testing machine rises and leaves the specimen 90, the specimen 90 is removed, and the test ends.

[0038] Features of this application:

[0039] S1. Displacement stroke and maximum load of this instrument (the airport runway base fatigue performance loading test base, hereinafter the same): It adopts a hydraulic servo actuator with a rated loading capacity of ±500kN and supports a stroke of ±200 mm, meeting the multi-condition requirements of metal, composite materials and large-size asphalt specimens. Existing SCB fatigue testing systems are mostly portable or laboratory-grade small devices, and their loading range is generally no more than 5kN, which is difficult to meet the fatigue testing requirements of large-size, high-strength concrete or composite material specimens. This instrument can meet these requirements.

[0040] S2. Maximum load size of this instrument: This test base can support specimens with a diameter ≤300mm by adjusting the distance between the lower supports;

[0041] S3. Multiple experimental modes: Through software control and the replacement of the upper loading device, it can switch between three-point bending, four-point bending, single-axis tension and compression and other requirements, making it a multi-purpose machine;

[0042] S4, Wideband High-Precision Control System: Supports fatigue loading from low frequency to high frequency, meeting the needs of high-speed fatigue testing;

[0043] S5. Dynamic stability optimization: The high-strength alloy steel frame and pre-tightened bolt structure are adopted to ensure no loosening or plastic deformation under cyclic loads.

[0044] S6. Instrument Durability: The anti-fatigue design extends the life of the test base and reduces maintenance costs during long-term use.

[0045] S7. Large stroke and large load: It adopts hydraulic servo actuators with a rated load capacity of ±500kN and supports a stroke of ±200 mm to meet the multi-condition requirements of metal, composite materials and large-size asphalt specimens.

[0046] S8. Improved accuracy and range: The precise control of the servo system greatly improves the accuracy and maximum range of the load, ensuring the reliability and repeatability of the experimental results.

[0047] S9. Increase the diversity of specimen materials: This device can not only conduct experiments on semi-rigid base specimens, but also on various materials such as asphalt concrete and ordinary concrete.

[0048] S10. Improved experimental compatibility: This technology significantly improves experimental compatibility. In addition to supporting semi-circular bending experiments, it further expands to support multiple three-point bending test modes and uniaxial tension and compression, greatly enhancing the versatility and experimental diversity of the testing platform.

[0049] For other details, please refer to the existing technology.

[0050] The above description is only a preferred embodiment of the present utility model. It should be noted that those skilled in the art can make several changes and improvements without departing from the overall concept of the present utility model, and these should also be considered within the protection scope of the present utility model.

Claims

1. A fatigue performance loading test base for airport runway base layers, comprising a bottom plate (10), characterized in that: A fixing rod (11) is fixed in the center of the bottom of the bottom plate (10). The fixing rod (11) is used to fix it to the testing machine. Both ends of the bottom plate (10) are provided with bolt fixing fittings, which are used to fix the bolts; An adjustment block is provided on each of the two upper edges of the bottom plate (10): a left adjustment block (20) and a right adjustment block (30). The left adjustment block (20) and the right adjustment block (30) have the same structure and are symmetrically arranged. A bolt (32) is inserted through the bottom of the right adjustment block (30). The adjustment block is fixed to the bottom plate (10) by the cooperation of the bolt (32) and the bolt fixing fitting. The upper inner edges of the left adjustment block (20) and the right adjustment block (30) are fixed with supports (40), which are used to support the lower edge of the sample (90).

2. The fatigue performance loading test bed for airport runway base course as claimed in claim 1, wherein: The bolt fixing fitting is a first strip hole (12) or a screw hole set along the axial direction of the bottom plate (10). When the bolt fixing fitting is a first strip hole (12) set along the axial direction of the bottom plate (10), the bolt (32) passes through the entire first strip hole (12) and the lower end of the bolt (32) is threaded to a nut. The "adjusting block and bottom plate (10) are fixed together" is completed by tightening the nut. When the bolt fixing fitting is a screw hole, the bolt (32) is screwed into the screw hole. The "adjusting block and bottom plate (10) are fixed together" is completed by "tightening the bolt (32) in the screw hole".

3. The fatigue performance loading test bed for airport runway base course as claimed in claim 2, characterized in that: When the bolt fixing fitting is a first strip hole (12) or a screw hole set along the axial direction of the bottom plate (10), in order to facilitate alignment, the bottom of the right adjustment block (30) is provided with two alignment lines, and the part between the two alignment lines is an alignment band (31). The width of the alignment band (31) is the same as the width of the first strip hole (12), and the alignment band (31) extends to the two ends of the right adjustment block (30).

4. The fatigue performance loading test bed for airport runway base course of claim 1, wherein: The support (40) is cylindrical.

5. The fatigue performance loading test bed for airport runway base course as claimed in claim 1 is characterized in that: The adjustment block has an alloy steel frame.

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