A device for preparing a crack initiation zone

Abstract

The application belongs to the field of crack propagation test, and particularly relates to a crack initiation zone preparation device. The device comprises a rotor, a stator and a self-locking nut. The rotor comprises a tapered portion and a loading portion. The tapered portion is provided with external threads, and the loading portion is provided with a loading profile. The stator has an outer diameter smaller than the aperture of the crack initiation zone. The stator comprises two or more stator portions arranged in a circumferential direction. The two or more stator portions together form a cylindrical shape. One end of the stator is provided with internal threads matched with the tapered portion, and the other end is provided with external threads. The self-locking nut is matched with the external threads of the stator, and is used to fixedly connect different stator portions. The application can obtain a crack initiation zone with high stress concentration on a wider range of structures without loading fatigue load, improves the structure adaptability of the crack initiation zone prepared on the aperture, reduces the test period, and saves the test cost.

Description

Technical Field

[0001] This application belongs to the field of crack propagation testing, and specifically relates to a device for preparing crack initiation regions. Background Technology

[0002] Crack propagation tests are conducted according to GJB776-89. For holes and notches, when the material thickness is equal to or less than 1.25 mm, the assumed initial crack should be a penetrating crack with a radius of 1.25 mm on one side of the hole. When the thickness is greater than 1.25 mm, the assumed initial crack should be a corner crack with a radius of 1.25 mm on one side of the hole.

[0003] Current methods for obtaining the initial crack initiation zone mainly involve applying fatigue loads and cutting thin-sheet structures. Traditional methods require additional energy and time to apply fatigue loads to obtain the crack initiation zone, and are not suitable for all structures. Cutting thin-sheet structures often results in insufficient stress concentration at the defect tip, necessitating further fatigue loading to generate a more significant stress concentration crack initiation zone. This still cannot avoid issues related to energy, time, and applicability.

[0004] Therefore, there is an urgent need for a technical solution to overcome or mitigate at least one of the aforementioned defects in the existing technology. Utility Model Content

[0005] The purpose of this application is to provide an apparatus for preparing crack initiation regions to solve at least one problem existing in the prior art.

[0006] The technical solution of this application is:

[0007] An apparatus for preparing a crack initiation region, comprising:

[0008] The rotor includes a tapered portion and a loading portion, the tapered portion being provided with an external thread, and the loading portion being provided with a loading profile.

[0009] The stator has an outer diameter smaller than the aperture of the crack initiation region. The stator includes two or more stator parts arranged circumferentially, which together form a cylinder. One end of the stator is provided with an internal thread that mates with the tapered part, and the other end is provided with an external thread.

[0010] The self-locking nut engages with the external thread of the stator to securely connect different stator sections.

[0011] In at least one embodiment of this application, the loading surface of the loading part is hexagonal.

[0012] In at least one embodiment of this application, the rotor is rotated by turning the loading part with a hex wrench.

[0013] In at least one embodiment of this application, the aperture of the crack initiation region is 8 mm, and the outer diameter of the stator is 7.5 mm.

[0014] In at least one embodiment of this application, the stator includes a left stator portion and a right stator portion, both of which are semi-cylindrical.

[0015] In at least one embodiment of this application, the stator includes a first stator portion, a second stator portion, and a third stator portion, wherein the first stator portion, the second stator portion, and the third stator portion are all one-third cylindrical.

[0016] The utility model has at least the following beneficial technical effects:

[0017] The crack initiation region preparation device of this application can obtain crack initiation regions with high stress concentration at the hole edge on a wider range of structures without applying fatigue loads, thereby improving the structural adaptability of preparing crack initiation regions at the hole edge, reducing the test cycle, and saving test costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a crack initiation region preparation apparatus according to one embodiment of this application;

[0019] Figure 2 This is a schematic diagram of the left stator / right stator of one embodiment of this application.

[0020] in:

[0021] 1-Rotor; 2-Stator; 3-Self-locking nut. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0023] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.

[0024] The following is in conjunction with the appendix Figures 1 to 2 This application will be described in further detail.

[0025] This application provides a device for preparing a crack initiation region, including: a rotor 1, a stator 2, and a self-locking nut 3.

[0026] like Figure 1 As shown, rotor 1 includes a conical portion and a loading portion. The conical portion is provided with an external thread, which is a conical winding. The loading portion is connected to the upper end of the conical portion. By applying a load to the loading portion from the outside, rotor 1 rotates under the action of external force. In a preferred embodiment of this application, the loading surface of the loading portion can be hexagonal. Rotating the loading surface of the loading portion with a hexagonal wrench rotates rotor 1.

[0027] The outer diameter of the stator 2 is smaller than the aperture of the crack initiation region. The stator 2 includes two or more stator parts arranged circumferentially. The specific number of stator parts depends on the manufacturing requirements. The two or more stator parts together form a cylinder. One end of the stator 2 is provided with an internal thread that mates with the tapered part, and the other end is provided with an external thread.

[0028] In one embodiment of this application, the stator 2 includes a left stator portion and a right stator portion, both of which are semi-cylindrical. The two semi-cylindrical portions together form an integral cylindrical stator 2. The outer diameter of the stator 2 is slightly smaller than the aperture of the crack initiation region, so that the stator 2 can be inserted into the opening in the crack initiation region. One end of the left stator portion and the right stator portion is provided with an internal thread that mates with the tapered portion, and the other end is provided with an external thread.

[0029] In another embodiment of this application, the stator 2 is composed of three stator parts, including a first stator part, a second stator part, and a third stator part. The first stator part, the second stator part, and the third stator part are all one-third cylindrical, forming an integral cylindrical stator 2.

[0030] The self-locking nut 3 engages with the external thread of the stator 2 to securely connect different stator sections. The self-locking nut 3 can restrict the axial displacement of the stator 2 in the threaded hole of the crack initiation region, but does not restrict the displacement of the stator 2 in the crack initiation direction.

[0031] The crack initiation region preparation device of this application has bolt holes with a diameter of 8 mm in the crack initiation region. Taking the preparation of crack initiation regions on both sides of the hole as an example, a stator 2 with an outer diameter of 7.5 mm is used, and the stator 2 is a symmetrical piece. The stator 2 is passed through the Φ8 bolt holes, and the stator 2 structure is installed on the side where the crack initiation region does not need to be prepared, and the rotor 1 structure is installed on the other side. The rotor 1 and the stator 2 have a transmission thread for mating. A bending moment load is applied by the loading part structure at the upper end of the rotor 2. Under the drive of the bending moment, the rotor 2 and the stator 2 generate relative movement along the thread axis. Due to the restriction of the self-locking nut 3 on the stator 2, the stator 2 is fixed in the thread axis, and the rotor 1 generates downward displacement. Since the threads of the rotor 1 and the stator 2 are tapered, the rotor 1 will expand the stator 2, causing the stator 2 to generate displacement in the direction perpendicular to the thread axis. Restricted by the Φ8 bolt holes, it is squeezed with the bolt holes. During the further transmission of the rotor 1, the bolt holes generate crack initiation regions at the position where the stator 2 is separated.

[0032] The crack initiation region preparation device of this application can quickly prepare the crack initiation region, reduce costs, and improve the stress concentration factor at the crack tip.

[0033] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A device for preparing a crack initiation region, characterized in that, include: The rotor (1) includes a tapered portion and a loading portion. The tapered portion is provided with an external thread, and the loading portion is provided with a loading profile. Stator (2), the outer diameter of the stator (2) is smaller than the aperture of the crack initiation region, the stator (2) includes two or more stator parts arranged circumferentially, the two or more stator parts together form a cylinder, one end of the stator (2) is provided with an internal thread that mates with the tapered part, and the other end is provided with an external thread; The self-locking nut (3) engages with the external thread of the stator (2) to fix different stator parts together.

2. The crack initiation region preparation device according to claim 1, characterized in that, The loading surface of the loading part is hexagonal.

3. The crack initiation region preparation device according to claim 2, characterized in that, The rotor (1) is rotated by turning the loading part with a hex wrench.

4. The crack initiation region preparation device according to claim 1, characterized in that, The diameter of the crack initiation region is 8 mm, and the outer diameter of the stator (2) is 7.5 mm.

5. The crack initiation region preparation device according to claim 1, characterized in that, The stator (2) includes a left stator section and a right stator section, both of which are semi-cylindrical.

6. The crack initiation region preparation apparatus according to claim 1, characterized in that, The stator (2) includes a first stator section, a second stator section and a third stator section, all of which are one-third cylindrical in shape.

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