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CN-122016456-A - Fiber reinforced composite material fretting fatigue test fixture suitable for single-axis testing machine

CN122016456ACN 122016456 ACN122016456 ACN 122016456ACN-122016456-A

Abstract

The invention discloses a fiber reinforced composite material fretting fatigue test fixture suitable for a single-axis testing machine, which comprises: an upper clamp assembly with a micro-motion pad limiting device, a lower clamp assembly, a micro-motion pad, an upper gasket, a lower gasket, a test piece and a stress ring assembly. The upper clamp assembly and the lower clamp assembly are clamped through the hydraulic clamping head and used for fixing a test piece and transmitting axial load. The test pieces are arranged in the limiting grooves of the upper clamp and the lower clamp, and the upper gasket and the lower gasket are arranged between the two test pieces. The clamp is screwed down through the fastening bolt to fix the test piece to prevent slipping, and the fastening screw penetrates through the clamp, the test piece and the gasket to further fix the test piece. The micro-motion pad is arranged in the limit groove of the micro-motion pad of the upper clamp, thereby ensuring centering and transmitting normal load. The invention solves the problem of the non-adaptation of the fiber reinforced composite material and the metal material clamp, and has the advantages of ensuring the parallelism of the test piece and the centering of the micro-motion pad, avoiding the slipping of the test piece, ensuring the test precision and improving the success rate of the experiment.

Inventors

  • DENG JINGLEI
  • ZHANG HONGJIAN
  • CUI HAITAO
  • XU YING

Assignees

  • 南京航空航天大学

Dates

Publication Date
20260512
Application Date
20260114

Claims (6)

  1. 1. The micro fatigue test fixture for the fiber reinforced composite material is suitable for a single-axis testing machine and is characterized by comprising an upper fixture assembly (1) with a micro pad limiting device, an upper gasket (2), a lower gasket (3), a lower fixture assembly (4) and a micro pad (5); the upper clamp assembly (1) and the lower clamp assembly (4) are both of flat plate clamping structures, and rectangular grooves are formed in the inner sides of the flat plate clamping structures; The upper parts of the two test pieces (6) which are oppositely arranged and the upper gasket (2) positioned between the upper parts of the two test pieces (6) are clamped in the rectangular groove of the upper clamp assembly (1); the lower parts of the two test pieces (6) and the lower gasket (3) positioned between the lower parts of the two test pieces (6) are clamped in the rectangular groove of the lower clamp assembly (4); The upper part of the upper clamp assembly (1) is clamped by a hydraulic upper clamp head (15), the lower part of the lower clamp assembly (4) is clamped by a hydraulic lower clamp head (16), and the hydraulic upper clamp head (15) and the hydraulic lower clamp head (16) are used for providing clamping force and transmitting axial load; The micro-motion pad limiting device comprises a boss and a through hole, wherein the boss is arranged on the outer side of the upper clamp assembly (1) and far away from the clamping end, the through hole is arranged on the boss, the through hole is in the shape of a combined through hole with a square hole profile center added with a circular hole, two micro-motion pads (5) are respectively embedded into the through hole from two sides of the upper clamp assembly (1), and the circular hole is used for being connected with a stress applying rod piece of a stress ring assembly for providing normal load.
  2. 2. The micro fatigue test fixture for fiber reinforced composite materials according to claim 1, wherein the upper fixture assembly (1) and the lower fixture assembly (4) are respectively provided with a boss for connecting a fastening bolt, and the fastening bolt is connected with a nut after passing through the boss, so as to further fix the two test pieces (6) and an upper gasket (2) and a lower gasket (3) between the two test pieces (6).
  3. 3. The fiber reinforced composite fretting fatigue test fixture according to claim 1, wherein the upper fixture assembly (1) and the lower fixture assembly (4) are further provided with set screws (7) respectively passing through the fixture assembly, the two test pieces (6) and a spacer therebetween.
  4. 4. The fiber reinforced composite fretting fatigue test fixture according to claim 2, wherein four connected through holes are provided in a rectangular array on the boss for connecting the fastening bolt.
  5. 5. A fiber reinforced composite fretting fatigue test fixture according to claim 3, characterized in that the set screw (7) is arranged close to the clamping end, the end faces of the set screw (7) being lower than the surface of the fixture assembly.
  6. 6. The fiber reinforced composite fretting fatigue test fixture according to any of claims 1-5, wherein the height of the boss outside the upper fixture assembly (1) away from the clamping end is such that the fretting pad (5) is fully embedded in the through hole.

Description

Fiber reinforced composite material fretting fatigue test fixture suitable for single-axis testing machine Technical Field The invention relates to the technical field of material tests, in particular to a fretting fatigue test fixture device of a fiber reinforced composite material suitable for a single-axis testing machine. Background Fretting fatigue is a common fatigue failure mode, and is a physical phenomenon that under the action of cyclic load, two mutually contacted structural units have contact load, and simultaneously, tiny displacement relatively slides to generate complex abrasion action, so that the fatigue strength of a structure is obviously reduced, and the failure and damage process is accelerated. On aircraft engines and aircraft, there is little fatigue in a significant portion of the components, especially some critical components. In recent years, due to the excellent mechanical properties of the composite material, the composite material is widely applied to various fields, particularly on aviation and aerospace, and the damage of fretting fatigue to a composite material connecting structure is gradually highlighted, so that the fretting fatigue experiment of the contact interface of the composite material and a metal material is of great significance. However, the conventional fretting fatigue test is mainly focused on metal materials, the test fixture device of the metal materials is not suitable for fiber reinforced composite materials, metal samples are generally connected in a mode of punching through bolts, but the performance of the composite materials is seriously reduced after punching, and stress concentration fracture often occurs around holes, which is not suitable for the purpose of the test. The existing micro-motion fatigue test device adopts the method that a micro-motion pad limit groove is added on the basis of a common fatigue test device so as to be suitable for micro-motion working conditions, the structure is complex, and the micro-motion fatigue test device is fixed only through bolt tightening and is easy to slip. Disclosure of Invention Aiming at the prior art, the invention provides the fiber reinforced composite material fretting fatigue test fixture suitable for the single-shaft testing machine, which solves the problem of easy slipping in the composite material fretting fatigue test and improves the test accuracy and success rate. The technical scheme is that the fiber reinforced composite micro fatigue test fixture suitable for the single-axis testing machine comprises an upper fixture component with a micro pad limiting device, an upper gasket, a lower fixture component and a micro pad; the upper clamp assembly and the lower clamp assembly are both of flat plate clamping structures, and rectangular grooves are formed in the inner sides of the flat plate clamping structures; The upper parts of the two test pieces which are oppositely arranged and the upper gasket positioned between the upper parts of the two test pieces are clamped in the rectangular groove of the upper clamp assembly; The lower parts of the two test pieces and the lower gasket positioned between the lower parts of the two test pieces are clamped in the rectangular groove of the lower clamp assembly; the upper part of the upper clamp assembly is clamped by a hydraulic upper chuck, the lower part of the lower clamp assembly is clamped by a hydraulic lower chuck, and the hydraulic upper chuck and the hydraulic lower chuck are used for providing clamping force and transmitting axial load; The micro-motion pad limiting device comprises a boss and a through hole, wherein the boss is arranged on the outer side of the upper clamp assembly and far away from the clamping end, the through hole is arranged on the boss, the through hole is in the shape of a combined through hole with a square hole, a round hole is added in the center of the outline of the square hole, two micro-motion pads are respectively embedded into the through hole from two sides of the upper clamp assembly, and the round hole is used for being connected with a stress application rod piece of a stress ring assembly for providing a normal load. Further, the upper clamp assembly and the lower clamp assembly are respectively provided with a boss for connecting a fastening bolt, and the fastening bolt penetrates through the boss and then is connected with a nut for further fixing the two test pieces, and an upper gasket and a lower gasket which are positioned between the two test pieces. Further, the upper clamp assembly and the lower clamp assembly are respectively provided with a set screw penetrating through the clamp assembly, the two test pieces and the gasket therebetween. Further, four connected through holes are formed in the boss for connecting the fastening bolts in a rectangular array mode. Further, the set screw is arranged close to the clamping end, and the end faces of the set screw are lower than the surface of the cl