High-impact teaching appliance with novel-structure energy absorption device

Abstract

The invention relates to a high-impact teaching appliance with a novel-structure energy absorption device, the novel-structure high-impact teaching appliance is subjected to structural design and parameter design, and design of a nonlinear spring buffer structure in the high-impact teaching appliance is completed through establishment and solution of a motion differential equation of the high-impact teaching appliance. And UG software is used to realize modeling of the high-impact teaching appliance with a new structure. By performing kinematics analysis on the new-structure high-impact teaching appliance, the kinematics performance of the new-structure high-impact teaching appliance and the kinematics performance of a traditional high-impact teaching appliance are compared and analyzed, and the advantages of the new-structure high-impact teaching appliance in kinematics compared with the traditional high-impact teaching appliance are verified. Finite element strength analysis is carried out on the new-structure high-impact teaching appliance, and it is verified that the strength of the new-structure high-impact teaching appliance meets the requirement and is better than that of a traditional high-impact teaching appliance. The correctness of the design of the high-impact teaching appliance with the novel structure is verified from two aspects.

Description

Technical Field

[0001] The invention relates to the field of energy absorbing devices, in particular to a high-impact teaching tool with an energy absorbing device of a new structure. Background Art

[0002] As some high-impact conveying systems become more automated and their structures more complex, the performance requirements for teaching aids used to assist in detecting the integrity of the conveying process are getting higher and higher. The high-impact teaching aids of a certain complex conveying system are important auxiliary devices for the functional detection of the conveying system. They are used frequently in daily life, and have a short service life and poor use effect. In addition, this high-impact teaching aid is a standard-issued spare part, and because it is not a special wearing part or a commonly purchased part, its production and procurement costs are relatively high. It is difficult to replenish and repair it after it is damaged. Therefore, how to increase its service life and enable it to maintain normal function during frequent use is an urgent problem that needs to be solved at this stage.

[0003] In a complex conveying system, the positioning method of the load part during the conveying process is bottom positioning. When the load part completes the process of conveying into the tube, the head of the load part continues to impact forward due to inertia, so that the head of the load part is embedded in the tube to complete the conveying action. When using high-impact teaching tools to replace the load part to simulate the above process, the head does not need to be embedded in the tube, and the whole needs to be recovered for simulation again. Therefore, the high-impact teaching tool is to split the load part into two parts, the head and the tail, and connect them with a circular cross-section tension spring, and then carry out weight adjustment and design. However, after long-term use, it was found that this type of high-impact teaching tool has a high damage rate during use. Its main damage mode is that the head and tail joint closing part is severely damaged after multiple conveying processes, and because the metal of the closing part has severe plastic deformation, it is difficult to repair and cannot continue to be used. After analysis, the main cause of the fault is that the head reset speed is too large, resulting in a large impact between the head and the tail, causing deformation of the tail, and then resulting in a low overall service life of the high-impact teaching tool. Summary of the invention

[0004] In order to effectively solve the above problems, the present invention provides a pipeline internal state detection device.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: a high-impact teaching tool with a new structural energy absorption device, including an outer shell, a load member, a buffer pad, a pull rod, a U-shaped compression plate and a nonlinear spring, a cavity is opened in the middle of the outer shell, a groove is arranged at the front end, a partition is arranged between the groove and the cavity, a load member is arranged in the groove, a buffer pad is arranged on the rear surface of the load member, a pull rod is horizontally arranged in the middle of the rear end of the load member, the pull rod passes through the partition and extends into the cavity, a U-shaped compression plate is arranged at the rear end of the pull rod located in the cavity, a nonlinear spring is arranged between the compression plate and the partition, and the nonlinear spring is sleeved on the outside of the pull rod.

[0006] Furthermore, the nonlinear spring is an annular spring.

[0007] Furthermore, the parameter calculation method of the nonlinear spring is as follows: Step 1: Determine the kinetic energy of high impact teaching tools E and the maximum working load of the nonlinear spring , calculate the maximum compression of the spring : ; Step 2: Determine the outer diameter of the nonlinear spring according to the position requirements of the buffer structure D , determine the height of a single ring , single ring thickness , half cone angle Select Between, the friction parameters Pick The corresponding friction angle is ; Step 3: Calculate the compression of a single ring according to the compression formula : In the formula, is the inner diameter of the annular spring, ; Step 4: Calculate the total number of rings of the annular spring : Step 5: Calculate the total length of the spring in the buffer device in the free state : .

[0008] Furthermore, the maximum compression of the nonlinear spring 0.015-0.025 , outer diameter D It is 0.18-0.22m, and the spring stiffness is 8e+6N / mm.

[0009] After adopting the above technical solution, the present invention has the following advantages compared with the prior art: The present invention proposes a buffer structure design scheme for a new structure high-impact teaching tool. The new structure high-impact teaching tool is structurally designed and parameter designed. By establishing and solving the differential equation of motion of the high-impact teaching tool, the design of the nonlinear spring buffer structure in the high-impact teaching tool is completed, and the modeling of the new structure high-impact teaching tool is realized by using UG software. By performing kinematic analysis on the new structure high-impact teaching tool, the kinematic performance of the new structure high-impact teaching tool and the traditional high-impact teaching tool is compared and analyzed, and the kinematic advantages of the new structure high-impact teaching tool over the traditional high-impact teaching tool are verified. The finite element strength analysis of the new structure high-impact teaching tool is performed to verify that the strength of the new structure high-impact teaching tool meets the requirements and is superior to the traditional high-impact teaching tool. The correctness of the design of the new structure high-impact teaching tool is verified from two aspects.

[0010] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the UG model diagram of the existing circular cross-section tension spring high impact teaching aid; Figure 2 This is the total deformation result diagram of the finite element analysis of the small stiffness circular cross-section tension spring for high impact teaching; Figure 3 This is the equivalent elastic strain result diagram of the finite element analysis of the small stiffness circular cross-section tension spring for high impact teaching; Figure 4 This is the equivalent stress result diagram of the finite element analysis of the small stiffness circular cross-section tension spring for high impact teaching; Figure 5 This is the total deformation result diagram of the finite element analysis of the high-strength circular cross-section tension spring for high-impact teaching; Figure 6 This is the equivalent elastic strain result diagram of the finite element analysis of the high-impact teaching of the large-rigidity circular cross-section tension spring; Figure 7 This is the equivalent stress result diagram of the finite element analysis of the high-impact teaching of the large-rigidity circular cross-section tension spring; Figure 8 It is a schematic diagram of the annular spring structure; Fig. 9 It is the characteristic curve of annular spring; Fig.10 The structure diagram of the present invention is shown in FIG. 1 , wherein the components represented by the reference numerals are: 1, load-bearing member; 2, U-shaped pressing piece; 3, pull rod; 4, nonlinear spring; 5, housing; 6, buffer pad; 7, partition; Fig.11 A comparison diagram of the speed change over time of the high-impact teaching tool with a new structure energy absorption device of the present invention and the traditional tension spring high-impact teaching tool; Fig.12 A comparison diagram of the acceleration changes over time of the high-impact teaching tool with a new structural energy absorption device of the present invention and the traditional tension spring high-impact teaching tool; Fig.13 The displacement variation diagram of the high impact teaching tool with a new structure energy absorption device of the present invention and the traditional tension spring high impact teaching tool over time; Fig.14 It is the flow chart of finite element simulation preprocessing; Fig.15 This is a pre-simulation pre-processing diagram of the high-impact teaching tool with a new structural energy-absorbing device of the present invention; Fig.16 This is a finite element analysis total deformation result diagram of the high impact teaching device with a new structural energy absorption device of the present invention; Fig.17 This is a finite element analysis equivalent elastic strain result diagram of the high impact teaching device with a new structural energy absorption device of the present invention; Fig.18 This is a diagram showing the maximum principal stress results of a finite element analysis of a high impact teaching device having a new structural energy absorption device according to the present invention. DETAILED DESCRIPTION

[0012] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0013] The high-impact teaching aid model established based on actual high-impact teaching aids needs to be optimized before being imported into subsequent simulation software. First of all, on the premise of ensuring the validity of the model, in order to improve the simulation effect of subsequent simulation and improve the test performance of high-impact teaching aids, the high-impact teaching aids need to be simplified.

[0014] According to the need for subsequent finite element analysis, it is simplified without affecting the simulation effect, and unnecessary details and features are deleted to reduce the complexity and burden of calculation during finite element mesh analysis. At the same time, under the premise of ensuring accuracy, larger tolerances and simplified parameters are used as much as possible. For example: for high-impact teaching aids with circular cross-section tension springs inside, according to the simplification principle and simulation experience, the original circular cross-section tension springs in the high-impact teaching aids can be removed. During simulation, the built-in functions of the workbench can be used to add spring constraints. This can not only reduce the complexity and calculation burden during mesh analysis, but also increase the mesh density at other locations to achieve fixed-point analysis of specific key locations. At the same time, since the main damage position of the high-impact teaching aid is at the joint between the head of the load part and the shell, and the bottom of the shell is restricted after the load part is transported into the tube, the filling inside the shell can be simplified in the high-impact teaching aid structure with the same structure as the actual load part. Only the actual parameters of the head of the load part need to be guaranteed to achieve the same simulation effect.

[0015] Taking the high impact teaching aid with a circular cross-section tension spring as an example, the model established based on the existing high impact teaching aid is as follows Figure 1 As shown, the main components of this type of high-impact teaching aid with a circular cross-section tension spring inside include a housing, a load member, a screw sleeve, a rear pull rod, a circular cross-section tension spring, a front pull rod, etc. The head of the load member is connected to the circular cross-section tension spring through the front pull rod, and the other end of the spring is connected to the rear pull rod. The rear pull rod is connected to the bottom of the housing through the screw sleeve. There is a gap between the head of the load member and the housing.

[0016] Next, a finite element analysis is performed on the existing high-impact teaching aids with a circular cross-section tension spring inside, and the specific process is as follows; The high-impact teaching aid with a circular cross-section tension spring inside is divided into two cases according to the stiffness of the circular cross-section tension spring during simulation, one is the case of large stiffness, and the other is the case of small stiffness. The stiffness of the circular cross-section tension spring inside the high-impact teaching aid mainly affects the displacement of the head of the high-impact teaching aid load part. When the stiffness is small, the displacement of the head of the high-impact teaching aid load part increases, and the time for the high-impact teaching aid to return to the initial equilibrium position increases. When the stiffness of the circular cross-section tension spring inside the high-impact teaching aid is large, the displacement of the head of the high-impact teaching aid load part is small, and the time for the high-impact teaching aid to return to the initial equilibrium position is reduced. However, the stiffness requirements for the internal parts of the high-impact teaching aid are relatively high. Both stiffness cases need to be simulated. According to the actual situation, the large stiffness is set to 7e+6N / m and the small stiffness is set to 1e+6N / m.

[0017] The total deformation diagram, equivalent elastic strain diagram, and equivalent stress diagram obtained by simulation under low stiffness conditions are shown in the figure below. Figure 2-4 shown.

[0018] In the case of small stiffness of circular cross-section tension spring, the force of high impact teaching tools is relatively uniform, and the maximum stress is 15MPa, but the main deformation is concentrated in the mouth. The main reason is that in the case of small stiffness of circular cross-section tension spring, the displacement of the load head is large for each impact, and the number of reciprocating movements of the load head is large, which all aggravates the interaction between the load head and the joint of the load and the shell. As a result, the mouth is deformed and the life of the high impact teaching tools is reduced.

[0019] The total deformation diagram, equivalent elastic strain diagram, and equivalent stress diagram obtained by simulation under large stiffness are shown in the figure below. Figure 5-7 As shown. When analyzing the high-impact teaching aids with circular cross-section tension springs under high stiffness conditions, it was found that the force at the joint between the load part and the shell was not the largest, but the force at the connection position between the bottom of the shell and the circular cross-section tension spring was very large, with the maximum stress reaching 28MPa, and the deformation at this position was also the largest. The reason is that the stiffness of the circular cross-section tension spring in the high-impact teaching aid is too large. Under the same load, the stiffness is large, the deformation of the spring is small, and the movement distance of the head of the load part is reduced. The load is concentrated, and the stress is mainly concentrated at the connection between the bottom of the shell and the spring, resulting in excessive local stress. At the same time, due to the high stiffness of the spring, more energy will be stored when it is loaded, and the movement distance of the head of the load part will be reduced, and the friction energy consumption will be less. More energy will be released when unloading, which will cause greater stress between the rear pull rod and the bottom of the shell, thereby causing damage to the internal structure of the high-impact teaching aid.

[0020] The specific process of designing nonlinear spring buffer structure is as follows: The internal buffer structure of high-impact teaching tools is a device that absorbs the impact kinetic energy when the high-impact teaching tools are transported into the tube and reduces the impact of the high-impact teaching tools. Usually, a spring buffer device is selected. When designing the internal buffer structure of high-impact teaching tools, a specific structure can be selected for design according to specific requirements. Combining the finite element analysis results of the above two types of traditional high-impact teaching tools and the reality that the buffering performance of traditional circular cross-section tension springs cannot meet the requirements, this section will complete the parameter design and model establishment of a new structure high-impact teaching tool, aiming to solve the problems existing in the use of the above two types of traditional high-impact teaching tools.

[0021] Through finite element analysis of two types of high-impact teaching tools, it is proposed to use nonlinear springs as buffer devices in high-impact teaching tools. The structural principle of the buffer device is to connect the head of the high-impact teaching tool load piece with the compression plate that carries the nonlinear spring through a pull rod, and there is a buffer pad between the specially designed shell and the head of the load piece. In the shock-absorbing device, the rubber buffer pad is a very common component. Various methods have been used at home and abroad to increase its buffering performance. It is concluded that when the material density is constant, the stress distribution of the rubber buffer pad is related to the stiffness of other parts of the mechanism, which provides ideas for the subsequent design of buffer pads in new structures of high-impact teaching tools. The nonlinear spring is fixed to the raised position of the compression plate and the shell through the action of the pull rod to achieve pre-compression of the head of the load piece. Its mechanism of action is that during the transportation of the high-impact teaching tool load into the tube, after the bottom edge stops moving, the load part impacts forward due to inertia, and the movement of the load part head drives the nonlinear spring to compress. The spring compression stores energy. After reaching the maximum displacement, the load part speed is reduced to 0, and the head of the high-impact teaching tool load part moves backward under the action of the spring. During this process, the spring releases elastic potential energy, which is converted into reverse kinetic energy of the load part head, and the buffer pad is compressed. During the reciprocating motion of the nonlinear spring, due to its variable stiffness characteristics, part of the elastic potential energy is converted into internal energy and is gradually consumed. Such a structural design can not only reduce the load of high-impact teaching tools when they are impacted, but also optimize their structural design.

[0022] When the new structure high-impact teaching aid is in action, the rubber pad and the nonlinear spring work together to offset the impact force when the head of the load part hits the shell. During the forward rush stage of the load part head, the speed of the load part gradually decreases, the nonlinear spring is compressed, and the nonlinear spring stores energy. When the head of the high-impact teaching aid reaches the farthest position, the direction of the high-impact teaching aid accelerates. When it reaches the initial position, the initial velocity is the largest. The bottom of the load part head will act on the rubber pad, which plays a buffering role and reduces the impact of the impact. At the same time, a gap is set between the head of the load part and the shell to reduce the effect of the high-impact teaching aid on the inner wall of the shell throughout the entire process. At the same time, the position of the connecting rod is limited inside the shell, and a gap is also set. At the same time, the middle position of the connecting rod can be smoothed to reduce the hard contact at this position.

[0023] Features of the buffer device: The internal buffer spring adopts a nonlinear spring, and at the same time optimizes the internal structure, simplifies unnecessary structures, and solves the problem of stress concentration. It can reduce the impact of high-impact teaching tools, improve the test effect, and increase the service life.

[0024] Combined with the overall design plan and the application requirements of high-impact teaching aids, there are two types of nonlinear springs that can be selected: disc springs and ring springs. The above two types of nonlinear springs have different structural principles, different mechanical properties, and are suitable for different application scenarios.

[0025] The disc spring buffer device uses disc springs as buffer components, and is mainly composed of a series of disc spring sheets and a push rod. The energy dissipation characteristics of this type of buffer device are mainly related to the number, shape and arrangement of the disc spring sheets, and it has the characteristics of bearing large loads and small deformation. The disc spring can increase its load-bearing capacity by overlapping and combining. At the same time, there is friction between each adjacent two sheets in the overlapping combination, so that the maximum buffer load it can actually bear is much higher than the theoretical calculated value. With its excellent buffering performance, it is widely used in aerospace and military fields.

[0026] The annular spring buffer uses an annular spring as the buffer element. Its structure is similar to that of a disc spring and can also be stacked to increase the maximum load capacity. From the characteristic curve of the annular spring, it can be seen that when subjected to an external load, the elastic force of each ring of the annular spring can balance the external load, and in a stretch-compression cycle, the annular spring can consume about 60%-70% of the energy. Therefore, this type of spring is usually used when it is necessary to absorb a large amount of recoil energy and the action time is extremely short. However, since most of the energy consumed by the annular spring during operation is converted into internal energy, the spring temperature will rise sharply. Under this condition, the spring characteristics change and the buffering performance decreases. Therefore, the annular spring is not suitable for continuous working backgrounds.

[0027] Comparison of the characteristics of the above two types of nonlinear springs: (1) Design structure: The shape of the annular spring is continuous and simple, while the shape of the disc spring is special and relatively complex; (2) Materials: Annular springs have a wide range of materials, while disc springs have high material performance requirements and require heat treatment; (3) Buffering characteristics: Annular springs can withstand high loads and have strong elastic recovery capabilities. Buffer springs have outstanding energy dissipation performance. Disc springs can achieve a large span of stiffness through different overlapping combinations. The application environment of high-impact teaching tools not only has high requirements on the strength of the buffer structure, but also has certain requirements on the service life, spatial volume, buffering effect, etc. of the nonlinear spring. Combined with the requirements of the application background of high-impact teaching tools, and considering the performance of the above two springs, it is planned to use annular springs as buffer springs for the buffer structure of high-impact teaching tools.

[0028] The design process of nonlinear spring parameters in high impact teaching tools is as follows: The actual load of a complex conveying system weighs more than 50 kg, the head of the load weighs 30 kg, and the initial speed of the load into the pipe is 5 m / s. Combined with the energy that the buffer device needs to absorb E , as well as the structural limitations of high-impact teaching aids, complete the design of the nonlinear spring.

[0029] (1) Establishment and solution of the differential equation of motion of high-impact teaching tools The nonlinear spring used in high-impact teaching tools needs to be pre-stressed. The nonlinear spring buffer is fixed in the high-impact teaching tools and does not move. The head of the load part and the shell are connected by a connecting rod and a clamping plate. After the high-impact teaching tools are transported into the tube, the head of the load part drives the connecting rod to drive the clamping plate to move forward. The clamping plate rests on the rear end of the nonlinear spring to compress the nonlinear spring. When the compression is in place, the compressed nonlinear spring stretches, and the spring force drives the head of the load part to move in the opposite direction. After moving a certain distance, it reaches the maximum speed position. Due to inertia, it continues to move, and then begins to compress the buffer pad. The load part continues to move until the speed is 0. Thereafter, it reciprocates. The kinematic analysis of the high-impact teaching tools with circular cross-section tension springs inside is now carried out, and the parameter design of the buffer spring in the new structure high-impact teaching tools is realized by analogy.

[0030] The stress of traditional high-impact teaching tools Conduct analysis.

[0031] In the two stages of high impact teaching tool movement, friction resistance and spring force When the friction resistance points to the direction of the load head, it is positive, otherwise it is negative.

[0032] The force of high impact teaching tools during movement can be expressed as: Where: —preload of spring, N; k —Stiffness of nonlinear spring, N / mm; —Displacement of the load head, mm; —friction resistance of the spring, N; The differential equation of motion for the high impact teaching aid is Where: m —Mass of high impact teaching aids, kg; —Acceleration of high impact teaching aids, m / s 2 ; —Force on high impact teaching tools, N; Substituting the above two-stage formulas into the corresponding stages, we can obtain the motion differential equations of different stages: Forward phase: Return stage: (2) Structure and characteristics of annular spring like Figure 8 As shown, the annular spring is composed of an outer ring with multiple inner conical surfaces and an inner ring with an outer conical surface.

[0033] like Fig. 9 As shown, the main parameters of the annular spring include the inner diameter of the spring D , outer diameter d、 The height H of a single spring, the thickness of a single spring, the semi-cone angle β, etc.

[0034] From the characteristic curve of the annular spring, it can be obtained that the area enclosed by the characteristic curve is the energy lost by friction during the loading and unloading process of the spring, which accounts for almost 60%-70% of the work done by the spring in the entire process. This shows that the spring has a strong shock-absorbing ability and its energy consumption performance is better than other springs.

[0035] Combined with the structure and characteristic curve of the annular spring, it can be seen that the annular spring has the following characteristics: 1. Compact structure: The ring spring has a compact structure and occupies a small space, which is suitable for application backgrounds with limited space.

[0036] 2. Strong shock-absorbing ability: The annular spring has strong shock-absorbing ability and can effectively reduce the impact of impact loads.

[0037] 3. Easy maintenance: The annular spring has a simple structure and is easy to replace.

[0038] (3) Nonlinear spring parameter design Step 1: Determine the kinetic energy of high impact teaching tools E and the maximum working load of the nonlinear spring , calculate the maximum compression of the spring : ; Step 2: Determine the outer diameter of the nonlinear spring according to the position requirements of the buffer structure D , determine the height of a single ring , single ring thickness , half cone angle Select Between, the friction parameters Pick The corresponding friction angle is ; Step 3: Calculate the compression of a single ring according to the compression formula : In the formula, is the inner diameter of the annular spring, ; Step 4: Calculate the total number of rings of the annular spring : Step 5: Calculate the total length of the spring in the buffer device in the free state : .

[0039] Combined with the empirical formula, the two main parameters that affect the design of the annular spring are stiffness and the maximum compression of the nonlinear spring. According to the kinetic energy of the high-impact teaching aids, the maximum compression is selected based on the calculation results. It is 0.02m and the spring stiffness is 8e+6N / mm.

[0040] Through calculation, the nonlinear spring parameters are determined as shown in Table 1: Table 1 Nonlinear parameters Spring parameters

[0041] The process of establishing the new structure high impact teaching aid model is as follows: According to the nonlinear spring parameters designed above, the model is established using UG software. Fig.10 .

[0042] like Fig.10 As shown, the high-impact teaching tool with a new structure energy absorption device includes a shell 5, a load member 1, a buffer pad 6, a pull rod 3, a U-shaped clamping plate 2 and a nonlinear spring 4, wherein the load member head and the shell are fixed in position by clamping the nonlinear spring with the clamping plate. A rubber buffer pad is designed between the load member head and the shell. The two ends of the pull rod are respectively connected to the load member head and the clamping plate, and there is always pressure on the clamping plate. The working principle of the buffer structure of the new structure high-impact teaching tool is: the positioning method of the load member during the conveying into the tube is bottom edge positioning. During the conveying into the tube, after the bottom edge stops moving, the load member impacts forward due to inertia, the shell is restricted, and the load member head continues to move forward. The load member is always affected by the spring force, and the load member head drives the nonlinear spring to compress. After reaching a certain position, the load member head moves in the opposite direction, and the spring force drives the load member head to accelerate in the opposite direction, and finally reaches the rubber pad. After a short period of action, the load member moves in the direction. In the process of reciprocating motion, the buffer structure mainly consumes energy through friction through the nonlinear spring, and the load member stops at the initial position after several reciprocating motions.

[0043] The verification and analysis process of the new structure high impact teaching aid buffer is as follows: Kinematic analysis: The head weight of a high-impact teaching tool in a complex conveying system is 30kg, the conveying tube speed is 5m / s, the nonlinear spring stiffness in the high-impact teaching tool is 8e+6N / m, and the nonlinear spring preload is 600N. According to the actual movement of the high-impact teaching tool, the movement of the high-impact teaching tool in the chamber is divided into four processes: recoil, recoil, forward rush, and return. The kinematic analysis of the new structure high-impact teaching tool is carried out through MATLAB software to solve the relationship between the speed, acceleration, displacement and time of the new structure high-impact teaching tool during the action process.

[0044] Then, by comparing and analyzing the kinematic analysis results of the new structure high-impact teaching tools with those of traditional high-impact teaching tools, the advantages of the new structure high-impact teaching tools are analyzed and verified.

[0045] (1) Kinematic model analysis of new structure high-impact teaching tools Now the high impact teaching tools are subjected to stress Conduct analysis.

[0046] In the two stages of high impact teaching tool movement, friction resistance and spring force When the friction resistance points to the direction of the load head, it is positive, otherwise it is negative.

[0047] The force of high impact teaching tools during movement can be expressed as:

[0048] Where: —preload of spring, N; —Stiffness of nonlinear spring when loaded, N / mm; —Stiffness of nonlinear spring when unloaded, N / mm; —Displacement of the load head, mm; —friction resistance of the spring, N; The differential equation of motion for the high impact teaching aid is: Where: —Mass of high impact teaching aids, kg; —Acceleration of high impact teaching aids, m / s 2 ; —Force on high impact teaching tools, N; Substituting the above two-stage formulas into the corresponding stages, we can obtain the motion differential equations of different stages: Forward phase: Return stage: The Runge-Kutta method is used to solve the motion differential equation through MATLAB software programming, and the relationship between the velocity, acceleration and displacement of high-impact teaching tools and time is solved.

[0049] According to the spring design principle, the spring preload is set to twice the weight of the load head, which is 600N. The relationship between the two stiffnesses can be calculated based on the energy consumption of the annular spring during the second action process. .

[0050] The kinematic performance advantages of the new structure high impact teaching tools were verified by comparing the kinematic analysis of the new structure high impact teaching tools with the traditional ones through MATLAB.

[0051] The velocity, acceleration and displacement of the new structure high impact teaching tool and the traditional circular section tension spring high impact teaching tool over time are shown in the figure Figure 11-13 .

[0052] By comparison, it can be found that the cycle of the new structure high impact teaching tool is shorter, less than 0.02s. Under the same initial velocity, the new structure high impact teaching tool returns to the initial position first, while the traditional high impact teaching tool needs to go through several cycles to consume the kinetic energy of the load head. Due to the large nonlinear spring stiffness in the new structure high impact teaching tool, the displacement of the load head is small. Since the pre-stress is set at the beginning of the movement of the load head, the acceleration of the new structure high impact teaching tool load head is also large, reaching 5e+3m / s at the beginning. 2 .

[0053] Finite element analysis: In order to verify the rationality of the buffer mechanism of the new structure high impact teaching tools designed by calculation, the stress and strain simulation calculation of the new structure high impact teaching tools will be carried out by using the finite element analysis method. And the strength analysis will be carried out by comparing and analyzing the traditional high impact teaching tools.

[0054] In order to improve the simulation efficiency and reduce the amount of redundant calculation, the high impact teaching aids model should be simplified before simulation, such as Fig.14 As shown, it is mainly reflected in that the connecting rod and the head of the high-impact teaching tool load piece are processed in the same way as the actual load piece structure.

[0055] First, the simplified new structure high impact teaching tool model is imported into the workbench. Because there is a rubber pad in the designed buffer device, the rubber material needs to be imported after the model is imported. In order to ensure the appropriate strength of the structure and the efficiency of buffering, the elastic modulus of the rubber also needs to be determined. After repeated comparison and analysis, and consulting the data, the density, material constant, and incompressibility parameters of the rubber are determined.

[0056] The buffer structure is meshed using hexahedral units. When performing finite element analysis, the mesh must be encrypted to make the calculation results more accurate, but as the mesh density increases, the amount of calculation will also increase. After repeated comparisons, I chose a mesh unit size of 0.01 meters for finite element simulation. Fig.15 shown.

[0057] The finite element simulation results of the new structure high impact teaching tool are as follows Figure 16-18 ; According to the simulation results, the load at the buffer pad is the largest, the stress is 0.3MPa, and the elastic strain at this position is also the largest. According to the simulation results, there is no stress concentration phenomenon in the high-impact teaching aids with new structures. The high-impact teaching aids have a stable structure and the stress is far less than the yield limit.

[0058] Comparative analysis of results: (1) When consuming the same recoil energy, the deformation variable of the buffer mechanism in the new structure high-impact teaching tool is the smallest, and the action time of the buffer mechanism in the high-impact teaching tool is also short. Due to the presence of the rubber pad, the buffer device also absorbs and disperses energy, while reducing the rigid contact between the components. The mechanical properties are better than those of traditional high-impact teaching tools; (2) In the new structure of the high-impact teaching equipment buffer device, the stress is mainly concentrated on the buffer pad position. The maximum load of the rubber pad can reach 0.6MPa. According to the data, the maximum stress that the rubber pad can withstand can reach 10MPa, which fully meets the strength requirements. In addition, the high-impact teaching equipment will not be used continuously and frequently, so the rubber pad has a long service life. The loads on other components in the high-impact teaching equipment are not large, which improves the service life of the high-impact teaching equipment; (3) The disc spring buffer device occupies a small space in the high impact teaching tool and has a small mass. Other areas in the high impact teaching tool can be filled with iron sand and other materials to simulate the real mass distribution of the actual load part so that the test effect of the high impact teaching tool is consistent with the actual load part. Compared with other traditional circular cross-section tension springs, the high impact teaching tool has improved testing capabilities.

[0059] The above is an example of the best implementation of the present invention, and the parts not described in detail are common knowledge of ordinary technicians in the field. The protection scope of the present invention shall be based on the content of the claims, and any equivalent transformation based on the technical enlightenment of the present invention is also within the protection scope of the present invention.

Claims

1. A high impact teaching tool with a new structure energy absorption device, characterized in that: The invention comprises a shell (5), a load member (1), a buffer pad (6), a pull rod (3), a U-shaped compression plate (2) and a nonlinear spring (4), wherein a cavity is opened in the middle of the shell (5), a groove is arranged at the front end, a partition plate (7) is arranged between the groove and the cavity, a load member (1) is arranged in the groove, a buffer pad is arranged on the rear surface of the load member (1), a pull rod (3) is arranged horizontally in the middle of the rear end of the load member (1), the pull rod (3) penetrates the partition plate (7) and then extends into the cavity, a U-shaped compression plate (2) is arranged at the rear end of the pull rod (3) located in the cavity, a nonlinear spring (4) is arranged between the compression plate (2) and the partition plate (7), and the nonlinear spring (4) is sleeved on the outside of the pull rod (3).

2. The high impact teaching tool with a new structural energy absorption device according to claim 1, characterized in that: The nonlinear spring is an annular spring.

3. The high impact teaching tool with a new structure energy absorption device according to claim 1, characterized in that: The parameter calculation method of the nonlinear spring is as follows: Step 1: Determine the kinetic energy of high impact teaching tools E and the maximum working load of the nonlinear spring , calculate the maximum compression of the spring : ； Step 2: Determine the outer diameter of the nonlinear spring according to the position requirements of the buffer structure D , determine the height of a single ring , single ring thickness , half cone angle Select Between, the friction parameters Pick The corresponding friction angle is ; Step 3: Calculate the compression of a single ring according to the compression formula : In the formula, is the inner diameter of the annular spring, ; Step 4: Calculate the total number of rings of the annular spring : ； Step 5: Calculate the total length of the spring in the buffer device in the free state , .

4. The high impact teaching tool with a new structural energy absorption device according to claim 1, characterized in that: The maximum compression of the nonlinear spring 0.015-0.025 , outer diameter D It is 0.18-0.22m, and the spring stiffness is 8e+6N / mm.

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