GB2625355A

GB2625355A - Axial crush initiator pattern

Info

Publication number: GB2625355A
Application number: GB2218944.3A
Authority: GB
Inventors: Altubo Andres Ines; Onoufriou Elpida; Tyler Street Mark
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2022-12-15
Filing date: 2022-12-15
Publication date: 2024-06-19
Also published as: GB202218944D0

Abstract

An axially extending crush section 10 for a vehicle 1 (fig 1) comprising a first row 21 of crush initiators 25 that are spaced axially to define a first folding wavelength 30 (fig 5) and a second row 22 of crush initiators 25 that are spaced axially to define a second folding wavelength 30 (fig 5). An internal web 15’ separates the first row 21 of crush initiators 25 and the second row 22 of crush initiators 25. The crush initiators 25 of the first row 21 are parallel to and axially offset from the crush initiators 25 of the second row 22, and the first and second folding wavelengths are approximately equal. There may also be a third row 23 of crush initiators 25 defining a third folding wavelength, with identical spacing to the first and/or second rows.

Description

AXIAL CRUSH INITIATOR PATTERN

TECHNICAL FIELD

The present disclosure relates to an Axial Crush Initiator Pattern. In particular, but not exclusively it relates to an Axial Crush Initiator Pattern for use with structural components of a vehicle to control deformation of the structural component of the vehicle in a frontal collision.

BACKGROUND

For several decades now, attention of vehicle designers has increasingly turned to how vehicle passenger safety may be improved during a vehicle collision. Attention has focused on how the vehicle structure may deform, and how much energy may be absorbed Although design rules have evolved, some solutions have come at the cost of increased vehicle weight, while the solutions are not easily adaptable to different vehicle component geometries.

It is an aim of the present invention to address one or more of the disadvantages associated with

the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide an apparatus, and a vehicle comprising the apparatus, as claimed in the appended claims.

According to an aspect of the invention there is provided an axially-extending crush section for a vehicle. The axially-extending crush section comprises a first row of crush initiators that are spaced axially to define a first folding wavelength and a second row of crush initiators that are spaced axially to define a second folding wavelength. An internal web separates the first row of crush initiators and the second row of crush initiators. The crush initiators of the first row are parallel to and axially offset from the crush initiators of the second row, and the first and second folding wavelengths are approximately equal.

This provides the advantage that the folding behaviour of a structural component that comprises the axially-extending crush section may be optimised in the case of a vehicle collision, by controlling at least one of the total amount of energy absorbed, the peak instantaneous energy absorption and / or minimising the risk of component tearing.

In some examples, the axially-extending crush section comprises a first side wall and a second side wall. The second side wall may be opposite the first side wall, and the first side wall and second side wall may each comprise a first row of crush initiators and a second row of crush initiators. An external cross-section profile of the axially-extending crush section may be quadrilateral, for example, rectangular.

This provides the advantage that the axially-extending section may be incorporated into "box-section" type structures, as may be used in vehicle manufacture.

In some examples, the first row of crush initiators of the first side wall and the first row of crush initiators of the second side wall may be axially offset. The second row of crush initiators of the first side wall and the second row of crush initiators of the second side wall may also be axially offset.

The axial offset of the first row of crush initiators of the first and second side walls may be substantially equal to the axial offset of the second row of crush initiators of the first and second side walls.

This provides the advantage that the manner in which folding of the section occurs may be controlled by specifying the geometry of the different rows of crush initiators.

In some examples, the crush initiators of the first and second rows may each comprise an indentation in one of the first side wall or second side wall of the axially-extending crush section. The indentations may, for example, be produced by a pressing process.

This has the advantage that the features which control folding may be simply and cheaply produced.

In some examples, a perimeter of each indentation may comprise a rounded shape.

The rounded shape has the advantage that it reduces areas of stress concentration local to the initiators, which may otherwise lead to localised failure and/or tearing of the structural component, comprising the performance of the axially-extending crush section.

In some examples, the first folding wavelength may be based at least in part on a height, a width and! or a thickness of a first cell that comprises the first row of crush initiators and the second folding wavelength may be based at least in part on a height, a width and / or a thickness of a second cell that comprises the second row of crush initiators.

This has the advantage that the folding wavelength may be controlled by adjustment of the cells that comprise the structural component to which the axially-extending crush section is applied.

In some examples, the crush initiators of the first row may be axially offset from the crush initiators of the second row by half the first folding wavelength. The internal web may connect the first side wall and the second side wall, with the internal web running axially along the axially-extending crush section. The first row of crush initiators on the first side wall of the axially-extending crush section may be mostly or entirely to one side of an intersection point between the internal web and the first side wall. The parallel second row of crush initiators on the first side of the axially-extending crush section may be mostly or entirely to the other side of the intersection point between the internal web and the first side wall.

This has the advantage that asymmetric folding is promoted, in which lateral stretching of the internal web is reduced. This minimises the risk of localised tearing, for example, at or in the vicinity of the intersection point between the first and second side walls and the internal web. This allows more energy to be absorbed during a vehicle collision.

In some examples, the internal web may be perpendicular to the first side wall and the second side wall and the first side wall and the second side wall may be parallel faces.

This has the advantage that the section may be applied to commonly-used structural components, such as rectangular sections with an internal web that connects opposite side walls of the section.

In some examples, a distance of the first row from a plane of the internal web may be equal to a second distance of the second row of crush initiators from the plane of the internal web.

This has the advantage that a more uniform folding behaviour may be achieved over the extent of the axially-extending crush section.

In some examples, the axially-extending crush section may comprise a second internal web connecting the first side wall and the second side wall, wherein the second internal web runs axially along the axially-extending crush section, parallel to the internal web. The axially-extending crush section may comprise a third row of crush initiators that are spaced axially to define a third folding wavelength. The third row of crush initiators on the first side wall of the axially-extending crush section may be mostly or entirely to one side of an intersection point between the second internal web and the first side wall. The parallel second row of crush initiators on the first side of the axially-extending crush section may be mostly or entirely to the other side of the intersection point between the second internal web and the first side wall. The third row of crush initiators may have an identical spacing between adjacent crush initiators, as the crush initiators of the first and/or second rows, and may be axially aligned with the first row of crush initiators.

This has the advantage that the axially-extending crush section may also be applied to other geometries of structural component, which comprise more than one internal web.

In some examples, at least one of the first row of crush initiators, the second row of crush initiators and / or the third row of crush initiators may intersect an edge of the first side wall of the axially-extending crush section and/or an edge of the second side wall of the axially-extending crush section.

This has the advantage that the risk of localised tearing at or in the vicinity of a corner of a structural component may be reduced.

In some examples, the first row of crush initiators may be located along a first edge of the first side wall or second side wall. The third row of crush initiators may be located along a second edge of the first side wall or second side wall that is opposing the first edge. The second row of crush initiators may be between the first row of crush initiators and the third row of crush initiators.

In some examples, at least one of the first row, second row and/or third row of crush initiators of the first or second side wall may further comprise a starting crush initiator configured to deform prior to deformation of the other crush initiators of said at least one of the first row, second row and/or third row of crush initiators, based on a different shape and/or location offset of the starting crush initiator relative to said other crush initiators. The location offset of the starting crush initiator may determine the location at which axial crushing is initiated.

This has the advantage that the designer may choose the location at which crushing should be initiated, and may control the peak forces initiating the crushing.

In some examples, the axially-extending crush section may be an extruded section.

This has the advantage that the axially-extending crush section may be easily manufactured.

In some examples, the axially-extending crush section comprises aluminium and for magnesium.

This has the advantage that the axially-extending crush section may be lightweight.

According to an aspect of the invention there is provided a vehicle, comprising an axially-extending crush section.

This has the advantage that the above advantages may be incorporated into a vehicle, such as road vehicle.

According to a further aspect of the invention there is provided an axially-extending crush section for a vehicle. The axially-extending crush section comprises a first row of crush initiators that are spaced axially to define a first folding wavelength and a second row of crush initiators that are spaced axially to define a second folding wavelength. The crush initiators of the first row are parallel to and axially offset from the crush initiators of the second row.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination that falls within the scope of the appended claims. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination that falls within the scope of the appended claims, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 illustrates an example of a vehicle; FIG. 2 illustrates an example of a structural component comprising an axial crush initiation section which comprises an axial crush initiator pattern; FIG. 3 illustrates an enlarged view of the axial crush initiator pattern of the example illustrated in FIG. 2; FIG. 4 illustrates the example structural component of FIG.2, viewed from an alternative viewpoint to FIG. 2; and FIG. 5 illustrates an example of deformation in the side walls of the structural component at three different planes within the structural component

DETAILED DESCRIPTION

FIG. 1 illustrates an example of a vehicle in which embodiments of the invention can be implemented.

In some, but not necessarily all examples, the vehicle is a passenger vehicle, also referred to as a passenger car or as an automobile. In other examples, embodiments of the invention can be implemented for other applications, such as commercial vehicles.

FIG. 1 is a front perspective view and illustrates a longitudinal x-axis between the front and rear of the vehicle representing a centreline, an orthogonal lateral y-axis between left and right lateral sides of the vehicle, and a vertical z-axis. A forward/fore direction typically faced by a driver's seat is in the negative x-direction; rearward/aft is +x. A rightward direction as seen from the driver's seat is in the positive y-direction; leftward is -y. These are a first lateral direction and a second lateral direction.

The vehicle 1 of FIG 1 comprises structural components 5 (see FIG 2), to which other components of the vehicle 1, such as a vehicle suspension and /or engine mount may be attached.

It may therefore be appreciated that the structural component 5 may comprise features (for example circular holes, mounting points etc) that are provided to permit other components such as those related to vehicle suspensions and/or engine mounts to be connected to the structural component.

An example of a structural component 5 is illustrated in FIG. 2.

In FIG. 2, the example structural component 5 is a hollow beam. Although not shown in FIG. 2, the hollow beam may be one of a pair of substantially parallel hollow beams that run substantially longitudinally forward, in the negative x direction from a bulkhead between the engine compartment and the passenger compartment, towards the front of the vehicle 1.

The structural component 5 may be optimised for high stiffness and low weight. To further optimise the component for strength and weight, the structural component may comprise at least one internal web 15. In the example of FIG. 2, two internal webs 15' 15" are shown.

The external cross-section profile of the structural component 5 may be a quadrilateral. For example, the external cross-section profile of the structural component 5 may be substantially rectangular, that is, the external cross-section profile may comprise two pairs of substantially parallel side walls, in which the first pair of parallel side walls 12 and second pair of substantially parallel side walls 14 are substantially orthogonal to each other. Radii may be applied at corners formed between a side of the first pair of parallel sides 12, and a side of the second pair of parallel sides 14.

In the illustrative example of FIG. 2, the first pair of substantially parallel side walls 12 comprises a first side wall 12' and a second side wall 12" of the structural component 5, and the second pair of substantially parallel side walls 14 comprises a third side wall 14' and a fourth side wall 14" of the structural component 5.

The at least one internal web 15 may connect a pair of side walls of the structural component. For example, the at least one internal web may connect the first pair of side walls 12, or in other embodiments, may connect the second pair of side walls 14.

The at least one internal web may be parallel to a pair of side walls of the structural component, to which the internal webs 15 are not connected.

In the illustrative example of FIG. 2, the at least one internal web 15 connects the first side wall 12' and second side wall 12" of the first pair of side walls 12, and is parallel to the third side wall 14' and fourth side wall 14" of the second pair of side walls 14. It may be appreciated that other arrangements are also possible.

The structural component may be formed by an extrusion process. For example, the structural component may be formed by extruding aluminium or alloys comprising aluminium and / or magnesium. Alternatively, the structural components may be formed from other means. For example, the structural components may be fabricated from flat section material such as plate material, and welded to form the structural components.

A requirement of the vehicle 1 may be that it shall provide a measure of protection for its occupants in the event of a crash and in a range of different scenarios.

The structural component 5 may therefore be configured to plastically deform in a crash, as plastic deformation of the structural component 5 absorbs energy. For example, the structural component 5, when it is aligned in the x-direction, may be configured to deform in the event of a frontal or substantially frontal crash. A frontal crash is one in which the front of the vehicle 1 is in contact with an obstacle (for example, another vehicle or a stationary obstacle such as a wall) in front of the vehicle. During the frontal crash, the front of the vehicle 1 may be pushed rearwards in the positive x direction.

Hence, during a frontal crash, structural components 5 that run substantially longitudinally forward in the negative x direction from the bulkhead between the passenger compartment and engine compartment may be deformed. Deformation of the structural components may reduce the length of the structural component in the x-direction. In this context, the structural components 5 may be axially-deformed.

It may be appreciated that under crash conditions, it is desirable that the structure of the vehicle deforms in a reliable and predictable manner, such that energy may be reliably and predictably absorbed, whereby the energy required to be absorbed by the occupants in the passenger compartment may be reduced. It may also be appreciated that it may be desirable that the structure that is deformed is lightweight. This is because this reduces the total mass of the vehicle 1, reducing the environmental impact of the vehicle 1 by reducing vehicle fuel consumption.

Under crash conditions, controlled, progressive deformation of the structural component 5 may be preferred to uncontrolled deformation which may lead to tearing or increased tearing of the structural component 5. This is because deformation of the structural component 5 On which connections and / or joints of the structural component remains intact) may absorb more energy than an uncontrolled deformation, and in a more controlled manner, than localised tearing of a portion of the structural component 5. Uncontrolled deformation is not preferred because it may lead to an unpredictable deformation response from the surrounding structure.

It can therefore be appreciated that it is desirable to produce a lightweight, deformable structure that is capable of absorbing more energy than conventional designs. This may be particularly desirable if the vehicle comprises features that tend to increase vehicle mass and therefore the energy that must be absorbed in a crash scenario. For example, vehicle mass may increase if the vehicle comprises an electrical storage device configured to provide electrical energy to an electric traction motor.

Hollow structural components, such as the structural component 5 of FIG. 2, when subjected to axial loading/crush will typically deform with a general deformation mode. The general deformation mode may comprise global or local buckling (deformation) depending on the geometry of the component, such as a slenderness ratio or aspect ratio of the component.

The general deformation mode and the local deformation mode each have an associated natural folding wavelength.

The characteristic wavelength (folding wavelength) of the global deformation may be a function of the length of structural component 5.

The characteristic wavelength (folding wavelength) of the local deformation may be a function of the height and width dimensions and thickness of the individual cells of the cross section of structural component 5, in which the individual cells are bounded by the side walls and at least one internal web of the structural component 5.

Hence, if a vehicle 1, comprises at least one hollow structural components, running in a substantial longitudinal direction (x direction) forward of the passenger compartment / engine firewall, the hollow structural component may deform with a characteristic folding (buckling) wavelength, if the structural component 5 is subjected to an impact in a longitudinal direction (x direction).

When a structural component 5 deforms by folding perpendicularly to the longitudinal axis of the structural component, the surface of the structural component deforms (folds) with a characteristic local folding wavelength. The longitudinal separation between areas of the undeformed structural component which form adjacent peaks or adjacent troughs of the deformed structural component corresponds to the crush wavelength.

It may be appreciated that in other embodiments, structural components may not run longitudinally (x direction). For example, the components may run transversely (in the +/-y direction). The principles now disclosed with respect to crushing of components in a longitudinal (x direction) may therefore also be applicable to crushing of components in a vehicle transverse (+/-y) direction -i.e., for vehicle side impact.

It may be desirable to control the location and manner in which the structural component 5 deforms.

As is illustrated in FIG. 2, the structural component 5 therefore comprises an axially-extending crush section 10. The axially-extending crush section 10 comprises an axial crush initiator pattern. The purpose of the axially-extending crush section 10 is to control the location and manner in which the structural component 5 may deform.

It may be appreciated that the geometry of the axially-extending crush section 10 may be determined by the energy to be absorbed by the crush section. For example, this may determine the size (for example, length in an axial direction) of the axially-extending crush section 10.

The features of the axially-extending crush-section 10 will now be discussed with reference to FIG. 3, in which FIG. 3 is a magnified view of the axially-extending crush section of FIG. 2.

In the example of FIG.3, the internal webs 15', 15"are connected at a first end to a first side wall 12' of the first pair of side walls 12 and at a second end to a second side wall 12" of the first pair of side walls 12. In this example illustration, the first internal web 15' is approximately parallel to the second internal web 15", the third side wall 14' and the fourth side wall 14". In other example embodiments, the first internal web 15' may not be parallel with the third side wall 14', fourth side wall 14" or second internal web 15" (if present in the embodiment).

FIG. 3 also illustrates that the first side wall 12' of the first pair of side walls 12 comprises a first row 21 of axial crush initiators 25. A spacing of the axial crush initiators 25 of the first row may be set to be substantially equal to the folding wavelength 30 of the structural component 5, that comprises the axially-extending crush section 10.

As is subsequently disclosed, the purpose of the axial crush initiators is to locate the initiation and progression of the folding pattern to a predetermined axial portion of the structural component 5, to control a peak force initiating the folding of the structural component 5, and to maximise energy absorbed.

In the illustrative example of FIG.3, the spacing between adjacent axial crush initiators 25 of the first row 21 is constant, and equal to the set folding wavelength 30. In a specific implementation, the spacing between adjacent axial crush initiators 25 of the first row 21 is a value selected from the range approximately 5 centimetres to 10 centimetres.

FIG. 3 also illustrates that the first side wall 12' of the first pair of substantially parallel side walls 12 comprises a second row 22 of axial crush initiators 25, that are spaced axially to define a set folding wavelength 30. A spacing between adjacent axial crush initiators 25 in the second row may be substantially equal to the spacing between adjacent axial crush initiators 25 in the first row.

In this example, the first row of axial crush initiators and the second row of axial crush initiators are parallel and are aligned along axes that are parallel with the longitudinal axis (x-axis) of the axially-extending crush section 10.

However, the first row 21 of axial crush initiators 25 and the second row 22 of axial crush initiators 25 are substantially located on opposite sides of internal web 15', i.e., the first row 21 of axial crush initiators 25 is substantially to one side of the internal web 15', and the second row 22 of axial crush initiators 25 is substantially to the other side of the internal web 15".

In this context, "substantially located" means that although the majority of an axial crush initiator may be to one side of the internal web, the perimeter of the axial crush initiator may cross the internal web to the other side of the internal web -i.e., the axial crush initiator may be mostly or entirely to one side of an intersection point between the internal web and a side wall. Crossing the internal web 15' is beneficial because it may reduce the initiating peak force as defined above. Reducing the peak force assists with prolonging the time period over which the change in momentum of the vehicle is applied to any occupants in the vehicle.

In some, but not necessarily all examples, the internal web 15' may be equidistant between the first row 21 of axial crush initiators 25, and the second row 22 of axial crush initiators 25.

In some, but not necessarily all examples, the first row 21 of axial crush initiators 25, and the second row 22 of axial crush initiators 25 are placed either side of the internal web 15' and may cross over the internal web 15' to provide an indent in the internal web 15'. Indents in the internal web 15' beneficially tune the initiating peak force without having to modify the thickness of the internal web 15'.

The first row 21 of axial crush initiators 25 and the second row 22 of axial crush initiators 25 are also axially offset. In this example, the axial crush initiators 25 of the first row 21 are axially offset from the axial crush initiators 25 of the second row 22 by a distance 31. The distance 31 may be substantially equal to half the folding wavelength 30.

The axial crush initiators 25 each comprise an indentation formed in a surface of the axially-extending crush section 10. The indentations of the axial crush initiators 25 may be formed by a pressing process. In the example shown in FIG. 3, the axial crush initiators are formed in the surface of the first side wall 12' of the first pair of side walls 12.

The perimeter 26 of each axial crush initiator 25 may define a rounded shape configured to reduce areas of stress concentration which may otherwise lead to localised failure and/or tearing. The rounded shape may conform to a specific mathematical description, such as an ellipse. Alternatively, the rounded shape may be determined by numerical iterative techniques. For example, the shape may have been determined to maximise separation between the perimeters of crush initiators 25 of adjacent rows of crush initiators.

In some embodiments, the axial crush initiators 25 may be identical. In other embodiments, there are at least two sub-groups of axial crush initiators 25. Within a sub-group of axial crush initiators, the axial crush initiators may be identical. However, the axial crush-initiators of different sub-groups would be different. For example, a row 21,22,23 of axial crush initiators 25 may comprise at least one sub-group of axial crush initiators 25.

The axial crush initiators of different subgroups may differ in at least one of: size of indentation, depth of indentation; shape of indentation, location offset of indentation. The depth of indentation advantageously controls or tunes the initiating peak force. The different subgroups of axial crush initiators may be provided to control the manner in which the section 10 is crushed. For example, the different subgroups of axial crush initiators may reduce initial peak loads during folding.

In some but not necessarily all embodiments, the location of at least one axial crush initiator may differ from the rows and spacings of the other axial crush initiators. For example, the at least one initiator may be offset in the z direction from the rows of other initiators, and/or may not be equidistant from the nearest initiators in an adjacent row. This initiator may be configured to be a starting crush initiator, configured to deform prior to the remaining crush initiators. This may be desirable because it enables the location at which deformation is initiated to be controlled.

A subgroup of axial crush initiators comprises at least one axial crush initiator.

In some but not necessarily all embodiments, the axially-extending crush section may comprise further rows of axially-extending crush initiators.

For example, in FIG. 3, a third row 23 of axial crush initiators 25 are shown. In all embodiments, adjacent rows of axial crush initiators 21, 22, 23 are on opposing sides of an internal web 15' 15" (for example, a first internal web, a second internal web etc). Adjacent rows of axial crush initiators 21, 22, 23 may cross over internal webs 15', 15" from opposing directions. The initiators crossing over the internal webs to provide the local indents on the webs are beneficial in controlling the magnitude of the initiating peak force. The internal web between adjacent rows of axial crush initiators may be equidistant between the adjacent rows of axial crush initiators.

It may be appreciated that in embodiments in which the axially-extending crush section comprises a plurality of internal webs 15, the plurality of internal webs 15 may not equally-subdivide the axially-extending crush section.

For example, in the example of FIG. 3 in which a first internal web 15' is between the first row 21 of axial crush initiators, and a second row 22 of axial crush initiators 25; and a second internal web 15" is between the second row 22 of axial crush initiators 25 and a third row 23 of axial crush initiators 25, the height of a cavity (cell) formed between side wall 14' and internal web 15' may be different to the height of a cavity formed between internal web 15' and internal web 15" and for may be different to the height of a cavity between internal web 15" and side wall 14". The different cell height may cause the component 10 to collapse with multiple wavelengths.

For example, if the individual cells that make the complete cross-section of component 10 comprise different geometries (i.e., different width, height and thickness), in the absence of crush initiators 25, component 10 may collapse with a single resultant wavelength or may collapse with different wavelengths across the different cells, depending upon the geometries. By suitable selection of the number and location of the crush initiators, a common folding wavelength 30 may be established across the cells of component 10.

A single common wavelength across the section 10 may be desirable because it provides more robust and repeatable folding of the section 10. In contrast, different folding wavelengths across different cells may not be desirable due to an increased likelihood of local tearing across the boundaries of the cells.

FIG. 3 also illustrates that a first row of axial crush initiators 25 may intersect a first edge of the first side 12' of the axially-extending crush section initiators and a different row (in this case, a third row 23) of axial crush initiators 25 may intersect a second edge of the first side wall 12", wherein the first and second edges of the first side wall 12' are opposing. Axial crush initiators that intersect an edge of a side wall may be a different shape to axial crush initiators that do not intersect an edge of a side wall. This is at least because the perimeter of an axial crush initiator that intersects with an edge of a side lies in two planes.

It may be appreciated that in some embodiments, the first edge and / or second edge may comprise a radiused corner.

In FIG. 3, the third row of axial crush initiators are axially offset from the second row of axial crush initiators by half the folding wavelength 30. The first and third rows of axial crush initiators are therefore axially aligned.

FIG. 4 illustrates an alternative view of the axially-extending crush section 10, showing the second side wall 12" of the section 10. It illustrates that the second side wall 12" of the first pair of side walls 12 also comprises rows of axial crush initiators.

The pattern, spacing and alignment of the axial crush initiators of the second side wall 12" may be identical to the pattern, spacing and alignment of the axial crush initiators of the first side wall 12'.

For example, the rows of axial crush initiators of the first side wall 12' may be axially aligned with the corresponding rows of axial crush initiators of the second side wall 12"-i.e., the first row of the first side wall is axially aligned with the first row of the second side wall; the second row of the first side wall is axially aligned with the second row of the second side wall etc. In these embodiments, as the rows of axial crush initiators of the first side wall 12' are axially aligned with the corresponding rows of axial crush initiators of the second side wall 12, the rows of axial crush initiators of the first side wall 12' have an axial offset of zero relative to the corresponding rows of axial crush initiators of the second side wall 12'.

In other embodiments, the axial alignment of the axial crush initiators of the second side wall 12" may be different to the axial crush initiators of the first side wall 12' -i.e., the rows of axial crush initiators of the first side wall 12' may have a non-zero axial offset of zero relative to the corresponding rows of axial crush initiators of the second side wall 12'. This non-zero axial offset (axial misalignment) of the initiators of side walls 12' and 12" may promote bending of the section 10 in a preferred direction (for example, bending about an axis in the + or -z direction).

The behaviour of the axially-extending crush section under crush conditions will now be explained, with reference to FIG. 5.

As previously disclosed, when a structural component 5 deforms with a crush wavelength, some portions of the structural component 5 may fold outwards, while other portions of the crush section may fold inwards.

The separation between a maxima of a first portion of the structural component 5 that folds outwards, and an adjacent minima of a second portion of the structural component 5 that folds inwards, may correspond to half the folding wavelength 30, while the separation between adjacent maxima of the structural component 5 that fold outwards corresponds to the folding wavelength 30, and the separation between adjacent minima of the structural component 5 that fold inwards corresponds to the folding wavelength 30.

As previously disclosed, the length of the folding wavelength 30 is dependent at least in part on the geometry of the axially-extending crush section 10, namely the height, width and thickness of the individual cells.

The pattern of the crush initiators 25 of FIGS 2 -4 may also determine the manner in which the section 10 deforms, namely, whether the section deforms with a symmetrical folding pattern, or an asymmetric folding pattern, or with a combination of symmetric and asymmetric folding patterns in which a first portion of the section 10 deforms with a symmetric folding patten and a second portion, different to the first portion, deforms with an asymmetric folding pattern.

Considering first a structural component 5 that does not comprise at least one internal web 15, or a pattern of crush initiators 25, as the structural component 5 is axially crushed, areas at the same axial location will fold in one direction (for example, outwards), and areas axially offset by half the crush wavelength will fold in the opposite direction (for example, inwards).

Typically, the folding direction will reverse across the corner between two adjacent sides of a rectangular section with corners.

Introducing the at least one internal web 15 into the structural component 5 may modify the deformation behaviour. This is because as the at least one internal web 15 mechanically connects opposing side walls of the structural component 5 and divides each opposing side wall into at least two separate areas, one either side of the web. The inward / outward deformation / folding of the opposing sides is therefore constrained at least in part by the at least one internal web 15.

Depending upon the relative strength of opposing side walls the at least one internal web may determine if the folding direction of opposing side walls is continuous across the web or the folding direction of opposing side walls reverses across each web.

Introducing the at least one internal web 15 into the structural component 5 may complicate deformation behaviour. This is because as the at least one internal web 15 mechanically connects opposing side walls of the structural component 5, inward / outward deformation of the opposing sides is constrained at least in part by the at least one internal web 15.

This constraint may create localised stress concentrations proximal to the interface between the at least one internal web and internal surface of the first side wall and/or second side wall.

If the localised stress concentrations exceed the elastic limit of the material from which the section is made, localised plastic deformation will occur. Plastic deformation may be desirable because it is energy absorbent.

However, if the localised plastic deformation exceeds the plastic limit of the material, then localised tearing of the material may occur proximal to the interface between the at least one internal web and the internal surface of the first side wall and/or second side wall. Tearing of the material may be undesirable because less energy may be absorbed than under plastic deformation.

Prevention of localised tearing can be accomplished by changing the material of the structural component 5 or changing the geometry of the structural component 5. For example, the thickness of the at least one internal web 15 and / or its connection to the first side wall 12' and / or second side wall 12" of the section 10 may be changed. Similarly, the geometry of the intersections between the first and second pairs of side walls may be changed -for example, by altering the radii between orthogonal side walls and/or increasing the localised thickness of the component side walls.

However, these changes may be undesirable due to associated increases in cost and/or weight of the structural component 5.

FIG. 5 illustrates an example of deformation behaviour of a structural component 5 in which the strength of the at least one internal web 15 has been chosen relative to other portions of the structural component 5, such that tearing of the internal web 15 and/or its connection with the side walls of the structural component is minimised or does not occur.

In FIG. 5, the deformation of the side walls 12', 12" of the structural component 5 is shown at three different planes within the structural component 5. The planes are parallel to each other, and are parallel to the plane of the at least one internal web 15.

The planes are: - * A first level 51, to one side of the at least one internal web 15.

* A second level 52, in the plane of the at least one internal web 15.

* A third level 53, to the other side of the at least one internal web 15.

In FIG. 5, deformation of side walls 12', 12" is significantly reduced in the second level 52 in the plane of the at least one internal web 15, relative to the first level 51 and the third level 53. This is because the at least one internal web 15 prevents the side walls folding outwards and inwards in the plane of the at least one internal web However, as the section 10 is crushed, portions of the section which are not as constrained by the at least one internal web adopt an undulating (folded) surface, the wavelength of the undulations corresponding to the folding wavelength 30.

FIG. 5 illustrates that the first level 51 and third level 53 deform in an anti-phase manner to each other. This is described as asymmetric folding in this document. This may be desirable because it may controllably absorb more energy than symmetric folding, as asymmetric folding is less likely to be subject to localised tearing.

Symmetric folding describes the folding pattern where first level 51 and third level 53 deform in an in-phase manner across the web resulting in lateral extension the at least one internal web on each of the outward folding phases of the deformation. This lateral extension of the web may lead to tearing of both the web and the face at the connection.

Although an improvement in the energy absorbed has been achieved, the mass of the section has also increased due to the strengthening of the internal web 15.

An advantage of the axial crush initiator pattern as illustrated in FIGS 2 -4 is that it enables an increase in energy absorption of the structure, by producing deformation of the side walls of the section 5 as illustrated in FIG. 5, but without requiring as great a mass increase to the at least one internal web to prevent tearing. A thicker web may increase the initiating peak force above a target, which may be difficult to tune with indents on the web due to limitations of indent depth. Another advantage is that the crush initiator pattern promotes a consistent chosen folding wavelength across the section even when different cells sizes are required The structure comprising the axial crush initiator pattern therefore enables improved component deformation for a given component weight.

This is achieved because the axial crush initiator pattern is configured to promote folding of the at least one internal web 15 as the structure 5 is axially deformed. This is because adjacent rows of axial crush initiators are mostly on either side of the at least one internal web, with the phasing of adjacent rows of crush initiators 25 anti-phased (axially offset by substantially half the folding wavelength 30). As the at least one internal web is connected to the opposing side walls 12', 12" of the structure, the folding of the at least one internal web is accompanied by outward folding of the sides 12', 12" to one side of the at least internal web, and inward folding of the sides 12', 12" to the other side of the at least one internal web. This reduces lateral in-plane stretching of the at least one internal web.

Thus, the axial crush initiator pattern provides an alternative means of promoting the crush pattern of FIG. 5 (asymmetric folding), An additional advantage of the pattern is that a maximum force generated during deformation may be controlled, by modification of the shape, depth and / or location of the axial crush initiators 25. This is because the different initiators, for example, as different subsets of initiators, may be configured to plastically deform in preference to other portions by modifying the location and magnitude of the peak buckling force and/or initial buckling force. Crushing of the section 10, is therefore progressive. Furthermore, the spacing between adjacent crush initiators in the rows of crush initiators may be used to control the folding wavelength 30.

As previously disclosed, a hollow section has a natural crush wavelength, in which the crush wavelength is dependent on the dimensions of the section. In embodiments in which the webs 15 are unequally-spaced, it may be appreciated that the unequally-sized cells within the structure may each have a separate natural crush wavelength. This may complicate crushing behaviour. By controlling the spacing between adjacent initiators to a fixed value, the crush wavelength of each cell of the section 10 may be controlled.

The number and location of the crush initiators in the rows of crush initiators may also be selected to control the energy absorbed and the axial location at which the energy is absorbed, and deformation occurs. Controlling the axial location at which deformation occurs may be desirable as it enables a vehicle designer to select, at a vehicle level, portions of the structural component 5 that are to deform, and portions of the structural component 5 that are not to deform. This may be desirable, because deformation may be permitted in portions of the structural component 5 that are not connected to other components of the vehicle 1 while deformation may be prevented in portions of the structural component 5 that are proximal to vehicle components that may be susceptible to damage by deformation -for example an electrical storage device, configured to provide electrical energy to an electric traction motor.

The axial crush initiator pattern of the axial crush initiation section 10 may also control the length of the section 10 over which crushing occurs. For example, in FIG. 3 the initiator pattern comprises two initiators 25 in the first row 21, three initiators 25 in the second row 22 and two initiators 25 in the third row 23 (a "2-3-2" pattern), in which the spacing between adjacent initiators in each row is substantially equal to the folding wavelength 30. Changing the number of initiators to three in the first row, four in the second row and 3 in the third row, (a "3-4-3") pattern, increases the axial length over which deformation occurs, and as a consequence, may increase the maximum energy that may be absorbed without tearing of the structural component.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example, the number, size, and shape of the axial crush initiators may be modified, the side walls, and number of side walls of the structure on which the axial crush initiators are provided may be modified. Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not. Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

CLAIMS1. An axially-extending crush section for a vehicle, comprising: a first row of crush initiators that are spaced axially to define a first folding wavelength; a second row of crush initiators that are spaced axially to define a second folding wavelength; and an internal web, separating the first row of crush initiators and the second row of crush initiators; wherein the crush initiators of the first row are parallel to and axially offset from the crush initiators of the second row, and the first and second folding wavelengths are approximately equal.
2. An axially-extending crush section for a vehicle as claimed in claim 1, wherein the axially-extending crush section comprises a first side wall and a second side wall opposite the first side wall, and the first side wall and second side wall each comprise a first row of crush initiators and a second row of crush initiators.
3. An axially-extending crush section for a vehicle as claimed in claim 2 wherein the first row of crush initiators of the first side wall and the first row of crush initiators of the second side wall are axially offset; and the second row of crush initiators of the first side wall and the second row of crush initiators of the second side wall are axially offset; wherein the axial offset of the first row of crush initiators of the first and second side walls is substantially equal to the axial offset of the second row of crush initiators of the first and second side walls.
4. An axially-extending crush section for a vehicle as claimed in claim 2 or 3, wherein the crush initiators of the first and second rows each comprise an indentation in one of the first side wall and second side wall of the axially-extending crush section.
5. An axially-extending crush section for a vehicle as claimed in claim 4, wherein a perimeter of each indentation comprises a rounded shape.
6. An axially-extending crush section for a vehicle as claimed in any of claims 2 to 5, wherein the first folding wavelength is based at least in part on a height, a width and / or a thickness of the walls defining a first cell that comprises the first row of crush initiators and the second folding wavelength is based at least in part on a height, a width and / or a thickness of the walls defining a second cell that comprises the second row of crush initiators.
7. An axially-extending crush section for a vehicle as claimed in any of claims 2 to 6, wherein the crush initiators of the first row of the first side wall are axially offset from the crush initiators of the second row of the first side wall by half the first folding wavelength; and the crush initiators of the first row of the second side wall are axially offset from the crush initiators of the second row of the second side wall by half the first folding wavelength.
8. An axially-extending crush section for a vehicle as claimed in any of claims 2 to 7, wherein the internal web connects the first side wall and the second side wall, wherein the internal web runs axially along the axially-extending crush section, and the first row of crush initiators on the first side wall of the axially-extending crush section is mostly or entirely to one side of an intersection point between the internal web and the first side wall and the parallel second row of crush initiators on the first side wall of the axially-extending crush section is mostly or entirely to the other side of the intersection point between the internal web and the first side wall.
9. An axially-extending crush section for a vehicle as claimed in any of claims 2 to 8, wherein the internal web is perpendicular to the first side wall and the second side wall and wherein the first side wall and the second side wall are parallel faces.
10. An axially-extending crush section for a vehicle as claimed in any of claims 2 to 9, wherein a first distance of the first row of crush initiators from a plane of the internal web is equal to a second distance of the second row of crush initiators from the plane of the internal web.
11. An axially-extending crush section for a vehicle as claimed in any of claims 2 to 10, wherein the axially-extending crush section comprises a second internal web connecting the first side wall and the second side wall, wherein the second internal web runs axially along the axially-extending crush section, parallel to the internal web; the axially-extending crush section comprises a third row of crush initiators that are spaced axially on the first side wall and the second side wall to define a third folding wavelength, the third row of crush initiators on the first side wall of the axially-extending crush section is mostly or entirely to one side of a second intersection point between the second internal web and the first side wall the parallel second row of initiators on the first side wall of the axially-extending crush section is mostly or entirely to the other side of the second intersection point between the second internal web and the first side wall; and wherein the third row of crush initiators have an identical spacing between adjacent crush initiators as the crush initiators of the first and/or second rows, and are axially aligned with the first row of crush initiators.
12. An axially-extending crush section for a vehicle as claimed in any of claims 2 to 11, wherein at least one of the first row of crush initiators, the second row of crush initiators and / or the third row of crush initiators intersect an edge of the first side wall of the axially-extending crush section and/or an edge of the second side wall of the axially-extending crush section.
13. An axially-extending crush section for a vehicle as claimed in claim 12 when dependent on claim 11, wherein the first row of crush initiators is located along a first edge of the first side wall or second side wall the third row of crush initiators is located along a second edge of the first side wall or second side wall, wherein the second edge is opposing the first edge; and the second row of crush initiators is between the first row of crush initiators and the third row of crush initiators.
14. An axially-extending crush section for a vehicle as claimed in any of claims 2 to 13, wherein at least one of the first row, second row and/or third row of crush initiators of the first or second side wall further comprises a starting crush initiator configured to deform prior to deformation of the other crush initiators of said at least one of the first row, second row and/or third row of crush initiators, based on a different shape and / or location offset of the starting crush initiator relative to said other crush initiators.
15. A vehicle, comprising an axially-extending crush section as claimed in any preceding claim.