FR2635177A1 - Armour, particularly for protection against projectiles with hollow charges - Google Patents

Armour, particularly for protection against projectiles with hollow charges Download PDF

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Publication number
FR2635177A1
FR2635177A1 FR7814829A FR7814829A FR2635177A1 FR 2635177 A1 FR2635177 A1 FR 2635177A1 FR 7814829 A FR7814829 A FR 7814829A FR 7814829 A FR7814829 A FR 7814829A FR 2635177 A1 FR2635177 A1 FR 2635177A1
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France
Prior art keywords
shielding
silica
blocks
glass
jet
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Granted
Application number
FR7814829A
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French (fr)
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FR2635177B1 (en
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FRANCE ETAT ARMEMENT
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FRANCE ETAT ARMEMENT
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Publication date
Application filed by FRANCE ETAT ARMEMENT filed Critical FRANCE ETAT ARMEMENT
Priority to FR7814829A priority Critical patent/FR2635177B1/en
Publication of FR2635177A1 publication Critical patent/FR2635177A1/en
Application granted granted Critical
Publication of FR2635177B1 publication Critical patent/FR2635177B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41WEAPONS
    • F41HARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
    • F41H5/00Armour; Armour plates
    • F41H5/02Plate construction
    • F41H5/04Plate construction composed of more than one layer
    • F41H5/0414Layered armour containing ceramic material
    • F41H5/0421Ceramic layers in combination with metal layers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41WEAPONS
    • F41HARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
    • F41H5/00Armour; Armour plates
    • F41H5/02Plate construction
    • F41H5/04Plate construction composed of more than one layer
    • F41H5/0492Layered armour containing hard elements, e.g. plates, spheres, rods, separated from each other, the elements being connected to a further flexible layer or being embedded in a plastics or an elastomer matrix

Abstract

The armour comprises blocks 2 of glass or of silica-based material. These blocks 2 are surrounded by a rigid material 3 having an acoustic impedance greater than that of the material constituting the said blocks. Application in particular to the protection of combat vehicles against projectiles with a hollow charge. <IMAGE>

Description

 The present invention relates to armor, in particular for self-propelled combat vehicles such as tanks, intended to protect the latter in particular against hollow charge projectiles.

 The known shields are generally of homogeneous steel structure. It is known that the jet formed on impact of hollow charge projectiles with such armor penetrates inside these at a speed of the order of several kilometers to the second. This jet causes the shielding to creep, forming a crater with a much larger diameter than that of the jet.

In this mode of penetration, the only element liable to impede the progression of the jet is the resistance axially opposed to the jet by the metal of the shielding.

 To resist the impact of hollow charges, it is thus necessary to choose very large armor thicknesses, which correlatively increases the weight of the armored vehicle to the detriment of its performance and mobility.

 Attempts have been made to increase the effectiveness of shielding with materials other than steel. Thus it has been proposed to use glass plates embedded in a material absorbing the shock wave. These shields have improved efficiency compared to those made of steel. In fact, during the penetration of the jet into the glass, the latter undergoes a structural transformation on contact with the jet which results in a local modification of the volume of the glass. The latter tends to close the crater formed by the jet. This phenomenon induces radial forces which tend to slow the speed of the jet. These radial forces are added to the above-mentioned axial force, so that the effectiveness of the shield is considerably increased.

 However, this increase in the efficiency of the shields based on glass plates is small compared to that of the steel plates, since the retarding effect of the above-mentioned radial forces is relatively weak.

 The object of the present invention is precisely to increase the efficiency of glass block shields or more generally, containing a silica-based material.

According to the invention, the shielding is characterized in that the blocks of silica-based material are surrounded at least in part by a rigid material having an impedance
greater acoustic than that of the material constituting said blocks.

The fact that the plates of silica-based material are surrounded at least in part by a rigid material having an acoustic impedance greater than that of the silica-based material makes it possible to surprisingly increase the effectiveness of the shielding. This increase in efficiency can be explained as follows
The rigid material surrounding the silica-based material generates shock wave reflections on the impact of the jet of the hollow charge which considerably reinforce the radial stresses liable to impede the progression of the jet.

 According to an advantageous version of the invention, the blocks of silica-based material are entirely confined in a frame made up of said material having an acoustic impedance greater than that of the silica-based material.

 This total confinement is favorable to the development of radial stresses to the jet liable to disturb the progression of the latter.

 According to a preferred version of the invention, the material having an acoustic impedance greater than that of the silica-based material is steel.

 Preferably the silica-based material is confined with prestress in the reinforcement constituted by said material having an acoustic impedance greater than that of the silica-based material.

 This prestressing makes it possible to further improve the effectiveness of the shielding by reinforcing the disruptive radial effects of the jet of the hollow charge. In fact, due to this prestress, the stored energy is restored during the rupture of the glass by the jet towards the impact zone thereof, disturbing its progression.

 Other features and advantages of the invention will become apparent in the description below.

In the accompanying drawings given by way of nonlimiting examples
Figure 1 is a cross-sectional view of a shielding element according to the invention.

 FIG. 2 is a view showing the penetration of the jet of a hollow charge into the shielding element of FIG. 1.

 FIG. 3 is a diagram showing the evolution of the volume of the glass as a function of the pressure induced by the jet.

 Figure 4 is a partial cross-sectional view of a shield according to the invention.

 Figure 5 is a perspective view of a parallelipipedic shielding element, incompletely assembled.

 Figure 6 is a sectional view along the plane VI-VI of Figure 5, the element being completely assembled and prestressed.

 Figure 7 is a perspective view of a cylindrical shielding element.

 FIG. 8 is a sectional view along the plane VIII-VIII of FIG. 7.

 Figure 9 is a sectional view of another alternative shielding element.

 Figure 10 is a cross-sectional view of a shield inclined with respect to the impact direction of the jet of a hollow charge projectile.

 Figure 11 is a cross-sectional view of another shield.

 FIG. 12 is a cross-sectional view of another version of shielding.

 In the embodiment of FIG. 1, the element 1 constituting a shield according to the invention, comprises a block 2 of silica-based material surrounded by a frame 3 of a rigid material having an acoustic impedance greater than that of block material 2.

 The silica-based material is preferably soda-lime or borosilicate glass, but may also consist of quartz, silica, granite or any other amorphous or crystalline species containing silica.

 The material constituting the reinforcement 3 is preferably steel, but can also be constituted by another metal with an atomic number greater than that of titanium, which in particular excludes aluminum.

Sl'impact 'imp4ct
In fig. 2 / of a hollow charge projectile with the shielding element 1, the jet 4 first crosses the reinforcement 3 then enters the glass block 2 by forming a hole 5 with a diameter greater than that jet 4. We see that this hole 5 is tightened at its rear part 5a. This tightening 5a is due to the following two phenomena whose effects combine
Under the effect of the compression and the heating generated by the jet 4, the silica contained in the glass 2 is locally transformed into a crystalline variety called "Stishovite" substantially twice as dense as the glass, which results in a variation local glass volume. This variation in volume induces radial disturbances which have the effect of dispersing or fragmenting the jet 4, thereby reducing its effects.

 This tightening effect of the hole 5 is reinforced by the action of shock waves which are reflected against the walls of the confinement frame 3. This effect would be appreciably negligible if the material 3 had an acoustic impedance lower than that of the glass 2 .

 Figure 3 shows that the compression of the glass 2 generates.

in 6 a change of crystalline state, then a relaxation in 7.

After this expansion, the glass returns to its initial state by inducing in Sa a radial pulse to the jet 4. Thus, the efficiency of a block of glass 2 having a thickness e can be equivalent to that of a steel shielding d 'thickness equal to 6th.

 In the embodiment of FIG. 4, the shielding comprises two successive layers of shielding elements 1. These shielding elements 1 can have a thickness comprised between the 30th and once their largest dimension.

 These shielding elements 1 are embedded in a damping material 8 constituted for example by a plastic foam such as polyethylene or polyurethane.

 During the impact of the jet 4 with one of the shielding elements 1, this damping material 8 absorbs the shock waves generated laterally towards the other elements 1. Furthermore, the asymmetry of the point of impact with respect to the edges of each shielding element I generates return shock waves delayed differently from one another and therefore acting on the jet 4 at different times. This considerably limits the effects of these return shock waves.

 In FIG. 4, it can also be seen that the shielding elements 1 of one of the layers are offset with respect to the elements 1 of the other layer to provide effective protection in the event of an impact located between the elements of shield 1 of the first layer.

 In FIG. 4, it can also be seen that an empty space 9 is left between the damping material 8 containing the shielding elements 1 and an inner layer 10 of homogeneous shielding, for example of steel. This space 9 makes it possible to disperse the jet 4 which would have had to reach this space, and consequently to reduce its efficiency.

 According to a preferred version of the invention, the glass blocks 2 of the shielding elements 1 are confined with prestress in the rigid frame 3. This prestress or compression of the glass blocks 2 inside the frame 3 is preferably carried out in a direction perpendicular to the axis of the jet 4. This constraint can however also be multidirectional.

 In the embodiment of FIGS. 5 and 6, the parallelepipedic shielding element il comprises a steel frame 12 which surrounds the glass block 13 with the exception of the two opposite faces 13a and 13b of this block. These faces 13a and 13b project very slightly from either side of the frame 12.

On these two faces 13a and 13b are applied plates 14 and 15. These plates 14 and 15 are fixed to the frame 12 for example by means of tie rods 16, as indicated in FIGS. 5 and 6. The tightening of the tie rods 16 allows to induce in the glass block, a compression stress F normal to the faces 13a and 13b of the glass block 13. The stress can also be obtained by heating the frame 12 before introduction of the glass block 13. This stress s 'then exercises when removing the frame 12 resulting from its cooling. It is thus possible to achieve compression constraints of the order of 30-hectobars, the value of which can be predetermined.

 These constraints favor the crystalline transformation of the silica contained in the glass and consequently lead to an increase in the tightening 5a of the hole 5 formed during the penetration of the jet of the hollow charge. Consequently, the prestressing of the glass blocks 13 of the shielding makes it possible to improve the efficiency of the latter.

 In the embodiment of Figures 7 and 8, the shielding element 17 contains a glass block 18 cylindrical. This block 18 is housed in an annular steel frame 19 closed by two discs 20 also made of steel. These discs 20 can be fixed to the frame 19 by means of tie rods (not shown) or the like.

 The prestress can be induced by heating the frame 19 before the introduction of the glass block 18. These stresses are directed radially with respect to the axis of the glass block 18. These stresses therefore act radially with respect to an axial jet.

 The energy stored by this prestress is restored during the rupture of the glass by the jet of the projectile by generating radial forces which disturb the progression of this jet.

In the embodiment of FIG. 9, which is a variant of the shielding element of FIGS. 5 and 6, the glass block 21 parallelepiped is between two containment flanges 22 whose adjacent edges 22a and 22b are linked together by a weld 23. This connection can be replaced by a tightening by means of
It can also be seen, in FIG. 9, that plates 24, 25 are inserted between the glass block 21 and the adjacent edges 22a and 22b of the two flanges 22. These plates 24 and 25 are made of a ductile material, such as copper, to allow a perfect junction between the glass block 21 and the welded edges 22a and 22b of the two flanges 22.

 The effectiveness of the shielding according to the invention is also remarkable when the penetration of the projectile is made at an angle inclined relative to the outer surface of the shielding.

 Indeed, as indicated in FIG. 10, the confinement plates 26 and 27 due to their acoustic impedance greater than that of glass 18, induce in the latter reflected compression waves (see arrows F) which, when they relax, asymmetrically disturb the jet 29 by closing the hole 30 formed by the latter.

 In the embodiment of FIG. 11, the armor comprises a layer of steel 31 constituting a pre-armor for the small projectiles of the battlefield. This layer 31 is followed by a layer of damping material 32 to reduce the effect of the Xclats liable to detach from the internal face of the pre-shielding layer 31. This layer of damping material 32 precedes a double layer of shielding elements 33 embedded in this damping material 32. This damping material 32 transmits neither the shock wave nor the fracture of the shielding elements 33 so that the destroyed shielding area is never greater than that corresponding to the shielding element 33 hit by the projectile and those adjoining it.

 The double layer of shielding elements 33 is separated from the inner layer of steel shielding 32 by an empty space 35 making it possible to disperse the effects of the jet of the hollow charge projectile.

 Figure 12 shows a variant of the shielding described above. It includes external and internal layers 36 and 37 of steel shielding. Between these two layers 36 and 37 extend rows of shielding elements 38 arranged obliquely to the layers 36 and 37. As in the embodiment according to FIG. 11, the shielding elements 38 are embedded in a damping material 39. In addition, the different rows of shielding elements38 are separated from one another by empty spaces 40. This embodiment makes it possible to obtain a relatively light shielding in which the projectile meets whatever its angle of incidence, one or more elements of shield 38 and an empty space 39 for dispersing the effects of the jet of hollow charges.

 Of course, the invention is not limited to the examples that Liron has just described and many modifications can be made to them without departing from the scope of the invention.

 Thus, the blocks of glass or of material based on silica can be of various shapes such as prisms with any polygonal base, or spheres.

The prestressing of glass blocks or other silica-based material can be carried out by means of mechanical, hydraulic or pneumatic cylinders, or by tempering
The glass can also be poured inside molds constituting the containment frame
Of course, the shielding according to the invention also provides effective protection against conventional projectiles.

Claims (10)

 1. - Shielding in particular for protection against projectiles with a hollow charge, comprising blocks of glass or of silica-based material, characterized in that these blocks are surrounded at least in part by a rigid material having an acoustic impedance greater than that of the material constituting said blocks.
 2. - Shielding according to claim I, characterized in that the blocks of silica-based material are entirely confined in a frame formed by said material having an acoustic impedance greater than that of the silica-based material.
 3. - Shielding according to any one of claims 1 or 2, characterized in that the material having an acoustic impedance greater than that of the silica-based material is steel.
 4. - Shielding according to any one of claims 1 to 3, characterized in that the silica-based material is confined with prestress in the frame formed by said material having an acoustic impedance greater than that of.
 silica-based material.
 5. - Shielding according to claim 4, characterized in that the blocks of silica-based material are prestressed in a transverse direction relative to the impact direction of the shaped charges.
 6. - Shielding according to any one of claims 1 to 5, characterized in that the blocks of silica-based material and confined in their frame are embedded in a material capable of damping the shock waves.
 7. - Shield according to claim 6, characterized in that it comprises several successive layers of blocks of silica-based material, the blocks of one of the layers being offset with respect to the blocks of the adjacent layer and said layers being substantially parallel to the outer surface of the shield.
 8. - Shield according to any one of claims 1 to 7, characterized in that it comprises an outer layer of shielding steel.
 9. - Shield according to any one of claims 1 to 8, characterized in that the layer or layers of blocks of silica-based material are separated by an empty space of one. internal shielding layer.
 10. - Shielding according to any one of claims 1 to 6, characterized in that it comprises an outer layer and an inner layer of conventional shielding and in that between these two shielding layers are arranged parallel rows of blocks of silica-based material, these rows being oblique to the outer and inner shielding layers and these rows being separated by empty spaces.
FR7814829A 1978-05-19 1978-05-19 Shielding particularly for protection against hollow-loaded projectiles Expired - Lifetime FR2635177B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
FR7814829A FR2635177B1 (en) 1978-05-19 1978-05-19 Shielding particularly for protection against hollow-loaded projectiles

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7814829A FR2635177B1 (en) 1978-05-19 1978-05-19 Shielding particularly for protection against hollow-loaded projectiles

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FR2635177A1 true FR2635177A1 (en) 1990-02-09
FR2635177B1 FR2635177B1 (en) 1991-10-11

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5370034A (en) * 1993-07-02 1994-12-06 Fmc Corporation Reactive armor system with improved flyplates
EP1288607A1 (en) * 2001-08-24 2003-03-05 Israel Military Industries Ltd. Anti-ballistic ceramic articles
EP1668201A2 (en) * 2003-07-22 2006-06-14 BUARQUE DE MACEDO, Pedro Manoel Prestressed, strong foam glass tiles

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3324768A (en) * 1950-05-22 1967-06-13 Robert J Eichelberger Panels for protection of armor against shaped charges
US3616115A (en) * 1968-09-24 1971-10-26 North American Rockwell Lightweight ballistic armor
US3684631A (en) * 1969-12-12 1972-08-15 Textron Inc Glass armor fabrication

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3324768A (en) * 1950-05-22 1967-06-13 Robert J Eichelberger Panels for protection of armor against shaped charges
US3616115A (en) * 1968-09-24 1971-10-26 North American Rockwell Lightweight ballistic armor
US3684631A (en) * 1969-12-12 1972-08-15 Textron Inc Glass armor fabrication

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5370034A (en) * 1993-07-02 1994-12-06 Fmc Corporation Reactive armor system with improved flyplates
EP1288607A1 (en) * 2001-08-24 2003-03-05 Israel Military Industries Ltd. Anti-ballistic ceramic articles
EP1668201A2 (en) * 2003-07-22 2006-06-14 BUARQUE DE MACEDO, Pedro Manoel Prestressed, strong foam glass tiles
EP1668201A4 (en) * 2003-07-22 2009-12-23 Macedo Pedro B Prestressed, strong foam glass tiles

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Publication number Publication date
FR2635177B1 (en) 1991-10-11

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