GB2425580A - A structural element designed to withstand a transverse load tending to bend the element - Google Patents
A structural element designed to withstand a transverse load tending to bend the element Download PDFInfo
- Publication number
- GB2425580A GB2425580A GB0605912A GB0605912A GB2425580A GB 2425580 A GB2425580 A GB 2425580A GB 0605912 A GB0605912 A GB 0605912A GB 0605912 A GB0605912 A GB 0605912A GB 2425580 A GB2425580 A GB 2425580A
- Authority
- GB
- United Kingdom
- Prior art keywords
- teeth
- structural element
- transverse
- load
- another
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005540 biological transmission Effects 0.000 claims abstract description 3
- 230000008878 coupling Effects 0.000 claims abstract description 3
- 238000010168 coupling process Methods 0.000 claims abstract description 3
- 238000005859 coupling reaction Methods 0.000 claims abstract description 3
- 230000001419 dependent effect Effects 0.000 claims abstract description 3
- 238000000926 separation method Methods 0.000 claims description 2
- 238000005452 bending Methods 0.000 description 5
- 208000027418 Wounds and injury Diseases 0.000 description 4
- 230000006378 damage Effects 0.000 description 4
- 208000014674 injury Diseases 0.000 description 4
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 210000000038 chest Anatomy 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- IHQKEDIOMGYHEB-UHFFFAOYSA-M sodium dimethylarsinate Chemical class [Na+].C[As](C)([O-])=O IHQKEDIOMGYHEB-UHFFFAOYSA-M 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D1/00—Steering controls, i.e. means for initiating a change of direction of the vehicle
- B62D1/02—Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
- B62D1/04—Hand wheels
- B62D1/11—Hand wheels incorporating energy-absorbing arrangements, e.g. by being yieldable or collapsible
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
- B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
- B60N2/24—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles
- B60N2/42—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats
- B60N2/4207—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats characterised by the direction of the g-forces
- B60N2/4214—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats characterised by the direction of the g-forces longitudinal
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
- B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
- B60N2/24—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles
- B60N2/42—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats
- B60N2/427—Seats or parts thereof displaced during a crash
- B60N2/42709—Seats or parts thereof displaced during a crash involving residual deformation or fracture of the structure
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
- B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
- B60N2/68—Seat frames
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D1/00—Steering controls, i.e. means for initiating a change of direction of the vehicle
- B62D1/02—Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
- B62D1/16—Steering columns
- B62D1/18—Steering columns yieldable or adjustable, e.g. tiltable
- B62D1/19—Steering columns yieldable or adjustable, e.g. tiltable incorporating energy-absorbing arrangements, e.g. by being yieldable or collapsible
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F7/00—Vibration-dampers; Shock-absorbers
- F16F7/12—Vibration-dampers; Shock-absorbers using plastic deformation of members
- F16F7/123—Deformation involving a bending action, e.g. strap moving through multiple rollers, folding of members
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Transportation (AREA)
- Aviation & Aerospace Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- General Engineering & Computer Science (AREA)
- Air Bags (AREA)
- Seats For Vehicles (AREA)
Abstract
An elongate structural element 20 is designed to withstand a transverse load tending to bend the element. The element 20 has at least one pair of transversely extending surfaces 17 that face towards one another, the outer edges of the surfaces 17 being forced towards and away from one another as the element is bent on application of a transverse load. The transverse surfaces 17 are coupled for transmission of force from one to the other, the effectiveness of the coupling being dependent upon the direction and extent of the deformation of the element by the applied load. Two opposed transverse surfaces 17 are coupled to one another by means of a weak bridge 26 designed to rupture when a predetermined load is exceeded.
Description
DESIGN OF STRUCTURAL ELEMENTS
The present invention relates to a structural element and in particular to a structural element designed to withstand a transverse load acting to bend the element. The structural element may be a cantilever beam (i.e. one loaded between a point of support and an unsupported end) or else the load may be applied between two points of support of the structural element.
Certain structural elements in a motor vehicle need to be designed to yield plastically when the load to which they are subjected during normal use of the vehicle is exceeded.
One such structural element is the armature of the steering wheel. The armature comprises a central hub that is secured to the steering column and spokes that connect the hub to the rim of the wheel. The spokes must not bend to any significant extent when the vehicle is being steered or when the steering wheel is used as a support for the driver while getting in and out of the vehicle or when the driver pulls and pushed on the rim of the steering wheel to adjust the position of his seat. However, the armature is required to deform in the event of a collision to absorb energy and reduce injury to the driver.
In conventional structural elements designed to withstand a transverse loading, once the loading limit has been exceeded, their deformation increases substantially linearly as the load increases, in other words their resistance to bending (also termed the yield) and the rate at which they absorb impact energy is substanLially constant.
Us 5,040,646 describes a component consisting of a straight metal rod which is long relative to its transverse dimensions. Unlike the structural elements of the invention, this rod is designed to withstand axial loading rather than transverse loading. The rod is adapted to buckle inelastically in the direction of the axis of its larger principal moment of inertia under an axially acting compressive load. The rod is provided with spur teeth on at least one of its broadsides, which extend transversely to the longitudinal direction and which extend at right angles to the axis of the larger principal moment of inertia. When the tips of these teeth meet after the rod has buckled resistance to further buckling is increased.
While the prior art teaches how resistance to buckling can be increased after an element has been deformed, there are instances when one may wish the yield of an element to decrease rather than increase after a threshold load is exceeded. With elements subjected to transverse rather than axial loading, it may be desirable for the yield to vary with the direction in which the load is applied.
There are also occasions when a more complex shape of the graph of load versus deflection (herein termed the yield curve) is required. An example of such a component is the back of a seat in a motor vehicle. The frame of the seat back must be sufficiently rigid to support the weight of the driver and the forces normally applied to the frame, for example when adjusting the position of the seat or the back rest. However, the seat back must deform to reduce the risk of whiplash in the event of a rear end collision. During such a collision, the seat back should at first collapse as it catches the back of the occupant but, once the back, neck and head of the occupant are all fully supported, the resistance to deformation should again increase to prevent injury to the occupant.
The present invention seeks therefore to provide a structural element that can be designed to allow its yield to be varied as a function of the loading so as to enable the yield curve to be optimised to suit the functional requirements of the structural element.
According to the present invention, there is provided an elongate structural element designed to withstand a transverse load tending to bend the element, wherein the element has at least one pair of transversely extending surfaces that face towards one another, the outer edges of the surfaces being forced towards and away from one another as the element is bent by the application of a transverse load, wherein the transverse surfaces are coupled for transmission of force from one to the other, the effectiveness of the coupling being dependent upon the direction and extent of the deformation of the element by the applied load, two opposed transverse surfaces being coupled to one another by means of a weak bridge designed to rupture when a predetermined load is exceeded.
In a simple embodiment, the element may have a single transverse notch defining two facing and mutually spaced transverse surfaces connected by the weak bridge. The effect of the bridge across the notch is to stiffen the element until the applied force is sufficient to rupture the bridge.
Thereafter, the resistance of the element to bending will be reduced.
Instead of a single notch, the element may have several notches defining a set of comb-like teeth which extend transversely to the length of the beam and generally parallel to the direction of the applied load. In this case, some of the notches may be bridged and others left separated from one another. In the case of spaced teeth, they will act to increase the stiffness of the element after it has been bent sufficiently for their sides or tips to touch.
If the teeth all have the same length and separation, or the bridges are all designed to rupture simultaneously, there will be a relatively abrupt transition from one level of resistance to another, be it low to high or high to low.
Should a more gradual transition be required, then the spacing between the teeth may be graduated so that gaps between the teeth are closed sequentially rather than simultaneously. Alternatively, the shape of the gap between each pair of opposed surfaces may be non-uniform so that the gap closes by working its way up gradually from the roots of the teeth to their tips.
It is possible to strengthen a structural element in one direction only by providing teeth with only a nominal spacing that project from one side of the element. When the force applied tends to deform the side from which the teeth project into a concave curve, the tips of the teeth contact one another and resist the bending. On the other hand, when the force applied tends to bend the side into a convex curve then the tips of the teeth simply move apart and offer no resistance to the bending of the element.
In this way, the invention allows the yield curve of a structural element to be adapted to achieve optimum resistance at all stages in its deformation.
The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:- Fig. 1 is a section through a first structural element not in accordance with the invention, Fig. 2 is a similar section showing an embodiment of the invention, and Fig. 3 is a section showing a further embodiment of the invention.
Fig. 1 shows a structural element 10 in the form of a cantilever beam that is anchored at one end to a support 12.
The beam may for example be a spoke of a steering wheel projecting from a support formed by the central hub of the steering wheel. In an another example, the element may be a side element of a frame surrounding the back of a seat. In both these examples, the element is intended to be rigid during normal use but should yield in the event of a collision to reduce the risk of injury to the driver or a passenger. The invention allows a structural element to yield at different rates depending on the severity and the direction of the impact.
The element 10 in Fig. 1 has teeth 14 projecting from one side and resilient inserts 15 are arranged between some of the teeth 14. If the element 10 is bent in the direction of the arrow 16, the teeth 14 play no part in the deformation of the element. It will yield when a predetermined loading is exceeded and the extent of the deformation will then increase substantially linearly with the load.
When the element is bent in the direction of the arrow 18, on the other hand, the deformation is at first resisted by the compression of the resilient inserts 15. When the inserts 15 are fully compressed or when the opposed surfaces 17 at the tips of the teeth 14 not separated by inserts 15 come into contact with one another, the stiffness of the element is substantially increased and the rate of deformation will then drop as the loading is increased.
In the case of a steering wheel spoke, this would mean that at first the spoke will yield to prevent serious injury to the driver's rib cage. When however an air bag in the steering wheel is deployed, the spoke will not collapse under the increased loading but will provide a firm a reaction surface for the air bag to allow the driver to be pushed back into this seat by the air bag.
In the case of a seat back, the initial yield will allow the drivers back to be cushioned at the commencement of a rear end collision but once the driver's back is fully supported in the seat, the increased stiffness of the structural element will prevent the seat back from collapsing entirely.
While the element of Figure 1 allows the stiffness of the element to be increased after a certain amount of deformation has taken place, the invention teaches how it is possible to design element such that the stiffness will reduce after a threshold has been exceeded.
The embodiment of the invention in Figure 2 has two teeth 24 that are connected by a weak bridge 26. When the structural element 20 is loaded in the direction of the arrow 30 it will at first resist bending on account of the bridge 26. However, once the loading has exceeded the threshold needed to rupture the bridge, the stiffness of the element will be reduced significantly.
The embodiment of the invention illustrated in Fig. 3 has teeth serving different functions on its opposite sides.
Figure 3 also shows that the teeth 42 not interconnected by a bridge 26 may have a web 42a and a head 42b. The transverse surfaces of the heads 42b may be shaped to slip relative to one another, as in the case of the surfaces 42c, or to lock relative to one another, as in the case of the surfaces 42d. Furthermore, the webs can be designed to take the transfer load. Once again, the webs may be reinforced by placing compressible inserts (not shown) between them.
The embodiment of Figure 2 shows how it is possible to have an asymmetrical element that will bend more readily in one direction than in the other. The gaps between the teeth 24 and the teeth 28 are only nominal and will close at soon as the element is bent in the direction of the arrow 32.
However, the gaps will merely widen when the element is bent in the direction of the arrow 30 and the teeth 28 will not contribute to the stiffness of the element when bent in that direction.
A seat back is an example of a structural element that benefits from having asymmetrical properties. Under normal loads, the seat back should of course not move at all allowing the driver push against it when getting in and out of the vehicle or while adjusting position of the seat or the steering wheel. In the event of a rear end collision, the seat back is forced backwards by the weight of the driver or passenger and its ideal response would be to yield until the driver is fully supported by the back of the seat and then to become stiffer so that the back of the seat does not collapse. In the event of a forward collision, on the other hand, there is a risk that a heavy load in the back of the vehicle may move push the back of the seat forward tending the crush the driver between the seat and the steering wheel. Therefore, a seat back needs to be stiff at all times when resisting impacts acting to move it forwards.
Such a yield curve can be achieved by providing a seat back with closely spaced forward facing teeth and more widely spaced rearward facing teeth with bridges connecting the tips of the forward facing teeth. Such a design provides the high stiffness required to resist a heavy load intruding into the front passenger area in a severe frontal impact while allowing the seat back to yield in a rear impact. The bridges would provide high initial stiffness to assist the driver during and entry and exit. The bridges would act in tension or in compression depending on the direction in which the load is applied.
Of course the length, width and spacing of the teeth are all parameters that will affect the variation of stiffness with applied load. It will therefore be clear from the above description that the combination of spaced teeth and bridges will allow the yield curve to be varied at will enabling the stiffness of any structural element to be optimised under different degrees of deformation. -.9-
Claims (8)
1. An elongate structural element designed to withstand a transverse load tending to bend the element, wherein the element has at least one pair of transversely extending surfaces that face towards one another, the outer edges of the surfaces being forced towards and away from one another as the element is bent by the application of a transverse load, wherein the transverse surfaces are coupled for transmission of force from one to the other, the effectiveness of the coupling being dependent upon the direction and extent of the deformation of the element by the applied load, two opposed transverse surfaces being coupled to one another by means of a weak bridge designed to rupture when a predetermined load is exceeded.
2. A structural element as claimed in claim 1, wherein the element has a single transverse notch defining two facing and mutually spaced transverse surfaces.
3. A structural element as claimed in claim 1, wherein the element has several notches defining a set of comb-like teeth which extend transversely to the length of the beam and generally parallel to the direction of the applied load.
4. A structural element as claimed in claim 3, wherein the teeth all have the same length and separation.
5. A structural element as claimed in claim 3, wherein the spacing between the teeth is graduated so that gaps between the teeth are closed sequentially as the element is between.
6. A structural element as claimed in claim 3, wherein the shape of the gap between each pair of opposed surfaces is non-uniform so that the gap closes by working - 10 - its way up gradually from the roots of the teeth to their tips.
7. A structural element as claimed in any preceding claim, wherein the structural element is strengthened in one direction more than the other by providing teeth with only a nominal spacing that project from one side of the element.
8. A structural element constructed substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0508439A GB2426806A (en) | 2005-04-27 | 2005-04-27 | A structural element designed to withstand a transverse load tending to bend the element |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0605912D0 GB0605912D0 (en) | 2006-05-03 |
| GB2425580A true GB2425580A (en) | 2006-11-01 |
| GB2425580B GB2425580B (en) | 2009-08-05 |
Family
ID=34640162
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0508439A Withdrawn GB2426806A (en) | 2005-04-27 | 2005-04-27 | A structural element designed to withstand a transverse load tending to bend the element |
| GB0605912A Expired - Fee Related GB2425580B (en) | 2005-04-27 | 2006-03-27 | Design of strutural elements |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0508439A Withdrawn GB2426806A (en) | 2005-04-27 | 2005-04-27 | A structural element designed to withstand a transverse load tending to bend the element |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE102006018359B4 (en) |
| GB (2) | GB2426806A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102009007410A1 (en) * | 2009-02-04 | 2010-08-05 | Bayerische Motoren Werke Aktiengesellschaft | Impact absorption device for use in front area of motor vehicle, has reinforcement elements comprising pin- or pillar elements that are slided together in area wise in temporal manner and hooked with each other |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5040646A (en) * | 1988-11-15 | 1991-08-20 | Kolbenschmidt Aktiengesellschaft | Component for absorbing energy |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3838594A1 (en) * | 1988-11-15 | 1990-05-17 | Kolbenschmidt Ag | INSTALLATION COMPONENT FOR ABSORPTION OF ENERGY |
| US6588557B2 (en) * | 2001-04-04 | 2003-07-08 | Daimlerchrysler Corporation | Blow molded (HIC) formation with energy buffers |
| JP2003301880A (en) * | 2002-04-08 | 2003-10-24 | Nissan Motor Co Ltd | Structural member |
| JP4662331B2 (en) | 2004-09-30 | 2011-03-30 | キョーラク株式会社 | Shock absorber for vehicle |
-
2005
- 2005-04-27 GB GB0508439A patent/GB2426806A/en not_active Withdrawn
-
2006
- 2006-03-27 GB GB0605912A patent/GB2425580B/en not_active Expired - Fee Related
- 2006-04-19 DE DE102006018359.2A patent/DE102006018359B4/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5040646A (en) * | 1988-11-15 | 1991-08-20 | Kolbenschmidt Aktiengesellschaft | Component for absorbing energy |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2426806A (en) | 2006-12-06 |
| DE102006018359A1 (en) | 2006-11-16 |
| GB0508439D0 (en) | 2005-06-01 |
| DE102006018359B4 (en) | 2019-03-21 |
| GB2425580B (en) | 2009-08-05 |
| GB0605912D0 (en) | 2006-05-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20210327 |