Embedded composite material lightweight combined truss for aircraft packaging box

Abstract

The invention discloses a pre-embedded composite material lightweight combined truss for an aircraft packaging box. The pre-embedded composite material lightweight combined truss comprises truss main beams, transverse reinforcing beams, metal pre-embedded front and rear end limiting mounting seats, truss reinforced internal and external mounting seats, reinforcing short beams, bolt assemblies and the like. The combined truss body is made of a composite material, the weight index advantage is obvious compared with that of a metal truss, the truss main beam and the reinforcing beam are formed through the mold pressing technology, and the mechanical property is stable. Metal embedded parts are additionally arranged in the main beam and the reinforcing beam, so that the supporting capacity and the impact resistance of the truss are remarkably improved, and abundant mechanical interfaces are provided for a limiting mechanism, a roller seat and the like. The combined truss and the packaging box body are co-cured and formed, the thermal expansion coefficients are the same, and the technical problem that an interface is prone to layering under the pre-buried high-low temperature alternating working condition of a metal truss is solved.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft packaging boxes, in particular to an aircraft packaging box with a pre-embedded composite material lightweight composite truss. Background Art

[0002] With the continuous development of aircraft models, each type of aircraft has higher and higher requirements for the technical indicators of packaging boxes, especially for lightweight indicators. Most mainstream aircraft packaging boxes are open from the top or the end door. The packaging box body requires an internal truss to achieve structural reinforcement, support, and guidance. The traditional design and manufacturing ideas use metal trusses welded by metal materials such as steel or aluminum. Although they can achieve the function, they are very heavy. The present invention proposes a composite lightweight composite truss, which can be made of a variety of materials such as glass fiber, carbon fiber, basalt fiber, etc., and is formed by a molding process. Finally, the final assembly is completed by gluing and riveting processes. It has the characteristics of lightweight, easy to form, and rich interfaces. The weight is only about 40% of the traditional steel truss, which effectively improves the weight index of the aircraft packaging box.

[0003] Among the many types of military bridges, an important type is the detachable bridge, also called the prefabricated bridge. This type of bridge mostly adopts a truss structure. The truss units are made of metal rods, and then multiple truss units are connected and assembled into a truss bridge using simple parts. The FRP truss is composed of two FRP components with the same structure and integrally formed, which are snapped together. The middle is filled with polyurethane foam, metal joints are set at both ends, prepreg is wrapped on the outside, and reinforcement blocks are set at the joints to further improve the strength of the joints. It has strong designability, high bearing capacity, and light overall weight. For example, the technical solution disclosed in the patent "An integrally formed fiber-reinforced composite truss and its preparation method" with patent application number 2023105418696. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a composite lightweight composite truss embedded in an aircraft packaging box that meets packaging safety indicators and is lighter in weight and more adaptable to ambient temperature changes. The technical solution adopted by the present invention is a composite lightweight composite truss embedded in an aircraft packaging box, including two truss main beams extending in the length direction, at least three reinforcing cross beams are arranged between the two truss main beams, and mounting seats adapted to the aircraft are arranged on the reinforcing cross beams, and at least two limit mounting seats are embedded on the truss main beams. The composite truss body is made of composite material with high specific strength, and has obvious advantages over metal trusses in weight index, which significantly improves the lightweight index of the packaging box; and the composite truss has strong designability, and can fully consider structural avoidance and local performance enhancement according to the structural characteristics of the packaging box and the internal aircraft shape; The limit mounting seat is a metal embedded part, including a rear limit mounting seat, a front limit mounting seat, an external mounting seat, an auxiliary limit mounting seat and a roller mounting seat; metal embedded parts are added to the main beam and the reinforcement beam according to the requirements of the packaging box structure, which significantly improves the truss support, torsion resistance and impact resistance, and the metal embedded parts can provide rich mechanical interfaces for external components such as limit mechanisms and roller seats; the material of the combined truss and the packaging box body are made of the same resin and have the same thermal expansion coefficient. Co-curing molding solves the technical problem of easy stratification of the interface of the metal embedded truss under high and low temperature alternating working conditions.

[0005] The beneficial effect of the present invention is that the lightweight effect of the aircraft packaging box is improved, and the traditional metal truss is replaced by a composite material composite truss; the composite material composite truss can be co-cured with the packaging box body, thereby improving the stability, structural strength and rigidity of the packaging box body, and solving the problem of easy delamination of the interface of the metal truss in the embedded structure of the packaging box. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 for Figure 1 Lightweight composite truss front and side view Figure 2 Figure 2 Front view of lightweight composite truss; Figure 3 for Figure 3 Top view of lightweight composite truss; Figure 4 Side view of lightweight composite truss; Figure 5 Partial view of lightweight composite truss; Marked in the figure: 1-truss main beam, 2-non-beveled transverse reinforcement beam, 3-metal embedded rear end limit mounting seat, 4-truss reinforced internal mounting seat, 5-transverse reinforcement beam, 6-reinforced short beam one, 7-metal embedded auxiliary limit mounting seat, 8-metal embedded roller mounting seat, 9-bolt assembly, 10-reinforced short beam two, 11-metal embedded front end limit mounting seat, 12-truss reinforced external mounting seat. DETAILED DESCRIPTION

[0007] The present invention will be further described below in conjunction with the accompanying drawings.

[0008] Embodiment 1: The aircraft packaging box in this embodiment is pre-embedded with a composite material lightweight composite truss, comprising a truss main beam (1), a non-beveled transverse reinforcement beam (2), a metal pre-embedded rear end limit mounting seat (3), a truss reinforced internal mounting seat (4), a transverse reinforcement beam (5), a reinforced short beam 1 (6), a metal pre-embedded auxiliary limit mounting seat (7), a metal pre-embedded roller mounting seat (8), a bolt assembly (9), a reinforced short beam 2 (10), a metal pre-embedded front end limit mounting seat (11), and a truss reinforced external mounting seat (12).

[0009] The cross-section of the truss main beam (1) is an "I" shape, and the molding length can be selected according to the size of the packaging box. Generally, the overall length of a single main beam is within 10m. Taking full consideration of the economic index and the mechanical performance index, the glass fiber prepreg molding process is preferably used, and the molding is heated and cured, so that the molding accuracy is high, the main beam has good flatness and straightness, and the mechanical performance is stable.

[0010] The non-bevel transverse reinforcing beam (2) provided in this embodiment has a special-shaped end cross section. The height difference between the reinforcing beam (2) and the truss main beam (1) adopts a non-bevel transition method. Considering the structural characteristics of the protruding part of the aircraft, the rear end of the truss is provided with the maximum passing capacity. The two ends can be inserted into the inner side of the truss main beam (1) and connected by gluing and rivets. The structural form of the transverse reinforcing beam (5) is similar to the non-bevel transverse reinforcing beam (2). In order to improve the strength of the transverse reinforcing beam, the height difference between the transverse reinforcing beam (5) and the truss main beam (1) adopts a bevel transition method to improve the connection strength and reliability of the transverse reinforcing beam (5) at the end. The reinforcing short beam 1 (6) and the reinforcing short beam 2 (10) are both rectangular in cross section and only differ in length. They are formed by continuous fiber molding process. The two ends are inserted between the two transverse reinforcing beams (5) and fixed by gluing and riveting to improve the overall structural stability of the truss and the force transmission effect.

[0011] The metal embedded rear end limit mounting seat (3), metal embedded auxiliary limit mounting seat (7), metal embedded roller mounting seat (8), and metal embedded front end limit mounting seat (11) provided in this embodiment are made of metal, preferably high-strength steel, and are all designed with a symmetrical structure and are formed by machining. Every two embedded parts of the same specification form a group, which are embedded in the two sides of the vertical ribs of the truss main beam (1) and the transverse reinforcement beam (5), and adopt a micro-interference fit. Two through holes with a diameter of 8.5 mm are opened on the vertical plate of each metal embedded part, and through holes with a diameter of 9 mm are opened at corresponding positions of the truss main beam (1) and the transverse reinforcement beam (5). They are connected by two groups of M8 bolt assemblies (9) of the same specification. The bolt assemblies (9) are preferably made of stainless steel. Bolts, nuts, and spring washers are used in combination. After assembly, they are coated with resin of the same specification as the packaging box. The truss effectively improves the height direction support capacity and impact load resistance capacity, and at the same time improves the torsion resistance of the truss, making up for the shortcomings of the composite material main beam with weak impact load resistance performance. Two M5 threaded holes and two M8 threaded holes are designed on the upper surface of each metal embedded part, and two M5 threaded holes are designed on the lower surface. Countersunk holes are opened at positions corresponding to the M5 threaded holes of each metal embedded part on the truss main beam (1) and the transverse reinforcement beam (5), and the metal embedded parts are connected to each beam by M5 countersunk screws. Through holes are opened at positions corresponding to the M8 threaded holes of each metal embedded part on the truss main beam (1) and the transverse reinforcement beam (5), and are used for connecting and installing various limit structures, roller seats and other parts after the packaging box is formed.

[0012] The truss strengthening internal mounting seat (4) and the truss strengthening external mounting seat (12) provided in this embodiment are made of metal material, preferably high-strength steel, and are formed by machining and used in groups. The truss strengthening internal mounting seat (4) is embedded in the inner side of the vertical rib of the truss main beam (1), and the truss strengthening external mounting seat (12) is embedded in the outer side of the vertical rib of the truss main beam (1). Two through holes with a diameter of 8.5 mm are opened on the vertical plate, and a through hole with a diameter of 9 mm is opened at the corresponding position of the truss main beam (1). They are connected by two sets of M8 bolt assemblies (9) of the same specification, thereby improving the support capacity of the truss in the height direction and the torsion resistance of the main beam. Four M5 threaded holes are designed on the upper and lower surfaces of the truss strengthening internal mounting seat (4) and the truss strengthening external mounting seat (12). Countersunk holes are opened at the corresponding positions of the truss main beam (1) and the M5 threaded holes, and the connection with the truss main beam (1) is achieved by countersunk screws. The truss reinforced internal mounting seat (4) is provided with four M6 threaded interfaces for connecting the truss with the pre-buried metal slings of the packaging box to form a basket structure, thereby improving the overall structural strength of the packaging box.

[0013] Embodiment 2: On the basis of Example 1, in order to improve the lightweight and mechanical effect of the combined truss, further optimization is performed. Each beam of the truss can be formed by a carbon fiber prepreg molding process, and a woven cloth and a unidirectional tape are used in combination to take into account multi-angle force conditions, and after being heated and cured at above 160°C, each metal embedded part can be preferably machined with titanium alloy. This method can reduce the weight by more than 25% compared with the glass fiber + steel embedded solution. Furthermore, on the basis of the existing structure, an oblique reinforcement beam can be added between the two truss main beams (1) and the transverse reinforcement beam (5) to improve the mechanical properties of the truss.

[0014] In summary, the aircraft packaging box of the present application has a pre-embedded composite lightweight composite truss. The composite truss body is made of composite material and can be molded with glass fiber prepreg or carbon fiber prepreg. After heating and curing, the truss main beam and reinforcing beam are designed in a targeted manner, and the cross-sectional shape, length, etc. can be designed independently. According to the structural characteristics of the packaging box and the internal aircraft shape, the structural avoidance and mechanical working conditions are fully considered. The beams are connected by gluing and riveting. Metal embedded parts are added inside the main beam and reinforcing beam. Every two embedded parts of the same specification form a group, which are embedded in the truss main beam and reinforcing beam on both sides of the vertical ribs. A micro-interference fit is used to improve the truss's supporting capacity and impact resistance. At the same time, it can provide a rich mechanical interface for external components such as limit mechanisms and roller seats. The composite truss is co-cured and formed with the packaging box body, integrating the truss and the packaging box, significantly improving the mechanical properties of the packaging box.

[0015] Compared with traditional aircraft packaging box technology solutions, it has obvious technical advantages in the following aspects.

[0016] (1) The composite truss body is made of composite material with high specific strength and obvious weight advantage over metal trusses, which significantly improves the lightweight effect.

[0017] (2) Metal embedded parts are added inside the main beam and reinforcement beam of the composite truss according to the requirements of the packaging box structure, which significantly improves the support, torsion resistance and impact resistance of the truss. The metal embedded parts can also provide a rich mechanical interface for external components such as limit mechanisms and roller seats.

[0018] (3) The combined truss realizes the integration of structure and function. While supporting the aircraft, it can be co-cured and formed with the packaging box as a whole to improve the strength and rigidity of the packaging box.

[0019] (4) The material of the combined truss and the packaging box body can be made of the same resin with the same thermal expansion coefficient. After co-curing and molding, they become one body, solving the technical problem of easy delamination of the interface of the metal embedded truss under high and low temperature alternating working conditions.

Claims

1. An aircraft packaging box with pre-embedded composite material lightweight composite truss, characterized by: The invention comprises two truss main beams (1) extending in the length direction, at least three reinforcing cross beams are arranged between the two truss main beams (1), mounting seats (4) adapted to the aircraft are arranged on the reinforcing cross beams, and at least two limit mounting seats are pre-embedded on the truss main beams (1).

2. The aircraft packaging box pre-embedded composite material lightweight composite truss according to claim 1, characterized in that: The reinforced cross beam includes a non-bevel transverse reinforced beam (2), a transverse reinforced beam (5), a first reinforced short beam (6), and a second reinforced short beam (10). The aircraft packaging box pre-embedded composite material lightweight composite truss as described in claim 1 is characterized in that the limit mounting seat is a metal embedded part, including a rear end limit mounting seat (3), a front end limit mounting seat (11), an external mounting seat (12), an auxiliary limit mounting seat (7) and a roller mounting seat (8).

3. The aircraft packaging box pre-embedded composite material lightweight composite truss according to claim 1, characterized in that: The cross-sectional shapes of the truss main beam (1) and the reinforcing cross beam are both "I" shaped, formed by a glass fiber prepreg molding process, and heated and cured, and the truss main beam and the reinforcing cross beam are assembled by gluing and riveting.

4. The aircraft packaging box pre-embedded composite material lightweight composite truss according to claim 4, characterized in that: The end surface of the non-bevel transverse reinforcing beam (2) is designed with a special-shaped cross-section, and the height difference between the non-bevel transverse reinforcing beam (2) and the truss main beam (1) adopts a non-bevel transition method. The two ends of the non-bevel transverse reinforcing beam (2) in the length direction can be inserted into the inner side of the truss main beam (1) and connected by gluing and rivets.

5. The aircraft packaging box pre-embedded composite material lightweight composite truss according to claim 3, characterized in that: The rear end limit mounting seat (3) and the front end limit mounting seat (11) are both made of metal and adopt a symmetrical structural design. Two of them form a group and are respectively embedded in both sides of the vertical reinforcement of the truss main beam (1), and are screwed to the truss main beam (1) through two groups of bolt assemblies (9) of the same specification.

6. The aircraft packaging box pre-embedded composite material lightweight composite truss according to claim 3, characterized in that: The auxiliary limit mounting seat (7) is a metal embedded part, adopting a symmetrical structural design, two in a group, respectively embedded in the two sides of the vertical rib of the transverse reinforcement beam (5), and screwed to the transverse reinforcement beam (5) through a bolt assembly (9), with a threaded hole reserved for the installation of the limit structure.

7. The aircraft packaging box pre-embedded composite material lightweight composite truss according to claim 3, characterized in that: The roller mounting seat (8) is a metal embedded part with a symmetrical structural design. Two of them form a group and are respectively embedded in the two sides of the vertical reinforcement of the truss main beam (1). They are screwed to the truss main beam (1) through two groups of bolt assemblies (9) of the same specification, and a roller seat mounting threaded hole is reserved on the upper part.

8. The aircraft packaging box pre-embedded composite material lightweight composite truss according to claim 7, characterized in that: The bolt assembly (9) includes bolts, nuts, and spring washers made of stainless steel, and is coated with a resin of the same specification as the packaging box after assembly.

Images