US20080250548A1

US20080250548A1 - Anti-blast and shock optimal reduction buffer

Info

Publication number: US20080250548A1
Application number: US11/735,340
Authority: US
Inventors: James H. Stuhmiller; Philemon Chan; Louise Stuhmiller
Original assignee: L3 Communications Corp
Current assignee: L3 Technologies Inc
Priority date: 2007-04-13
Filing date: 2007-04-13
Publication date: 2008-10-16

Abstract

A cushion for use in a helmet or body armor to mitigate shock loads (i.e. blasts or blunt impact) against the human body includes a matrix having a plurality of fluid pockets. The fluid pockets themselves are either deformable, or they can be reconfigured (e.g. emptied) and are, therefore, connected in fluid communication with an empty receiver pocket. In the latter case, a vent connects each fluid pocket to at least one receiver pocket, and a valve is imbedded into the vent to control fluid flow through the vent. In either case, when the cushion receives a shock load, fluid in the cushion is transferred to reconfigure the cushion for mitigation of the resultant forces.

Description

FIELD OF THE INVENTION

The present invention pertains generally to systems for protecting the body from shock loading due to a violent impact or blast. Shock loading is the very rapid application and short duration of applied force. More particularly, the present invention pertains to cushions for mitigating the adverse effects that can result from forces to the head and body that are caused by shock loads. The present invention is particularly, but not exclusively, useful as a protective cushion that incorporates fluid transfer, fluid compression, and membrane deformation techniques, into a helmet, vest, shoes, or clothing, for mitigating the injury effects of shock loadings.

BACKGROUND OF THE INVENTION

A primary objective of any protective gear is to somehow mitigate the adverse effects that shock loading can have on the body. Low level impacts to the head can produce mild Traumatic Brain Injury (mTBI), while high level impacts to the head can produce massive internal injury and death. Impacts to the torso can produce lung contusion, pneumothorax (collapsed lung), heart contusion, and rupture of internal organs. Impacts to the extremities can lead to traumatic amputation.
In a combat environment, head protection is particularly important and is underscored by the fact fifty-nine percent of blast-injured patients develop some form of brain injury. These brain injuries are, unfortunately, in addition to other injuries that may also be sustained. Similar brain injuries can occur in sports. Analyses of helmet impacts in football have produced data that indicate that an acceleration of 106 g's is estimated to produce mTBI, 80% of the time, while an acceleration of 66 g's is estimated to produce mTBI 25% of the time. Extrapolation of these data leads to the conclusion that accelerations must be less than 50 g's to be safe. It is the objective of effective head gear to transmit the impact force in such a way as to minimize the head acceleration.
Impact to the torso can produce significant internal injury. Even when the person is wearing personal body armor (military or law enforcement) that provides protection from the penetration of bullets and fragments, blunt trauma can occur from the inward deformation of the armor. Currently, armor designs are limited by these deformations. Research shows that these injuries are caused by the very short time duration that the impact is delivered to the body. It has been estimated that if the chest wall is accelerated to an inward velocity of 20-30 m/s, even for a very short time which produces a very small deformation, death can occur. Smaller chest velocities produce lesser forms of injury. Although a absolutely safe level has not been established, it is probably less that 8 m/s. The body can withstand, without injury, greater deformation if it applied over a long period of time. It is the objective of effective body protection gear to transmit the impulse of the impact force in such a way as to maximize the duration of the impulse delivered to the torso and, therefore, minimize the chest wall velocity.
To put this in proper perspective, survivable explosions from an IED might produce blast loading with durations from less than one millisecond to as much as 10 milliseconds. The impact from the deformation of body armor has a duration ranging from less than one millisecond to a few milliseconds. The impact of helmets in sports or in a motorcycle accident is, again, only a few milliseconds. Mitigation of a shock loading is done typically by positioning a protective system between the impact source and the part body that is to be protected. The protective system must, therefore, act extremely quickly to distribute the impact force and duration over the largest area and largest duration to achieve the greatest effectiveness.
The efficacy of the protective system depends on several different factors, the more important of which include: 1) material characteristics of the protective body; 2) structural configuration of the protective body; and 3) attributes of the applied impact force. Of these, only the first two factors (material characteristics and configuration) can be controlled; the attributes of the applied impact force depend on the application. The concern of the present invention is toward the design of protective systems to protect the head, torso, and extremities from shock loading, that is, from large loads that occur with short time durations. These protective systems are judged on their ability to lower head acceleration, chest velocity, and other correlates of internal injury.
Open and closed cell foam or liquid or gas-liquid gels are commonly used as cushioning material in headgear or behind body armor or in shoes. These materials, especially the foams, are designed to provide a certain crushing load when stressed at a certain rate. Although these materials may be efficacious for some types of force loadings, they do not provide the theoretical optimum protection possible and have characteristics that lose their cushioning ability as the duration of the loading decreases. For the shock loading of interest, other materials, with an appropriate structural configuration, are more effective.
In light of the above, it is an object of the present invention to provide a cushioning device for mitigating shock loads on a human body that incorporates the dynamic properties of fluid density and compression, membrane characteristics and response, and fluid motion and exchange. Another object of the present invention is to provide a cushioning device for mitigating shock loads that can be specifically configured (i.e. customized) to conform with different types of body regions (headgear, body armor shoes, etc,) and to respond to different shock loading magnitudes and rates, for different applications. Still another object of the present invention is to provide a cushioning device for a protective headgear or body armor that provides resistance against unwanted motion and affords protection against shock loads. Yet another object of the present invention is to provide a cushioning device for mitigating shock loads on the head and body of a human being that is comfortable to wear, is relatively simple to manufacture, and is comparatively cost effective.

SUMMARY OF THE INVENTION

In accordance with the present invention, a protective device for mitigating the adverse effects of shock loading against the head and body of the wearer, employs a cushion that includes a matrix of fluid pockets. As envisioned for the present invention, both the matrix and the fluid pockets are deformable. Specifically, deformation of the cushion results from the forced transfer of fluid within the cushion, from the compression of the fluid, and/or the deformation of the membrane containing the fluid. In particular, this deformation can be accomplished either by reconfiguring the fluid pockets or by transferring fluid in a fluid pocket, from one location to another location.
For a preferred embodiment of the present invention, a plurality of fluid pockets is formed by a viscoelastic membrane and is arranged in a matrix. Similarly, a plurality of empty receiver pockets is formed in the matrix. Further, vents are formed in the membrane matrix to connect each fluid pocket in fluid communication with at least one receiver pocket. A valve or baffle that is imbedded in each vent can then be used to control the flow of fluid through the vent. For the present invention, the viscoelastic material that is used for the membrane is preferably a semicrystalline polymer, such as polyurethane-PU or polyethylene-PE.
As envisioned for the present invention, the valves that are imbedded in the vents can be of several types. One possibility is to use one-way valves that will open whenever a pressure in the respective fluid pocket “p_f” exceeds a predetermined value. In this case, the valve may actually rupture at “p_f” for a one-time use of the cushion. Alternatively, the valves may be two-way valves. In this case, each valve will permit fluid to flow from a fluid pocket into a receiver pocket when pressure in the fluid pocket exceeds “p_f”. For the two-way valve, however, fluid will back flow into the fluid pocket, from the receiver pocket, when a pressure in the receiver pocket “P_r” is greater than “p_f”.
For an alternate embodiment of the present invention, there are no receiver pockets; only fluid pockets. In this embodiment, the matrix itself (e.g. membrane) deforms. This causes the fluid pockets to be reconfigured, to thereby absorb the effects of an external force.
Insofar as fluids for use with the present invention are concerned, the present invention envisions using either a liquid or a gas. Generally, the choice will depend on the application. If a gas is to be used, expansion and contraction of the gas may be significant over a range of operational temperatures between −40° F. and 160° F. The consequent volume differential may be as much as 25%, and should be accounted for. On the other hand, if a liquid is to be used, it must have a boiling temperature above the operational temperature range, and a freezing temperature that is below the range.
An important aspect of the present invention is that the configuration of fluid pockets, and receiver pockets if used, can be customized. Stated differently, the cushion may have any of several different configurations, arrangements or presentations. Further, based on material selection for manufacture of the cushion and the consequent operational thresholds for valves, baffles and membrane expansions, it can, in effect, be “tuned” to have a desired protective response to a blast impact.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

FIG. 1 is a perspective schematic view of a protective cushion in accordance with the present invention, with the cushion shown having a fluid transfer system incorporated into a helmet for use as a head protector;

FIG. 2 is a view of the cushion as seen along the line 2-2 in FIG. 1 with portions of the helmet removed for clarity;

FIG. 3A is a cross section view of a portion of the cushion as seen along the line 3-3 in FIG. 2 before a blast impact;

FIG. 3B is a view of the cushion as seen in FIG. 3A after a blast impact;

FIG. 4A is a schematic plan view showing an alternate embodiment of a fluid system for use in the cushion of the present invention, with the fluid system shown before a blast impact;

FIG. 4B is a view of the fluid system shown in FIG. 4A with partial fluid transfer, after a blast impact;

FIG. 4C is a view of the fluid system shown in FIG. 4A with complete fluid transfer, after a blast impact;

FIG. 5A is a schematic plan view showing another alternate embodiment of a fluid system for use in the cushion of the present invention, with the fluid system shown before a blast impact;

FIG. 5B is a view of the fluid system shown in FIG. 5A, after a blast impact;

FIG. 6A is a cross section view of yet another alternate embodiment of a fluid system for use in the cushion of the present invention, as would be seen along the line 3-3 in FIG. 2 before a blast impact; and

FIG. 6B is a view of the fluid system shown in FIG. 6A, after a blast impact.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIG. 1, a device for mitigating blast impacts in accordance with the present invention is shown and is generally designated 10. As shown, the device 10 includes a cushion 12 that has been incorporated as part of a helmet 14 to provide head protection. More specifically, for the embodiment of the present invention shown in FIG. 1, the cushion 12 is configured as a matrix 16 having a plurality of rings 18, of which the rings 18 a and 18 b are exemplary. The matrix 16 is also shown to have a plurality of strips 20, of which the strips 20 a and 20 b are exemplary. As will be appreciated by the skilled artisan, the rings 18 and strips 20 can be used together, in combination, or individually.
Referring now to FIG. 2, the rings 18 and strips 20 of the cushion 12 are shown, in detail, to include a plurality of fluid pockets 22 that are interconnected with a plurality of receiver pockets 24. The fluid pockets 22 a and 22 b, and the receiver pockets 24 a and 24 b that are shown are only exemplary. FIG. 2 also shows that the cushion 12 is positioned inside the helmet 14 to protect the head 26 of a user. This also is exemplary. Although the cushion 12 shown in FIG. 2 is being used for protection of a head 26, it is to be understood that cushions 12 can be uniquely configured and used for protection of other body parts, such as the torso, legs, arms and neck.
FIGS. 3A and 3B best show the structural and functional interaction between a fluid pocket 22 and its associated receiver pockets 24. More specifically, in FIG. 3A, the fluid pocket 22 a is shown to be filled with a fluid 27 having a fluid pressure “p_f”. Normally (i.e. before a shock loading), p_fwill be zero. Further, FIG. 3A shows that a vent 28 a is provided to establish fluid communication between the fluid pocket 22 a and the adjacent receiver pocket 24 a. Also, a valve 30 a is shown imbedded into the vent 28 a. Similarly, a vent 28 b, in combination with a valve 30 b, is provided to establish fluid communication between the fluid pocket 22 a and the adjacent receiver pocket 24 b. As intended for the present invention, the cushion 12 will include numerous such fluid connections throughout its matrix 16. As implied above, the actual number and placement of the rings 18 and strips 20 is a matter of design choice.
In the event of a blast (shock loading) 32 (or a blunt force impact), indicated by the arrow in FIG. 3A, the helmet 14 will act as a plate member having an impact surface 34 and a force transfer surface 36. Structurally, the helmet 14 will transfer the effect of the blast 32 to the fluid pocket 22 a. For fluid pocket 22 a, the result will be an increase in pressure (p_f) on fluid 27 in the fluid pocket 22 a. Additional fluid pockets 22 will, of course, also be affected. And, each fluid pocket 22 will respond substantially the same as described here for the fluid pocket 22 a.
Functionally, due to the over-pressure of “p_f” that results in fluid pocket 22 a, in response to the blast 32, the valves 30 a and 30 b will open. This permits fluid 27 to flow from fluid pocket 22 a into the receiver pockets 24 a and 24 b through respective vents 28 a and 28 b. Consequently, as shown in FIG. 3B, the receiver pockets 24 a and 24 b fill with fluid 27. As the receiver pockets 24 a and 24 b fill with fluid 27, a pressure “P_r” is established on the fluid 27 in the receiver pockets 24 a and 24 b. As intended for the present invention, this transfer of the fluid 27 from the fluid pocket 22 a into the receiver pockets 24 a and 24 b mitigates the adverse effects of the blast 32 on the head 26. If the valves 30 a and 30 b are one-way valves, the cushion 12 will remain in the configuration shown in FIG. 3B after the effects have subsided. In this case, P_rwill, most likely, equal p_f. On the other hand, if the valves 30 a and 30 b are two-way valves, fluid 27 can back flow from the receiver pockets 24 a and 24 b into fluid pocket 22 a, as long as p_ris greater than p_f.
As indicated above, the fluid transfer system described above with reference to FIGS. 2, 3A and 3B is but one embodiment envisioned for the present invention. Other systems are envisioned. Furthermore, it is to be appreciated that elements of one system can be incorporated into another. The result here, is that fluid systems can be individually customized for the cushion 12. For this purpose, the specifics of a cushion 12 for the device 10 will be determined, in large part, by the particular application. With this in mind, several structural variations for fluid systems that can be incorporated into a cushion 12 are envisioned for the present invention.
In FIGS. 4A-C a fluid system, generally designated 38, is shown to include a central fluid pocket 40 that is surrounded by numerous receiver pockets 42/44. Specifically, the receiver pockets 42/44 are positioned along the periphery 46 of the central fluid pocket 40, and are connected for fluid communication with the pocket 40 via a respective valve/baffle 48. The receiver pockets 42 a, 42b and 44 a, 44 b are exemplary. For this particular fluid system 38, the receiver pockets 42 are designed to have a higher modulus of elasticity than do the receiver pockets 44. Accordingly, the receiver pockets 44 will expand under a relative lower pressure (compared to receiver pockets 42). Thus, fluid 27 can transfer from the fluid pocket 40 into the receiver pockets 44 first, before transferring into the receiver pockets 42. Indeed, the receiver pockets 44 may expand, without any expansion of the receiver pockets 42 (see FIG. 4B). A higher pressure (e.g. greater impact from blast 32), however, may cause all receiver pockets 42/44 to expand (see FIG. 4C). The receiver pockets might each be made of different material so that the transfer of fluid occurs at different times, at different pressures, and with different effects on the cushioning body. In this way, the cushioning load can be customized to match any application.
Till now, the fluid systems considered for the present invention (i.e. shown in FIGS. 3A/B and FIGS. 4A/B/C) have relied on the transfer of a fluid from a fluid pocket into a receiver pocket. FIGS. 5A and 5B, however, show a fluid system in which there are no receiver pockets. Only a single fluid pocket 50 is involved. As will be appreciated by the skilled artisan, however, a plurality of similar fluid pockets 50 can be provided in a same matrix 16, and can be arranged therein in a variety of configurations. In any event, as envisioned for the present invention, a fluid pocket 50 is preferably manufactured with a region 52 made of material having a different modulus of elasticity than another region 54. More specifically, this elasticity differential can be employed for the purpose of predicting and controlling the deformation of the fluid pocket 50 in response to shock loading 32. For instance, as shown in FIGS. 5A/B, with properly selected materials, the fluid pocket 50 (FIG. 5A) will predictably reconfigure to the fluid pocket 50′ (FIG. 5B).
In FIGS. 6A and 6B yet another type of fluid system for use in the cushion 12 of the present invention is shown. In this embodiment, a boundary member 56 is positioned opposite a plate member (e.g. helmet 14). As shown for this embodiment of cushion 12, a membrane 60 forms a plurality of fluid pockets 62 on the boundary member 56. Note: for most embodiments of the present invention, the boundary member 56 will be made of the same material as is used for the membrane 60. In any event, for the embodiment shown in FIGS. 6A and 6B, the fluid pockets 62 establish a network of fluid escape channels 64. Importantly, each fluid pocket 62 is designed to have a weak point 66. Specifically, this weak point 66 is engineered to rupture when an overpressure (e.g. blast 32) is caused on the plate member (helmet 14). The intended result is for fluid to transfer from the fluid pockets 62 into the fluid escape channels 64.
For all embodiments of the fluid systems disclosed above, the present invention envisions a mitigation of the forces imposed by a shock loading 32 against a human body. Specifically, the energy that is absorbed by the cushion 12, after an impact from blast 32, is used up in the fluid transfer process. In the case of the embodiment shown in FIGS. 5A and 5B, the energy is dissipated by the transformation of the fluid pocket 50. For purposes of the present invention, as mentioned numerous times herein, the particular embodiment of the fluid system that is used for construction of the cushion 12, and its configuration, are primarily design considerations. Further, although the specific materials used for construction of the cushion 12 can be varied, the use of a semicrystalline polymer, such as polyurethane-PU or polyethylene-PE, is recommended.
For all embodiments of the fluid systems disclosed above, the present invention envisions a transfer of fluid within or between fluid pockets. Another embodiment allows the membrane walls to deform permanently or to rupture and vent fluid into uncontained regions. These embodiments will result in single-use cushion devices.
While the particular Anti-Blast and Shock Optimal Reduction Buffer as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.

Claims

1. A device for mitigating shock loads on a human body which comprises:

a plate member having a force impact surface and a force transfer surface, wherein the transfer surface is opposite the impact surface; and

a fluid cushion positioned between the force transfer surface of the plate member and a portion of the human body, wherein the fluid cushion includes a boundary member defining at least one fluid pocket for holding a fluid therein, and wherein the fluid pocket is deformable in response to a force against the impact surface of the plate member to move fluid in the fluid pocket to mitigate the resultant force against the human body.

2. A device as recited in claim 1 wherein the plate member is a helmet and the fluid is a gas.

3. A device as recited in claim 1 wherein the boundary member deforms to reconfigure the fluid pocket in response to the force against the impact surface of the plate member.

4. A device as recited in claim 1 further comprising:

at least one receiver pocket formed by the boundary member in the fluid cushion; and

at least one vent formed in the fluid cushion by the boundary member, with the vent connecting the fluid pocket in fluid communication with the receiver pocket for transfer of fluid from the fluid pocket and into the receiver pocket for mitigation of the resultant force.

5. A device as recited in claim 4 wherein there are a plurality of fluid pockets and a plurality of receiver pockets.

6. A device as recited in claim 4 further comprising a valve imbedded in the vent to establish a predetermined fluid flow therethrough.

7. A device as recited in claim 6 wherein the boundary member is a membrane.

8. A device as recited in claim 6 wherein the valve opens to allow fluid flow from the fluid pocket to the receiver pocket when a pressure in the fluid pocket “p_f” exceeds a predetermined value.

9. A device as recited in claim 8 wherein the valve is a two-way valve to permit a back flow of fluid from the receiver pocket to the fluid pocket when a fluid pressure in the receiver pocket “P_r” exceeds “p_f”.

10. A device as recited in claim 8 wherein the vent is rupturable for a one-time use of the device.

11. A fluid cushion for mitigating shock loads on an object which comprises:

a matrix positioned against the object; and

a plurality of fluid pockets formed by the matrix and selectively distributed through the matrix, wherein the fluid pockets hold a fluid and are deformable in response to a shock load on the cushion, to move fluid in the fluid pockets, to mitigate the resultant force acting on the object.

12. A fluid cushion as recited in claim 11 wherein the object is the head of a human being, wherein the cushion is incorporated into a helmet and further wherein the matrix deforms to reconfigure the fluid pocket in response to the shock load.

13. A fluid cushion as recited in claim 11 further comprising:

a plurality of receiver pockets formed by the matrix; and

a plurality of vents formed in the matrix, with each vent connecting a fluid pocket in fluid communication with a receiver pocket for transfer of fluid from the fluid pocket and into the receiver pocket for mitigation of the resultant force.

14. A fluid cushion as recited in claim 13 further comprising a plurality of valves with each valve imbedded in a respective vent to establish a predetermined fluid flow therethrough, and wherein the valve opens to allow fluid flow from the fluid pocket to the receiver pocket when a pressure in the fluid pocket “p_f” exceeds a predetermined value.

15. A fluid cushion as recited in claim 14 wherein the valve is a two-way valve to permit a back flow of fluid from the receiver pocket to the fluid pocket when a fluid pressure in the receiver pocket “P_r” exceeds “p_f”.

16. A method for manufacturing a fluid cushion to mitigate shock loads on an object when the fluid cushion is positioned against the object, the method comprising the steps of:

creating a plurality of fluid pockets for holding a fluid therein;

distributing the plurality of fluid pockets in a matrix; and

connecting each fluid pocket in fluid communication with a receiver pocket, via a vent, for transfer of fluid from the fluid pocket to the receiver pocket in response to an impact of the shock load on the matrix, to mitigate the resultant force action on the object.

17. A method as recited in claim 16 wherein the object is the head of a human being, wherein the cushion is incorporated into a helmet and further wherein the matrix is a viscoelastic membrane and the fluid is a gas.

18. A method as recited in claim 17 further comprising the step of imbedding a valve in a respective vent to establish a predetermined flow therethrough.

19. A method as recited in claim 18 wherein each valve opens to allow fluid flow from the fluid pocket to the receiver pocket when a pressure in the fluid pocket “p_f” exceeds a predetermined value.

20. A method as recited in claim 19 wherein the valve is a two-way valve to permit a back flow of fluid from the receiver pocket to the fluid pocket when a fluid pressure in the receiver pocket “P_r” exceeds “p_f”.