ES2650620B2 - Equipment and method for testing articulated reticular structures - Google Patents

Abstract

Equipment for testing in teaching of articulated reticular structures characterized by being removable and that the bars can be adjusted at any angle in the plane in which the assembly is carried out. The structural elements will be rigid bars in the case that they are subjected to compression stresses and flexible bars in the case that they are exposed to tensile stresses, in this way it will be possible to know visually what kind of stresses are subjected to. of the bars that make up this model. In addition, due to the use of fusible pins in the bars, it will be possible to verify which is the bar that undergoes greater compressive stresses. Another object of the invention is a method of assembling the equipment for testing articulated lattice structures.

Description

DESCRIPTION

EQUIPMENT AND METHOD FOR TESTING ARTICULATED RETICULAR STRUCTURES

5 SECTOR OF THE TECHNIQUE

The following invention has its application in the field of formation and allows us to analyze different articulated bar structures in order to find out if their bars are in traction or compression, as well! as the comparison, between these structures, in terms of the loads they can bear.

STATE OF THE TECHNIQUE

At present, the use of structural test systems is on the order of the day in the field of teaching. Its use in the 15 laboratories of the faculties of technical careers is very common.

For these structural systems, there are different types of solutions to make the union between bars, such as the use of adhesives, rivets, welding, etc. However, currently, the most used solution for structural joints of this type is by means of bolted joints.

20 Analyzing the techniques currently on the market, you can

Note that there are deficiencies. The first of these would be that these union systems would not allow the union of bars with any angle between them. For example, based on the most used union system, by threading in solid spheres, and focusing on a piano, the union 25 can only be made in as many angles as holes for threaded bars can be made in the union ball. The second of the shortcomings to

It should be noted that these systems use rigid elements, that is, rigid bars. In this way it cannot be seen visually, once we finish the assembly of the structure, which elements or bars work by traction or compression.

5 The main feature of this invention is a structural system

that allows the union of the bars at any angle. This union will be removable and will be made by tightening, or also called, adjustment by interference. On the other hand, it will not only consist of rigid bars like the current systems, but that rigid bars and cables will be available. Both 10 elements will be adjustable and allow us to play with a wide variety of models. The use of cables or bars will be restricted to whether the element is in tension or compression within the structural assembly. In addition, the bars subjected to compression will be provided with a fuse that will indicate the moment at which, in the bar, we exceed a certain value of axial force, thus allowing comparison in similar systems.

DESCRIPTION OF THE INVENTION

The present invention relates to an equipment for testing articulated reticular structures (Figure 17), which shows a concrete example 20 of the multiple possible variables, comprising the following elements: junction nodes (1, Figure 1) , inner rigid bar (8, Figure 2) and outer rigid bar (7, Figure 2), fuse pin (13, Figure 2) to regulate the length of the bars, union head for flexible bar (15, Figure 4) and finally of a support for loads (23, Figure 6).

25 The main element would be the junction node (1, Figure 1) which consists of

a cylindrical element with a concentric groove (6) with a T section that allows the attachment of rigid bars or flexible bars (cables) in a 2D system and at any required angle. For possible access to the concentric groove, an opening (2) is available. On the sides of the piece it

It has a groove (3) whose function will be to allow the union between two articulated 2D reticular structures in order to bracing them and forming a 3D structure.

The outer rigid bar (7, Figure 2) hollow inside, consists of 5 multiple holes (9) to make the variation in length depending on the requirements of the model. This bar has at one end an oval shaped head (14) which allows anchoring to the knot. The inner rigid bar (8, Figure 2) consists of a hole (10) for length adjustment. This bar has at one end an oval shaped head (14) equal to that of the outer rigid bar 10, which allows anchoring to the knot. The inner rigid bar (8) is inserted into the outer rigid bar (7), so that the surface (11) slides over the (12) concentrically, thus allowing the regulation of the length of the assembly (Figure 3) . To fix both elements, a fuse pin is available (13, Figure 2 and 3). This pin 15 consists of an element according to the size of the holes of the bars. It has a low shear strength (for example, very small diameter wooden pin) in this way in the face of certain efforts its breakage will occur and this will allow us to make the comparison between similar systems. In addition, both bars as already mentioned, are provided 20 at one of their ends of the union head (14) to perform the union by tightening the knot.

The union head for flexible bar (15, Figure 4) consists of a fastening system by means of threaded element (16) with which the flexible bar (17) or the element that can fulfill its same function would be tied and work only to traction. This way you can verify if it works with traction or compression, since if they did it under compression it would not work. To make the mooring, the flexible bar (17) is introduced through the hole (18) and it is secured by means of the threaded element (16) which in this case consists of a hexagonal head screw (19) for Ship Allen This bar has at one end an oval shaped head (14) equal to that of the

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rigid outer and inner bar, which allows anchoring to the knot. In (Figure 5) the Integra assembly of a flexible bar can be seen.

Finally, we have the load support (23, Figure 6) that is not part of the articulated reticular structure, but is important in the objective of the invention. This support allows the structure to be loaded to generate stress on the structural elements. The shear stresses generated in the pins (13) by the axil of the bars can cause the structure to collapse due to the shear breakage of the pin. In this way we can make the comparison, in terms of resistance, of several different models loaded with the same load and see which would resist more for the same type of load. The load support consists of a hook (20) to allow moving the position of the loads in the structure. This hook derives on a base (21) on which the weights (22) would rest.

Another object of the invention is a method of assembling the equipment for the test of articulated reticular structures, as noted above, firstly it is preceded to assemble the articulated 2D reticular structure, characterized by the fixation of the external rigid bars, internal rigid bars o Flexible bars are made by tightening or adjusting by interference of their oval shaped heads (14) in the concentric groove (6) with T-section of the knot (Figure 7). To explain how this system works in detail, we turn to Figure 7. First, it consists in introducing the head of the outer rigid bar, inner rigid bar or flexible bar in the concentric groove (6) through the opening (2), to locate the bar in the desired position and make a 90 ° turn, applying a pair P1, clockwise, always in the position we want to hold. This way any hitch movement will be totally restricted. This action will be carried out with all the bars and cables used in the structure.

Then, we will assemble the 3D bracing (bars with a secondary function in the structure to give it

3D dimension, as shown in figure 8. To obtain a structure

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stable 3D three-dimensional articulated reticular is necessary to use the set formed by the outer bar and inner bar (Figure 3) to join both 2D articulated reticular structures, this is achieved by the longitudinal union of the nodes that are part of each of the structures 5 articulated lattices, always symmetrically (Figure 8). First the end of the bar is introduced through the longitudinal hole (3) of the knot, it is rotated 90 ° and is supported, its exit being totally restricted. The fully defined bracing is shown in (Figure 9).

Finally, to complete the method and use, as indicated above, proceed to hang the load (s) in the desired place of the reticular structure articulated by the load support (23), in this way it will be possible to verify if the Flexible bars work by traction and which is the most critical rigid bar.

15 DESCRIPTION OF THE FIGURES

For an easy understanding of the invention the following figures are attached:

o FIGURE 1: Perspective view and cutting of the junction knot.

o FIGURE 2: Side view of the inner rigid bar, outer rigid bar, and the pin.

20 or FIGURE 3: Perspective view of the inner rigid bar assembly,

outer rig and fuse pin mounted in a certain position.

o FIGURE 4: Perspective view of the union head for flexible bar.

o FIGURE 5: Perspective view of the complete flexible bar.

o FIGURE 6: Perspective view of the support for weights with load and without discharge.

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o FIGURE 7: Views and cut of the union mechanism by tightening.

o FIGURE 8: Views and section of the joint mechanism of 2D articulated reticular structures to generate a 3D articulated reticular structure.

o FIGURE 9: Perspective view of fully defined bracing.

o FIGURE 10: View step 1, initial joint bar-knot.

o FIGURE 11: View step 2, completion of the upper part of the mesh structure articulated with compression (4 rigid bars).

o FIGURE 12: View step 3, assembly of the 3 flexible bars interleaved vertically.

o FIGURE 13: View Step 4, assembly of the lower part of flexible bars with traction of the articulated reticular structure

o FIGURE 14: View step 5, assembly of the 2 transverse rigid bars.

o FIGURE 15: View step 6, assembly of joint bars between symmetrical 2D articulated reticular structures to form a bridge-type articulated reticular structure.

o FIGURE 16: View step 7, assembly of the symmetrical articulated reticular structure.

o FIGURE 17: View step 8, example reticular structure articulated with loads.

o FIGURE 18: Complete view example 1, articulated reticular structure type Pratt.

o FIGURE 19: Complete view example 2, articulated reticular structure type inverted Howe.

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o FIGURE 20: Complete view example 3, articulated reticular structure covered type.

PREFERRED EMBODIMENT OF THE INVENTION

Next, a description is made of the embodiment of the assembly of the invention with reference to the numbering adopted in the figures. The model chosen as an example is a 3D articulated reticular structure consisting, in turn, of two 2D articulated reticular structures. The possible constructions are multiple, this articulated reticular structure is characterized by its assemblies with bars intercalated to compression and traction.

Before starting the description we will introduce a new term "rigid bar" consisting of the assembly formed by the inner rigid bar, outer rigid bar and the pin (Figure 3). In addition, it is specified that the assembly will be carried out on a horizontal piano without tightening or adjusting for interference of the elements until all these are not in their final position.

To begin assembly (Figure 10), a union is made between a rigid bar (31) and the knot (30). It is mounted with the necessary length using the appropriate hole (70, Figure 10) and fixed with the fuse pin (13). At the other end the union would be made with another knot (32). From this new node a new bar (33) of length determined by the hole (72, Figure 11) is set at 135 ° with respect to the bar (31) ending at the junction with the node (34). The top part assembly would be compromised (Figure 11). It is worth noting the use of rigid bars only in this area because the latticework acts as a beam and the upper part works under compression, the use of flexible bars being useless.

Once we have the entire upper part of the lattice mounted we proceed with the vertical interleaved assemblies, in the nodes (32, 34 and 36), the flexible bars (39, 41 and 43) hang, because they work by traction (Figure 12). They are placed in an upright position. At the other end of the flexible bar,

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the union head is fixed to new knots (40, 42 and 44). The fixing of the heads for flexible bar with the bar itself has been explained previously in (Figure 4).

The next step is to complete the lower lattice line, which corresponds to the part that works with traction (Figure 13). The 5 knots (31, 40, 42, 44 and 38) are joined with the 4 flexible bars (45, 47, 49 and 51).

To end this lattice example, it is necessary to add two transverse rigid bars (53 and 55), which in this particular model work under compression, which join the nodes (40 and 44) with the node (34), these two forming an angle of 45 ° over the horizontal (Figure 14).

Once the 2D articulated reticular structure is finished, all its nodes will be joined, in their longitudinal direction, with new nodes (130, 132, 134, 136, 138, 140, 142 and 144; Figure 15) using the 8 rigid bars (60, 61, 62, 63, 64, 65, 66 and 67; Figure 15) with the length fixed by the drill (72). These bars are bracing (bars with a secondary function in a structure). To explain the methodology of this type of union, knot in the longitudinal axis, we refer to it (Figure 8). In this way a new symmetric articulated reticular structure would be generated to the first, giving rise to the stable three-dimensional final articulated reticular structure (Figure 16). Finally, we would proceed to hang the load (s) in the desired place of the structure (Figure 17).

Three older examples have been added to see the variation of the stresses that the structural elements undergo when changing the design of the articulated reticular structure and to be able to verify, in each structure, which bar or bars are those that resist the greatest tensions due to the rupture of the fuse pin of said bar. The process would consist of loading the structure to be tested until one of the pins breaks.

(Figure 18) corresponds to a Pratt articulated reticular structure that differs, from the example discussed in the explanation, in the orientation

contrary to its crossbars. This causes a modification in the

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work carried out by the elements that make it up, from traction to compression and vice versa. It should be noted that there are elements that do not vary. An articulated reticular structure model of the example model is shown in (Figure 19), but unlike this model works in an inverted way. As a consequence of this, the arrangement of the efforts in the elements that compose it varies. The last example corresponds to (Figure 20) and is an articulated reticular structure for roof.

Claims (6)

5 10 fifteen twenty 25 30 35 1. Equipment for testing articulated reticular structures, characterized by comprising: - a diverse set of bars of adjustable length (24) composed of rigid bars (24) formed in turn by two bars, one inside (8) and one outside (7) that are coupled together and fixed by means of a pin ( 13), and flexible bars (17); - a junction knot (1) characterized by comprising a concentric groove with a T section (6) which in turn has an opening (2) in its upper part that allows the fastening of the oval shaped heads (14) of the inner rigid bar (7), outer rigid bar (11) or flexible bar (17) in a 2D system at any angle; and on its side it has another central hole (3) that allows the union between knot-knot and bracing them in order to form a 3D articulated reticular structure; - a union head (15) for fastening and joining the flexible bars (17); - and a support for loads (23). 2. Equipment for testing articulated reticular structures, according to claim 1, characterized in that the internally rigid outer bar (7) consists of several holes (9) that allows the variation of length and at one end a head (14) for its fixation by tightening the junction knot (1), while the inner rigid bar (8) has a single hole (10) for length adjustment and at one end a union head (14) for fixing by tightening the joint node (1). 3. Equipment for testing articulated reticular structures, according to claims 1 and 2, characterized in that the fuse pin (13) has a section according to the holes (9 and 10) of the set of rigid bars (24), and low resistance to the cut that allows to determine which bar undergoes greater axial tension in each possible design of the articulated reticular structure. 4. Equipment for testing articulated reticular structures, according to claims 1 to 3, characterized in that it comprises a clamping mechanism, and regulation of the length of the flexible bar (17), by means of a threaded element (19), through a hole (18), through which the flexible bar (17) is inserted, and at its end an oval-shaped head (14) protrudes, which will allow its attachment to the joint node (1). 5. Equipment for testing articulated reticular structures, according to claim 1 in which the load support (23) characterized by comprising a hook (20) that allows moving the position of the loads in the structure, from which it derives on a base 5 (21) on which the weights would rest (22). 6. Method of assembling the equipment for the test of articulated reticular structures, according to previous claims, characterized by comprising the following steps: a) assembling the 2D articulated reticular structure which in turn comprises introducing the 10 head of the outer rigid bar (7), inner rigid bar (8) or flexible bar (17) in the concentric groove (6) through the opening (2) of the junction node (1), and then place the bar in the desired position and make a 90 ° turn, applying a pair P1, clockwise, in the position that you want to hold the fastener being completely restricted any movement of the hitch; 15 b) assemble the bracings in order to obtain a 3D three-dimensional articulated structure, set formed by an outer bar and inner bar to join both 2D articulated reticular structures, which is achieved by the longitudinal union of the nodes that are part of each of the symmetrically articulated reticular structures for this purpose the end of the bar is introduced through the longitudinal hole 20 (3) of the junction knot (1), it is rotated 90 ° and is supported, being completely restricted its exit; c) proceed to hang the load (s) in the desired place of the reticular structure articulated by means of the load support (23), in this way it will be possible to verify if the flexible bars work by traction and which is the most critical rigid bar . 25