WO2009101200A1

WO2009101200A1 - An impact test joint for a crash test dummy and coupling mechanism therefor

Info

Publication number: WO2009101200A1
Application number: PCT/EP2009/051772
Authority: WO
Inventors: James Manning
Original assignee: Trl Limited
Priority date: 2008-02-14
Filing date: 2009-02-16
Publication date: 2009-08-20
Also published as: GB2457471B; GB0802692D0; GB2457471A

Abstract

A coupling mechanism for operably coupling a connecting element to a joint component of an impact test joint for a crash test dummy comprises a regulator element comprising an aperture within which a part of the connecting element is received; and a restrictive element arranged to be received within the aperture of the regulator element, and form an interference fit therewith. The restrictive element is further arranged to couple with the part of the connecting element received within the aperture of the regulator element such that movement of the connecting element relative to the regulator element is resisted.

Description

AN IMPACT TEST JOINT FOR A CRASH TEST DUMMY AND COUPLING

MECHANISM THEREFOR

Field of the Invention

This invention relates generally to a coupling mechanism, and more particularly to a coupling mechanism for operably coupling a connecting element to a joint component of an impact test joint.

Background of the Invention

In the field of this invention it is known for vehicle to pedestrian impacts to result in potentially serious and even life threatening injuries to the pedestrian. In order to reduce the number and severity of such injuries, many energy management devices and methods have been developed by manufacturers of vehicles and front end modules for vehicles.

Energy management devices and methods need to be tested in order to evaluate their performance, and to verify their ability to provide protection to a road user or pedestrian during impact, and thereby to help reduce the number of road users and pedestrians killed or seriously injured through vehicle to pedestrian impacts. As will be appreciated, it is not feasible to evaluate the performance of such energy management devices and methods using human subjects. This is not only due to moral and ethical considerations, but also due to individual people being physiologically different, making the repeatability and reproducibility of tests, and thereby the validity of such tests, questionable.

As a consequence, many test devices have been developed to assess the pedestrian impact performance of a vehicle. Such devices range from full Anthropometric Test Dummies (ATD' s) to individual impactors that are used to individually represent, for example, the head, upper leg and/or full leg portions of a person. It is important for such test devices to represent as closely as possible the physiology of the human body. By way of example, a human knee is able to be loaded, with the ligaments, etc. within the knee joint resisting the load until failure occurs. It is therefore important that a knee joint of an ATD or impactor represents this resistance of the human knee joint in order to provide a realistic failure mode. A problem with known test devices is their accuracy in representing the biofidelity of a human body, and thereby accurately representing the behaviour of the human body, such as the resistance of the human knee joint described above.

The continued development of improved energy management devices and methods necessitates the requirement for test tools and devices that more accurately represent the biofidelity of, say, a pedestrian. In particular, active safety systems are being fitted to vehicles that attempt to anticipate an impact as it happens. Upon anticipation of an impact, such systems prepare or deploy some form of protection means at the time of impact, providing a greater level of protection to the occupants of the vehicle or to vulnerable road users. In the field of pedestrian safety, it is important that these active safety systems are tested with test tools and devices that represent the human body as accurately as possible. By way of example, in a case of a knee joint, if the stiffness of the knee joint is not accurately replicated during testing, and, for example, the stiffness is too low, it is possible that the vehicle sensors will not detect an impact during testing. Conversely, if the stiffness of a replicated knee joint is too high during testing, the testing may result in the sensor threshold being set too high, and as a result an active safety system may not register a subsequent impact with a human knee.

United Kingdom Patent Application number GB2401191A describes a bendable knee joint for use in pedestrian protection tests. The knee joint described in this document comprises four ^λligament' components utilising springs and cables to reproduce the required stiffness and resistance indicative of a human knee.

A problem with the knee joint described in GB2401191A is that it is expensive and complex to manufacture. Furthermore, such a knee joint is relatively large and bulky, which affects the ability of the device to replicate a human knee joint during an impact in terms of size, mass and mass distribution.

Another problem with the knee joint described in

GB2401191A is that the knee joint is designed to be used in a single impact direction, with the stiffness and resistance reproduced by the ligament components not being uniform in all directions about an axis of the knee j oint .

A further problem with known test tools is that they are designed and developed to represent the 50^th percentile male. This represents the most common size of the human body. However, this may result in some road users and pedestrians being inaccurately represented during testing, and thereby remaining less protected and vulnerable during impacts.

A still further problem with known test tools, known ATDs, known impactors and associated testing mechanisms is that they are designed and developed based on an assumption that the majority of pedestrian impacts occur on the side of the body (e.g. a leg), where the pedestrian would be crossing the road in a perpendicular direction of travel to that of the vehicle. However, impacts occurring at different angles do, of course, happen, where pedestrians are impacted in the front or rear of the body.

Consequently, a stiffness of the knee joint differs depending upon the direction that the (impact) load is applied. Furthermore, the stiffness of knee joints differs from that of, say, an elbow joint or the like.

Accordingly, known test tools also tend to be limited to replicating only a single type of joint.

US-A-4349339 shows a leg for an anthropomorphic dummy, for use in the dynamic testing of passenger restraint systems. The leg of US-A-4349339 is designed to measure skeletal forces.

Thus, there is a need for an improved impact test dummy and test joint in which at least some of the above mentioned problems and disadvantages of the prior art may be alleviated.

Summary of Invention

Accordingly, the invention seeks to mitigate, alleviate or eliminate one or more of the abovementioned problems and/or disadvantages singly or in any combination.

According to a first aspect of the invention, there is provided a coupling mechanism for operably coupling a connecting element to a joint component of an impact test joint. The coupling mechanism comprises a regulator element comprising an aperture within which a part of the connecting element is received; and a restrictive element arranged to be received within the aperture of the regulator element, and form an interference fit therewith. The restrictive element is further arranged to couple with the part of the connecting element received within the aperture of the regulator element, such that movement of the connecting element relative to the regulator element is resisted.

In this manner, embodiments of the invention provide an advantage of an impact test joint for a crash test dummy that is capable of substantially reproducing the stiffness and resistance indicative of, say, a human knee, whilst comprising relatively small and simple components. Consequently, a cost and complexity of manufacturing such an impact test joint can be substantially reduced. Furthermore, since the impact test joint may be produced in a relatively small form, the ability of the impact test joint to replicate, say, a human knee joint during impact may be substantially improved.

As will be appreciated by a skilled artisan, the resistance to movement of the connecting element relative to the regulator element is provided by the interference fit between the restrictive element and the aperture of the regulator element. Consequently, the resistance to this movement, and thus the stiffness of the impact test joint, may be varied by varying at least one of the regulator element and the restrictive element in order to vary the frictional and other characteristics of the interference fit there between. In this manner, the impact test joint is capable of being configured to reproduce different stiffness levels, for example to represent impacts other than side-on impacts, or to represent road users and pedestrians outside of the scope of the known arrangement of using a 50^th percentile male.

In one optional embodiment of the invention, in situ, the aperture of the regulator element and the joint component comprise a substantially common central axis. In this manner, the impact test joint is capable of bending in substantially any direction about the substantially common central axis. Additionally, the stiffness and resistance reproduced by the coupling mechanism of the first joint component may be substantially equal in any direction about the substantially common central axis.

As will be appreciated by a skilled artisan, this may provide an advantage that the impact test joint does not require accurate alignment in relation to a point of impact about the common central axis, in order to ensure a proper resistance is afforded during a test impact. Consequently, setting up an impact test joint can be less time consuming than for known devices, and significantly less prone to test results being invalid due to an incorrect alignment of the knee joint.

According to a second aspect of the invention there is provided a crash test dummy having an impact test joint comprising a first joint component, a second joint component and a connecting element, the first joint component comprising a coupling mechanism for operably coupling the connecting element to the first joint component according to the first aspect of the invention.

According to a third aspect of the invention there is provided a kit of parts for a coupling mechanism according to the first aspect of the invention.

Brief Description of the Drawings

Exemplary embodiments of the invention will now be described, with reference to the accompanying drawings, in which: FIG. 1 illustrates an impact test joint according to some embodiments of the invention.

FIG's 2, 3 and 4 illustrate cross-sectional views of the impact test joint of FIG. 1.

Description of Embodiments

Embodiments of the invention will be described with reference to a test dummy that is suitable for vehicle crash testing. However, it is envisaged that the term ^λtest dummy' used henceforth encompasses any object that may be suitable to assess stress applied to a joint including at least a full test dummy to replicate a human being as well as any corresponding ^λjoint' of a human being.

Referring now to the drawings, and in particular FIG. 1, there is illustrated an impact test joint 100 according to some embodiments of the invention. The impact test joint comprises a first joint component 110 and a second joint component 120. The first and second joint components 110, 120 are arranged to be operably coupled to leg components 130, 140 respectively.

Referring now to FIG's 2 and 3, there is illustrated a cross-sectional view of the impact test joint 100 of FIG. 1. The first joint component 110 of the impact test joint 100 comprises a coupling mechanism 210 for operably coupling a connecting element 220 to the first joint component 110. The coupling mechanism 210 comprises a regulator element 230 comprising an aperture 240, within which a part of the connecting element 220 is received. For the illustrated embodiment, the regulator element 230 comprises a generally cylindrical configuration, and the aperture 240 also comprises a generally cylindrical configuration.

The coupling mechanism 210 further comprises a restrictive element 250 arranged to be received at least partially within the aperture 240 of the regulator element 230, and form an interference fit therewith. For the illustrated embodiment, the restrictive element 250 comprises a generally circular cross-sectional configuration. The restrictive element 250 is further arranged to couple with the part of the connecting element 220 received within the aperture 240 of the regulator element 230, such that movement of the connecting element 220 relative to the regulator element 230 is resisted.

For the illustrated embodiment, the connecting element 220, in use, extends from the first joint component 110 and is received within a coupling mechanism 260 located within the second joint component 120. The coupling mechanism 260 within the second joint component 120 retains the part of the connecting element 220 received therein .

As will be appreciated by a skilled artisan, when subjected to an impact, such as during an energy management test simulating a vehicle to pedestrian impact, forces exerted on the impact test joint, if large enough, cause the impact test joint to bend. FIG. 4 illustrates the impact test joint of FIG' s 2 and 3 in such a bent (impacted) configuration.

For the illustrated embodiment, the first and second joint components 110, 120 are arranged to pivot relative to one another about circumferences of their respective contact surfaces 410, 420, as illustrated at W . This pivoting of the first and second joint components 110,

120 causes an increase in a distance between the coupling mechanism 260 of the second joint component 120 and the regulator element 230 of the coupling mechanism 210 of the first joint component 110.

As previously mentioned, for the illustrated embodiment, a compression disc 295 is provided between the first and second joint components 110, 120. In particular, and as can be seen in FIG. 4, the compression disc 295 is located between the contact surfaces 410, 420. In this manner, the compression disc 295 provides a yielding surface about which the first and second joint components

110, 120 may pivot.

As previously mentioned, the restrictive element 250 of the coupling mechanism 210 of the first joint component 110 is received generally within the aperture 240 of the regulator element 230, and forms an interference fit therewith. In this manner, although movement of the connecting element 220 relative to the regulator element 230 is resisted, if a large enough force to overcome the friction of the interference fit is exerted on the connecting element 220 in a direction generally parallel with the aperture 240, the restrictive element 250 is capable of movement generally along the aperture 240 of the regulator element 230.

Referring back to FIG. 4, as can be seen, the pivoting of the first and second joint components 110, 120 has resulted in the restrictive element 250 moving along the aperture 240 of the regulator element 230, substantially in a direction as indicated by arrow ^λB' . In this manner, whilst the coupling mechanism 210 enables bending of the impact test joint, the interference fit between the restrictive element 250 and the aperture 240 of the regulator element 230 enables the stiffness and resistance indicative of, say, a human knee to be substantially reproduced.

Thus, embodiments of the invention provide the advantage of an impact test joint capable of reproducing the stiffness and resistance indicative of, for example, a human knee, whilst comprising a low number of relatively small and simple components that may be quickly and easily constructed. Consequently, the cost and complexity of manufacturing such an impact test joint may be substantially reduced. Furthermore, since the impact test joint may be produced in a relatively small form, the ability of the impact test joint to replicate, for example, a human knee joint during impact may be substantially improved.

As will be appreciated by a skilled artisan, the resistance to movement of the connecting element relative to the regulator element is provided by the interference between the restrictive element and the aperture of the regulator element. Consequently, the resistance to this movement, and thus the stiffness of the impact test joint, may be varied (e.g. by replacing one or more components in terms of a component with a differing length, diameter, configurational design or property) by varying at least one of the regulator element and the restrictive element in order to vary the frictional characteristics of the interference fit there between. In this manner, the impact test joint is capable of being configured to reproduce different stiffness levels, for example to represent impacts other than side-on impacts, or to represent road users and pedestrians outside of the scope of the 50^th percentile male and other joints.

In accordance with the illustrated embodiment, in situ, the aperture 240 of the regulator element 230 and the first joint component 110 comprise a substantially common central axis ^λC:C (as illustrated in FIG. 3) . Furthermore, when the impact test joint 100 is in a non- bent configuration, for example as illustrated in FIG. 2, the connecting element 220 and the second joint component 120 also comprise the same substantially common central axis ^λC:C. In this manner, the impact test joint 100 is capable of bending in substantially any direction about the substantially common central axis ^λC:C. Additionally, the stiffness and resistance reproduced by the coupling mechanism 210 of the first joint component 110 is substantially equal in any direction about the substantially common central axis ^λC:C.

As will be appreciated by a skilled artisan, this provides the advantage that the impact test joint does not require accurate alignment in relation to the point of impact about the common central axis in order to ensure that the proper resistance is afforded during a test impact. Consequently, setting up the impact test joint can be less time consuming than for known test crash dummy devices, and significantly less prone to test results being invalid due to incorrect alignment of, say, the knee joint.

Referring back to FIG' s 2 and 3, for the illustrated embodiment, the coupling mechanism 210 further comprises a generally cylindrical sleeve 270, within which the regulator element 230 and a washer 280 are located. The sleeve 270 substantially restricts the regulator element 230 from deforming in a radially outwards direction, which might otherwise be caused by the restrictive element 250 being pulled there through. In accordance with one embodiment of the invention, the regulator element 230 is retained within the sleeve 270 by way of an interference fit.

The first joint component 110 comprises a generally hollow, cylindrical configuration. Within the first joint component 110, a first flange section 112 provides a reduced diameter section 115. In use, the sleeve 270 is located within the reduced diameter section 115 of the first joint component 110. A second flange section 117 is located generally at, for the illustrated orientation, a lower end of the reduced diameter section 115. The washer 280 substantially prevents the sleeve 270 from passing through the second flange section 117. The sleeve 270 may form an interference fit with sides of the reduced diameter section 115 of the first joint component 110. In situ, the washer 280 is located within the sleeve 270, adjacent the second flange section 117.

As previously mentioned, the second joint component 120 comprises a coupling mechanism 260. For the illustrated embodiment, the coupling mechanism 260 of the second joint component 120 comprises a retaining formation 125, within which is located a rotation element 260. The rotation element 260 comprises an aperture 265 through which, in use, the connecting element 220 passes. The rotation element 260 generally avoids shearing of the connecting element 220 when the impact test joint 100 is caused to bend, as illustrated in FIG. 4. The retaining formation 125 and rotation element 260 may be lubricated to improve rotation of the rotation element 260 within the retaining formation 125.

The retaining formation 125 extends from the second joint component 120, and, in use, can be received within the first joint component 110, as illustrated in FIG. 2. The first joint component 110 comprises a soft washer 290 that, when the retaining formation 125 is received within the first joint component 110, provides a yielding contact between the retaining formation 125 and the first joint component 110. For the illustrated embodiment, a compression disc 295 is provided between the first and second joint components 110, 120.

In some embodiments of the invention, it is envisaged that the regulator element may be manufactured from polyurethane, the soft washer 290 may be manufactured from silicone, the sleeve and/or compression disc 295 and/or restrictive element and/or joint components 110, 120 and/or rotation element may be manufactured from steel .

For the illustrated embodiment, the connecting element 220 comprises a bolt, or similar formed device, comprising a head 222 at one end thereof. The head 222 of the connecting element 220 comprises a diameter greater than that of the aperture 265 of the rotation element 260. In this manner, the head of the connecting element 220 is prevented from passing through the aperture 265 of the rotation element 260. In this manner, the connecting element 220 is prevented from being pulled through the rotation element 260, and in this manner coupled to the second joint component 120.

The opposing end of the connecting element 220, which is received within the aperture 240 of the regulator element 230 of the coupling mechanism 210 of the first joint component 110, comprises a threaded formation 225. A corresponding threaded formation 255 is provided within an aperture of the restrictive element 250. In this manner, the threaded formations 225, 255 may be caused to engage one another by rotation of the connecting element 220 relative to the restrictive element 250. As will be appreciated by a skilled artisan, by tightening the engagement between the connecting element 220 and the restrictive element 250 to a predetermined torque setting, a substantially reliable and repeatable stiffness of the impact test joint may be achieved. In accordance with some embodiments of the invention, the regulator element 230 comprises a yielding material, in order to take into account off-centre movement caused by the pivoting movement of the first and second joint components 110, 120 relative to one another. Furthermore, the restrictive element 250 may also, or alternatively, comprise yielding material. In accordance with some embodiments of the invention, the restrictive element 250 may comprise a material with higher yield properties than that of the regulator element 230 in order to substantially prevent deformation of the restrictive element 250 as it is pulled through the regulator element 230.

Although the invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term Comprising' does not exclude the presence of other elements or steps.

Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also, the inclusion of a feature in one category of claims does not imply a limitation to this category, but rather indicates that the feature is equally applicable to other claim categories, as appropriate.

Furthermore, the order of features in the claims does not imply any specific order in which the features must be performed and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order. In addition, singular references do not exclude a plurality. Thus, references to ^λa' , ^λan' , ^λfirst' , 'second' etc. do not preclude a plurality.

Thus, an improved coupling mechanism and a crash test dummy comprising an impact test joint having the coupling mechanism have been described, which substantially addresses at least some of the shortcomings of past and present access control techniques and/or mechanisms.

Claims

1. A coupling mechanism for operably coupling a connecting element to a joint component of an impact test joint, wherein the coupling mechanism is characterised by: a regulator element comprising an aperture within which a part of the connecting element is received; and a restrictive element arranged to be received at least partially within the aperture of the regulator element, and form an interference fit therewith; wherein the restrictive element is further arranged to couple with the part of the connecting element received within the aperture of the regulator element, such that movement of the connecting element relative to the regulator element is resisted.

2. The coupling mechanism of Claim 1 further characterised in that, in a first orientation, the aperture of the regulator element and the joint component comprise a substantially common central axis.

3. The coupling mechanism of Claim 2 further characterised in that the aperture of the regulator element comprises a generally cylindrical configuration.

4. The coupling mechanism of Claim 3 further characterised in that the restrictive element comprises a generally circular cross-sectional configuration.

5. The coupling mechanism of any preceding Claim further characterised by a generally cylindrical sleeve, within which the regulator element is located.

6. The coupling mechanism of Claim 5 further characterised in that the regulator element is retained within the sleeve by way of an interference fit.

7. The coupling mechanism of any preceding Claim further characterised in that the restrictive element comprises a threaded formation within an aperture thereof adapted to engage with a corresponding threaded formation of the connecting element.

8. The coupling mechanism of any preceding Claim further characterised in that the regulator element is formed of an at least partially yielding material.

9. The coupling mechanism of Claim 8 further characterised in that the regulator element is made from polyurethane .

10. The coupling mechanism of any preceding Claim further characterised in that the restrictive element comprises a material with higher yield properties than that of the regulator element.

11. The coupling mechanism of Claim 10 further characterised in that the restrictive element is made from steel.

12. A test dummy comprising an impact test joint comprising a first joint component, a second joint component and a connecting element, the first joint component comprising a coupling mechanism for operably coupling the connecting element to the first joint component according to any preceding Claim.

13. The test dummy of Claim 12 further characterised by the connecting element in use extending from the first joint component and being received within a coupling mechanism located within the second joint component.

14. The test dummy of Claim 13 further characterised by the first and second joint components being arranged to pivot relative to one another about circumferences of respective contact surfaces.

15. The test dummy of any of Claims 12 to 14 further characterised in that the aperture of the regulator element of the coupling mechanism, first and second joint components and the connecting element comprise a substantially common central axis.

16. The test dummy of any of Claims 12 to 15 further characterised in that the second joint component comprising a coupling mechanism, the coupling mechanism of the second joint component comprising a retaining formation within which is located a rotation element; such that the rotation element comprises an aperture through which, in use, the connecting element passes.

17. The test dummy of Claim 16 further characterised in that the retaining formation extends from the second joint component, and in use is received within the first joint component.

18. The test dummy of Claim 17 further characterised in that the first joint component comprises a soft washer that, when the retaining formation is received within the first joint component, provides a yielding contact between the retaining formation and the first joint component .

19. The test dummy of any of Claims 12 to 18 further characterised in that the connecting element comprises a threaded formation arranged to engage a corresponding threaded formation provided within an aperture of the restrictive element.

20. A kit of parts for a coupling mechanism adapted according to any of Claims 1 to 11.