JPH07243796A - Shock absorption fender - Google Patents

Abstract

PURPOSE: To obtain a lightweight shock absorbing protective material excellent in strength and flexibility in which impact of a flying object, e.g. a gun, fragments of a shell, a stone, and the like, can be absorbed and scattered very effectively by employing a panel of rigid structure having multiple polygonal cells each having three to eight side faces. CONSTITUTION: A shock absorbing protective material is bonded to an outer metal surface 12, e.g. a body part forming the outermost region of an armored truck subjected to direct attack. A composite material 13 contiguous to the surface 12 is a cloth in the form of matrix of high strength modulus resin. A polygonal panel 15 abuts on a thermoplastic rein layer 14 and each cell part 3 has eight side faces. The multi-side structure is rigid and made of high modulus synthetic resin or metal. The cell parts serve as an interlocked energy absorbing means and a spacer providing an air gap when they are open. The cell part is an independent cavity having diameter of about 0.1-8 inch and coupled with the entire panel 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a means for improving impact resistance and kinetic energy absorption characteristics of protective materials such as bulletproof vests, helmets, armored vehicle members, building members and building structures. More specifically, when used alone or in combination with conventional protective materials and / or protective structures, it more effectively absorbs impact from projectiles such as bullets, debris such as shells and stones. It also provides a diffuser protection structure.

[0002]

BACKGROUND OF THE INVENTION Protective equipment for the human body has been used by military personnel, police officers and the like as a protective means to protect themselves from bullets, shell fragments and other flying objects. The structure of personal protective equipment must be lightweight and flexible, depending on its intended use. Protective equipment for the human body is required to protect the body from flying objects, and also to be able to suppress the deformation of the back side of the protective equipment and the impact energy to the human body to a minimum, and to have a lightweight and flexible structure. To be done.

Conventional armored vehicles utilize protective panels and / or panels of various materials such as metals, ceramics, composite structures, glass fibers, nylon, aramid fibers, and semi-crystalline polyolefin structures. . The armored vehicle protective materials and components must be lightweight structures capable of combating anticipated flying threats. Such a protective structure has a structure that transfers the kinetic energy of a moving projectile and must not penetrate the projectile and the debris generated by an explosion etc. I have to.

That is, a protective material for an armored vehicle or the like is intended to provide a lightweight structure in which a projectile and its fragments do not penetrate. Such a protective structure for an armored vehicle or the like is used for various vehicles such as a land vehicle, an aircraft and a ship.

A defense structure for combating flying objects such as projectiles is intended to achieve all or part of the following. 1) Increase the contact area of the projectile that comes into contact with the protective material,
The projectile is deformed at the time of impact in order to slow the impact and speed of travel. 2) Force the power of the projectile to slow down, change the direction of travel (yaw) or destroy it, and destabilize the energy of the projectile. 3) Use a strong protective material that achieves a marginal condition and adopt a sufficient thickness. That is, sufficient conditions are adopted so that the projectile does not penetrate the protective material.

Protective material manufacturing technology further employs a thinly divided layered body within a protective structure of hard or relatively rigid material to effectively transfer the kinetic energy of a projectile impinging on the divided layered body. To provide a structure for absorption by. However, this technique also has its weaknesses. Another protective material manufacturing technique employs a structure in which metal members and the like are held in a metal matrix so as to deflect the projectile from its normal course in the event of a collision.

US Pat. No. 2,723,214
In order to exert a protective effect, No. 3 forms at least the outermost layer of the protective material with a plurality of relatively compact rigid plate materials having sufficient strength without being penetrated or greatly curved, It is taught that when the individual plates are impacted by a projectile, etc., the plates move substantially along the projecting direction along with the projectile, and transfer the impact force to the adjacent layer or elastic material. is doing. As a result, the kinetic energy of the projectile is converted to potential energy stored in the elastic material layer that is deformed by the projectile. The converted potential energy is reconverted into kinetic energy when the forward movement of the projectile (on the body side) is stopped, accelerating the projectile in the opposite outward direction. Therefore,
The impact force transmitted to the wearer of the protective equipment on the innermost (body side) surface of the protective material is only the remaining portion of the force that remains without being absorbed by the deformation of the elastic layer, and such residual portion is fired. There is a big difference from the impact force applied to the small area where the body collides, and it spreads over a wide range and is transmitted to the wearer as a weak impact force.

[0008]

However, in reality, the above-mentioned type of protective material is effective for a projectile in which the tip of a flying object flying at a high speed is a rigid body, but is flexible and lightweight. It is hard to become a body. However, the presently available materials forming the flakes used for the outermost layer of the protective material as described above sometimes occur in the case where the protective performance is not completely functioned due to dissolution or disintegration, and flying at high speed. It does not provide complete protection from the impact of a projectile with a hard tip. Therefore, when this type of protective material is impacted by a projectile with a hard tip flying at high speed, at least the outermost layer of the collided plate piece, and possibly some of the inner layer, will be destroyed. Before fully absorbing kinetic energy and converting it to heat energy, sound energy, plate piece deformation energy, etc., the plate material layer, which is the intermediate layer of the protective material, cannot be moved together with the flying projectile and is deformed or Destroyed. Therefore, in practice, it reduces the energy transmitted through the protective material to the wearer to a minimum, so that more than the number of board layers would be required if no intermediate board layers were assumed to be destroyed. Layers are needed. However, the number of board layers that can be employed is limited due to flexibility and weight limitations. Flexibility issues are discussed in US Pat. No. 2,723,214, where the protective material surface (inner surface) is adjacent to the wearer.
In order to be a rigid body that does not substantially deform, considering that when the individual plate areas of the intermediate continuous layer increase by a factor of 4, the practical limit is about 5 plate layers. To be understood.

Further, when a material, which is usually an elastic body, used in the composite protective material is collided with a high-speed flying object, it acts as a rigid body against the adjacent outer layer, and is deformed flexibly. Therefore, it does not absorb shock sufficiently and does not efficiently convert kinetic energy of flying objects into potential energy. The contents of U.S. Pat. No. 4,186,648 issued to Klossen et al. Are incorporated herein by reference. This patent discloses a protective material structure in which the structure of the present invention can be employed. The present invention teaches the use of a plurality of woven fabric layers made of polyester resin fibers used and supported in an elastic matrix.

US Pat. No. 2,697,054 to Dietz et al. Discloses a thin layer plastic structure that absorbs kinetic energy, particularly flying fragments. U.S. Pat. No. 4,732,944 is issued by Artistic Glass Products, Inc. to
Disclosed is an ionomer resin film sold under the trademark IFLEX ". The present invention uses this film.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to an improved protective material structure. This improvement involves the use of at least one panel with the ability to absorb kinetic energy. This panel has a rigid metal structure or a high modulus synthetic resin structure forming a large number of connected polygonal cell parts (polyhedral cylindrical structure) having 3 to 8 side surfaces. The cell portion is an independent cavity having a diameter of about 0.1 to 8 inches (0.25 cm to 20.3 cm) and constitutes a sheet of cell portions bonded together in a matrix over the entire panel.

[0012] Preferably, the cell portions of the panel are honeycomb shaped (ie, a hexagonal matrix), and when used in human body armor, these cell portions are about 0.1 to 1 parts.
The diameter is inch (0.25 cm to 2.54 cm) and is about 0.003 to 0.250 inch (0.0076).
2 cm to 0.635 cm), preferably about 0.03
Has a wall thickness of up to about 0.025 to 12.0 inches (0.0635 cm to 30.48 cm), and preferably about 3.0 inches (7.
It has a core thickness of up to 62 cm. Advantageously, this panel is used primarily with armor constructions that form the anti-projectile outer layer (i.e., the attack-back surface, which is the impact surface that is impacted).

In the case of human body armor, this panel is located either between the armor material layers or on the back side of the armor material layer to improve resistance to projectiles and to disperse impact energy. The panel also provides voids between the materials and layers employed in the armor construction. The presence of voids between individual armor materials and layers dramatically improves the anti-projectile properties of that modality. The panels of the present invention are very light weight and provide a multi-protective layer and a means of bonding (fixing) the protective material when used as a void filler.

As used herein, the term "rigid body" refers to a semi-flexible, semi-rigid structure having sufficient strength without spontaneously collapsing. To make the improved armor of the present invention, at least one substantially rigid layer is joined by some means to an existing armor structure. The resulting product can retain its shape by itself and has impact resistance. When there is only one layer, this panel usually forms the inner part of the composite. That is, a portion that is not exposed to the outside, for example, a portion that is not directly subjected to the impact of flying objects. When there is more than one layer, a simple composite is formed, for example, the panel of the invention is sandwiched between two layers, which structure is useful, for example, when used as a helmet. Other shaped composites are useful as well,
For example, a composite of multiple alternating layers of panels and fiber layers for a rigid projectile would be useful.

To form an improved vehicle armor, one or more panels of the present invention are bonded or secured parallel to the inside of the outermost rigid armor material to reduce kinetic energy transfer. , Prevent the destruction of the protective layer and avoid the deformation of the entire protective material. The panels of the invention can be used as voids between successive layers of protective material or between protective materials. Voids between armor material layers are generally recognized as an effective means of minimizing the transfer and diffusion of energy that prematurely destroys successive armor material layers upon impact of a flying object. Honeycomb panels are lightweight, structurally stiff cavities that isolate and dissipate impacts (diffuse strain forces) and are integrally bonded to layers of composite armor. Is something that can be done. As used herein, "penetration of needles" means the penetration of knives, ice picks, sharp weapons, shell fragments, and the like.

Specifically, the invention according to claim 1 is
"A protective structure having at least one panel for absorbing kinetic energy, the panel comprising 3 to 8
A protective structure having a multiplicity of polygonal cell parts having side faces, the cell parts having a diameter of about 0.1 to 8 inches and provided on the entire surface of the panel. Structure. It is.

The invention according to claim 2 is "the protective structure according to claim 1, wherein the cell portion of the panel is opened in a direction of impact." The invention according to claim 3 is "the protective structure according to claim 2, wherein the cell portion of the panel has a honeycomb shape." The invention according to claim 4 is "the protective structure according to claim 1, wherein the polygonal cell portion is welded." The invention according to claim 5 is
"The thickness of the side wall of the cell portion is about 0.003 to 0.25.
The protective structure according to claim 1, wherein the protective structure is 0 inch. It is.

The invention according to claim 6 is the protective structure according to claim 1, wherein the core thickness of the cell portion is about 0.025 to 12.0 inches. The invention according to claim 7 is "the protective structure according to claim 6, wherein the core thickness is about 0.025 to 3.0 inches." The invention described in claim 8 is "the protective structure according to claim 1, wherein the panel is made of metal." The invention according to claim 9 is "the protective structure according to claim 1, wherein the panel is made of a high modulus synthetic resin."

According to a tenth aspect of the present invention, "the high modulus synthetic resin is selected from the group consisting of polyurethane, p-aramid, ionomer, polycarbonate, fluorine-treated hydrocarbon, polyolefin and polyetherimide. 10. The protective structure according to claim 9, wherein the protective structure is provided. The invention according to claim 11 is
2. The protective structure according to claim 1, wherein the panel includes at least one strong high modulus resin layer on at least one side of the polygonal cell portion. The invention described in claim 12 is “the protective structure according to claim 11, wherein the resin layer is a thermoplastic resin layer”.

The thirteenth aspect of the present invention is the protective structure according to the twelfth aspect, wherein the thermoplastic resin is selected from the group consisting of polycarbonate and ionomer. The invention according to claim 14 is
12. The protective structure according to claim 11, wherein the cell portion contains a particulate friction material. The invention according to claim 15 is a "protective structure, comprising at least one projectile-resistant outer layer and at least one kinetic energy absorbing inner layer, the inner layer comprising from 3 to Having at least one rigid panel with a number of joined polygonal cell parts having eight sides, said cell parts having a diameter of about 0.1 to 1 inch; Is about 0.0
A protective structure characterized by being from 03 to 0.030 inches. It is.

The invention according to claim 16 is the "protective structure according to claim 15, characterized in that the panel has a honeycomb shape." The invention according to claim 17 is
16. The protective structure of claim 15, wherein the panel is sandwiched by a pair of thermoplastic layers. The invention according to claim 18 is "the protective structure according to claim 15, wherein the panel is made of a high modulus synthetic resin." The invention according to claim 19 is "the protective structure according to claim 18, wherein the plurality of polygonal cell portions are welded."
The invention according to claim 20 is "the protective structure according to claim 15, characterized in that the cell portion contains an inorganic sandy body in an amount sufficient to prevent penetration of the needle-shaped material." is there.

It is an object of the present invention to provide a shock absorbing panel in the structure of the armor. Another object of the invention is to provide spacer means for forming voids in the armor between different layers of armor material. Yet another object of the present invention is to provide an energy absorbing layer for a lightweight personal protective material. Other objects of the present invention will be made clearer and a more detailed understanding can be obtained from the description of the preferred embodiments described below with reference to the accompanying drawings.

[0023]

With the above structure, the shock absorbing protective material of the present invention is
It is excellent in flexibility and is lightweight because it has a cell part, and very effectively absorbs and diffuses impacts from flying objects such as bullets, fragments of shells and stones, etc. It surely protects. Further, in the invention according to claim 2, the shock is efficiently and surely absorbed and diffused in the cell portion. According to the invention described in claim 3, the invention is lightweight and extremely excellent in strength. In the invention according to claim 4, the cell parts are firmly bonded to each other, and the overall strength is excellent. In the invention described in claims 5 to 7, the weight and strength of the cell portion are appropriately set.

According to the invention described in claim 8, the panel has excellent strength and is easy to manufacture, and aluminum, iron, other alloys or the like can be selected according to the purpose. According to the ninth and tenth aspects of the present invention, the panel is extremely lightweight, has excellent strength, and is easy to manufacture. According to the invention of claim 11, the strength of the panel is very excellent.

According to the twelfth and thirteenth aspects of the present invention, the manufacturing is easy and the shock absorption is excellent. According to the fourteenth aspect of the present invention, penetration of the needle-shaped material can be very effectively prevented. According to the fifteenth aspect of the invention, the kinetic energy of the projectile or the like can be effectively absorbed. In the sixteenth aspect of the present invention, the invention is lightweight and extremely excellent in strength. According to the invention of claim 17, the strength of the panel is very excellent. According to the eighteenth aspect of the present invention, it is lightweight, easy to manufacture, and excellent in shock absorption. In the invention described in claim 19, the cell portion is integrated and the overall strength is extremely excellent. According to the invention of claim 20, it is possible to very effectively prevent penetration of the needle-shaped material.

[0026]

The invention will be understood in more detail by the following description and the accompanying drawings. Although specific terms are used in the text for clarity of explanation, these terms are used only for the specific structure of the present invention selected for the description of the drawings. Explain the drawing. The lightweight armor structure 10 shown in FIGS. 1 and 2 includes an outer metal surface 1
2. For example, it is adhered to the body portion forming the outermost region of the armored vehicle that is directly subjected to impact. The composite 15 adjacent the surface 12 is a resin matrix woven fabric.
This resin matrix may be the same as or different from the resin.

This resin is a high strength modulus resin (high s
trength modulus resin), for example, ethylene-
Acrylate or methacrylate copolymer (SURL
YN), vinyl ester phenol,
Bismaleimides, polyamides, and even strong medium modulus thermoplastics, ionomers (ie cross-linked ethylene-methyl acrylate or methyl methacrylate copolymers), and also polycarbonates, polyurethanes, nylons, aramids. , Improved epoxy and other resins.

The addition of fibers usually sufficiently improves the modulus and elongation properties of these resins. Suitable fibers to add include fiberglass, carbon, polyester, nylon, aramid (ie Tiv
iron, Kevlar29, KEVLAR49 and K
EVLAR129), a semi-crystalline polyolefin (ie S
PECTRA semi-crystalline polystyrene and polyethylene),
NORDYL, TORON, VECTRAN, TECH
A fiber such as NORA.

The fibers used in the composite 13 are also hybrid fibers, for example, aramid and carbon, aramid and glass, aramid and carbon and glass, carbon and glass and Spectra, and other combination fibers can be used. . Fiber hybrids not only reduce costs, but often also improve the performance of armor constructions. The combined fiber of aramid fiber and carbon is significantly lighter than glass fiber. The flexibility modulus of aramid is about twice that of glass fiber, and typical high-strength carbon fibers have more than three times the strength of the glass fibers in the composite. However, aramid fibers have a lower compressive force than carbon and glass fibers, and carbon fibers are not as shock resistant as aramid fibers. Therefore, the hybridization of these two types of fibers is lighter than (1) similar glass fiber reinforced plastics,
(2) It is superior to the all-aramid type composite in module, compression force and bending force, and (3) It is superior to the all-carbon type composite in impact resistance and fracture resistance.

Layer 14 is a thermoplastic resin and is preferably
Ionomer or polycarbonate. A preferred ionomer is the cross-linked ethylene-ethylene acrylate copolymer sold under the trademark "NOVIFLEX" by Artistic Glass Products.

Adjacent to the layer 14 is a polygonal panel 15, each cell portion having 3 to 8 sides. Suitably, the panel 15 has a honeycomb-shaped cell part.
The preferred honeycomb panel is from Spracall Systems, Inc. of Sunnyvale, Calif.
The trademark "COR" is attached. The honeycomb structure can be formed by adhesive, welding or melting.
This multi-sided structure is a rigid body and is made of a high modulus synthetic resin or metal. The cell portion of the multi-sided panel may be closed, penetrating, open, or empty or filled inside. When the cell parts are open, they act as kinetic energy absorbing means and void-providing spacers. The direction of the cell part is the protective material that is used,
It is determined by the effect desired and the material properties within the core.

The metal formed into a polygon or a honeycomb is
It is determined by the method of use, and for example, steel or the like is preferable. Aluminum is preferred for human body protection and for aircraft. However, other kinds of metals can be used depending on other usage and usage environment.

In FIG. 3, a protective structure 20 for producing a lightweight protective material is provided. The structure 20 has an outer ceramic tile 21 that is initially impacted. For example, a resin type composite 22 of polyethylene fibers or aramid fibers is adjacent to the ceramic tile 21 to absorb the main impact. Adjacent to the composite 22 is a layer 23 of thermoplastic, preferably polycarbonate or ionomer. The semi-rigid honeycomb layer 24, preferably made of aramid, forms the inner layer and acts as an energy absorbing means and void.

FIG. 4 discloses a protective composite 29 used to prevent needle penetration. The composite 29 is an outer cloth body 30 made of high module fibers and a thermoplastic resin.
have. The polygonal panel 32 is sandwiched between two thermoplastic material layers 31 and 35 and attached to the cloth body 30. The cell portion 33 of the polygonal panel 31 contains a friction material in the form of particles or sand for preventing the penetration of needle-shaped objects.

FIG. 5 illustrates an outer metal layer 37 that resists initial impact.
2 illustrates a protective structure 36 having a. The layer 38 adjacent to the metal layer 37 may be a protective fabric or a rigid thermoplastic sheet. The rigid thermoplastic layer 39 sandwiches with the layer 38 a honeycomb panel 40 including a core portion that is open or penetrates in a direction away from impact. The panel 40 may have, for example, a core diameter of about 0.125 inch (0.3175 cm), a gauge of about 0.012 inch (0.0305 cm), and a core thickness of about 0.025 inch (0.0635 cm). It may have a cell part having a core part.
The panel 40 has a layer 38 made of a thermoplastic elastomer 41.
And the layer 39.

The particles, sands, tiles, etc. used can be any suitable metal or ceramic.
Materials shaped into particles, sand, etc. preferably overlap one another to prevent penetration of needles. The particles are preferably about -10 to -3 mesh.

The ceramic material that can be used in the present invention is one or more of the following oxides or a mixture thereof. That is, magnesium, calcium, strontium, barium, aluminum, scandium, yttrium, lanthanum elements, actinides, gallium, indium, thallium, silicon, titanium, zirconium, hafnium, thorium, germanium, tin, lead,
Valadium, niobium, tantalum, chromium, molybdenum, tungsten, and uranium are available. Reduction metal
Composites such as carbides, borate oxides and silica oxides can also be used. Other suitable ceramic materials are
Zilicon-mullite, mullite, alpha-alumina, magnesium silica salt, zircon, feldspar, lithia pyroxene, cordierite and alumina silica salt. A preferred product available is Matei Bishop's "MAT
TECEL (trade name) ", E.I. I. "TORVEX (registered trademark)" of DuPont Nemua, "W1 (trade name)" of Corning Glass, Inc. and "THERMACOME (registered trademark)" of American Laver Corporation. Other available products are described in British Patent 882,482.

Other suitable useful metal oxides include, for example, alumina, titania, hafnia, thoria, zirconia, magnesia, or silica, and combinations of metal oxides such as boria-alumina or silica-alumina. included. Suitably, the oxide is a group II, III of the periodic table.
And IV, one or more metals, or oxides thereof.

Preferred friction materials are YC, Ti as described above.
B ₂ , HfB ₂ , WC, VB ₂ , VC, VN, NbB ₂ , N
bN, a _{TiB 2, CrB 2, MoB 2} , W 2 B , and S-2 glass, for example, a steel steel, Ni, Ti and the like. Thus, according to the present invention, maximum resistance to a constant weight and thickness of armor is obtained when the impact energy of a flying object is laterally diffused as quickly as possible.
The faster this lateral diffusion, the weaker the impact force per unit area. With the structure of the present invention, the impact force is diffused,
Reduces and does not penetrate protective material. Although only part of the present invention has been described in the embodiments, the present disclosure is merely an example, and modifications to the structures and combinations thereof are within the scope of the present invention.

[0040]

As described in detail above, according to the present invention,
It is said that it is possible to provide a shock absorbing protective material which is excellent in strength and flexibility, is light in weight, and very effectively absorbs and diffuses shocks from flying objects such as bullets, fragments of shells and the like, and stones. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a protective material layer of the present invention.

FIG. 2 is a side sectional view showing the protective member of FIG.

FIG. 3 is an exploded perspective view of another embodiment of the present invention.

FIG. 4 is an exploded perspective view of still another embodiment of the present invention.

FIG. 5 is a side sectional view showing an example of a protective support layer.

[Explanation of symbols]

 10 Protective Material Structure Part 12 Metal Surface 13 Composite 14 Layer 15 Panel 20 Protective Structure 24 Honeycomb Layer 32 Panel 33 Cell Part 36 Protective Structure 40 Panel

Claims (20)

[Claims] 1. A protective structure having at least one panel for absorbing kinetic energy, said panel being a rigid structure having a number of polygonal cell parts having 3 to 8 sides. And the cell portion has a diameter of about 0.1 to 8 inches and is provided on the entire surface of the panel. 2. The protective structure according to claim 1, wherein the cell portion of the panel is opened in a direction of impact. 3. The protective structure according to claim 2, wherein the cell portion of the panel has a honeycomb shape. 4. The protective structure according to claim 1, wherein the polygonal cell portion is welded. 5. The protective structure according to claim 1, wherein the side wall of the cell portion has a thickness of about 0.003 to 0.250 inch. 6. The core thickness of the cell portion is about 0.025 to 1.
The protective structure according to claim 1, wherein the protective structure is 2.0 inches. 7. The protective structure of claim 6, wherein the core thickness is about 0.025 to 3.0 inches. 8. The protective structure according to claim 1, wherein the panel is made of metal. 9. The protective structure according to claim 1, wherein the panel is made of a high modulus synthetic resin. 10. The high modulus synthetic resin is polyurethane, p-aramid, ionomer, polycarbonate,
10. A protective structure according to claim 9, which is selected from the group consisting of fluorine-treated hydrocarbons, polyolefins and polyetherimides. 11. The protective structure according to claim 1, wherein the panel includes at least one high-strength modulus resin layer on at least one side of the polygonal cell portion. 12. The protective structure according to claim 11, wherein the resin layer is a thermoplastic resin layer. 13. The protective structure according to claim 12, wherein the thermoplastic resin is selected from the group consisting of polycarbonate and ionomer. 14. The protective structure according to claim 11, wherein the cell portion contains a particulate friction material. 15. A protective structure having at least one projectile resistant outer layer and at least one kinetic energy absorbing inner layer, the inner layer having three to eight side surfaces. Having at least one rigid panel with a number of joined polygonal cell sections having a diameter of about 0.1 to 1 inch and a wall thickness of about 0. Protective structure characterized by being 0.003 to 0.030 inches. 16. The protective structure according to claim 15, wherein the panel has a honeycomb shape. 17. The protective structure of claim 15, wherein the panel is sandwiched by a pair of thermoplastic layers. 18. The protective structure according to claim 15, wherein the panel is made of a high modulus synthetic resin. 19. The protective structure according to claim 18, wherein the plurality of polygonal cell portions are welded. 20. The protective structure according to claim 15, wherein the cell portion contains a sufficient amount of inorganic sandy matter to prevent penetration of needle-like objects.