The constraint conversion device and the demonstration teaching aid for constructing the influence lines of a multi-span statically determinate beam using the kinematic method

Abstract

This invention discloses a constraint conversion device and a demonstration teaching aid for constructing the influence line of a multi-span statically determinate beam using the kinematic method. The device includes: a first connecting member for connecting and fixing a first rigid member; a second connecting member for connecting and fixing a second rigid member; several shear constraint conversion boxes of the same shape, height, and proportionally varying length and width, with adjacent shear constraint conversion boxes nested together to form a retractable shear constraint conversion box group; each shear constraint conversion box has a first pin hole, and after all shear constraint conversion boxes are nested and overlapped, all the first pin holes can be fixed by a first pin shaft; and a hinge constraint conversion track, one end of which is fixedly connected to the first connecting member, and the other end of which is hinged or fixedly connected to the shear constraint conversion box group. Advantages: This invention allows switching between shear constraints and hinge constraints; it allows students to assemble the required structural form and release the corresponding constraints, intuitively displaying the structural motion form and deepening students' understanding of the mechanism's motion mode under external forces.

Description

Technical Field

[0001] This invention relates to a constraint conversion device and a demonstration teaching aid for constructing influence lines of multi-span statically determinate beams using the kinematic method, belonging to the technical field of structural mechanics teaching and research. Background Technology

[0002] In structural mechanics, drawing influence lines is used to solve the problem of calculating the internal forces of a structure under moving loads. There are generally two methods for drawing influence lines: the static method and the kinematic method. The kinematic method transforms the static problem of drawing influence lines into a geometric problem of drawing displacement diagrams. Its advantage is that the shape of the influence lines can be obtained without calculation.

[0003] The kinematic method for constructing influence lines first involves removing the constraints corresponding to the desired quantity and replacing them with constraint forces, resulting in a geometrically variable system. Then, the system is allowed to undergo virtual displacement, with the generalized displacement corresponding to that quantity being a unit displacement. However, in actual learning, students often struggle to understand the motion modes of the geometrically variable system under constraint forces after constraint removal. Therefore, a demonstrative teaching aid is urgently needed to intuitively demonstrate how a geometrically variable system moves under constraint forces after constraint removal. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a constraint conversion device and a demonstration teaching tool for drawing the influence line of a multi-span statically determinate beam using the kinematic method.

[0005] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution.

[0006] On one hand, the present invention provides a constraint conversion device, comprising:

[0007] The first connector connects to and fixes the first rigid member;

[0008] The second connector connects to and fixes the second rigid member;

[0009] Several shear constraint conversion boxes with the same shape, height, and proportionally varying length and width are nested together to form a telescopic shear constraint conversion box group; each shear constraint conversion box has a first pin hole, and after all the shear constraint conversion boxes are nested together and their positions overlap, all the first pin holes can be fixed by the first pin shaft.

[0010] A hinged constraint conversion track, one end of which is fixedly connected to a first connector, and the other end of which is hinged or fixedly connected to the shear constraint conversion box assembly.

[0011] Furthermore, the shear constraint box has a square structure.

[0012] Furthermore, a tension limiting structure is provided between adjacent shear constraint conversion boxes. The tension limiting structure includes a limiting key and a limiting groove. The limiting key is located at the lower end of the inner edge of the outer shear constraint conversion box, and the limiting groove is opened on the outer edge of the inner shear constraint conversion box, with no groove at the upper end of the outer edge. The limiting key is slidably placed in the limiting groove.

[0013] Furthermore, both the first and second connecting members include rigid rod slots and fastening rings.

[0014] The rigid rod slot is inserted into one end of the rigid rod, and the fastening ring is placed on the rigid rod slot. The diameter of the rigid rod slot is changed by rotating the fastening ring in order to press one end of the rigid rod.

[0015] Furthermore, the innermost shear constraint conversion box in the shear constraint conversion box group has a protrusion at its lower end, and the protrusion has three through holes in the vertical direction;

[0016] The hinge constraint conversion track connects to the shear constraint conversion box at one end, which includes a first protrusion and a second protrusion. The first protrusion has two through holes in the vertical direction, and the second protrusion has one through hole.

[0017] The first protrusion is inserted into the extension and passes through two through holes on the extension and the first protrusion respectively via two fixed shafts, so that the hinge constraint conversion track is fixedly connected to the shear constraint conversion box.

[0018] The second protrusion is inserted into the extension and passes through a fixed shaft through a through hole on each of the extension and the second protrusion, so that the hinge constraint conversion track is hinged to the shear constraint conversion box.

[0019] Secondly, a demonstration tool for constructing influence lines of multi-span statically determinate beams using the kinematic method includes:

[0020] Rigid members, fixed supports, hinged supports, support slots, slot frames, constraint conversion devices;

[0021] The inner side of the card slot frame is provided with several support card slots, which are used to fix the fixed support or to hinge the hinge support.

[0022] The hinged support is hinged to the rigid rod;

[0023] Several rigid members are connected in sequence by the constraint conversion device. The end of the rigid member at the first end that is not connected to the constraint conversion device is connected to the fixed support. The end of the rigid member at the last end that is not connected to the constraint conversion device is a free end or a hinged support.

[0024] Furthermore, the support slot is a circular slot hole opened in the slot frame.

[0025] The beneficial effects achieved by this invention are as follows:

[0026] The constraint conversion device provided by this invention can switch between shear constraints and hinge constraints. The provided structural mechanics deformation demonstration teaching aid components allow students to assemble the desired structural form and release the corresponding constraints, intuitively displaying the structural motion patterns and deepening students' understanding of the mechanism's motion modes under external forces. The use of the demonstration teaching aid provides an interactive and practical learning method, increasing student interest and participation. Students can understand and apply knowledge through self-operation and exploration, thus better engaging in the learning process. Attached Figure Description

[0027] Figure 1 This invention provides a structural form for demonstrating the influence line of shear force on a multi-span statically determinate beam using the kinematic method of this invention.

[0028] Figure 2 This invention provides a structural form for demonstrating the influence line of bending moment for multi-span statically determinate beams using the kinematic method of this invention.

[0029] Figure 3 This is a detailed diagram of the shear constraint state of the constraint conversion device of the present invention;

[0030] Figure 4 This is a detailed view of the shear constraint box of the present invention;

[0031] Figure 5 This is a detailed view of the shear constraint box keyway of the present invention;

[0032] Figure 6 This is a detailed diagram of the hinge constraint state of the constraint conversion device of the present invention;

[0033] Figure 7 This is a detailed diagram of the fixed constraint state of the constraint conversion device of the present invention;

[0034] Figure 8 This is a schematic diagram of the rigid rod slot of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0036] Example 1: This invention discloses a constraint conversion device, such as... Figures 3-8 As shown, the constraint conversion device includes a shear constraint conversion box 21, a hinge constraint conversion track 22, a first rigid rod slot 23, a second rigid rod slot 24, and a fastening ring 25.

[0037] Several shear constraint conversion boxes 21 with the same shape, the same height, and proportionally varying length and width are connected together to form a telescopic shear constraint conversion box group; each shear constraint conversion box 21 is provided with a first pin hole 26, and after all the shear constraint conversion boxes 21 are connected and their positions overlap, all the first pin holes 26 can be fixed by the first pin shaft 31.

[0038] The shear constraint box 21 has a square structure, as shown below. Figure 5 As shown, a tension limiting structure is provided between adjacent shear constraint conversion boxes 21. The tension limiting structure includes a limiting key 202 and a limiting groove 201. The limiting key 202 is located at the lower end of the inner edge of the outer shear constraint conversion box 21, and the limiting groove 201 is formed on the outer edge of the inner shear constraint conversion box 21, with no groove at the upper end of the outer edge. The limiting key 202 is slidably placed in the limiting groove 201. The setting of the limiting key 202 and the limiting groove 201 ensures that the shear constraint boxes 21 can be locked together when pulled open.

[0039] like Figure 3 , Figure 6 , Figure 7 and Figure 8 As shown, the first and second connectors each include a first rigid rod slot 23, a second rigid rod slot 24, and a fastening ring 25. The first rigid rod slot 23 and the second rigid rod slot 24 are respectively inserted into one end of the rigid rod. The fastening ring 25 is placed on the first rigid rod slot 23 and the second rigid rod slot 24, and the diameter of the first rigid rod slot 23 and the second rigid rod slot 24 can be changed by rotating the fastening ring 25 in order to press one end of the rigid rod.

[0040] One end of the hinge constraint conversion track 22 is fixedly connected to the second rigid rod slot 24, and the other end of the hinge constraint conversion track 22 is hinged or fixedly connected to the shear constraint conversion box assembly.

[0041] like Figure 3 , Figure 6 and Figure 7 As shown, the innermost shear constraint conversion box 21 in the shear constraint conversion box group has a protrusion 30 at its lower end, and the protrusion has three through holes in the vertical direction; the hinge constraint conversion track 22, which connects to one end of the shear constraint conversion box 21, includes a first protrusion 222 and a second protrusion 221. The first protrusion 222 has two through holes in the vertical direction, and the second protrusion 221 has one through hole.

[0042] The other end of the hinge constraint conversion track 22 is fixedly connected to the shear constraint conversion box assembly in the following manner: the first protrusion 222 is inserted into the extension 30, and the first fixed shaft 27 and the second fixed shaft 28 pass through the two through holes on the extension and the first protrusion 222 respectively, so that the hinge constraint conversion track 22 is fixedly connected to the shear constraint conversion box 21.

[0043] The other end of the hinge constraint conversion track 22 is hinged to the shear constraint conversion box assembly in the following manner: the second protrusion 221 is inserted into the extension 30, and a third fixed shaft 29 passes through a through hole on the extension 30 and the second protrusion 221, so that the hinge constraint conversion track 22 is hinged to the shear constraint conversion box 21.

[0044] Figure 3 The constraint conversion device is in a shear constraint state, the first pin hole 26 is in a relaxed state, and the hinge constraint conversion track 22 is fixedly connected to the shear constraint box 21 through the corresponding through holes fastened by the first fixed shaft 27 and the second fixed shaft 28.

[0045] like Figure 4 As shown, the innermost box in the shear constraint transformation box group is a solid box, while the rest are hollow boxes.

[0046] Figure 6 The constraint conversion device is in a hinge constraint state, the first pin hole 26 is in a fastened state, and the hinge constraint conversion track 22 is fastened to the corresponding through hole 29 and hinged to the shear constraint box 21 through the third fixed shaft 29.

[0047] Figure 7 The constraint conversion device is in a fixed constraint state. The first pin hole 26 is in a tight state by inserting the first pin shaft 31. The hinge constraint conversion track 22 is fixedly connected to the shear constraint box 21 by fastening the corresponding through holes through the first fixed shaft 27 and the second fixed shaft 28.

[0048] Example 2: This invention discloses a demonstration tool for constructing influence lines of multi-span statically determinate beams using the kinematic method, for demonstrating the shape of shear force and bending moment influence lines, including:

[0049] 1. Rigid member; 2. First constraint conversion device; 3. Second constraint conversion device; 4. Third constraint conversion device; 5. Fixed support; 6. Hinge support; 7. Support slot; 8. Slot frame.

[0050] The support slot 7 is a circular slot in the slot frame, used to fix the fixed support 5 or the hinged support 6 as shown. The slot design of the support slot 7 makes it easy to replace the fixed support 5, the hinged support 6, etc., for various demonstrations.

[0051] like Figure 1As shown, this is a structural form of a teaching aid for demonstrating the influence line of a multi-span statically determinate beam using the kinematic method of this invention. Point A is a fixed support, and points B, C, and D are hinged supports. The first constraint conversion device 2 is in a shear constraint state, and the second constraint conversion device 3 is in a hinge constraint state, demonstrating the shape of the shear force influence line at point E.

[0052] like Figure 2 As shown, this is another structural form of the teaching aid for demonstrating the influence line of a multi-span statically determinate beam using the kinematic method of the present invention. The second constraint conversion device 3 is in a hinged constraint state, and the third constraint conversion device 4 is in a fixed state, demonstrating the shape of the bending moment influence line at point F.

[0053] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A constraint conversion device, characterized by, include: The first connector connects to and fixes the first rigid member; The second connector connects to and fixes the second rigid member; Several shear constraint conversion boxes (21) with the same shape, the same height, and proportionally varying length and width are connected together to form a telescopic shear constraint conversion box group; each shear constraint conversion box (21) is provided with a first pin hole (26), and after all the shear constraint conversion boxes (21) are connected and their positions overlap, all the first pin holes (26) can be fixed by the first pin shaft; A hinged constraint conversion track (22) is provided, with one end of the hinged constraint conversion track (22) fixedly connected to a first connector, and the other end of the hinged constraint conversion track (22) hinged or fixedly connected to the shear constraint conversion box assembly. The innermost shear constraint conversion box (21) in the shear constraint conversion box group has a protrusion (30) at its lower end, and the protrusion has three through holes in the vertical direction; The hinge constraint conversion track (22) connecting to the shear constraint conversion box (21) includes a first protrusion (222) and a second protrusion (221). The first protrusion (222) has two through holes in the vertical direction, and the second protrusion (221) has one through hole. The first protrusion (222) is inserted into the extension (30) and passes through two through holes on the extension and the first protrusion (222) respectively through two fixed shafts, so that the hinge constraint conversion track (22) is fixedly connected to the shear constraint conversion box (21); The second protrusion (221) is inserted into the extension (30) and passes through a through hole on the extension and the second protrusion (221) by a fixed shaft, so that the hinge constraint conversion track (22) is hinged to the shear constraint conversion box (21).

2. The constraint translation device of claim 1, wherein, The shear constraint box (21) has a square structure.

3. The constraint translation device of claim 2, wherein, A tension limiting structure is provided between adjacent shear constraint conversion boxes (21). The tension limiting structure includes a limiting key (202) and a limiting groove (201). The limiting key (202) is located at the lower end of the inner edge of the outer shear constraint conversion box (21). The limiting groove (201) is opened on the outer edge of the inner shear constraint conversion box (21), and the upper end of the outer edge is not slotted. The limiting key (202) is slidably placed in the limiting groove (201).

4. The constraint translation device of claim 1, wherein, Both the first and second connectors include rigid rod slots and fastening rings (25). The rigid rod slot is inserted into one end of the rigid rod, and the fastening ring (25) is placed on the rigid rod slot. The diameter of the rigid rod slot is changed by rotating the fastening ring (25) in order to press one end of the rigid rod.

5. A demonstration teaching aid for motorized method of influence line of multi-span statically determinate beam, characterized in that, include: Rigid rod (1), fixed support (5), hinge support (6), support slot (7), slot frame (8), constraint conversion device as described in any one of claims 1-4; The inner side of the slot frame (8) is provided with several support slots (7), which are used to fix the fixed support (5) or the hinge support (6). The hinge support (6) is hinged to the rigid rod (1); Several rigid members (1) are connected in sequence through the constraint conversion device. The end of the rigid member (1) at the first end that is not connected to the constraint conversion device is connected to the fixed support (5). The end of the rigid member (1) at the end that is not connected to the constraint conversion device is a free end or a hinged support (6).

6. The demonstration tool for motorized law of multi-span statically determinate beam influence line according to claim 5, characterized in that, The support slot (7) is a circular slot hole opened in the slot frame.

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