WO2001019666A1 - Method and device for active control of deformation behavior for structural elements - Google Patents

Method and device for active control of deformation behavior for structural elements Download PDF

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Publication number
WO2001019666A1
WO2001019666A1 PCT/SE2000/001716 SE0001716W WO0119666A1 WO 2001019666 A1 WO2001019666 A1 WO 2001019666A1 SE 0001716 W SE0001716 W SE 0001716W WO 0119666 A1 WO0119666 A1 WO 0119666A1
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WO
WIPO (PCT)
Prior art keywords
structural element
deformation
actuators
components
collision
Prior art date
Application number
PCT/SE2000/001716
Other languages
French (fr)
Inventor
Mats Gustavsson
Original Assignee
Saab Ab
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Saab Ab filed Critical Saab Ab
Priority to AU74649/00A priority Critical patent/AU7464900A/en
Publication of WO2001019666A1 publication Critical patent/WO2001019666A1/en

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Classifications

    • 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
    • F16F15/00—Suppression of vibrations in systems; Means or arrangements for avoiding or reducing out-of-balance forces, e.g. due to motion
    • F16F15/02—Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D21/00—Understructures, i.e. chassis frame on which a vehicle body may be mounted
    • B62D21/15—Understructures, i.e. chassis frame on which a vehicle body may be mounted having impact absorbing means, e.g. a frame designed to permanently or temporarily change shape or dimension upon impact with another body

Definitions

  • the present invention relates to a device and a method which, under certain circumstances, allows active control of the deformation behaviour in a structural element, when this element, for some reason, for example in a collision between a vehicle and another object, is subjected to rapid deformation.
  • a structural element when this element, for some reason, for example in a collision between a vehicle and another object, is subjected to rapid deformation.
  • what is aspired to is maximum energy absorption and a process of deformation that produces an even force on vital load during the period of deformation of the element.
  • Deformation of an element, such as a beam where the element is bent with short radii of curvature requires more energy than a deformation of the same element where the element is bent with longer radii of curvature.
  • the invention illustrates a device and a method for initiating vibrations in a structural element in association with deformation, so as to control the bending of the element during the process of deformation in order to achieve a high energy abso ⁇ tion and a more favourable stiffness.
  • the deformation pattern of structures when subjected to loading is determined largely by the current geometry of the structure.
  • structure here refers primarily to a structure in the form of a structural element, such as supporting beams in vehicles, or other equivalent structural elements which absorb energy when subjected to an extraordinary load, for example in a collision.
  • a beam that is loaded by forces applied at both ends is shown in Fig. 1.
  • the bending of the beam, i.e. its deformation shape, during deformation adheres to, in principle, a first form, where the radius of curvature r in the curve defined by the beam is long.
  • a beam of the type described constitutes a structure in a vehicle for abso ⁇ tion of energy at the moment of collision, then we have an example of a structure where energy abso ⁇ tion and stiffness are not optimized.
  • One pu ⁇ ose of the device in the WO document is to facilitate adaptation of deformation and energy abso ⁇ tion to different collision situations.
  • One aspect of the present invention relates to a device and a method for actively controlling the deformation pattern in a structural element when this is subjected to sudden loading, for example in the form of forces which produce forced deformation, such as in a collision between objects in which the element is inco ⁇ orated in at least one of the objects, whereby the deformation pattern, that is to say the buckling that the element is subjected to, can be controlled in such a way that the energy abso ⁇ tion and the stiffness of the element is optimized.
  • the structural element is subjected to vibration excitation in conjunction with the deformation.
  • the produced vibration excitation in the element is controlled so that the element is excited by at least one force that effects the element with a frequency spectrum that is selected and based on the resonance modes of the element. In this way, the element is given a desirable mode of vibration. This means that it is possible to determine in which way the structural element vibrates before deformation by choosing suitable excitation areas and excitation spectra. By initiating in this way an optimal vibration pattern in association with the developing deformation, the deformation can be guided so that the deformation shape of the element on deformation wholly or partly concurs with the imposed vibration pattern.
  • the forces that initiate the imposed controlled vibration can be achieved by means of actuators. These actuators can also be used during deformation to further influence and/or monitor this deformation. Activation of the actuators can be done by means of collision detectors, for example based on movement or acceleration detection.
  • the actuators are preferably comprised of piezo-electrical components, which are fitted on the structural element in areas determined by calculations or measurements, so as to direct the element in to the desired vibration, which is accomplished by directing the electrical signal to the respective components.
  • Other utilizable actuators are electrostriction or magnetostriction components, as well as components based on electroactive material or storage material.
  • electromagnetic or electro-electro interference can also be employed to produce the desired dynamic motion force.
  • Impulse excitation by pre-stressing the element or by means of powder charges can also be used, although in these cases there is a limit to the extent to which the excitation spectra can be controlled.
  • One advantage of using the invention is that deformation of the various beams and other structural elements is influenced in such a way that the deformation occurs during maximum energy abso ⁇ tion.
  • An additional advantage is that it will be possible to produce mechanical structures with a better design, since the invention facilitates the possibility of controlling the deformation of the said structures anyway, so that it absorbs a large amount of energy when subjected to loading from an external source, such as in a collision where the structure is inco ⁇ orated in a vehicle.
  • the invention can be employed to advantage in structural elements in vehicles, such as cars and trains, in order to improve their safety in a collision.
  • the invention however, has applications in other areas, for example at quaysides, berthing places for boats, loading bays and similar places, where fixed devices can be installed according to the invention for absorbing energy on collision with the device.
  • Figure 1 shows a beam deformed by forces applied at its ends, as well as the basic deformation shape of the beam, where the radius of curvature r for the curvature shown by the beam is large.
  • Figure 2 shows the same beam as in Figure 2, where forces applied by means of actuators causes the beam to vibrate in a vibration mode of higher order (4 th bending mode in this case), whereby the radius of curvature r of the vibration will be much shorter than the radius of the basic deformation shape.
  • Figure 3 shows the units for controlling and initiating the actuators located on the beam.
  • Figure 2 shows a beam 1 that is assumed to constitute a longitudinal structural element in vehicles such as a car or a train.
  • the collision forces are symbolised in the drawings by the forces F in the beam's 1 longitudinal direction.
  • the beam 1 are arranged a number of actuators 2, the task of which is to convey to the beam the applied forces, which with a pre-selected frequency spectra causes the beam to oscillate according to a predetermined vibration 3.
  • Figure 2 shows a vibration that represents a resonance mode for the beam, where the beam is now forced to define curves with shorter radii of curvature r during the vibration.
  • a resonance mode is preferably chosen for the structural element, the beam in this case, for which the greatest energy abso ⁇ tion or desired stiffness is attained during deformation.
  • the actuators are in the form of piezo-electric components arranged along the beam.
  • the actuators are arranged according to calculations in which account is taken of both the dimensions and the geometrical form of the beam or the structural element.
  • the arrangement of the actuators is such that the individual actuators operate in phase with each other and create an amplitude maximum for the vibration at the position of each actuator.
  • a beam 1 is given as an example of a structural element.
  • the said elements can be embodied by a structure of choice.
  • a collision detector 4 is fitted in an entity, for example a vehicle or other device, where a structure is used for energy abso ⁇ tion on deformation according to the invention.
  • the collision detectors 4 can be embodied by motion detectors or by accelerometers of the type used in release mechanisms for air bags.
  • the collision detectors 4 are connected to a control unit 5, which comprises at least one microprocessor.
  • the control unit 5 is programmed to provide current to each actuator 2 with a frequency spectrum that is adjusted to the respective structural elements in the vehicle, in order to attain the predetermined vibration.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Body Structure For Vehicles (AREA)
  • Vibration Prevention Devices (AREA)
  • Vibration Dampers (AREA)

Abstract

This invention relates to a method and a device for actively controlling the deformation shape on deformation of a structural element (1), such as a beam in a vehicle, where the invention involves imposing controllable dynamic forces on the structural element (1) so as to force it, in association with deformation, to vibrate according to an imposed oscillation, so that deformation of the structural element (1) is determined entirely or partly according to the imposed vibration.

Description

Method and Device for Active Control of Deformation Behaviour for Structural Elements. TECHNICAL FIELD
The present invention relates to a device and a method which, under certain circumstances, allows active control of the deformation behaviour in a structural element, when this element, for some reason, for example in a collision between a vehicle and another object, is subjected to rapid deformation. On such occasions, what is aspired to is maximum energy absorption and a process of deformation that produces an even force on vital load during the period of deformation of the element. Deformation of an element, such as a beam, where the element is bent with short radii of curvature requires more energy than a deformation of the same element where the element is bent with longer radii of curvature. The invention illustrates a device and a method for initiating vibrations in a structural element in association with deformation, so as to control the bending of the element during the process of deformation in order to achieve a high energy absoφtion and a more favourable stiffness.
STATE OF THE ART
The deformation pattern of structures when subjected to loading is determined largely by the current geometry of the structure. The term structure here refers primarily to a structure in the form of a structural element, such as supporting beams in vehicles, or other equivalent structural elements which absorb energy when subjected to an extraordinary load, for example in a collision. A beam that is loaded by forces applied at both ends is shown in Fig. 1. The bending of the beam, i.e. its deformation shape, during deformation adheres to, in principle, a first form, where the radius of curvature r in the curve defined by the beam is long. This means that the beam in this example is easily broken at some point along its length, so that the beam is unable to absorb as much deformation energy as desired and results in a highly variable stiffness during the deformation process. If a beam of the type described constitutes a structure in a vehicle for absoφtion of energy at the moment of collision, then we have an example of a structure where energy absoφtion and stiffness are not optimized.
Several different solutions have been proposed for increasing the energy absoφtion of a structure at a moment of collision. "Active" beam systems in vehicles are already known; these are systems where a collision triggers an activity, which makes the beam system behave in a way different to its normal mechanical limitations. This type of active beam system is known from, for example, document US 4 050 537. In the aforementioned document, a powder charge is, in a collision situation, employed to change the cross- section of a box girder in such a way that its stiffness and thus its energy absoφtion capacity increases. Document WO 9 822 327 shows a front structure of a vehicle where a beam system is provided with charges of powder which are detonated sequentially in a collision. Here the intention is to weaken the beams and prevent them from snapping, so that the process of deformation and energy absoφtion can be controlled from a front section of the beams to sections behind. Consequently, energy absoφtion can be increased. One puφose of the device in the WO document is to facilitate adaptation of deformation and energy absoφtion to different collision situations.
DESCRIPTION OF THE INVENTION
One aspect of the present invention relates to a device and a method for actively controlling the deformation pattern in a structural element when this is subjected to sudden loading, for example in the form of forces which produce forced deformation, such as in a collision between objects in which the element is incoφorated in at least one of the objects, whereby the deformation pattern, that is to say the buckling that the element is subjected to, can be controlled in such a way that the energy absoφtion and the stiffness of the element is optimized. According to the aspect of the invention, the structural element is subjected to vibration excitation in conjunction with the deformation. The produced vibration excitation in the element is controlled so that the element is excited by at least one force that effects the element with a frequency spectrum that is selected and based on the resonance modes of the element. In this way, the element is given a desirable mode of vibration. This means that it is possible to determine in which way the structural element vibrates before deformation by choosing suitable excitation areas and excitation spectra. By initiating in this way an optimal vibration pattern in association with the developing deformation, the deformation can be guided so that the deformation shape of the element on deformation wholly or partly concurs with the imposed vibration pattern. The forces that initiate the imposed controlled vibration can be achieved by means of actuators. These actuators can also be used during deformation to further influence and/or monitor this deformation. Activation of the actuators can be done by means of collision detectors, for example based on movement or acceleration detection.
The actuators are preferably comprised of piezo-electrical components, which are fitted on the structural element in areas determined by calculations or measurements, so as to direct the element in to the desired vibration, which is accomplished by directing the electrical signal to the respective components. Other utilizable actuators are electrostriction or magnetostriction components, as well as components based on electroactive material or storage material. Apart from the aforementioned, electromagnetic or electro-electro interference can also be employed to produce the desired dynamic motion force. Impulse excitation by pre-stressing the element or by means of powder charges can also be used, although in these cases there is a limit to the extent to which the excitation spectra can be controlled.
One advantage of using the invention is that deformation of the various beams and other structural elements is influenced in such a way that the deformation occurs during maximum energy absoφtion. An additional advantage is that it will be possible to produce mechanical structures with a better design, since the invention facilitates the possibility of controlling the deformation of the said structures anyway, so that it absorbs a large amount of energy when subjected to loading from an external source, such as in a collision where the structure is incoφorated in a vehicle. The invention can be employed to advantage in structural elements in vehicles, such as cars and trains, in order to improve their safety in a collision. The invention, however, has applications in other areas, for example at quaysides, berthing places for boats, loading bays and similar places, where fixed devices can be installed according to the invention for absorbing energy on collision with the device.
DESCRIPTION OF DRAWINGS
Figure 1 shows a beam deformed by forces applied at its ends, as well as the basic deformation shape of the beam, where the radius of curvature r for the curvature shown by the beam is large.
Figure 2 shows the same beam as in Figure 2, where forces applied by means of actuators causes the beam to vibrate in a vibration mode of higher order (4th bending mode in this case), whereby the radius of curvature r of the vibration will be much shorter than the radius of the basic deformation shape.
Figure 3 shows the units for controlling and initiating the actuators located on the beam.
EMBODIMENTS
A number of versions are described below with the aid of the drawings.
Figure 2 shows a beam 1 that is assumed to constitute a longitudinal structural element in vehicles such as a car or a train. In a head-on collision, the collision forces are symbolised in the drawings by the forces F in the beam's 1 longitudinal direction. Along the beam 1 are arranged a number of actuators 2, the task of which is to convey to the beam the applied forces, which with a pre-selected frequency spectra causes the beam to oscillate according to a predetermined vibration 3. Figure 2 shows a vibration that represents a resonance mode for the beam, where the beam is now forced to define curves with shorter radii of curvature r during the vibration. A resonance mode is preferably chosen for the structural element, the beam in this case, for which the greatest energy absoφtion or desired stiffness is attained during deformation. In the example in Figure 2, the actuators are in the form of piezo-electric components arranged along the beam. Depending on which vibration mode is required in the beam, the actuators are arranged according to calculations in which account is taken of both the dimensions and the geometrical form of the beam or the structural element. In the illustrated example, the arrangement of the actuators is such that the individual actuators operate in phase with each other and create an amplitude maximum for the vibration at the position of each actuator.
In this particular case, a beam 1 is given as an example of a structural element. The said elements, however, can be embodied by a structure of choice. In an entity, for example a vehicle or other device, where a structure is used for energy absoφtion on deformation according to the invention, at least a collision detector 4 is fitted. The collision detectors 4 can be embodied by motion detectors or by accelerometers of the type used in release mechanisms for air bags. The collision detectors 4 are connected to a control unit 5, which comprises at least one microprocessor. The control unit 5 is programmed to provide current to each actuator 2 with a frequency spectrum that is adjusted to the respective structural elements in the vehicle, in order to attain the predetermined vibration.

Claims

1. A method for actively controlling the deformation shape on deformation of a structural element (1), such as a beam, characterized in that controllable dynamic forces in conjunction with deformation force the structural element (1) to vibrate according to an imposed vibration so that deformation of the structural element (1) is entirely or partly guided by the imposed vibration.
2. A method according to claim 1, characterized in that the controllable forces are generated by means of actuators (2) distributed along the structural element (1) and working together to generate the imposed vibration.
3. A method according to claim 1, characterized in that the actuators (2) are activated by a collision detector (4), such as a motion detector or an accelerometer.
4. A device at a structural element (1) for absorbing energy when the structural element (1) is subjected to deformation, characterized in that the actuators (2) are arranged on the surface of the structural element (1) at calculated points, and that the actuators are controlled to impose forces on the structural element (1), directing the structural element (1) into an imposed vibration, so that the deformation of the structural element (1) is guided by the imposed vibration during deformation.
5. A device according to claim 4, characterized in that the imposed vibration is based on the mechanical modes of resonance of the structural element (1).
6. A device according to claim 5, characterized in that the actuators (2) are embodied by any of the elements: piezo-electric components, electrostriction components, magnetostriction components, components . based on electro-active material or storage material, and components that employ electromagnetic or electro-electro interference.
7. A device according to claim 6, characterized in that activation of the actuators (2) is initiated by collision detection devices (4), such as motion detectors or accelerometers.
8. A device according to claim 7, characterized in that the collision detection devices (4) are connected to a control unit (5) comprising a microprocessor, which commands the actuators (2) to impose forces on the structural element (1) according to a predetermined pattern.
9. A device according to any of the above claims, characterized in that the structural element (1) is embodied, in a collision situation, by an energy absorbing structure in a vehicle or other entity.
PCT/SE2000/001716 1999-09-15 2000-09-05 Method and device for active control of deformation behavior for structural elements WO2001019666A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU74649/00A AU7464900A (en) 1999-09-15 2000-09-05 Method and device for active control of deformation behavior for structural elements

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9903280-7 1999-09-15
SE9903280A SE514790C2 (en) 1999-09-15 1999-09-15 Method and apparatus for actively controlling deformation patterns for structural elements

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WO2001019666A1 true WO2001019666A1 (en) 2001-03-22

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1440867A1 (en) * 2003-01-24 2004-07-28 Ford Global Technologies, Inc. Structural design component for automotive vehicles
EP1498343A3 (en) * 2003-07-18 2005-01-26 Honda Giken Kogyo Kabushiki Kaisha Apparatus for controlling rigidity of vehicle body
WO2013104652A1 (en) 2012-01-13 2013-07-18 A2 Research Ab A method and a device to start and sustain structural vibrations in a structural component

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4050537A (en) * 1973-12-22 1977-09-27 Dr. Ing. H.C.F. Porsche Aktiengesellschaft Installation for the energy absorption of vehicles
EP0788930A1 (en) * 1996-02-09 1997-08-13 Morton International, Inc. Stiffening system for structural member of motor vehicle frame
WO1998022327A1 (en) * 1996-11-21 1998-05-28 Ab Volvo Front structure in a vehicle

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4050537A (en) * 1973-12-22 1977-09-27 Dr. Ing. H.C.F. Porsche Aktiengesellschaft Installation for the energy absorption of vehicles
EP0788930A1 (en) * 1996-02-09 1997-08-13 Morton International, Inc. Stiffening system for structural member of motor vehicle frame
WO1998022327A1 (en) * 1996-11-21 1998-05-28 Ab Volvo Front structure in a vehicle

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1440867A1 (en) * 2003-01-24 2004-07-28 Ford Global Technologies, Inc. Structural design component for automotive vehicles
EP1498343A3 (en) * 2003-07-18 2005-01-26 Honda Giken Kogyo Kabushiki Kaisha Apparatus for controlling rigidity of vehicle body
WO2013104652A1 (en) 2012-01-13 2013-07-18 A2 Research Ab A method and a device to start and sustain structural vibrations in a structural component

Also Published As

Publication number Publication date
SE514790C2 (en) 2001-04-23
SE9903280L (en) 2001-03-16
SE9903280D0 (en) 1999-09-15
AU7464900A (en) 2001-04-17

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