Two-dimensional foundation excitation dry friction experimental device with adjustable normal force

Abstract

The invention discloses a normal force adjustable two-dimensional foundation excitation dry friction experimental device, which comprises an optical platform, a vibration exciter and a foundation framework, a two-dimensional translation sliding table is supported on the bottom surface of the foundation framework, a lifting platform is arranged in the foundation framework, a foundation friction plate is fixedly arranged at the top end of the lifting platform, and a vibration exciter is arranged on the foundation friction plate. An elastic supporting friction plate is arranged on the upper side of the basic friction plate, is suspended at the upper part of the basic frame through the stretching of a spring, and forms a friction pair with the basic friction plate; a balance weight disc is fixedly arranged in the middle of the top face of the elastic bearing friction plate. Three-way acceleration sensors are arranged between the top face of the balance weight disc and the bottom face of the base frame and between the lifting platform and the bottom face of the base frame. The two vibration exciters are arranged outside the foundation frame, and an angle of 90 degrees is formed between output ejector rods of the two vibration exciters. According to the invention, the dynamic two-dimensional friction experiment capable of simulating elastic supporting conditions and accurately adjusting normal force can be carried out, so that the nonlinear dynamic characteristics of the friction pair as a complete vibration system can be deeply studied.

Description

Technical Field

[0001] This invention relates to the field of friction testing technology, and in particular to a two-dimensional basic excitation dry friction test apparatus with adjustable normal force. Background Technology

[0002] Dry friction is a widespread phenomenon in complex mechanical systems, particularly at contact interfaces in connecting structures. This phenomenon arises from the presence of normal clamping forces between the contact surfaces and the tendency for relative motion between them during system operation. With a deeper understanding of dry friction, researchers have begun to utilize its energy dissipation mechanism, introducing it into vibration reduction design, leading to the development of a typical damping structure: the dry friction damper. Dry friction dampers are commonly used vibration reduction components in engineering structures and have high application value. Taking aero-engines as an example, they are widely used for vibration reduction in key components such as blades, integral bladed disks, stator housings, and rotor supports. Their damping performance is highly dependent on the complex dynamic behavior of the friction interface. In actual operating conditions, the contact interface is often under multi-frequency excitation. As a typical form of contact, two-dimensional friction under such multi-frequency excitation further leads to more complex nonlinear characteristics in the system response. Currently, research on the dynamic mechanism of two-dimensional interface friction is relatively weak. Systematically revealing the dynamic mechanism of two-dimensional interface friction under complex excitation conditions will provide crucial theoretical support for the high-reliability vibration reduction design of dry friction dampers.

[0003] In tribological research, experimental setups are crucial for revealing the mechanisms of dynamic friction and wear. Previous experimental research has primarily focused on one-dimensional friction and wear experiments at the interface level to explore the complex dynamic processes of contact interfaces under simple friction conditions. At the structural level, more attention has been paid to improving the vibration reduction performance and optimizing control strategies of dry friction dampers in engineering practice. However, such studies struggle to effectively separate and characterize the inherent properties of the friction interface, such as frequency characteristics. This situation leads to shortcomings in interface-level two-dimensional friction research. For example, in a dry friction damper-rotor system, the contact interface mainly exhibits a two-dimensional vortex pattern. However, the dynamic behavior of the friction pair is inevitably affected by the coupling influence of coexisting factors in the rotor system, such as bearings, couplings, and assembly errors, making it difficult to accurately identify the characteristics of the friction interface itself. This further demonstrates the necessity of conducting interface-level dynamic research focusing on the two-dimensional friction pair itself. Existing two-dimensional friction experimental setups typically use exciters to directly drive the relative motion between the moving and stationary friction components. Because the motion of such setups is forced, they cannot study the dynamic behavior of friction pairs supported by elastic elements, presenting significant limitations. Therefore, there is an urgent need for a dynamic two-dimensional friction experimental device that can simulate elastic support conditions and precisely adjust the normal force, in order to study in depth the nonlinear dynamic characteristics of the friction pair itself as a complete vibration system. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a dynamic two-dimensional friction experimental device that can simulate elastic support conditions and precisely adjust the normal force, so as to conduct in-depth research on the nonlinear dynamic characteristics of the friction pair itself as a complete vibration system.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] A two-dimensional basic excitation dry friction experimental device with adjustable normal force includes an optical platform and exciters. The optical platform has a base frame with a top opening, and a two-dimensional translational slide is supported on the bottom surface of the base frame. A lifting platform is located within the base frame, and a basic friction plate is fixedly mounted at its top. An elastic support friction plate is mounted on the upper side of the basic friction plate, and springs connect the edge of the elastic support friction plate to the side wall of the base frame. The elastic support friction plate is suspended above the base frame by the tension of the springs and forms a friction pair with the basic friction plate. A counterweight plate is fixedly mounted in the middle of the top surface of the elastic support friction plate, and triaxial acceleration sensors are mounted on the top surface of the counterweight plate and between the lifting platform and the bottom surface of the base frame. Two exciters are located outside the base frame, with their output rods at 90° to each other. Each exciter is connected to the outer wall of the base frame by a guide rail slider mechanism.

[0007] Furthermore, the basic frame is quadrilateral, and four springs are provided between the elastic support friction plate and the basic frame. A pad is fixedly provided between the bottom of the two-dimensional translation slide and the optical platform.

[0008] Furthermore, the sidewalls of the basic frame and the edges of the elastic support friction pads are provided with through holes for connecting springs.

[0009] Furthermore, the guide rail in the guide rail slider mechanism is horizontally set on the outer wall of the base frame, and the slider is fixedly connected to the output top rod of the vibrator.

[0010] Furthermore, the edge of the counterweight disk is evenly provided with threaded holes for installing counterweight blocks.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] 1. This patent employs a friction pair design with elastic support elements, effectively reproducing the dynamic behavior of the real friction contact interface in mechanical systems. It can be widely applied to various dry friction dampers, such as blade shoulders, flange dampers, and sealing grate damping rings for vibration reduction and frequency characteristic analysis. In contrast, direct-drive friction devices are limited by their rigid connection structure, i.e., the friction pair is directly connected to the drive module. They can typically only obtain the friction constitutive relationship under a specific motion trajectory based on the input of the drive module, and cannot explore the overall dynamic behavior of the friction-containing system. The spring between the basic frame and the elastic support friction plate makes the elastic support friction plate form a spring oscillator system, facilitating the study of the natural frequency, resonance response, frequency characteristics, and contact state of the friction contact system, surpassing the limitations of traditional devices that directly drive the moving and stationary friction components to undergo forced relative motion.

[0013] 2. The synergistic effect of the lifting platform and the spring allows for continuous and precise adjustment of the normal force between the friction pairs during the experiment, thus enabling a systematic study of the influence of the normal force on the dynamic characteristics of the contact interface. The guide rail slider mechanism and the two-dimensional translational slide table achieve precise transmission of the excitation output from the exciter in two directions within a two-dimensional plane, realizing the two-dimensional relative motion of the friction pairs, and making the experimental data easy to interpret. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention;

[0015] Figure 2 This is a diagram of the internal structure of the basic framework in this invention.

[0016] Figure label:

[0017] 1-Vibrator, 2-Basic frame, 3-Pad block, 4-Optical platform, 5-Spring, 6-Elastic support friction plate, 7-Triaxial acceleration sensor, 8-Counterweight plate, 9-Guide rail slider mechanism, 10-Two-dimensional translation slide, 11-Basic friction plate, 12-Lifting platform, 13-Adjustment knob. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] like Figure 1 and Figure 2As shown, a two-dimensional basic excitation dry friction experimental device with adjustable normal force includes an optical platform 4 and an exciter 1. The optical platform 4 is provided with a base frame 2 with a top opening. The bottom surface of the base frame 2 supports a two-dimensional translation slide 10. A lifting platform 12 is provided inside the base frame 2. A basic friction plate 11 is fixedly provided at the top of the lifting platform 12. An elastic support friction plate 6 is provided on the upper side of the basic friction plate 11. A spring 5 is connected between the edge of the elastic support friction plate 6 and the side wall of the base frame 2. The elastic support friction plate 6 is suspended above the base frame 2 by the tension of each spring 5 and forms a friction pair with the basic friction plate 11. A counterweight plate 8 is fixedly provided in the middle of the top surface of the elastic support friction plate 6. A triaxial acceleration sensor 7 is provided on the top surface of the counterweight plate 8 and between the lifting platform 12 and the bottom surface of the base frame 2. Two exciters 1 are provided outside the base frame 2. The output rods of the two exciters 1 are at 90° to each other. A guide rail slider mechanism 9 is connected between each exciter 1 and the outer wall of the base frame 2.

[0020] The base frame 2 is quadrilateral, and four springs 5 ​​are provided between the elastic support friction plate 6 and the base frame 2. A pad 3 is fixedly installed between the bottom of the two-dimensional translation slide 10 and the optical platform 4. The two-dimensional translation slide 10 is connected to the pad 3 by fixing bolts to support the two-dimensional translation slide 10. The springs 5 ​​between the base frame 2 and the elastic support friction plate 6 make the elastic support friction plate 6 form a spring oscillator system, and each of the four sides of the base frame 2 is connected to the elastic support friction plate 6 by a spring 5 to maintain uniform force on the elastic support friction plate 6.

[0021] The sidewalls of the basic frame 2 and the edges of the elastic support friction plate 6 are provided with through holes for connecting springs 5. The pre-set through holes facilitate the disassembly of springs 5 ​​so that springs 5 ​​with different stiffnesses can be quickly replaced during the experiment.

[0022] In this design, the guide rail of the guide rail slider mechanism 9 is horizontally mounted on the outer wall of the base frame 2, and the slider is fixedly connected to the output rod of the vibrator 1. When both vibrators 1 are started, the output rod of the first vibrator 1 moves, and the slider of that output rod moves synchronously. At this time, the base frame 2 is displaced, causing the guide rail corresponding to the second vibrator 1 to follow the displacement of the base frame 2. The slider and guide rail corresponding to the second vibrator 1 then move relative to each other. This method can avoid mutual interference between the movements of the two output rods.

[0023] The counterweight disk 8 has threaded holes evenly distributed along its edge for installing additional counterweights.

[0024] The experimental steps of this invention are as follows: First, based on the material properties of the elastic support friction plate 6 and the base friction plate 11, determine the spring 5 with appropriate stiffness and the counterweight with appropriate mass.

[0025] During the experiment, the adjustment knob 13 of the lifting platform 12 was first adjusted to determine the normal force according to the position scale of the lifting platform 12. Two exciters 1 were controlled by a signal generator and power amplifier to apply a two-dimensional excitation with the same frequency, amplitude, and a 90° phase difference to the base frame 2. The elastic support friction plate 6 underwent forced vibration under the combined action of the spring restoring force and friction. The two-dimensional translation slide 10 has degrees of freedom in both the X and Y directions; during this process, the uppermost slide of the two-dimensional translation slide 10 moved with the base frame 2. The vibration acceleration of the elastic support friction plate 6 and the base friction plate 11 was measured by two triaxial accelerometers 7, respectively. The vibration displacement and vibration velocity of the elastic support friction plate 6 and the base friction plate 11 were obtained by processing the data through a charge integrating amplifier connected to the two triaxial accelerometers 7. Thus, the two-dimensional tribodynamics experiment under the current excitation condition was completed.

[0026] By replacing springs 5 ​​with springs of different stiffness and adding or removing counterweights on the counterweight plate 8, friction pairs made of different materials can be matched. Based on this, by changing the excitation signal of the vibrator 1 and the height of the lifting platform 12, a two-dimensional tribodynamic response experiment of friction pairs made of different materials under different excitation forms and different normal forces can be systematically studied.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A two-dimensional foundation-excited dry friction experimental device with adjustable normal force, comprising an optical platform (4) and an exciter (1), characterized in that: The optical platform (4) is provided with a base frame (2) with a top opening. The bottom surface of the base frame (2) is supported by a two-dimensional translation slide (10). A lifting platform (12) is provided inside the base frame (2). A base friction plate (11) is fixedly provided at the top of the lifting platform (12). An elastic support friction plate (6) is provided on the upper side of the base friction plate (11). A spring (5) is connected between the edge of the elastic support friction plate (6) and the side wall of the base frame (2). The elastic support friction plate (6) is suspended by the tension of each spring (5). It floats on the upper part of the base frame (2) and forms a friction pair with the base friction plate (11); a counterweight plate (8) is fixedly installed in the middle of the top surface of the elastic support friction plate (6), and a triaxial acceleration sensor (7) is installed between the top surface of the counterweight plate (8) and the bottom surface of the lifting platform (12) and the base frame (2); two exciters (1) are installed outside the base frame (2), and the output top rods of the two exciters (1) are 90° to each other. Each exciter (1) is connected to the outer wall of the base frame (2) by a guide rail slider mechanism (9).

2. The two-dimensional foundation-excited dry friction experimental device with adjustable normal force according to claim 1, characterized in that: The basic frame (2) is quadrilateral, and four springs (5) are provided between the elastic support friction plate (6) and the basic frame (2). A pad (3) is fixedly provided between the bottom of the two-dimensional translation slide (10) and the optical platform (4).

3. The two-dimensional foundation-excited dry friction experimental device with adjustable normal force according to claim 2, characterized in that: The sidewalls of the basic frame (2) and the edges of the elastic support friction plate (6) are provided with through holes for connecting springs (5).

4. The two-dimensional foundation-excited dry friction experimental device with adjustable normal force according to claim 1, characterized in that: The guide rail in the guide rail slider mechanism (9) is horizontally set on the outer wall of the base frame (2), and the slider is fixedly connected to the output rod of the vibrator (1).

5. The two-dimensional foundation-excited dry friction experimental device with adjustable normal force according to claim 1, characterized in that: The edge of the counterweight plate (8) is provided with threaded holes for installing counterweight blocks.

Images