Abstract:
A volume-filling mechanical structure for modifying a crash comprising a honeycomb celled material expandable from a dormant state to a deployed state; a support surface cooperatively positioned with the honeycomb celled material to cover a surface of the honeycomb celled material in the deployed and dormant states; and a means for deploying said volume-filling mechanical structure from said dormant state to said deployed state.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application relates to, and claims priority to, U.S. Provisional Application Ser. No. 60/559,165 filed on Apr. 2, 2004, incorporated herein by reference in its entirety. 
     
    
     BACKGROUND  
       [0002]     The present disclosure generally relates to methods for modifying a crash deceleration pulse, and more particularly, to methods for modifying a crash deceleration pulse using volume filling mechanical structures, which are volumetrically reconfigurable such as to occupy a small volume when in a dormant state and a larger volume when deployed. The expanded volume also provides energy management and contact force and deceleration limiting properties to objects impacting the devices.  
         [0003]     In the vehicular arts, there are generally two types of dedicated crash energy management structures utilized for minimizing the effect of an impact event: those that are passive, and those that are active. The term active used in the context of dedicated energy management structures refers to selective expansion or movement of one component relative to another component.  
         [0004]     Typically, passive energy management structures have a static configuration in which their volume is fixed. The passive energy management structures can dissipate energy and modify the levels and timing of a force/deceleration pulse by being impacted (e.g., crushing or stroking of a piston in a cylinder) so as to absorb the kinetic energy associated with such an event. Since these passive crash energy management structures occupy a maximum volume in the uncrushed/unstroked initial state, these types of structures inherently occupy significant vehicular space that must be dedicated for crash energy management and/or occupant protection—the contraction space being otherwise unavailable for other use. Expressed another way, passive crash energy management and occupant protection structures use vehicular space equal to their initial volume, which consequently must be dedicated exclusively to impact energy management and/or occupant protection throughout the life of the vehicle. Because of this, some areas of a vehicle interior and/or exterior may be constrained in terms of their design/appearance because of the volume requirements of passive crash energy management and occupant protection devices.  
         [0005]     An example of a passive energy management structure that has been used in vehicles is an expanded honeycomb celled material, which is disposed in the expanded form within the vehicle environment.  FIG. 1  illustrates a honeycomb celled material and its process flow for fabricating the honeycomb-celled material. A roll  10  of sheet material having a preselected width W is cut to provide a number of substrate sheets  12 , each sheet having a number of closely spaced adhesive strips  14 . The sheets  12  are stacked and the adhesive cured to thereby form a block  16  having a thickness T. The block  16  is then cut into appropriate lengths L to thereby provide so-called bricks  18 . The bricks  18  are then expanded by physical separation of the upper and lower faces  20 ,  22 , where adhesive strips serve as nodes to form the honeycomb cells. A fully expanded brick is composed of a honeycomb celled material  24  having clearly apparent hexagonally shaped cells  26 . The ratio of the original thickness T to the expanded thickness T′ is between about 1 to 10 to about 1 to 60. The honeycomb celled material is then used in fully expanded form within the vehicle environment to provide impact energy management and/or occupant protection (through force and deceleration limiting) substantially parallel to the cellular axis. As noted, because the honeycomb material is used in the fully expanded form, significant vehicular space is used to accommodate the expanded form, which space is permanently occupied by this dedicated energy management/occupant protection structure.  
         [0006]     Active energy management/occupant protection structures generally have a predetermined size that expands or moves in response to a triggering event so as to increase their contribution to crash energy management/occupant protection. One type of dedicated active energy management/occupant protection structure is a stroking device, basically in the form of a piston and cylinder arrangement. Stroking devices can be designed, if desired, to have low forces in extension and significantly higher forces in compression (such as an extendable/retractable bumper system) which is, for example, installed at either the fore or aft end of the vehicle and oriented in the anticipated direction of crash induced crush. The rods of such devices would be extended to span the previously empty spaces in response to a triggering event, e.g., upon the detection of an imminent impact event or an occurring impact event (if located ahead of the crush front). This extension could be triggered alternatively by signals from a pre-crash warning system or from crash sensors or be a mechanical response to the crash itself. An example would be a forward extension of the rod due to its inertia under a high G crash pulse. Downsides of such an approach include high mass and limited expansion ratio.  
         [0007]     Another example of an active energy management/force and/or deceleration limiting structure is an impact protection curtain, e.g., a roll down inflatable or partially inflatable shade that may cover a window opening in response to a triggering event. The roll down curtain, while being flexible in bending when out of plane, is quite stiff in-plane.  
         [0008]     Therefore, there is a need in the art for an expandable energy management device for impact attenuation that efficiently utilizes vehicle space.  
       BRIEF SUMMARY  
       [0009]     Disclosed herein are methods for modifying a crash deceleration pulse. In one embodiment, the method comprises disposing an energy management device in operative communication with a vehicular surface in a load path, wherein the energy management device comprises a open celled material expandable from a non-expanded state to an expanded state, and an activation mechanism regulating expansion of the open celled material from the non-expanded state to the expanded state; activating the energy management device in response to or in anticipation of an impact event; expanding the open celled material from the non-expanded state to the expanded state; and impacting the expanded state of the open celled material and altering an impact pulse associated with the impact event relative to a baseline in which this energy management device is not present.  
         [0010]     The above described and other features are exemplified by the following figures and detailed description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Referring now to the figures, which are meant to be exemplary embodiments, and wherein the like elements are numbered alike.  
         [0012]      FIG. 1  is a perspective view of a manufacturing process to provide prior art honeycomb celled material;  
         [0013]      FIG. 2  is a perspective front view of an energy management device comprising compressed honeycomb cellular material in accordance with the present disclosure, shown prior to expansion (stowed or compacted state);  
         [0014]      FIG. 3  is a perspective front view of a device comprising expanded honeycomb cellular material in accordance with the present disclosure, shown in an expanded state;  
         [0015]      FIG. 4  is a perspective cut-away view of an energy management device according to the present disclosure, showing an example of an active activation system;  
         [0016]      FIG. 5  is a broken-away, top plan view, showing a trigger of an active activation system of  FIG. 4 ;  
         [0017]      FIG. 6  is a perspective side view of an energy management device having a support sheet and a protection shield in accordance with the present disclosure, shown prior to expansion (stored state);  
         [0018]      FIG. 7  is a perspective side view of the device depicted in  FIG. 6  upon deployment in accordance with the present disclosure; and  
         [0019]      FIG. 8  is a perspective view of a vehicle illustrating various support structures for employing the energy management assembly;  
         [0020]      FIG. 9  illustrates an exemplary application of an energy management device disposed intermediate a tire and rocker in a stowed configuration;  
         [0021]      FIG. 10  illustrates the exemplary application of energy management device of  FIG. 9  in an expanded configuration; and  
         [0022]      FIG. 11  graphically illustrates predicted velocity change and crush effectiveness in front loading of a crash pulse as a function of time for a baseline vehicle, a vehicle configured with a 125 PSI rated energy management assembly, and a vehicle configured with a 250 PSI rated energy management assembly. 
     
    
     DETAILED DESCRIPTION  
       [0023]     The present disclosure provides a method of employing active energy management structures (also referred to as force and deceleration delimiting devices) that comprises an expandable volume-filling mechanical structure for purposes of vehicle crash energy management and occupant protection. Advantageously, the expandable volume-filling mechanical structure effectively absorbs the kinetic energy associated with the impact event and can be configured to provide one of more of the following: crash energy dissipation, load path creation, modification of a vehicle deceleration pulse, local stiffening or reinforcement of the vehicle structure, stiffening or reinforcing closed section members subject to lateral loading, pedestrian impact protection, occupant protection, vehicle compatibility during impact events, crash protection to vulnerable components, e.g., engine, interior passenger compartment, and the like.  
         [0024]     In one embodiment, the energy management device of the present disclosure comprises an expandable open celled material, wherein expansion of the open celled material is in a plane transverse to the cellular axis of the cells defining the cellular structure. As previously expressed, the term “energy management” also refers to force and/or deceleration limiting since the devices described herein will function to limit the impact force on or deceleration of an object during an impact event. The expanded volume advantageously provides energy management properties to objects impacting the devices.  
         [0025]     In one embodiment, the energy management device of the present disclosure comprises an expandable open celled material, wherein expansion of the open celled material is in a plane transverse to the cellular axis of the cells defining the cellular structure. For this embodiment as well as the other embodiments disclosed herein, crash crush is intended optimally, but not necessarily, to be parallel to the cellular axis. By way of example, a suitable open celled material has a honeycomb cellular structure. In a stowed or compact configuration, the honeycomb cellular structure can generally be defined as a honeycomb brick. The honeycomb brick has an initial compact volume in the sense that it is substantially compressed perpendicular to the longitudinal axis of its cells and parallel to the direction in which it is to be deployed. For ease of understanding, reference will now be made to honeycomb cellular structures although it should be understood that other open celled materials that can be compressed and expanded in the manner discussed below are equally suitable for the energy management devices disclosed herein.  
         [0026]     The honeycomb brick occupies anywhere from about 1/10th to about 1/60th of the volume that it assumes when in it is fully expanded (i.e., the expansion ratio), depending on the original cell dimensions and wall thicknesses, although higher or lower ratios can be employed depending on the particular application. Honeycomb cell geometries with smaller values of the expansion ratio, in general, deliver larger crush forces.  
         [0027]     The materials for forming the honeycomb cellular structure are not intended to be limited. The choices for materials are generally dependent upon the desired crush force (stiffness) for a particular application (i.e., softer or harder metals or composites). In one embodiment, the honeycomb cellular structure is formed of a lightweight metallic material, e.g., aluminum. Other suitable materials that are non-metallic include, but are not limited to, polymers such as nylon, cellulose, and other like materials. The material composition and honeycomb geometries will be determined by the desired application.  
         [0028]     Turning to  FIGS. 2 and 3 , perspective views of a force and deceleration delimiting device  100  are shown that employ a honeycomb cellular structure  104 . In particular,  FIG. 2  illustrates the force and deceleration delimiting device in a stowed or compact configuration (i.e., a honeycomb brick configuration) whereas  FIG. 3  illustrates the force and deceleration delimiting device upon expansion in response to a triggering event.  
         [0029]     As shown more clearly in  FIG. 3 , the geometry of the cells form the honeycomb cellular structure, although as noted above, other shapes and configurations are possible that would permit compression and expansion in the manner described herein. The honeycomb cellular structure  104  generally terminates at an upper face  106  and a lower face  108 . Attached (such as, for example, by an adhesive) to the upper and lower faces  106 ,  108  are end cap members  110 ,  112 , respectively. The end cap members  110 ,  112  are substantially rigid and serve as guides for defining the configuration of the honeycombed cellular structure  104  between the stowed or compacted configuration as shown at  FIG. 2  and the expanded configuration as shown at  FIG. 3 . One of the end cap members, e.g.,  110 , is fixedly attached to the vehicle. As such, upon expansion of the force and deceleration delimiting device  100  in response to a triggering event, end cap member  112  moves relative to end cap member  110 . In this manner, upon deployment, the expansion of honeycomb material  104  is in a transverse plane P which is preferably perpendicularly oriented to an anticipated crash axis A without expansion or contraction of the crash axis dimension.  
         [0030]     The end cap members  110 ,  112  need not necessarily be planar as shown. Moreover, the end cap members do not need to have the same shape or size. For example, the end cap members  110 ,  112  may comprise a shape that compliments the area within the vehicle where the energy management device  100  is to be located. For example, in a wheel well, one or both of the end cap members may be curvilinear in shape as well as sized differently to accommodate the shape of the wheel well. As another example, such as may occur for expansion into a narrowing wedge shaped space, the end cap member (e.g.,  112 ) that moves as the honeycomb cellular structure  104  expands may be shorter than the stationary end cap member (e.g.,  110 ) so that the expanded honeycomb cellular structure  104  has a complimentary wedge shape.  
         [0031]     An activation mechanism  114  is operably connected to end cap members  110 ,  112  to facilitate selective expansion of the force and deceleration delimiting device  100  in response to a triggering event. The activation mechanism  114  controls the volumetric state of the honeycomb-cellular structure  104  such that when activated, expansion from the stowed or compact configuration to the expanded configuration occurs. One or more installation brackets  115  may be connected to one of the end cap members  110 ,  112  so that the force and deceleration delimiting device  100  is connectable to a selected surface of the motor vehicle.  
         [0032]     The force and deceleration delimiting device  100  may further include an optional support surface  105  for controlled directional expansion, which will be described in greater detail below. One support surface  105  or alternatively, two support surfaces can be employed to define a sandwich about the honeycomb cellular structure  104 , depending on the application. Optionally, the surfaces  105  can be naturally defined by the vehicle structure in which the energy management device  100  is disposed. In a preferred embodiment, the support surface  105  is cooperatively disposed with the honeycomb cellular structure  104  opposite to that of an impact, and more preferably, only when a natural vehicle support surface does not exist. Additionally, in applications in which there may be occupant/pedestrian impact directly against the expanded honeycomb cellular structure  104 , there may be a deployable front surface shield or screen  109 .  
         [0033]     An example of a suitable activation mechanism  114  is shown in  FIGS. 4 and 5 . An expansion agent in the form of a compressed spring  116  is abuttingly situated in tension between end cap members  110 ,  112  when the honeycomb cellular structure  104  is in the compact or stowed configuration. A trigger  118  for selectively releasing energy associated with the compressed spring includes a disk  120  that is rotatably mounted on one of the end cap members, e.g.,  110  as shown, wherein the disk has a pair of opposed fingers  122 . The shape of the disk  120  is receivable by a similarly shaped opening  124  formed in the end cap member  110 . The rotatable disk  120  is further supported by a rigid member (not shown, e.g., a bolt) that is fixedly attached to the opposing end cap member, e.g.,  112 . Although two opposing fingers are shown, it should be apparent that one or more fingers can be utilized. Moreover, it should be apparent that the shape of the disk  120  or the opening  124  is not intended to be limited and can vary as may be desired provided that locking engagement of the disk  120  against the end cap member  110  occurs in at least one rotational position of the disk and engagement release occurs at a different position.  
         [0034]     Activation of the activation mechanism  114  causes the disk  120  to rotate and causes the shape of disk to become aligned with the shape of the opening  124 . Upon alignment, the spring  116  is released causing rapid expansion of the honeycomb cellular structure  104 . The compressive forces associated with the spring provide the expansion, wherein the magnitude of expansion can generally be increased with greater compressive forces in the spring  116 . Other suitable expansion agents may include a pyrotechnic device or a pressurized air cylinder, for example, which is triggered upon rotation of the disk  120  as described or by other triggering means. Other triggering means could be electronically controlled, mechanically controlled, and the like. Alternatively, the activation mechanism  114  may be passive, wherein the impact event itself provides a mechanically trigger.  
         [0035]     As previously described, the triggering event activates the activation mechanism  114 . As such, the activation mechanism can be in operative communication with a controller for selectively activating the activation mechanism  114 . For example, the controller can be an electronic control module  128  that is adapted to receive a signal from a sensor or detector  126 , which signal is then interpreted by the electronic control module  128  to activate a solenoid  130 . Solenoid  130  includes a linking arm  132  that is shown in operative communication with the disk  120  to effect rotation thereof in response to the activation signal.  
         [0036]     As shown more clearly in  FIGS. 6 and 7 , the energy management device  100  further includes the optional support layer  105  and optional shield  109 . The support surface  105  functions as a support surface and guide for the force and deceleration delimiting device  100  during expansion thereof. In one embodiment, the support surface  105  and/or shield  109  are operably connected to the end cap member  112  as shown. In this manner, upon movement of end cap member  112  relative to end cap member  110  during expansion, the support surface  105  and shield  109  extend along with the honeycomb cellular structure  104 . For example, as shown, the support layer  105  and shield  109  can be spooled (or folded or otherwise compacted as may be desired) when the force and deceleration delimiting device is in the stowed or compacted configuration and linearly expand in the direction of force and deceleration delimiting device  100  expansion to provide the support surface/guide and mitigation functions. The support surface  105  preferably comprises a material that is substantially stiff upon extension and resistant to stretching.  
         [0037]     Optionally, the force and deceleration delimiting device  100  includes mounting plates  117 ,  119 , fixedly attached to the end cap members  110 ,  112 , respectively, which may further have connected thereto a connecting structure  107 . The vehicle connecting structure  107  may include tethers of a fixed length lying in the plane of honeycomb cellular structure  104  routed through openings that define the individual honeycomb cells so that expansion of the energy management device occurs along a desired direction path. More than one vehicle connecting structure  107  can be used and may be attached at various points of the honeycomb cellular structure  104 .  
         [0038]     When employed within a passenger compartment of a vehicle, the support surface  105 , if one is employed, faces away from the interior of a vehicle, whereas the honeycomb cellular structure  104  faces the interior of the vehicle. If required by the nature of the honeycomb cellular material  104 , a shield  109  faces the interior of the vehicle. However, it should be apparent by those in the art that placement and style of the device  100  will be determined by the desired application. In one embodiment, the support layer  105  and the honeycomb cellular structure  104  may be physically separate with respect to each other upon expansion thereof. In another embodiment, the support layer  105  and the honeycomb cellular structure  104  may be adjacent to each other, each being connected only at selected points, wherein the selected points may constrain the honeycomb material  104  at predetermined points. In a similar manner, the shield  109  may be disposed and connected at selected points along the honeycomb material.  
         [0039]     The force and deceleration delimiting device  100  further includes an optional protection shield  111  about the spooled support surface  105  and/or shield  109 . The protection shield  111  is comprised of any of a variety of suitable flexible materials known to those skilled in the art.  
         [0040]      FIG. 8  is a perspective view of a vehicle  140  illustrating various support structures and stationary surfaces for employing the energy management device  100 . For example, the force and deceleration delimiting device  100  can be used in conjunction with conventional padded interior surfaces in the vehicle  140 . Specifically, the device  100  can be used for the door pillars  142 , the header  144 , the door interiors  146 , dashboard  148 , the knee bolsters  150 , head rest  168 , and other areas such as under the carpet on the vehicle floor  152 , the seat  154  itself, or like surfaces where absorption of kinetic energy/limiting of forces/decelerations caused by impact of an object with the surface is desired and/or proper positioning of an occupant is desired during a triggering event such as an impact. For example, locating the energy management assembly under the carpet can be used to assist the positioning of an occupant&#39;s knees with respect to the knee bolster. In the seat area, the device can be strategically positioned to provide stiffening at an edge of the seat  154 . Forces/decelerations due to impact with other areas of the vehicle, such as the door pillars  142 , can be limited with device  100 . In addition, the device  100  can help protect occupants in impacts against exterior objects that might enter the vehicle  140 .  
         [0041]     As further shown in  FIG. 8 , the device  100  may be placed outside the vehicle  120 . As shown, the device  100  may be positioned at an exterior/interior surface of a bumper  156 ,  158 , hood  160 , trunk  162 , roof  172 , wheel well  170 , cowl  166 , and like areas.  
         [0042]     As further shown in  FIG. 8 , the device  100  may be placed outside the vehicle  120 . As shown, the device  100  may be positioned at an exterior/interior surface of a bumper  156 ,  158 , hood  160 , trunk  162 , roof  171 , wheel well  170 , cowl  166 , and like areas. Also, it should be apparent that the device  100  can be disposed within the empty spaces of the engine compartment, about the interior defining surfaces, as well as within and about the structural rails that define the vehicle.  
         [0043]     The force and deceleration delimiting device  100  can be tailored to the site of application. For example, for exterior sites such as the vehicle bumper and fender, triggering can occur prior to a triggering event, or at the time of the triggering event. The triggering event is not intended to be limited to a single event. For example, the triggering event may occur if a variety of conditions are detected or sensed, e.g., an impact event at a vehicle speed greater than 15 kilometers per hour. As such, a pre-crash sensor and/or an impact severity prediction algorithm can be employed to program the electronic control module  128 . The expansion of the honeycomb-celled structure would be rapid or slow, greater or lesser depending on how the system is programmed. Devices used in this location could be designed to be reversible in the event of false crash detection, as their deployment has no effect on the operation of the vehicle. For example, devices  100  within the vehicle  120  may be deployed either before or during an impact event. If deployed before the impact event, the expansion of the honeycomb-celled material could be fast or slow, and would require a pre-impact sensor (and, optimally, with a impact severity algorithm) for selective triggering. If deployed during an impact event, the expansion of the honeycomb-cellular structure must be rapid, and should occur only at speeds where significant crush will occur. Accordingly, triggering may be effected by crash caused displacements. Devices used in this location would not be reversible and would require a very accurate detection system, as their deployment could interfere with operation of the vehicle.  
         [0044]     As noted, the force and deceleration devices can be disposed in numerous locations throughout the vehicle for various functions. By way of example, for crash energy dissipation, the devices can be disposed internally to the rails for frontal and offset impact events, in empty spaces within the engine compartment such as between the engine block and dashboard area, and between the engine block and radiator as well as laterally alongside the engine block for side impacts.  
         [0045]     For load path creation, the devices can be disposed internally to the rails for frontal and offset impact events as well as variously in the front portion of the rails, in the s-bend region, and at rail kink and buckling points. In addition, the devices can be located the devices can be disposed internally to the rails for frontal and offset impact events as well as in empty spaces within the engine compartment. Also, the device can be disposed between the tire and rocker region within the wheel well and internal the central tunnel portion. Likewise, the device can be disposed internal to a central armrest, if present, when the armrest is in the up position.  
         [0046]     For modification including front loading of the vehicle deceleration pulse, the devices can be disposed within empty spaces within the engine compartment such as in front of the radiator as well as between the radiator and the engine block. In addition, the devices can be disposed internal to the rails at locations suitable responsive to frontal impact. Also, for modification including front loading of the vehicle deceleration pulse can be disposed behind and/or within the bumper.  
         [0047]     For local stiffening of the vehicle structure and alteration of failure crush modes, the devices can be disposed internal to the rails at locations suitable responsive to frontal and/or offset impact. For side impact events, the device can be disposed internal to the rocker section and internal to the B pillar for example.  
         [0048]     For stiffening of closed section members subjected to lateral loading, the devices can be disposed internal to the rocker and internal to the B pillar on low mass struck vehicle (deploy to increase stiffness—e.g., manually deploy within the rail after welding and painting operations are complete). For side impact events, the device can be disposed internal to the rocker, internal to the B pillar, internal to the central tunnel, internal to the central armrest when the armrest is in the up position, and the like.  
         [0049]     For pedestrian impact protection, the devices can be disposed within the bumper (either deploy in front of bumper or alternatively un-deploy within the bumper). Also, the devices can be disposed within the hood (either deploy over hood or deploy under hood if hood is too soft).  
         [0050]     For occupant impact protection, the devices can be disposed to provide a low energy alternative to knee bags, side curtains and the like. In addition, the device can stretch laterally under carpets within the dash area and/or be positioned to stretch laterally within the surface of an interior trim panel to cause device expansion toward the occupant. Likewise, the device can be position as deployable pusher blocks (within and internal to the door, within the vehicle interior up or down from the armrest and the like) and deployable head restraints (both between laterally adjacent seats and between front and back seating areas).  
         [0051]     For vehicle compatibility in an impact event, the devices can be disposed internal to the rocker sections as well as the B-pillar. In addition, the device can be disposed internal to the rails and bumper of a striking large mass vehicle (undeploy within rails and bumper to soften pulse). Likewise, the device can be disposed internal to the rocker and internal to the B pillar on low mass struck vehicle (deploy to increase stiffness—e.g., manually deploy within the rail after welding and painting operations are complete)  
         [0052]     For crash protection of vulnerable components, the devices can be disposed can be rapped around components such as the fuel tank.  
         [0053]      FIGS. 9-10  illustrate an exemplary application, wherein the force and deceleration-delimiting device  100  is disposed between a wheel well  170  and tire  172  of the vehicle. The direction of the vehicle is provided by arrow  176 . Upon activation such as may occur during a frontal impact event, the device  100  expands from the compact configuration as shown in  FIG. 9  to the expanded configuration of  FIG. 10 . An optional protective flap  174  is shown pivotably operative with the device expansion. In this manner, in a frontal impact event, expansion of the device permits the entire vehicle to absorb and dissipate the kinetic energy associated with the frontal impact event. The space normally apparent between the wheel well and the tire is minimized upon expansion of the device thereby providing a load path such that the entire vehicle is involved.  
         [0054]      FIG. 11  illustrates a modeled analysis of predicted velocity change and crush effectiveness in front loading of a crash pulse for a baseline vehicle, a vehicle configured with a 125 pounds per square inch (PSI) rated energy management assembly, and a vehicle configured with a 250 PSI rated energy management assembly. As shown, the crash pulse was more effectively front loaded with the energy-management device disposed in the path of the load relative to a baseline in which this added energy management assembly was not present. Moreover, as expected, the higher rated honeycomb cell structure provided the greatest velocity change in the initial part of the crash event. By front-loading the crash pulse, peak G&#39;s to which the objects within the vehicle are subjected by interactions with airbags and belt systems may be reduced. These predictions/conclusions are, of course, subject to experimental verification. As evidence, the effective acceleration increased from a baseline of 16.9 gravity (G) to 18.1 G and higher for various loads to the energy management device over a 40 millisecond time period.  
                                           TABLE 1                           illustrates side impact analysis of predicted effectiveness in       reducing penetration. Testing was done under standard test procedures       well known to those skilled in the art.                Model   Intrusion (mm)                        Comparative   Baseline   450       Example No. 1           Example No. 1   Baseline and Deployed Device   385                    
         [0055]     Side impact intrusion under constant loads, with and without a fully deployed energy-management device disposed therein, was analyzed. In each instance, the presence of the energy-management device was predicted to advantageously and effectively reduce intrusion.  
         [0056]     With regard to the above described applications and uses of energy management device, a reversible stored energy means for deployment may be used to return the device to its dormant (i.e., compact) state after it has been deployed if not crushed/damaged in a subsequent impact. Resetting of the means of deployment would involve resetting of the deployed honeycomb celled material  104  and a recharging or resetting of the stored energy device, which could be done manually or alternatively, automatically. Whether an irreversible or a reversible embodiment is chosen is generally dependent upon the application and the means of sensing and control used to trigger deployment. Devices based on pre-crash sensors, because of the potential for false detects, with many existing sensors, might well be designed to be reversible but the devices should be non-intrusive and not affect vehicle functionality. There is little motivation for designing devices to be reversible whose deployment is based on crash sensing or indirectly by displacements caused by vehicle crush. Stored energy means based on mechanical springs are less desirable than those based on compressed air as those based on compressed air, in contrast to those based on mechanical springs, are easily engineered to release the stored energy when not needed, which dramatically improves the safety of such devices. For example, in one embodiment, compressed air may be released when a vehicle is stopped and/or the ignition is turned off and then be automatically reintroduced when the vehicle is placed into gear or the ignition is turned on.  
         [0057]     It should be noted that the various forces discussed above which are needed directly or indirectly to expand or assist in expanding the honeycomb celled material  104  to its deployed state is generally about less than 1 kilo Newton (kN). The honeycomb-celled material may expand at a broad range of rates of expansion for example from about 0.01 to about 15 meters per second (m/s). Very simple means of bonding rigid end caps  110  and  112  to honeycomb celled material  104  in its dormant state may be used such as, for example, a two part room temperature curing epoxy adhesive.  
         [0058]     While the disclosure has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.