WO2003102489A1

WO2003102489A1 - Mine protection apparatus for a vehicle

Info

Publication number: WO2003102489A1
Application number: PCT/ZA2003/000071
Authority: WO
Inventors: Gerhardus Dirk Petrus Pretorius; Lambertus Gerhardus Hetcher; Becker Van Niekerk; Johan Van Der Merwe
Original assignee: ALVIS SOUTH AFRICA (PTE) Ltd
Current assignee: ALVIS SOUTH AFRICA (PTE) Ltd
Priority date: 2002-05-31
Filing date: 2003-05-30
Publication date: 2003-12-11
Anticipated expiration: 2004-11-30
Also published as: AU2003252190A1

Abstract

The invention provides a protection system for protecting a vehicle against an explosion beneath the vehicle, the vehicle having a body with sides and a floor, and a drive train with a transverse derive axle unit comprising a shield structure adapted to be positioned below the floor of the vehicle body and having mounting means for the vehicle axle unit.

Description

MINE PROTECTION APPARATUS FOR A VEHICLE

Field of the Invention

THIS invention relates to a protection apparatus for a vehicle.

Description of Prior Art

Methods of protecting a vehicle from the explosion of a land mine are well known in

the defence industry. Prior art methods and apparatus have focused on stopping or

deflecting the explosion, either by means of additional reinforcing armor plating,

armor positioned appropriately to deflect the explosion, or by means of reactive armor

which fires reactive charges to deflect the explosion away from the vehicle.

The disadvantage of simply using thickened reinforcing armour to withstand the

explosion, is that it makes the vehicle extremely heavy, and results in a decrease in

performance of the vehicle, and also limits the vehicles use in operations where

lightweight vehicles are required (for example in operations where vehicles are

required to be dropped by air). This is also a disadvantage of using armour to deflect

the explosion. A further disadvantage is that when armour is used to deflect the

explosion, the armor is typically placed obliquely under the vehicle in a "V" shape, meaning that the ride height of the vehicle needs to be increased to allow for the extra

size and bulk underneath the vehicle.

A disadvantage of using reactive armor, where a shaped charge counter-blast is

detonated on the underside of the vehicle is used to deflect the explosion of the

landmine, is the cost and the fact that reactive armor can be subject to malfunction, as

well as the hindrances relating to the safety procedures and other requirements that

would arise from carrying explosives on the vehicle.

The main focus of landmine protection is the effective management of the energy

released by the landmine explosion. This may be accomplished by the deflection of

the forces of the explosion, as well as the shrapnel, to the sides of the vehicle,

allowing the pressures to dissipate outwardly and minimizing the damage caused to

the vehicle.

Another strategy employed is to manage the energy transfer rate from the explosion to

the vehicle, thus allowing more time for the vehicle to absorb the energy and deform

in a manner safer for the occupants in side the vehicle. Object of the Invention

It is accordingly an object of the present invention to provide a protection apparatus

for a vehicle that will at least partially overcome the disadvantages mentioned above.

Disclosure of the Invention

According to a first aspect of the invention there is provided a protection system for

protecting a vehicle against an explosion underneath the vehicle, the vehicle having a

drive train with a transverse drive axle unit comprising a shield structure being

adapted to be positioned below a vehicle, and having mounting means for the vehicle

drive axle unit.

Also according to the invention the protection system wherein the transverse axle

drive unit includes a differential device unit and the shield structure provides

mounting means for the vehicle differential drive unit.

The shield structure comprises a pair of spaced longitudinal members linked together

by a plurality of transverse members, and a plurality of upwardly directed side struts.

The shield structure may further include a plurality of plate members which are secured to the longitudinal members and transverse members to form a shield.

The transverse members, upwardly directed side struts, longitudinal members and

plates may be individually replaceable should any part of the above structure be

damaged by an explosion.

The upwardly directed struts may be attached to the sides of the vehicle at spaced

intervals therealong.

The plate members may be adapted to deflect part of the explosion while absorbing

part of the explosion by deforming, as well as transferring the energy of the explosion

to the longitudinal members, transverse members and upwardly directed struts.

The mounting means for the vehicle differential may include an elastically resilient

buffer for transferring forces of an explosion to the shield structure. In one

arrangement the buffer comprises a resilient block of material disposed within the

internal corner of an inverted "L" structure limiting upward displacement of the

differential.

According to a second aspect of the invention there is provided a protection system for a vehicle, for protection against an explosion underneath the vehicle, comprising

a modular shield structure, mounted underneath the vehicle at attachment points at

intervals along the sides of the vehicle, so as to transfer forces from the explosion

substantially to the vehicle sides.

Also according to this aspect of the invention the shield structure may comprise a

plurality of transverse members, a plurality of upwardly orientated side struts, a

plurality of longitudinal members, and a plurality of plates, with the ends of the

upwardly orientated struts forming attachment points along the sides of the vehicle

body.

According to a third aspect of the invention there is provided a method of protecting a

vehicle from an explosion underneath the vehicle comprising the steps of shielding

the underside of the vehicle from the explosion by means of the replaceable shield

structure disclosed herein; mounting the shield structure to the sides of the vehicle at

attachment points therealong; and transferring the force of the explosion towards the

sides of the vehicle through the shield structures attachment points.

The above method may include the further steps of partly absorbing the energy of the

explosion by allowing the shield structure to deform in a predetermined manner. Also according to the method the vehicle includes a drive train within a transverse

axle drive unit and the axle train unit of the drive train is mounted on the shield

structure and the method includes the step of transferring a part of the force of an

explosion beneath the transverse axle drive unit to the shield structure.

In the above arrangement the transverse axle drive unit includes a differential drive

unit and the shield structure provides mounting means for the vehicle differential

drive unit, including the step of transferring a part of an explosion beneath the

differential drive unit to the shield structure.

Brief Description of the Drawings

In order to illustrate the invention an embodiment thereof is described hereunder

purely as an example, without limiting the scope of the invention, wherein:

Figure 1 is a schematic perspective view of a mine protection apparatus for a

vehicle in accordance with the invention shown not attached to the

vehicle; Figure 2 is an elevation side view of a mine protection apparatus for a vehicle in

accordance with the invention shown not attached to the vehicle;

Figure 3 is an elevation front view of a mine protection apparatus for a vehicle

in accordance with the invention shown attached to the bottom of a

vehicle body;

Figure 4 is an elevation front view of a mine protection apparatus for a vehicle

in accordance with the invention shown not attached to the bottom of a

vehicle body;

Figure 5 is a plan view of a mine protection apparatus for a vehicle in

accordance with the invention shown not attached to the vehicle;

Figure 6 is a printout from a computer simulated finite element stress analysis

program showing a stress analysis model of a mine protection

apparatus for a vehicle in accordance with the invention; Figure 7 is a printout from a computer simulated finite element stress analysis

program showing a computer simulated mine explosion underneath a

stress analysis model of a mine protection apparatus after 0.0125

seconds for a vehicle in accordance with the invention;

Figure 8 is a schematic front view of a prior art method of handling a mine

explosion by using a N-shaped section to deflect the mine explosion to

the sides of the vehicle;

Figure 9 is a schematic view of a mine protection apparatus in accordance with

the invention, showing the layout of the vehicle components;

Figure 10 is a perspective view of the underside of a vehicle fitted with a mine

protection apparatus in accordance with the invention showing the

fitment of the vehicles suspension components to the mine protection

apparatus structure;

Figure 11 is a printout from a computer simulated finite element stress analysis

program showing a finite element stress analysis model of a vehicle

fitted with a mine protection apparatus in accordance with the invention after 0.0125 seconds, when the explosion is detonated under

the vehicle differential;

Figure 12 is a printout from a computer simulated finite element stress analysis

program showing a wire frame model of a vehicle fitted with a mine

protection apparatus in accordance with the invention including a

simulated passenger;

Figure 13 is a printout from a computer simulated finite element stress analysis

program showing a cutaway of a finite element stress analysis model of

a vehicle fitted with a mine protection apparatus in accordance with the

invention, when the explosion is detonated behind the vehicle

differential after 0.005 seconds;

Figure 14 is a printout from a computer simulated finite element stress analysis

program showing a cutaway of a finite element stress analysis model of

a vehicle floor fitted with a mine protection apparatus in accordance

with the invention, when the explosion is detonated behind the vehicle

differential after 0.0025 seconds. Detailed Description of Drawings

Referring to the drawings, a protection apparatus for a vehicle (20) having a body

including sides (25) and a floor (24) forming a passenger compartment (22), for use in

protecting the vehicle (20) against an explosion (A) (see Figure 8) underneath the

vehicle (20) (See figure 3), comprises a modular shield structure (10) being adapted to

be positioned below the floor (24) of a vehicle (20), and having at least one mounting

point (6) adapted to mount a vehicle differential (7) (see figure 9) which forms part of

a transverse drive axle unit of the vehicle (20).

The shield structure (10) shown in Figure 2, 4 and 10, comprises a plurality of

transverse members (1), a plurality of obliquely upwardly orientated side struts (2)

and a plurality of longitudinal members (3), as well as a plurality of plates (4), which

are mounted across the struts (2) and the members (1,3).

The transverse members (1), obliquely upwardly orientated side struts (2),

longitudinal members (3) and plates (4) are individually replaceable should any of

them be damaged by an explosion (A).

The upwardly orientated struts (2) are attached to the sides of the vehicle (25) at

intervals by means of attachment points (8) shown in Figure 10. The plates (4) are arranged to partly deflect energy, pressure waves, shock waves and

shrapnel from the explosion (A) away from the vehicle (20), while partly absorbing

the energy of the explosion (A) by deforming. In addition, energy from the explosion

(A) is transferred from the plates (4) to the shield structure (10) in a predetermined

manner.

The mounting point (6) (see figure 15) for the vehicle differential (7) may include an

elastically resilient buffer (16) for transferring the forces of an explosion (A) to the

shield structure (10). In one arrangement the buffer (16) may be disposed within the

internal corner of an inverted "L" structure (15) (as shown in Figure 15) limiting

upward displacement of the differential (7).

The shield structure (10) is attached to the vehicle (20) at attachment points (8) along

the length of the vehicle (20), so as to transfer forces from the explosion (A)

substantially to the vehicle sides (25). In the embodiment shown, the ends of the

upwardly orientated struts (2) form the attachment points (8) along the sides of the

vehicle (25).

When an explosion (A) occurs underneath the vehicle (20), the forces of the explosion are transferred through the shield structure (10) substantially to the sides of the

vehicle (25) through the attachment points (8), allowing a delay in rate of transfer of

energy to the vehicle (20) while the forces are transferred along and up the sides of

the vehicle (25). This means that there is a delay in the transfer of energy to any

occupants of the vehicle (9), resulting in reduced casualties and injuries.

The shield structure (10) also partly absorbs the energy of the explosion (A) by having

the transverse members (1), obliquely upwardly orientated side struts (2), longitudinal

members (3), plates (4) and attachment points (8) deform in a pre-determined manner.

When an explosion occurs below or adjacent the vehicle differential 7, and those

plates (4) which are located below the vehicle differential (7) have deformed until

they strike the vehicle differential (7), then the forces of the explosion (A) are

transferred to the differential (7). The vehicle differential (7) in turn will transfer the

forces of the explosion (A) to the buffer (16) of the mounting points (6), and onwards

to the inverted "L" structure (15) mounted on the shield structure (10). The shield

structure (10) will then transfer these forces through the attachment points (8) to the

sides of the vehicle (25).

In order to test the design of the modular shield structure (10) to see whether it

deforms and transfers energy in an intended manner for certain pre-set conditions, use is made of a computer stress analysis and simulation programme. This programme

allows designers to mathematically model the vehicle, shield structure, the explosion,

and even passengers reasonable accurately, giving each of the models certain material

properties and physical constraints so as to closely replicate what happens to the

models in a real situation.

For a starting set of conditions (for example, a high temperature, high pressure point

source is inserted underneath the simulated shield structure at a certain distance to

simulate an explosion), the programme allows the designer to monitor the amount of

stress, and hence strain (ie deformation), that the components may endure at various

points in time after the mathematical model is subjected to the test conditions.

As examples, figures 6, 7, 11, 12, 13 and 14 show computer simulations of an

embodiment of the invention at various stages of testing, and for different test

conditions.

Figure 6 shows a computer simulation model of the shield structure (10) without any

simulated stresses being placed on it. Figure 12 also shows a computer simulation

model of part of the vehicle (20) and shield structure (10), as well as a passenger (9)

and seat (23) in a passenger compartment (22), without any simulated stresses being placed on it. By mathematically simulating a person inside the vehicle, and defining

attributes for the model which are similar to that of a person, a prediction can be made

as to what sort and extent of injuries could be expected from various sets of initial test

conditions.

Figure 7 shows a close up view from below the shield structure (10) next to a

differential mounting point (6) after a simulated explosion has been set off underneath

it, at a point in time 0.0125 seconds after the explosion. An aperture for receiving the

vehicle differential (21) can be seen.

The shading of the model indicates the amount of strain endured by that section of the

model, and the predicted deformation can be clearly seen. The deformed plate (4a)

shows that the plate will implode the most towards the centre of the plate, and gives

an indication of the extent of the deformation. Catastrophic failure (i.e. rupture) of

the plate may be expected when the stress or strain figures exceed those allowable for

the particular material that is being mathematically modelled.

Figure 11 is a view from behind the vehicle (20) of the inside of the passenger

compartment (22) and a seat (23), with the floor of the passenger compartment

removed to show the shield structure (10) underneath. The initial test condition in this case simulated the detonation of a mine underneath the vehicle differential, and the

shading of the figure shows the stress values on those components at a point in time

0.0125 seconds after the simulated detonation.

Figure 13 shows a cutaway view of the inside of the vehicle passenger compartment

(22) and shield structure (10) after a simulated land mine detonation behind the

vehicle differential at a point in time 0.005 seconds after the detonation. The shading

in Figure 13 indicates predicted strain (deformation) of the simulated components at

that time, the actual values being indicated by the legend accompanying the figure.

Figure 14 shows a close up cutaway view of the floor (24) of the passenger

compartment (22) and shield structure (10), showing strain values for a simulated land

mine explosion in front of the vehicle differential (7) at a point in time 0.0025 seconds

after the detonation. The shading in Figure 14 indicates predicted strain (deformation)

of the simulated components at that time, the actual values being indicated by the

legend accompanying the figure. Figure 14 shows how the plate (4a) directly above

the simulated detonation bends inwardly at its centre.

In all the simulation tests shown, the explosion is to a large degree dispersed and

absorbed by the shield structure. Doubtless variations of the invention in detail are possible without departing from the

principles set out in the consistory clauses.

Claims

1. A protection system for protecting a vehicle against an explosion beneath the vehicle, the vehicle having a body with sides and a floor, and a drive train with a transverse drive axle unit, the system comprising a shield structure adapted to be positioned below the vehicle body floor and having mounting means for the vehicle axle unit.

2. The protection system according to claim 1 wherein the transverse drive axle unit includes a differential drive unit and the shield structure provides mounting means for the vehicle differential drive unit.

3. The protection system according to claim 1 or claim 2 wherein the shield structure comprises a pair of spaced longitudinal members which are linked together by a plurality of transverse members, and a plurality of upwardly directed side struts which are secured to the sides of the vehicle body at spaced intervals therealong.

4. The protection system according to any one of claims 1 to 3 wherein the shield structure further includes a plurality of plate members which are secured to the longitudinal members and the transverse members to form a shield.

5. The protection system according to any one of claims 1 to 4 wherein the longitudinal members, the transverse members and the side struts are individually removable from the shield structure to allow replacement of any one of these.

6. The protection system according to claim 4 or claim 5 wherein the plate members are adapted to absorb a portion of an explosion by deforming.

7. The protection system according to any one of claims 1 to 6 wherein the mounting means for the vehicle axle unit or differential unit includes an elastically resilient buffer for transferring forces of an explosion to the shield structure.

8. The protection system according to claim 7 wherein the buffer comprises a elastically resilient block of material disposed within the internal corner of an inverted "L" structure which limits upward displacement of the axle unit or differential unit.

9. The protection system for protecting a vehicle against an explosion beneath the vehicle, the vehicle comprising a body with sides and a floor, the system comprising a shield structure mounted underneath the vehicle body floor at attachment points at intervals along the sides of the vehicle body, so as to transfer forces from the explosion substantially to the vehicle sides.

10. The protection system according to claim 9 wherein a shield structure comprises a pair of parallel longitudinal members which are coupled together by means of a plurality of transverse members, and a plurality of upwardly directed side struts which form attachment points for attaching the shield structure to the sides of the body of the vehicle.

11. A method of protecting a vehicle from the explosion beneath the vehicle comprising the steps of :

providing the protection system claimed in any one of claims 1 to 10;

securing the shield structure beneath the vehicle body floor by means of the upwardly directed side struts thereof which are secured at intervals along the side of the body of the vehicle;

and including the step of transferring the force of an explosion beneath the vehicle to the sides of the body of the vehicle through the shield structure.

12. The method according to claim 10 wherein the vehicle includes a drive train within a transverse axle drive unit and the axle train unit of the drive train is mounted on the shield structure and the method includes the step of transferring a part of the force of an explosion beneath the transverse axle drive unit to the shield structure.

13. The method according to claim 11 or claim 12 wherein the transverse axle drive unit includes a differential drive unit and the shield structure provides mounting means for the vehicle differential drive unit, including the step of transferring a part of an explosion beneath the differential drive unit to the shield structure.