Technical Field

The invention relates to a connector configuration comprises a non-metallic insert with low dielectric coefficient, high strength, spacer feature, and in mechanical assembly of composite parts in sandwich form that is used in fields such as radar, electronic warfare or communication.

State of the Art

Today, composite structures having sandwich form are widely used in sectors such as aviation and aerospace industry. These structures are formed with honeycomb or foam material placed between two thin composite or metal layers. Screws are used for connecting these structures to each other or connecting other objects to these structures. Screws cannot be mounted directly into the structure, for this reason, the common practice in this case is to drill a hole in the structure and place and insert into it. Insert is a standard fastener used to join sandwich structures built using honeycomb or foam material. Sandwich allows a locally varying resistance and strength to ensure proper distribution of a localized load within the panel. With sandwich structures, various structural parts such as chassis, profiles, brackets can be installed between various equipment such as boxes and cables that need to be connected on the sandwich structure. Inserts are usually used with screws or nut-like parts with threads on them. The connection between the insert and the sandwich structure is provided by applying adhesive with epoxy, polyester, cyanatester or resin system to the gap opened for insertion into the sandwich structure.

In the state of the art, inserts are usually grouped according to their type, size, materials and surface treatments. Widely available inserts on the market are usually made from aluminum, titanium and steel alloys. Non-standard inserts can be produced from different metals or plastic materials with carbon fiber additives. [1 ,2]

There must be no gap between the composite structure in the sandwich form to which the insert is applied and the part to be connected by screw, and the surfaces of the assembled parts must be in contact. In this way, the screw can be torqued at the appropriate value. However, current inserts cannot be used in cases where there must be a certain distance between the composite structure in sandwich form and the structures to be joined. Using current inserts, a connection can be made without the two parts to be joined touching each other and leaving the desired amount of space between them. However, in this case, a reliable installation will not be possible because the screw will not reach the desired torque value.

One of the best examples of a situation where there should be a certain distance between the composite structure in sandwich form and the structure to be joined is antenna-radome applications. The desired distance value and screw torque condition between the two parts joined by means of a protrusion from the antenna surface can be provided at the same time. In this case, the use of current inserts is made possible. However, it is often not possible to position a protrusion on the antenna side that will provide the distance between the antenna and the radome in antenna designs that currently have space problems. In addition, a metal structure to be added to the antenna side can adversely affect the antenna pattern and the broadcast. Therefore, it is still not possible to use current inserts.

Another problem with the use of current inserts in antenna-radome applications is that the insert material to be used on the sandwich composite radome side adversely affects the performance of the antenna. The fact that most of the inserts used in the state of the art are produced from metallic materials causes these inserts to adversely affect the antenna performance. Currently, optimum conditions cannot be achieved in antenna performance because the electromagnetic properties of inserts made of non-metallic materials do not exactly match the electromagnetic properties of the radome.

As a result of the research on the subject, application EP3128188B1 was found. The application relates to an insert for use with sandwich panels such as composite panels. Here, an insert is described that can be inserted into the slot without the use of adhesive or waiting for the adhesive to dry or harden. The insert contains a rotation preventer that can be configured to resist rotation and pulling out relative to the sandwich panel. However, it is not mentioned here that the material used in insert production has non-metallic properties such as PAI, PBI, PI, PEEK, PPS, PTFE, PET-P, PA, POM, UHMWPE and the protrusion that provides distance between the joined surfaces is not described. As a result of the research on the subject, some products have been found that can be developed according to various additional needs and whose designs can be changed. Examples include the insert with an eccentric body that prevents rotation in the structure in the patent document US4898756; the insert that provides proper alignment in the structure, that can be inserted without the need for additional equipment and that can provide effective adhesive-insert contact in US3646981 ; the weight-reducing insert with plastic slot in document US2008/0292425 A1 ; the insert that can cut its own slot and assemble itself into the panel in a surface-to-surface shape with friction welding in US57137O6.

The commercially available inserts on the market are mostly made of metallic material. In addition, the use of inserts in radome applications has not been found. Especially in large-size sandwich radomes consisting of a single piece, it must be possible to use the inserts without affecting the antenna pattern in order to maintain the form that can be disrupted by the effect of temperature and pressure and to provide the critical distance between the antenna-radome.

Therefore, due to the negative situations described above and the inadequacy of the existing solutions on the subject, it became necessary to make an improvement in the relevant technical field.

Object of the Invention

The invention is inspired by the present situations and aims to solve the drawbacks mentioned above.

The main object of the invention is to provide a connector configuration made of a low dielectric coefficient, high strength, non-metallic insert with spacer feature that is used in fields such as radar, electronic warfare or communication, used in the mechanical assembly of composite parts in sandwich form.

Another object of the invention is to achieve the desired distance between a sandwichshaped part and a part in a different form without the need for a spacer.

Another object of the invention is to obtain results closer to optimum performance in antenna-radome applications by ensuring that the antenna performance is minimally affected by the electrical properties of the insert material to match the radome material. The structural and characteristic features and all the advantages of the invention will be understood more clearly by means of the figures given below and the detailed description written by referring to these figures, and therefore evaluation should be made by considering these figures and the detailed description.

Figures to Help Understand the Invention

Figure 1 is the representative view of the insert contained in the connector configuration of the invention.

Figure 2 is the view of placing the insert into the sandwich.

Figure 3 is the view of the insert in the sandwich.

Figure 4 is the cross-sectional view of the connector configuration of the invention together with the antenna-radome.

Figure 5 is a graphical view of the Side Section Radiation Patterns of the Azimuth 0° and Elevation 0°Scan.

Figure 6 is a graphical view of the Elevation Section Radiation Patterns of the Azimuth 0°and Elevation 0°Scan.

Description of Part References

1. Sandwich

2. Insert

3. Slot

4. Adhesive

5. Adhesive channel

6. Notch

8. Screw

9. Antenna

10. Radome inner surface

11. Protrusion

12. Contact surface

Pi: Internal pressure

Po: External pressure Detailed Description of the Invention

This detailed description covers the preferred embodiments of the connector configuration, which is the subject of the invention, only for a better understanding of the subject.

The invention relates to a connector configuration used in the assembly of sandwich (1 ) radomes used in fields such as radar, electronic warfare or communication. The connector configuration comprises an insert (2) made of a non-metallic material with low dielectric coefficient, high strength and spacer properties. In Figure 1 , the representative view of the insert (2) is given. There are contact surface (12), adhesive channel (5) and notch (6) on the insert (2).

In a preferred embodiment of the invention, the insert (2) material can be selected to be a high-strength material with electrical properties close to the electrical properties of the radome. For this, the insert (2) is made of advanced engineering plastics with properties such as high strength, low dielectric coefficient, dimensional stability, low thermal expansion coefficient such as PAI, PBI, PI, PEEK, PPS, PTFE, PET-P, PA, POM, UHMWPE and similar, non-metallic materials. Different grades of materials, for example glass fiber reinforced materials, can also be selected for different applications and loading situations.

The insert (2) is applied into sandwich the (1) as follows: The insert (2) is positioned in a slot (3) to be connected to sandwich (1 ), as shown in Figure 2. After the insert (2) is positioned in the slot (3), adhesive (4) is applied to the adhesive channel (5) on the insert (2) to secure it in the sandwich (1 ). The adhesive (4) is compatible with the components that make up sandwich (1 ) and can preferably be made of epoxy, polyester, cyanatester or resin. The adhesive (4) chemically attaches to sandwich (1 ) components and mechanically locks the insert (2) in the sandwich (1 ). In this way, it ensures that the insert (2) is fixed to the sandwich (1 ). Figure 3 shows the insert (2) fixed in the sandwich (1 ). As shown in Figure 4, the antenna-radome installation can be made after the insert (2) is fixed to the radome in sandwich (1 ) structure. The sandwich (1 ) and the antenna (9) are linked to each other using a screw (8).

In a preferred embodiment of the invention, screw (8) and insert (2) may be made of the same material. In order to prevent screw (8) from affecting the antenna pattern, a low dielectric TORLON® or DELRIN® material can be used, taking into account the loading scenario on it. Different quality materials, e.g., glass fiber doped materials, can also be selected for the screw (8), considering different applications and loading situations.

In a preferred embodiment of the invention, the insert (2) contains a notch (6) to prevent the insert (2) from rotating in the sandwich (1) when driving the screw. The notch (6) is shown in Figure 1 .

In a preferred configuration of the invention, the distance between the antenna (9) and the radome inner surface (10) is provided by a protrusion (11 ) contained in the insert (2). In the antenna (9) design, the distance between the antenna and the radome is determined by considering the effect of the radome. Therefore, the protrusion (11 ) is determined depending on the design of the antenna (9). After the installation is made with the screw (8), it becomes possible to tighten the screw (8) by means of the protrusion (11 ) to the appropriate torque value with contact surface (12) formed between the antenna (9) and the radome.

In alternative embodiments of the invention, the insert (2) can be placed on the radar antenna (9) at certain periods and installed in such a way as to have minimal effect on the antenna pattern. Periodic and aperiodic or quasi-random placements of inserts (2) produced from advanced engineering plastics with low dielectric coefficient on the radar antenna (9) can provide minimal impact on the antenna pattern. The position and number of the insert (2) are determined by considering parameters such as antenna pattern, radome size and number of antennas. In addition, the difference between the internal pressure (Pi) and external pressure (Po) caused by the dry air pumped into the system, low pressure and temperature changes creates a certain load on the radome. These loads on the radome are an important factor in determining the insert (2) distribution and number of inserts (2) on the radome, especially the insert (2) size.

In an exemplary antenna-radome application where the invention is applied, firstly, the radiation patterns of the array antenna in the main axes were examined in order to compare the effects of the insert (2). Figure-5 and Figure-6 show the radiation patterns of Azimuth section and Elevation section for Azimuth 0° and Elevation 0° scanning of the array antenna. Here, it is seen that the use of metal insert (2) in the radome generally increases the side beam levels in the main axis. On the other hand, when the insert (2) made of material compatible with radome is used, it can be said that it has almost no effect on the side beam level. Examination of the radiation patterns of the array antenna at all coordinates in space makes the importance of using an insert (2) compatible with the radome more evident.

In conclusion, it can be said that the inserts (2) made of material compatible with the radome do not affect the radiation pattern and the side beam levels in the intermediate axes. It can be observed that those produced from metal materials generally cause the formation of more side beams with higher amplitudes in the intermediate and main axes. It can be shown that the insert (2) made of material compatible with the radome is more suitable to provide the expected side beam levels in the intermediate axes.

With the invention, an insert (2) has been developed to keep the distance between the radome and the antenna constant and to protect the radome form. The distance of the radome to the antenna (9) is fixed with the protrusion (11 ) on the insert (2). When installing the radar antenna-radome, it provides a critical distance between the antenna and the radome. In addition, the radome is installed with the screw (8) disposed at the antenna (9) side and the radome planarity is maintained in temperature and pressure changes.

References

[1] ECSS. Space Engineering Insert Design Handbook; 2011 .

[2] D. Zenkert. The Handbook of sandwich construction, EMAS Publishing; 1997.