Granular container protector for protecting impulse
The present invention discloses a granular container protector for protecting impulse comprising a plurality of granular media each having a certain elastic property and a certain mass; wherein the plurality of granular media is arranged one-dimensionally into a plurality of sections, each section including one or more granular medium having same elastic property and same mass; wherein the plurality of sections is arranged in a manner that a ratio of mass to elastic property of the granular media in each section decreases toward a central section from both side sections; wherein the plurality of sections is arranged to be a mirror image about the central section; and wherein the side sections and the central section form walls of the granular container protector.
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This application claims priority to Korean Patent Application No. 10-2005-0021244 filed on Mar. 15, 2005, which is incorporated in its entirety by this reference.
TECHNICAL FIELDThe present invention relates to a granular container protector for protecting impulse. More specifically, the present invention relates to a granular container protector for protecting impulse which lessens a big external impulse effectively by disintegrating it into a plurality of small impulses and releasing the small impulses little by little with time lag, using propagation characteristics of the impulse in a granular chain.
DISCUSSION OF RELATED TECHNOLOGYGenerally, it is a very important problem in a daily life to protect lives and personal properties from fatal disasters such as automobile collision, and gas explosion, etc. It becomes high interests in terms of an industrial aspect to lessen various kinds of mechanical impacts coming from outside as can be seen from various kinds of sports appliances such as a protective helmet or a tennis racket. In addition, it is also very important in an army to lessen impulses caused by a bomb explosion or military arms.
One possible effective protection method against an external impulse is to confine the impulse into a specific region. However, it is practically impossible to confine the impulse in a specific region perfectly and permanently. In the meanwhile, it is possible that one may construct an effective protector that confines a strong impulse inside it for a short time, makes the strong impulse into a plurality of weak impulses, and then releases them outside from the protector little by little with time lag. This kind of protection mechanism may be realized in a specially prepared granular chain.
Granular matter is ubiquitous around us and in our daily life. However, fundamental research has not been made much because of its complication and nonlinear nature. It has been proved analytically and numerically that the propagating mode in the granular chain with power-law type contact force, i.e., F ∝ δP, where δ is the squeezed distance between neighboring grains, is a solitary wave. The solitary wave in a granular chain with Hertzian contact force having p= 3/2 can be described by a soliton in a continuum limit. Some of soliton properties predicted by theory have been demonstrated by experiments.
Interestingly, this soliton or the solitary wave in a granular chain shows anomalous features of propagation when it passes an interface of a granular chain composed of different granules, which are discriminated by mass and elastic property. A known anomalous feature of the wave propagation in the granular chain is the total transmission of a solitary wave along with disintegration of the solitary wave into many smaller solitary waves when it passes the interface from the region of heavy granules to that of light granules where “heavy” means a larger value of m/η (where m is mass of a granule and η is an elastic property) and “light” means a smaller value of m/η, while neither disintegration nor total transmission occurs when it passes the interface from the region of light granules to that of heavy granules. The number of disintegrated solitary waves depends on the strength of pre-compression. An example of disintegration of a big solitary wave into smaller solitary waves is illustrated in
By using the above anomalous behaviors of total transmission which are propagating features of an impulse in a granular container composed of inhomogeneous granular chains, it is possible to confine incident impulse inside the granular container protector and to make a big solitary wave into a plurality of smaller solitary waves using the property of disintegration of an impulse at an interface. Thus, it is possible to reduce a strong impulse into many weak impulses inside the granular container protector thereby lessen the strong impulse effectively.
Therefore, the present invention is to provide a novel protector for protecting impulse by constructing a granular container having a specific arrangement. More specifically, a first aspect of the present invention is to provide a granular container protector for protecting impulse comprising a plurality of granular media each having a certain ratio of mass to elasticity; wherein the plurality of granular media is arranged one-dimensionally into a plurality of sections, each section composing of the same ratio of mass to elasticity; wherein the plurality of sections is arranged in a manner that a ratio of mass to elasticity of the granular media in each section decreases toward a central section from both side sections; wherein the plurality of sections is arranged to be a mirror image about the central section; and wherein the side sections form walls of the granular container protector; and wherein the central section can be replaced by materials that change the energy of impulse into heat.
A second aspect of the present invention is to provide a granular container protector for protecting impulse comprising a plurality of granules each having certain elasticity and a certain mass; wherein the plurality of granules is arranged one-dimensionally into a plurality of sections, each section having the same ratio of mass to elasticity; wherein the plurality of sections is divided into a first zone ranging from one side section to a central section and a second zone ranging from the other side section to the central section; wherein the plurality of sections is arranged in a manner that a ratio of mass to elasticity of the granules in the each section decreases in one same direction in the first zone and the second zone, respectively; and wherein the side sections and the central section form walls of the granular container protector.
Yet a third aspect of the present invention is to provide a three-dimensional granular container protector for protecting impulse, wherein the three-dimensional granular container protector is structured by stacking a plurality of the granular container protectors in accordance with the first and the second aspects described above in up and down directions and left and right directions.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings where same or similar reference numerals refer to the same structural elements.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 2 (a) and 2(d) illustrate a schematic diagram of a granular container protector for protecting impulse in accordance with the present invention.
FIGS. 2(c) and 2(e) illustrate schematic diagrams in order to compare with a granular container protector for protecting impulse illustrated in FIGS. 2 (a) and 2(d).
Hereinafter, the present invention is described in more detail with reference to preferred embodiments.
First, FIGS. 2(a) and 2(d) illustrate a schematic diagram of a standard form of the granular container protector for protecting impulse in accordance with the present invention. Further, FIGS. 2 (b), 2(c), and 2(e) illustrate schematic diagrams in accordance with the present invention in order to compare with a standard form of the granular container protector for protecting impulse illustrated in FIGS. 2 (a) and 2(d).
In FIGS. 2(a) to 2(e), circles, hatched octagons, and squares indicate p=1.5, p=2, and p=1, respectively and the ratio of mass to elastic property (i.e., m/η) is indicated as mass m of granules by setting the elasticity thereof to be a fixed value. In
Referring to
In an embodiment described above, although it is described and illustrated that three sections are included between walls of the granular container protector for protecting impulse of the present invention, it may be easily understood by a skilled person in the art that the number of section between the walls thereof may be any number having one or more when desired.
Further, in an embodiment illustrated in
FIGS. 2(b) and 2(c) are an example for performing a comparing experiment with a standard type granular container protector for protecting impulse as illustrated in
Hereinbelow, an effective protecting mechanism for protecting impulse in a granular container protector for protecting impulse in accordance with the present invention will be described. In a granular container protector for protecting impulse in accordance with the present invention illustrated in
The granular container protector for protecting impulse in accordance with the present invention must be practically a three-dimensional structure. However, a usual three-dimensional granular system has complicated distribution of force chains through which impulse may transmit. Accordingly, the nature of propagation of an impulse inside a three-dimensional granular container protector for protecting impulse does not show features appeared in a force chain system of one-dimensional granular container protector for protecting impulse of the present invention illustrated in
A protection from an impulse through a granular container protector for protecting impulse in accordance with the present invention may be understood by a numerical simulation on an equation of motion (1) of a grain written below:
mün=η[{δ0−(un−un−1)}p−{δ0−(un+1−un)}p] (1)
where δ0 is the displacement under pre-compression; ui is the displacement of the i-th grain from its initial equilibrium position due to an external perturbation; m is the mass of the grain; and η is the elastic constant of the grain depending on its radius, Young's modulus, and Poisson's ratio. The only parameter governing Equation (1) for a given pre-compression is the ratio m/η. As in the embodiments of the present invention, if a fixed value of η is given for all grains, different granules can be discriminated only by masses thereof. Therefore, light and heavy granules mean small and large values of m/η, respectively. Thus, it is easily understood by a skilled person in the art how masses of granules, an elastic property of granular medium, and a geometrical structure of granules may affect the results of the present invention.
In the embodiments of the present invention, most granules are chosen to be Hertzian contact force (i.e., p=3/2) which corresponds to a spherical shape. However, any skilled person in the art may understand that granules with irregular surfaces such as sand are close to another nonlinear contact, p=2. Further, a linear medium, p=1, is introduced in order to use for the walls of a granular container protector for protecting impulse. The properties of a propagating solitary wave inside a granular container protector for protecting impulse have been already studied in the art. In addition, a variety of modified type of a granular container protector for protecting impulse as illustrated in FIGS. 2(b) to 2(e) is provided in the present invention.
When using a stainless steel ball of diameter 1 mm as a grain, the value of η is 2.618×109(N/m3/2), the mass m=100 corresponds to a value of 2.36×10−3(Kg), and the velocity 10 corresponds to a value of 5.4×106(m/s) in Equation (1). In this embodiment, the time interval of snap shot is 0.40 μs and thus, the snap shot illustrated in
The energies of leading solitary waves leaving the granular container protector for protecting impulse appearing at the right and left ends of the snap shot illustrated in
The protection can be improved when the linear materials of the central section (wall) can be replaced by some dissipative materials that can transform the mechanical motions (i.e., mechanical energy) of granules into heat effectively. A typical dissipative material to be used for the present invention is sand or plastic. In case of plastic, it must be pulverized into particles, each having a coarse surface. Since the arrangement shown in
Meanwhile,
An effective protection against an external impact may be accomplished by using a granular container protector for protecting impulse of the present invention having an appropriate arrangement of m/η with a plurality of interfaces, because a big solitary wave can be disintegrated into a plurality of small solitary waves when it passes through an interface from a large granular medium having a larger value of m/η to a small granular medium having a smaller value of m/η. That is, it is possible to protect a big external impact by confining energy transmitted by a solitary wave inside the granular container protector and then releasing the energy in the form of a plurality of weak solitary waves little by little thereby disintegrating the big external impact effectively.
Although the present invention describes a granular container protector using a phenomenon of confining an impact appearing in a grain chain, it is easily conceivable by a skilled person in the art that other systems such as a electromagnetic system and a molecular biological chain may also possibly protect an external impact as accomplished by the granular container protector of the present invention, if non-linear interactions with a power-law type between structural elements of a system exist. Therefore, the spirit of the present invention is not only applied to a granular container protector, but also applied to any system with a power-law type described in the present invention.
As various modifications could be made in the constructions and method herein described and illustrated without departing from the scope of the present invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalent.
Claims
1. A granular container protector for protecting impulse comprising a plurality of granules each having certain elasticity and a certain mass;
- wherein said plurality of granules is arranged one-dimensionally into a plurality of sections, each section including a number of granules having the same elasticity and mass;
- wherein said plurality of sections is arranged in a manner that a ratio of mass to elasticity of said granules in each section decreases toward a central section from both side sections;
- wherein said plurality of sections is arranged to be a mirror image about said central section; and
- wherein said side sections and said central section form walls of said granular container protector.
2. The granular container protector as claimed in claim 1, wherein the number of section between said both side sections and said central section is three, respectively, and the number of said granules in each section are the same.
3. The granular container protector as claimed in claim 2, wherein said ratio of mass to elasticity of said granules in said plurality of sections is assigned to be 2.0, 1.0, 0.3, 0.1, 2.0, 0.1, 0.3, 1.0, and 2.0 starting from either one of said both side sections.
4. The granular container protector as claimed in claim 1, wherein each of said plurality of sections includes 20 granules.
5. The granular container protector as claimed in claim 2, wherein each of said plurality of sections includes 20 granules.
6. The granular container protector as claimed in claim 3, wherein each of said plurality of sections includes 20 granules.
7. The granular container protector as claimed claim 1, wherein each of said plurality of sections includes 50 granules.
8. The granular container protector as claimed claim 2, wherein each of said plurality of sections includes 50 granules.
9. The granular container protector as claimed claim 3, wherein each of said plurality of sections includes 50 granules.
10. The granular container protector as claimed in claim 1, wherein said central section can be replaced by a dissipative material changing energy of said impulse into heat.
11. The granular container protector as claimed in claim 10, wherein said dissipative material is sand or plastic.
12. A granular container protector for protecting impulse comprising a plurality of granules each having certain elasticity and a certain mass;
- wherein said plurality of granules is arranged one-dimensionally into a plurality of sections, each section including a number of granules having the same elasticity and mass;
- wherein said plurality of sections is divided into a first zone ranging from one side section to a central section and a second zone ranging from the other side section to said central section;
- wherein said plurality of sections is arranged in a manner that a ratio of mass to elasticity of said granules in said each section decreases in one same direction in said first zone and said second zone, respectively; and
- wherein said side sections and said central section form walls of said granular container protector.
13. The granular container protector as claimed in claim 12, wherein the number of section between said both side sections and said central section is three, respectively.
14. The granular container protector as claimed in claim 13, wherein said ratio of mass to elasticity of said granules in said plurality of sections is assigned to be 2.0, 1.0, 0.3, 0.1, 2.0, 0.1, 0.3, 1.0, and 2.0 starting from either one of said both side sections.
15. The granular container protector as claimed in claim 12, wherein each of said plurality of sections includes 20 granules.
16. The granular container protector as claimed in claim 13, wherein each of said plurality of sections includes 20 granules.
17. The granular container protector as claimed in claim 14, wherein each of said plurality of sections includes 20 granules.
18. The granular container protector as claimed in claim 15, wherein each of said plurality of sections includes 20 granules.
19. The granular container protector as claimed in claim 12, wherein each of said plurality of sections includes 50 granules.
20. The granular container protector as claimed in claim 13, wherein each of said plurality of sections includes 50 granules.
21. The granular container protector as claimed in claim 14, wherein each of said plurality of sections includes 50 granules.
22. The granular container protector as claimed in claim 15, wherein each of said plurality of sections includes 50 granules.
23. The granular container protector as claimed in claim 12, wherein said central section can be replaced by a dissipative material changing energy of said impulse into heat.
24. The granular container protector as claimed in claim 23, wherein said dissipative material is sand or plastic.
25. A three-dimensional granular container protector for protecting impulse, wherein said three-dimensional granular container protector is structured by stacking a plurality of said granular container protectors recited in claim 1 in up and down directions and left and right directions.
26. A three-dimensional granular container protector for protecting impulse, wherein said three-dimensional granular container protector is structured by stacking a plurality of said granular container protectors recited in claim 12 in up and down directions and left and right directions.
Type: Application
Filed: Mar 15, 2006
Publication Date: Sep 21, 2006
Applicant: Seoul National University Industry Foundation (Seoul)
Inventor: Jongbae Hong (Kyunggi-Do)
Application Number: 11/375,864
International Classification: F41H 5/02 (20060101); F42B 33/00 (20060101); F42D 5/00 (20060101); B65D 81/02 (20060101);