CN206671072U - A kind of three-point bending fatigue experimental device - Google Patents

Abstract

The utility model provides a three-point bending fatigue test device, which can expand the function of the tensile fatigue testing machine, so that it can carry out the three-point bending fatigue test; it adopts the design of the rotatable clamping mechanism, and can effectively carry out the bending fatigue of the negative stress ratio Test, and meet the boundary conditions of the three-point bending experiment, expand the test range; optimize the traditional three-point bending fixture, reduce the cost of the device, and solve the problem of positioning the test piece. The clamping structure adopted by the utility model effectively prevents the sliding problem of the test piece during the long-term fatigue test; the upper clamping structure in the clamping structure is adjustable, which is convenient for clamping test pieces with different thicknesses; the clamping structure consists of a roller and a trapezoidal Block composition, the roller ensures line contact with the test piece during the experiment and is easy to replace, ensuring the accuracy of the experiment; the trapezoidal block structure design prevents interference with the test piece during the experiment; the combination of upper and lower indenters can effectively reduce the negative stress ratio The load is applied during the bending fatigue test.

Description

A three-point bending fatigue test device

technical field

The utility model belongs to a device for testing the mechanical properties of a plate material, in particular to a bending fatigue test device suitable for a tensile fatigue test machine.

Background technique

In the actual work of many large and complex mechanical equipment, its components are often subjected to alternating bending loads. Therefore, it is very important to evaluate the fatigue performance of components through bending fatigue tests, and it can provide reference for design and manufacture.

The function of the bending fatigue testing machine is single, and the requirements for the size and shape of the test piece are relatively high, and the versatility is not strong. Tensile fatigue testing machines with stronger versatility and higher precision should be used in practical engineering fields. For the bending fatigue test, an experimental device is needed to expand the function of the tensile fatigue testing machine to perform a three-point bending fatigue test. The function of the utility model is to enable the electro-hydraulic servo fatigue testing machine to perform a three-point bending fatigue test.

The existing three-point bending test device can only perform quasi-static bending tests, but it cannot effectively perform bending fatigue tests, and it has the following shortcomings:

1. Unlike the quasi-static three-point bending test, during the bending fatigue test, the specimen will suddenly undergo fatigue failure without significant deformation. When the specimen breaks suddenly, if there is no corresponding protection, it may be dangerous, and it may cause secondary damage to the test fracture, which is not conducive to the later analysis. Therefore, the traditional three-point bending test fixture cannot effectively perform fatigue tests.

2. The design of the traditional three-point bending test fixture cannot carry out the bending fatigue test of the tension-compression cyclic load, that is, the negative stress ratio, and the scope of application is not wide.

Utility model content

Aiming at the deficiencies of the above-mentioned prior art, the utility model provides a three-point bending fatigue performance test device of a flat piece with fast positioning of the test piece, adjustable span of the fixture, strong versatility, negative stress ratio, and protection of the test piece.

In order to achieve the above object, the utility model adopts the following technical solutions:

A three-point bending fatigue test device, including an upper fixture and a lower fixture; the lower fixture includes a base with slide rails, left and right support structures arranged on the slide rails, and a first connecting rod vertically connected to the base; The left and right supporting structures can slide along the slide rail relative to the base; the left and right supporting structures both include a rotating shaft, a frame supporting the rotating shaft, and a first clamping mechanism arranged on the rotating shaft and capable of rotating around the rotating shaft; The first clamping mechanism includes a first upper pressing head and a first lower pressing head, and a first connecting piece connecting the first upper pressing head and the first lower pressing head; the first lower pressing head is non-adjustable and functions as The function of horizontal positioning and supporting the test piece; the first upper indenter is adjustable and can move relative to the first lower indenter along the first connecting piece, which is convenient for clamping test pieces with different thicknesses;

The upper fixture includes a second connecting rod and a second clamping mechanism connected to the second connecting rod, and the second clamping mechanism includes a second upper pressing head, a second lower pressing head, and a second upper pressing head connected to the second connecting rod. 1. The second connecting piece of the second lower pressing head; the second upper pressing head is not adjustable; the second lower pressing head is adjustable and can move relative to the second upper pressing head along the second connecting piece to facilitate clamping Test pieces of different thicknesses.

Further, the first upper pressing head, the first lower pressing head, the second upper pressing head, and the second lower pressing head are all composed of a trapezoidal block with a inferior arc groove on the top and a circular roller arranged in the inferior arc groove. column composition.

Further, the first connecting piece and the second connecting piece are several cylindrical pins respectively.

Further, the frames of the left and right support structures are respectively connected to the slide rails through anchor bolts.

Further, a ruler is provided on the base to adjust the span distance of the left and right support structures.

Further, the first upper pressing head and the second lower pressing head are respectively provided with adjustable bolts, and the positions are adjusted through the adjustable bolts.

The utility model has advantages and beneficial effects:

1. The utility model can expand the function of the tensile fatigue testing machine, so that it can perform three-point bending fatigue test;

2. The design of the rotatable clamping mechanism can effectively carry out the bending fatigue test with negative stress ratio, and meet the boundary conditions of the three-point bending test, expanding the test range;

3. Optimize the traditional three-point bending fixture, reduce the cost of the device, and solve the positioning problem of the test piece; the test piece may slip during the fatigue test with the traditional fixture, and the utility model effectively prevents the test piece during the long-term fatigue test through the clamping structure Sliding problem; the upper and lower clamping structures of the clamping structure are adjustable, which is convenient for clamping test pieces with different thicknesses;

4. The clamping structure is composed of a roller and a trapezoidal block. The roller ensures line contact with the test piece during the experiment and is easy to replace to ensure the accuracy of the experiment. The trapezoidal block structure design prevents interference with the test piece during the experiment;

5. The combination of upper and lower indenters can effectively apply load during the bending fatigue test with negative stress ratio;

6. The upper and lower fixtures are connected to the testing machine through connecting rods, which can ensure the alignment requirements of the loading line, indenter and base, and ensure the quality of data.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Fig. 2 is a schematic diagram of the structure of the upper fixture of the utility model;

Fig. 3 is a schematic diagram of the structure of the lower fixture of the utility model;

Fig. 4 is a schematic diagram of the utility model pressure head;

Symbols in the figure: 1-1, second clamping mechanism; 1-2, second connecting rod; 1-3, hex nut; 1-4, bracket; 1-5, second upper pressure head; 1-6, The second pressing head; 1-7, cylindrical pin; 1-8, hexagon socket bolt; 2, test piece; 3-1, base; 3-2, left support structure; 3-3, right support structure; 3- 4. Ruler; 3-5, first connecting rod; 3-6, first clamping mechanism; 3-7, fixed bracket; 3-8, screw; 3-9, bearing bush; 3-10, rotating shaft; 3- 11. End cover; 3-12. The first lower pressure head; 3-13. Hexagon socket bolt; 3-14. Hex nut; 3-15. The first upper pressure head; 3-16. Cylindrical pin; 4-1 , trapezoidal block; 4-2, inferior arc groove; 4-3, roller.

detailed description

Below in conjunction with concrete experiment and accompanying drawing, the utility model is further described.

As shown in Figure 1, the three-point bending fatigue device provided by the utility model consists of an upper clamp and a lower clamp. The lower fixture includes a base 3-1 with a slide rail, a left support structure 3-2 and a right support structure 3-3 arranged on the slide rail, and a first connecting rod 3-5 vertically connected to the base 3-1. A scale 3-4 is provided on the base 3-4. Both the left support structure 3-2 and the right support structure 3-3 are provided with a first clamping mechanism 3-6. The upper fixture includes a second clamping mechanism 1-1 and a second connecting rod 1-2 connected thereto. Both ends of the test piece 2 are respectively fixed to the first clamping mechanism 3-6 of the left support structure 3-2 and the right support structure 3-3, and the middle part is fixed in the second clamping mechanism 1-1.

As shown in FIG. 2 , the upper fixture includes: a second connecting rod 1-2, a bracket 1-4, a cylindrical pin 1-7, a second upper pressing head 1-5, and a second lower pressing head 1-6.

One end of the second connecting rod 1-2 is a smooth clamping end, which is connected to the upper chuck of the fatigue testing machine, and the other end is threaded, connected to the bracket 1-4, and fastened by the hex nut 1-3; the bracket 1-4 adopts Frame design, connected with the upper and lower indenters through two cylindrical pins 1-7; the second upper indenter 1-5 is fixed in the bracket 1-4, and the second lower indenter 1-6 can be moved along the cylindrical pin 1- 7 slide up and down; after the test piece 2 is clamped, the second lower pressure head 1-6 is adjusted by the adjustable inner hexagon bolt 1-8, and the test piece 2 is clamped; The column 4-3 is composed of the trapezoidal block 4-1, and the cylindrical roller 4-3 ensures that the indenter is in line contact with the test piece 2. The indenter directly acts on the test piece 2, and it will be worn out by long-term experiments. After the wear, only the roller 4-3 needs to be replaced.

As shown in Fig. 3, the left supporting mechanism 3-2 and the right supporting mechanism 3-3 both adopt a frame structure. It consists of a frame 3-7 with a built-in rotating shaft 3-10 and a first clamping mechanism 3-6.

The first clamping mechanism 3-6 is connected with the frame 3-7 through the rotating shaft 3-10, and can rotate around the rotating shaft 3-10. Both ends of the rotating shaft 3-10 are provided with end caps 3-11, and the end caps 3-11 are fixed to the frame 3-7 by screws 3-8. A bearing bush 3-9 is arranged on the rotating shaft 3-10. The first clamping mechanism 3-12 is provided with a first upper pressing head 3-15 and a first lower pressing head 3-12, and the upper and lower pressing heads are connected by four cylindrical pins 3-16. Among them, the first lower indenter 3-12 is not adjustable, and plays the role of horizontal positioning and supporting the test piece; the first upper indenter 3-15 can pass through the inner hexagonal bolt 3-13 and hexagonal nut arranged on the frame 3-7 3-14 adjustment, easy to clamp test pieces of different thickness. The left and right first clamping mechanisms 3-6 can prevent the test piece from sliding on the horizontal plane due to long-time fatigue test. When the specimen is damaged by fatigue, the specimen is clamped to protect the fracture of the specimen and the surrounding instruments. When carrying out the fatigue test with negative stress ratio, the first upper pressing head 3-15 and the first lower pressing head 3-12 play a supporting role at the same time.

Both the first upper pressing head 3-15 and the first lower pressing head 3-12 are composed of a circular roller 4-3 and a trapezoidal block 4-1, the upper surface of the trapezoidal block 4-1 has a inferior arc groove 4-2, The roller 4-3 can be pushed into the trapezoidal block 4-1 from the side for easy replacement.

The base 3-1 is provided with a T-shaped slide rail and a scale 3-4, and the left and right supporting structures can move along the slide rail, and are respectively connected to the base 3-1 through anchor bolts. Loosen the nuts on the anchor bolts, the left and right support structures can slide in the base slide rails to precisely adjust the span distance. The lower clamp is connected with the testing machine cylinder through the first connecting rod 3-5.

During the test, the upper and lower clamps are respectively installed on the upper and lower clamps of the tensile fatigue machine, and the load can be applied to the test piece, and the bending load and deformation data of the test piece can be read.

Before carrying out the material three-point bending fatigue test, the upper and lower fixtures are installed first. For the lower fixture, according to the specific requirements of the experiment and the test piece, loosen the anchor bolts between the base 3-1 and the left and right support structures, adjust the span of the left and right support structures according to the scale 3-4, and then tighten the anchor bolts . After the debugging is completed, the lower clamp is installed on the lower chuck of the fatigue testing machine and the first connecting rod 3-5 is clamped. For the upper grip directly install to the upper chuck of the testing machine and clamp the second connecting rod 1-2. Adjust the movable cylinder of the testing machine to a suitable position so that the test piece can pass through the left and right first clamping mechanism 3-6 and the second clamping mechanism 1-1. Adjust the first upper pressure head 3-15 through the adjustable bolts on the left and right support mechanisms, and tighten the hexagon socket bolt 3-13 to clamp the test piece. In the same way, adjust the second lower pressure head 1-6 of the upper fixture through the adjustable bolt, and tighten the nut after contacting the test piece. Once done, the experiment can begin.

Claims (6)

1. a kind of three-point bending fatigue experimental device, it is characterised in that including upper fixture and lower clamp；The lower clamp includes band The base of slide rail, the left and right supporting construction being arranged on slide rail, and the head rod being vertically connected with base；The left side, Right support structure can be slided along slide rail relative to base；The left and right supporting construction includes rotating shaft, supports the framework of rotating shaft, And it is arranged at the first clamping device that can be rotated in rotating shaft and around the shaft；First clamping device include the first seaming chuck and First push-down head, and the first seaming chuck of connection, the first connector of the first push-down head；First push-down head is non-adjustable, rises To the effect of horizontal location and support test specimen；First seaming chuck is adjustable, can be along the first connector relative to the first push-down head It is mobile, it is easy to clamp the testpieces of different-thickness；

The upper fixture includes the second connecting rod and the second clamping device being connected with the second connecting rod, second clamping device Including the second seaming chuck, the second push-down head, and the second seaming chuck of connection, the second connector of the second push-down head；Described second Seaming chuck is non-adjustable；Second push-down head is adjustable, can be moved along the second connector relative to the second seaming chuck, is easy to clamp not The testpieces of stack pile.

A kind of 2. three-point bending fatigue experimental device according to claim 1, it is characterised in that first seaming chuck, First push-down head, the second seaming chuck, the second push-down head are provided with the trapezoid block of minor arc groove by top and are arranged in minor arc groove Circular roller composition.

A kind of 3. three-point bending fatigue experimental device according to claim 1, it is characterised in that first connector and Second connector is respectively some cylindrical pins.

A kind of 4. three-point bending fatigue experimental device according to claim 1, it is characterised in that the left and right support knot The framework of structure is connected by foundation bolt with slide rail respectively.

5. a kind of three-point bending fatigue experimental device according to claim 1, it is characterised in that the base is provided with mark Chi, to adjust the span length of left and right supporting construction.

A kind of 6. three-point bending fatigue experimental device according to claim 1, it is characterised in that first seaming chuck, Second push-down head is respectively equipped with adjustable bolt, passes through adjustable bolt adjusting position.