WO2008135394A1

WO2008135394A1 - Impact test device for testing how an object behaves in an impact

Info

Publication number: WO2008135394A1
Application number: PCT/EP2008/054950
Authority: WO
Inventors: Christophe Grolleron
Original assignee: Renault S.A.S.
Priority date: 2007-04-24
Filing date: 2008-04-23
Publication date: 2008-11-13
Also published as: FR2915579B1; FR2915579A1

Abstract

Impact test device (1) for testing how an object (2) behaves in an impact, comprising: a first element (5) that can be moved until it collides with the object that is to be tested, and - a thrusting means (11) for moving the first element, characterized in that the first element (5) comprises a removable means against which the thrusting means comes into contact to allow the first element to be set in motion during a high-energy test and in that the thrusting means comprises a first guide means (10) for guiding a second element (8) and allows the latter to be moved until it collides with the object that is to be tested when the removable means is removed for a low-energy test.

Description

IMPACT TEST DEVICE FOR TESTING HOW AN OBJECT BEHAVES IN

AN IMPACT

The invention relates to an impact test device for testing how an object behaves in an impact.

Various types of impact test to which structures that are to be tested can be subjected are known. These various types of test are carried out using various dedicated types of device.

In the field of motor vehicles and, more specifically, in the field of motor vehicle impact testing using significant amounts of energy, impact test devices employing moving sleds are known, for example, from documents US 6 675 631 and US 5 483 845. These sleds are set in motion by the action of a pneumatic actuator. The dynamic characteristics of the sled can be controlled by this pneumatic actuator.

An impact test catapult for launching a motor vehicle against an obstacle is also known, from document JP 2004-257734.

A test device having a pendulum hammer structure for subjecting vehicle parts to impacts is also known, from document US 2004/0103713.

In the field of low-energy impact testing, gravity impact test devices are known, from documents JP 2003-156421, JP 2002-318181 and JP 2006-200912. In these devices, the objects are positioned a certain height above a collision surface and are then released so that they fall onto this surface. An impact test device in which it is a hammer which is released from a determined height and which falls onto a test specimen is also known, from document JP 11-230879. The impact energy can be adjusted by altering the height from which the hammer is released or by altering the mass of the hammer.

Finally, an impact test device with a pendulum hammer structure and equipped with a high-speed camera for studying the impacts is known from application EP 1 615 016.

All these devices of the prior art are highly specific to certain types of impact testing or to a restricted range of impact energies. They in particular allow tests to be carried out under relatively fixed conditions regarding the speed of impact, the masses set in motion and the dimensions of the test specimens that can be tested.

However, in certain industries, such as in the motor vehicle industry, where there is a need to carry out an enormous range of impact tests, and particularly a range of impact tests using highly varying amounts of energy, it is necessary to have access to a vast array of test devices or to resort to the services of external companies that have specialized in the study of impacts. This is because in the field of motor vehicles, impact tests have to be performed on whole vehicles and the energies dissipated are therefore of the order of 100 kJ. At the same time, impact tests have to be performed on isolated component parts or on instrumented test dummies, where the energies dissipated are then of the order of 100 J. Hence, there is a need for an impact test device of a simple structure that allows a broad range of impact tests to be performed in terms of the amount of energy dissipated. A device such as this would make it possible appreciably to increase the test capabilities of an industrial structure equipped therewith and would allow more in-depth testing to be carried out, and in particular would allow instrumented tests to be performed that occupy test devices for longer periods of time. In that way, it would be possible to gain a better understanding of the impact phenomena and the way in which the materials subjected to impacts behave.

An object of the invention is to provide an impact test device that gets around the aforementioned disadvantages and improves the impact test devices known from the prior art. In particular, the invention proposes an impact test device of a simple structure that allows a broad range of impact tests to be performed, particularly in terms of the amount of energy dissipated.

The invention more specifically relies upon an impact test device for testing how an object behaves in an impact, comprising:

- a first element that can be moved until it collides with the object that is to be tested, and

- a thrusting means for moving the first element, characterized in that the first element comprises a removable means against which the thrusting means comes into contact to allow the first element to be set in motion during a high-energy test and in that the thrusting means comprises a first guide means for guiding a second element and allows the latter to be moved until it collides with the object that is to be tested when the removable means is removed for a low- energy test.

According to an alternative form, the first element may comprise an aperture through which the thrusting means can move, the removable means allowing this aperture to be blanked off so that a high-energy test can be performed.

According to another alternative form, the removable means may comprise a cylinder equipped with a shoulder and the said blanking piece can move in the aperture until the shoulder comes into contact with the first element .

According to another alternative form, the thrusting means may comprise a shaft that can be moved in a translational movement and the end of which is intended to come into contact with the removable means in order to perform high-energy tests or with the second element when the removable means is removed in order to perform low-energy tests.

According to another alternative form, the first element may be a sled.

According to another alternative form, the test device may comprise a second guide means such as rails for guiding the translational movement of the first element.

According to another alternative form, the first guide means may comprise a bore made at the end of the shaft and collaborating with an extension made on the second element, the extension being a sliding fit in the said bore .

According to another alternative form, the thrusting means may comprise a pneumatic or hydraulic actuator.

The attached drawing depicts, by way of example, one embodiment of an impact test device according to the invention .

Figures 1 to 3 are schematic views of one embodiment of an impact test device according to the invention depicted in various phases of an impact test employing a significant amount of energy.

Figures 4 to 6 are schematic views of the same embodiment of an impact test device according to the invention depicted in various phases of an impact test employing a small amount of energy.

Figure 7 is a perspective view of the sled of this embodiment .

An impact test device 1 according to the invention is described hereinbelow with reference to Figures 1 to 6 which depict it in various test phases employing two different amounts of impact energy.

The impact test device mainly comprises a rigid structure 16, a thrusting device 11, a means 13 for clamping an object 2 that is to be tested, a first element 5 that can be moved and is intended to be brought into collision with the object that is to be tested during tests performed at high energy, a guide means 6 for guiding the first element, a removable second element 8 that can be moved and is intended to be brought into collision with the object that is to be tested and a guide means 10 for guiding this second element during tests performed at low energies.

A definition of high-energy and low-energy tests is given at the end of the description.

The thrusting device 11 comprises a shaft 4 that can be moved in a translational movement in a first direction and, for example, a pneumatic or hydraulic actuator 3 for setting this shaft in motion. The shaft 4 for this purpose is mechanically connected to the actuator or constitutes the rod of the actuator. The pneumatic or hydraulic actuator may, for example, be of the type described in document US 5 483 845 or of the type described in document US 6 675 631. These documents are incorporated by reference into the present application. The end 17 of the shaft 4 is intended to come into contact with the first element 5 during high-energy tests or the second element 8 during low-energy tests in order to impart a force to it and thus set it in motion in the direction of the object that is to be tested. The thrusting device is secured to the structure 16 of the test device.

The clamping means 13 is also secured to the structure 16 of the test device. It may in particular comprise any known positioning, holding and clamping means needed for positioning and holding the object that is to be tested.

The guide means 6 is also secured to the structure 16 of the test device. It allows the first element 5 to be guided in its translational movement in the first direction. It may comprise a rail on which a sled 5 that constitutes the first element 5 slides or rolls.

The first element 5, depicted in Figure 7, comprises a bore 12 passing through it in the first direction. This bore lies along the axis of the shaft 4 and has a diameter greater than that of the shaft. Thus, the shaft can move freely through the first element 5. The bore 12 and the shaft 4 are for example cylinders of revolution. The movement of the shaft 4 through the first element may, however, be prevented by a removable means 7 that blanks off the bore 12 so as to allow high-energy tests to be performed. This means for example consists of a cylinder 14 of a diameter smaller than that of the bore, this cylinder comprising a shoulder 15 which comes into abutment against a face 18 of the first element 5. As seen previously, when it is positioned on the first element, the movement of the shaft in the bore is prevented. Thus, the end 17 of the shaft 4 comes into contact with a face 19 of the removable means and can set the first element 5 in motion by applying a mechanical action to it.

Impact tests requiring significant amounts of energy are performed with the test device configured with the removable means in position on the first element. A test of this type is, for example, depicted in Figures 1 to 3. In Figure 1, the shaft 4 is retracted, in an initial position, stationary and in contact with the removable means in position on the first element. In Figure 2, the shaft 4 has left its initial position and is in motion. It sets the first element 5 in motion by means of the mechanical action it exerts thereon. In Figure 3, the shaft 4 has reached the end of its travel. It is immobilized in the deployed position. However, the first element is still in motion because of the energy imparted to it by the shaft 4 and because of its inertia. The first element is on the point of colliding with the object that is to be tested.

The shaft 4 at its end comprises the means of guiding a removable second element 8 that can be moved and is intended to be made to collide with the object that is to be tested. The guide means allows the second element to be guided in a translational movement in the first direction. The guide means comprises a bore 10. It is intended to collaborate with an extension 9 made on the second element. This extension for example consists of a cylindrical shaft of a diameter smaller than that of the bore 10. Thus, the second element is mounted or fitted as a sliding fit in the bore 10.

The impact tests that require low impact energies are performed with the test device configured with the removable means removed and the removable second element 8 in position at the end of the shaft 4. A test of this type is depicted for example in Figures 4 to 6. In Figure 4, the shaft 4 is retracted, in an initial position, stationary and in contact with the second element. The first element 5 has been moved to the end of its travel on the opposite side to the object to be tested. Thus, the shaft 4 passes through the first element. In Figure 5, the shaft 4 has left its initial position and is in motion. It imparts motion to the second element 8 through the mechanical action that its end 17 exerts on a face 20 of the second element. In Figure 6, the shaft 4 has reached the end of its travel. It is immobilized in the deployed position. However, the second element 8 is still in motion because of the energy imparted to it by the shaft 4 and because of its inertia. The second element is guided by the cooperation between the bore 10 and the extension 9 and is on the point of colliding with the object that is to be tested.

Use of the first element 5 or of the second element 8 to test the object means that impact tests can be performed that employ widely varying amounts of energy. For example, the first element may consist of a sled of a mass ranging between 350 kg and 1000 kg. The use of an element such as this makes it possible to cover a range of impact energies extending from 5 kJ

(approximately equivalent to 350 kg propelled at 5 m/s) to 100 kJ (approximately equivalent to 1000 kg propelled at 14 m/s), hereinabove termed "high energies" .

For example, the second element 8 may consist of a mass of between 10 kg and 50 kg. The use of such elements makes it possible to cover a range of impact energies extending from 100 J (approximately equivalent to 10 kg propelled at 5 m/s) to 6 kJ (approximately equivalent to 50 kg propelled at 15 m/s) hereinabove termed "low energy" .

Claims

1. Impact test device (1) for testing how an object (2) behaves in an impact, comprising: - a first element (5) that can be moved until it collides with the object that is to be tested, and a thrusting means (11) for moving the first element, characterized in that the first element comprises a removable means (7) against which the thrusting means comes into contact to allow the first element to be set in motion during a high-energy test and in that the thrusting means comprises a first guide means (10) for guiding a second element (8) and allows the latter to be moved until it collides with the object that is to be tested when the removable means is removed for a low-energy test.

2. Test device according to the preceding claim, characterized in that the first element comprises an aperture (12) through which the thrusting means can move when a low-energy test is being performed, and in that the removable means allows this aperture to be blanked off so that a high- energy test can be performed.

3. Test device according to the preceding claim, characterized in that the removable means comprises a cylinder (14) equipped with a shoulder (15) and the said blanking piece can slide in the aperture until the shoulder comes into contact with the first element (5) .

4. Test device according to one of the preceding claims, characterized in that the thrusting means comprises a shaft (4) that can be moved in a translational movement and the end of which is intended to come into contact with the removable means (7) in order to perform high-energy tests or with the second element (8) when the removable means is removed in order to perform low-energy tests .

5. Test device according to one of the preceding claims, characterized in that the first element (5) is a sled.

6. Test device according to one of the preceding claims, characterized in that it comprises a second guide means (6), such as rails, for guiding the translational movement of the first element

(5) .

7. Test device according to one of the preceding claims, characterized in that the first guide means (10) comprises a bore made at the end of the shaft (4) and collaborating with an extension (9) made on the second element (8), the extension being a sliding fit in the said bore.

8. Test device according to one of the preceding claims, characterized in that the thrusting means comprises a pneumatic or hydraulic actuator (3) .