FR2640738A1

FR2640738A1 - Radome exhibiting properties of strength at high temperature

Info

Publication number: FR2640738A1
Application number: FR8916026A
Authority: FR
Original assignee: Telefunken Systemtechnik AG
Current assignee: Telefunken Systemtechnik AG
Priority date: 1988-12-07
Filing date: 1989-12-05
Publication date: 1990-06-22

Abstract

Radome for missiles, exhibiting properties of strength at high temperature, consisting of a core made from a plastic and of a thin internal and external covering layer, characterised in that the radome is a hybrid radome including a core 1 made from a needled polyimide felt and covering layers 2, 3 made from heat curable or thermoplastic matrix materials, or polymer materials, which are strong at high temperature and reinforced with fibres, and in that the core 1 and the covering layers 2, 3 are solidly joined together without external addition of glue.

Description

L'invention a pour objet un rad8me pour missiles, présentant des propriétés de résistance a haute température, constitué d'un noyau en matière plastique et d'une couche de couverture intérieure et extérieure mince. The invention relates to a missile rad8me having high temperature resistance properties, consisting of a plastic core and a thin inner and outer covering layer.

Les radômes de ce type sont généralement connus et leur noyau est par exemple en matière syntactique. Ils présentent cet inconvénient qu'a haute température, le matériau du coeur se fissure. En effet, par suite d'un coefficient de dilatation thermique relativement élevé et de propriétés inhérentes au matériau, ce dernier, présente une mauvaise résistance au cisaillement par rapport aux couches de couverture. Radomes of this type are generally known and their nucleus is for example in syntactic matter. They have this disadvantage that at high temperature, the material of the core cracks. Indeed, as a result of a relatively high coefficient of thermal expansion and properties inherent in the material, the latter has poor shear strength compared to the cover layers.

L'invention a donc pour but de réaliser un radôme du type précité dont les caractéristiques mécaniques, thermiques et diélectriques conviennent â une utilisation permanente à haute température, par exemple jusqu'à 320 OC. The invention therefore aims to produce a radome of the aforementioned type whose mechanical, thermal and dielectric characteristics are suitable for permanent use at high temperature, for example up to 320 OC.

Le radôme suivant l'invention a pour avantage de supprimer le collage des couches de couverture sur le noyau. Le noyau en feutre aiguilleté de polyimide est compacté sous l'effet de la température et d'une compression, de manière qu'il en résulte avantageusement un matériau déformé sphériquement, de grande rigidité et de faible poids, présentant de bonnes caractéristiques diélectriques. I1 est avantageux en outre que le feutre aiguilleté de polyimide utilisé comme matériau pour le noyau, permette d'obtenir des propriétés mécaniques orientées, telles que la dureté, l'élasticité et la résistance mécanique, ainsi qu'une faible constante diélectrique S, un angle de pertes tg w réduit et une grande rigidité. The radome according to the invention has the advantage of eliminating the sticking of the covering layers on the core. The core of needled polyimide felt is compacted under the effect of temperature and compression, so that it advantageously results in a spherically deformed material, of high rigidity and low weight, having good dielectric characteristics. It is further advantageous that the needled polyimide felt used as material for the core, makes it possible to obtain oriented mechanical properties, such as hardness, elasticity and mechanical resistance, as well as a low dielectric constant S, a reduced loss angle tg w and high rigidity.

Diverses autres caractéristiques de l'invention ressortent de la description détaillée qui suit. Un mode de réalisation de l'invention est représenté à titre d'exemple non limitatif au dessin annexé. Various other characteristics of the invention will emerge from the detailed description which follows. An embodiment of the invention is shown by way of non-limiting example in the accompanying drawing.

La figure unique est une vue en coupe d'une partie d'un radôme. The single figure is a sectional view of part of a radome.

Le radôme que l'on ne voit qu'en partie et qui est un radôme hybride, comporte un noyau 1 en feutre aiguilleté de polyimide ainsi qu'une couche de couverture intérieure 2 et une couche de couverture extérieure 3 en matériaux de matrice thermodurcissables ou thermoplastiques ou polymères pouvant être renforcés par des fibres, le renforcement par des fibres pouvant être constitué de fibres continues. Les couches de couverture 2 et 3 qui sont solidement assemblées au noyau en feutre aiguilleté de polyimide, sans apport extérieur de colle, par un procédé thermique et de compression, peuvent être réalisées dans des matières de matrice polyimide thermodurcissables, par exemple à base de résine maléinimides, en matières de matrice polyimide thermoplastiques ou on peut utiliser des résines bimaléinimides ou des polyimides aromatiques. Les matières de matrice peuvent être réalisées de préférence avec un renforcement de fibres. The radome which is only partially seen and which is a hybrid radome, comprises a core 1 of needled polyimide felt as well as an inner covering layer 2 and an outer covering layer 3 made of thermosetting matrix materials or thermoplastics or polymers which can be reinforced by fibers, the reinforcement by fibers which can consist of continuous fibers. The covering layers 2 and 3 which are securely assembled to the core of needled polyimide felt, without external glue, by a thermal and compression process, can be produced in thermosetting polyimide matrix materials, for example based on resin maleinimides, in thermoplastic polyimide matrix materials or bimalinimide resins or aromatic polyimides can be used. The matrix materials can preferably be made with fiber reinforcement.

Claims

1. Radome for missiles, having high temperature resistance properties, consisting of a plastic core and a rinsed inner and outer covering layer, characterized in that the rad8u.te is a ra? > 6th hybrid comprising a core (1) of needled polyimide felt and cover layers (2, 3) of thermosetting or thermoplastic matrix materials, or by polymer materials, resistant to high temperature, and in that the core ( 1) and the cover layers (2, 3) are securely assembled together without any external adhesive.

2. Radome according to claim 1, characterized in that the covering layers (2, 3) are made of polyimide matrix materials, thermosetting.

3. Radome according to claim 2, characterized in that the polyimide matrix material is based on malein-imide resin.

4. Radome according to claim 1, characterized in that the cover layers (2, 3) are made of thermoplastic polyimide matrix materials.

5. Radome according to one of claims 1, 2, 3 or 4, characterized in that the covering layers (2, 3) are made of thermosetting or thermoplastic matrix materials, or by polymeric materials, reinforced by fibers , made of thermosetting and fiber reinforced polyimide matrix materials or of fiber reinforced thermoplastic polyimide matrix materials.

6. Rad6me according to one of claims 2 or 5, characterized in that one uses as matrix materials bimalinimide resins or aromatic polyimides.

7. Radome according to claim 1, characterized in that the covering layers (2, 3) are made of polybenzimidazole polymer.

8. Radome according to claim l, characterized in that the reinforcement by fibers is produced by continuous fibers.

9. Radome according to claim 1, characterized by a thermal and high temperature compression process for assembling the core (1) to the cover layers (2, 3).