WO2023100994A1

WO2023100994A1 - Glass fiber

Info

Publication number: WO2023100994A1
Application number: PCT/JP2022/044474
Authority: WO
Inventors: 文中村; 英俊福地
Original assignee: 日本板硝子株式会社
Priority date: 2021-12-02
Filing date: 2022-12-01
Publication date: 2023-06-08
Also published as: TW202337862A

Abstract

A glass fiber according to the present invention contains SiO2 that forms a glass skeleton, Al2O3 and MgO; and this glass fiber has cracking resistance.

Description

glass fiber

The present invention relates to glass fibers, glass fiber materials using the same, and resin-impregnated fiber materials.

Because glass fibers have a high modulus of elasticity, they are used in various fields. For example, as shown in Patent Document 1, they are sometimes used to rehabilitate existing pipes.

Japanese Unexamined Patent Application Publication No. 2021-11904

Such glass fibers may be used in various applications other than the tube configuration described above, and may be applied, for example, to objects that are constantly in motion, such as windmill blades. Such moving objects may be subjected to impacts, such as being hit by other objects, and such impacts may cause cracks to occur. However, studies on crack resistance are still insufficient, and glass fibers having high crack resistance have been desired. The present invention has been made to solve this problem, and an object of the present invention is to provide glass fibers, glass fiber materials, and resin-impregnated fiber materials having high crack resistance.

Section 1. SiO ₂ forming a glass skeleton;
Al ₂ O ₃ and
MgO;
contains
Glass fiber with crack resistance.

Section 2. Item _2. The glass fiber according to item 1, wherein the content of SiO2 is 55 mol% or more.

Item 3. Item 3. The glass fiber according to Item 1 or 2, wherein the MgO content is 30 mol% or less.

Section 4. Item 4. The glass fiber according to any one of Items 1 to 3, which has an elastic modulus of 90 GPa or more.

Item 5. Item 5. The glass fiber according to any one of Items 1 to 4, further containing a rare earth compound.

Item 6. Item 6. The glass fiber according to any one of Items 1 to 5, which has a crack load resistance of 400 g or more.

Item 7. Formed from the glass fiber according to any one of Items 1 to 6,
Fiberglass materials in the form of strands, chopped strands, yarns and rovings.

Item 8. A glass fiber material formed from the glass fiber according to any one of Items 1 to 6 and in the form of either a woven fabric or a non-woven fabric;
a resin with which the glass fiber material is impregnated;
A resin-impregnated fibrous material comprising:

Item 9. Item 9. The resin-impregnated fibrous material according to Item 8, which is used as a windmill blade for wind power generation, a helicopter blade, a drone blade, or a high-pressure tank structure.

According to the present invention, high crack resistance performance can be achieved.

It is a sectional view of a blade member. It is a sectional view of a high-pressure gas tank.

An embodiment of the glass fiber according to the present invention will be described. The glass fiber according to the present invention contains at least SiO ₂ , Al ₂ O ₃ and an elastic modulus adjusting component for improving the elastic modulus. A detailed description will be given below. In the following description, % indicating the content of the glass component is mol % unless otherwise specified.

<1. Components of Glass Fiber>
<1-1. _SiO2 >
SiO ₂ is the main component of glass fiber, that is, the component that forms the glass skeleton, and its content is set, for example, in the range of 50 to 70%. The content of SiO ₂ is preferably 55% or more, more preferably 60% or more, particularly 62% or more. If the content of SiO ₂ is too low, crack resistance and acid resistance may deteriorate. On the other hand, if the _SiO2 content is too high, the elastic modulus (eg Young's modulus) may decrease. Therefore, the content of SiO ₂ is preferably 67% or less, more preferably 65% or less, 63% or less, and particularly 60% or less.

<1-2. Al ₂ O ₃ >
Al ₂ O ₃ is a component that contributes to maintenance of the heat resistance, water resistance, etc. of the glass composition and also affects the devitrification temperature, viscosity, and the like. In particular, Al ₂ O ₃ contributes to increasing the crack resistance, which will be described later. Therefore, the content of Al ₂ O ₃ is set in the range of 10 to 26%. The content of Al ₂ O ₃ is preferably 10% or more, more preferably 12% or more, particularly preferably 15% or more, and may be 16% or more, further 17% or more in some cases. If the content of Al ₂ O ₃ is too high, the liquidus temperature rises significantly, which may cause problems in production. Therefore, the content of Al ₂ O ₃ is preferably 24% or less, more preferably 22% or less, and in some cases may be 20% or less, further 19% or less.

Especially considering mass production, the devitrification temperature of the glass composition is preferably sufficiently lower than the liquidus temperature. A suitable Al ₂ O ₃ content for lowering the devitrification temperature sufficiently below the liquidus temperature is 11-15%, more preferably 11-14%, especially 11.5-13.5%. As will be described later, an appropriate amount of Li ₂ O and/or B ₂ O ₃ should be added in order to sufficiently lower the devitrification temperature compared to the liquidus temperature.

<1-3. Ingredients for improving elastic modulus>
The glass fiber according to the present invention contains MgO as an elastic modulus adjusting component for improving the elastic modulus. In addition to this, other elastic modulus adjusting components, such as alkaline earth metal compounds and rare earth compounds, can be further contained. Examples of alkaline earth metal compounds include MgO and CaO. Examples of rare earth compounds include Y ₂ O ₃ , La ₂ O ₃ and CeO ₂ . At least one composition may be contained as the elastic modulus adjusting component, and two or more compositions may be contained. This will be explained below.
(MgO)
MgO is also a component that contributes to an improvement in elastic modulus (for example, Young's modulus) and affects devitrification temperature, viscosity, and the like. Moreover, MgO contributes to increasing the crack load resistance, which will be described later. Therefore, the content of MgO can be set, for example, in the range of 15 to 30%. The MgO content is preferably 17% or more, more preferably 18% or more, particularly preferably 20% or more, and may be 21% or more, further 22% or more in some cases. If the MgO content is too high, the liquidus temperature may rise significantly. Therefore, the MgO content is preferably 35% or less, more preferably 30% or less, and may be 28% or less, further 25% or less in some cases.

A suitable MgO content for lowering the devitrification temperature sufficiently below the liquidus temperature is 18 to 30%, more preferably 20 to 28%.

(CaO)
CaO is an optional component that contributes to the adjustment of elastic modulus (for example, Young's modulus), maintenance of water resistance, etc., and affects devitrification temperature, viscosity, and the like. The CaO content can be set, for example, in the range of 0 to 8%. Addition of an appropriate amount of CaO is preferable from the viewpoint of lowering the liquidus temperature. Therefore, it is preferable to add CaO (content rate of more than 0%), and the content rate is preferably 0.1% or more, more preferably 0.12% or more, and in some cases 2% or more, further 3% or more. may be However, too much CaO may reduce Young's modulus and acid resistance. Therefore, the CaO content is preferably 7% or less, more preferably 5% or less. A CaO content of less than 1% is particularly suitable for improving Young's modulus and crack load resistance.

(Total of MgO and CaO)
The total content of MgO and CaO is set in the range of 18-35%, preferably 20-30%.

( _Al2O3 _/ (MgO+CaO))
The molar ratio of Al ₂ O ₃ to the sum of MgO and CaO contents is set to less than one. This facilitates compatibility between a high Young's modulus and a liquidus temperature that is not too high. The molar ratio Al ₂ O ₃ /(MgO+CaO) is preferably 0.3 to 0.9, more preferably 0.35 to 0.85, and optionally 0.4 to 0.7, more preferably 0.4 to 0.4. It may be in the range of 6. However, the molar ratio Al ₂ O ₃ /(MgO+CaO), which is particularly suitable for improving crack load resistance, is 0.7 or more and less than 1, further 0.7 or more and 0.9 or less, and particularly 0.8 or more and 0.9 or less. is.

(MgO/RO (total amount of alkaline earth metal compounds))
It has been found that an increase in the MgO/RO ratio improves the acid resistance performance. For example, MgO/RO is preferably 0.5 or more, more preferably 0.7 or more.

(rare earth compound)
Examples of rare earth compounds include Y ₂ O ₃ , La ₂ O ₃ and CeO ₂ as described above. The content of rare earth compounds can be set, for example, in the range of 0 to 8%. The content of the rare earth compound is preferably 0.1% or more, more preferably 1% or more, particularly 3% or more. If the content of the rare earth compound is too high, the acid resistance may be weakened and the batch cost may increase. Therefore, the content of the rare earth compound is preferably 8% or less, more preferably 6% or less.

<1-4. Other Ingredients>
In addition to the components described above, the following components can be added to the glass fiber according to the present invention, if necessary. However, it is not limited to the following components, and other components may be added as appropriate.

( _ZrO2 )
ZrO ₂ is a component for improving acid resistance performance. The content of ZrO ₂ can be set, for example, in the range of 0.1-3%. The content of ZrO ₂ is preferably 0.1% or more, more preferably 0.3% or more, particularly 0.5% or more. If the ZrO ₂ content is too high, the glass tends to crystallize, which may result in devitrification. Therefore, the ZrO ₂ content is preferably 3% or less, more preferably 1.5% or less.

( _TiO2 )
TiO ₂ is a component for improving acid resistance performance. The content of TiO ₂ can be set, for example, in the range of 0.1 to 3%. The content of TiO ₂ is preferably 0.1 to 3% or more, more preferably 0.3% or more, particularly 0.5% or more. If the TiO ₂ content is too high, the uniformity of the glass is lost, and devitrification may occur in this case as well. Therefore, the TiO ₂ content is preferably 3% or less, more preferably 1.5% or less.

₍ _B2O3 )
B ₂ O ₃ is an optional component that forms the skeleton of the glass and affects properties such as devitrification temperature and viscosity. The content of B ₂ O ₃ is set in the range of 0-3%. Addition of a small amount of B ₂ O ₃ may contribute to lowering the devitrification temperature. Therefore, B ₂ O ₃ may be added (content rate of more than 0%), and when added, the content rate is preferably 0.1% or more, particularly preferably 0.3% or more, and in some cases 0.5%. 0.7% or more, or even 0.7% or more. However, too much B ₂ O ₃ may reduce Young's modulus. The content of B ₂ O ₃ is preferably 2.5% or less, more preferably 2% or less, particularly preferably 1.8% or less, and in some cases may be 1.6% or less, further 1.5% or less. An example of a preferable range of the B ₂ O ₃ content is 0.1 to 1.6%.

( _Li2O )
Li ₂ O is a component that modifies the skeleton of glass, and is an optional component that affects properties such as liquidus temperature, devitrification temperature and viscosity. The content of Li ₂ O is set in the range of 0 to 3%. Addition of Li ₂ O in this range is effective in lowering the devitrification temperature. Therefore, Li ₂ O may be added (content rate of more than 0%), and when added, the content rate is preferably 0.1% or more, further 0.2% or more, particularly 0.3% or more. , depending on the case, it may be 0.5% or more, further 0.7% or more. If the Li ₂ O content is too high, the Young's modulus may decrease. Therefore, the content of Li ₂ O is preferably 2.5% or less, more preferably 2% or less, particularly preferably 1.8% or less, and in some cases may be 1.6% or less, further 1.5% or less. . An example of a preferable Li ₂ O content range is 0.2 to 2.5%, which is higher than the Na ₂ O content.

( _Na2O )
Na ₂ O, like Li ₂ O, is an optional component that affects properties such as liquidus temperature, devitrification temperature and viscosity. However, since it has a greater effect of lowering the Young's modulus than Li ₂ O, its content is set in the range of 0 to 0.2%. It is desirable not to contain Na ₂ O basically, but for clarification of the glass melt, the limit is 0.2%, further the limit is 0.15%, for example, more than 0% and 0.1% It is preferable to add in the range of less than

In this specification, the content of transition element oxides (ZrO ₂ , Y ₂ O ₃ , La ₂ O ₃ , CeO _{2 ,} etc.) present with multiple valences in the glass fiber is the content of the metal. It is calculated by converting to the oxide with the maximum oxidation number.

(total of ingredients explained above)
The total content of the components (SiO ₂ , Al ₂ O ₃ , MgO) described above is preferably 95% or more, more preferably 97% or more, particularly 98% or more, especially 99% or more. It may exceed 99.5%, or even 99.9%, or even 100%.

<2. Properties of Glass Fiber>
<2-1. Elastic modulus>
In one embodiment of the present invention, the elastic modulus of glass fibers can be measured by Young's modulus. Young's modulus is preferably 90 GPa or more, more preferably 95 GPa or more, and particularly preferably 100 GPa or more. Although the upper limit of Young's modulus is not particularly limited, it may be 110 GPa or less. Young's modulus is measured as follows for bulk glass of the same composition rather than the glass fiber.

The Young's modulus is measured according to the ultrasonic pulse method described in Japanese Industrial Standards (JIS) R1602-1995. Each test piece is a rectangular parallelepiped of 5 mm x 25 mm x 35 mm. In addition, the measurement is performed at room temperature in the air, and a Panametrics model 25DL Plus is used as a measuring device.

It is known that glass fiber and bulk glass made of the same glass composition usually have a relatively low elastic modulus. This is believed to be due to the much more rapid cooling of the glass fibers as they are formed from the glass melt. However, since there is a positive correlation between the elastic modulus of glass fiber and the elastic modulus of bulk glass (the elastic modulus measured by the above JIS), the measured value by the above JIS is used as glass fiber or glass fiber It is appropriate to evaluate the properties of glass compositions for

<2-2. Crack load resistance>
In the present invention, the resistance to cracking, that is, the resistance to cracking, is evaluated when receiving an impact from the outside. A crack resistance load can be used as an index of crack resistance. Specifically, the crack load resistance of the glass fiber is, for example, 300 g or more, preferably 400 g or more, and more preferably 500 g or more. Surprisingly, according to one embodiment of the present invention, it is also possible to provide a glass composition with a particularly high crack load resistance, for example 900 g or more, even 1000 g or more, especially 1200 g or more. The upper limit of the crack load resistance is not particularly limited, but may be 2000 g or less.

The crack load resistance was measured by a test in which a Vickers indenter was pressed against the mirror-polished sample glass surface. The apparatus used is a Vickers hardness tester manufactured by Akashi Seisakusho. The sample glass was processed into a plate having parallel planes. The plane against which the indenter was pressed was mirror-polished using a cerium oxide abrasive suspension. A Vickers indenter was pressed against the mirror-polished surface for 15 seconds, and after 5 minutes of unloading, it was measured whether a crack had occurred from the apex of the square indentation remaining on the surface of the sample glass. Whether or not cracks occurred was determined by observation using a microscope incorporated in a Vickers hardness tester. The magnification of the microscope is 100x. This measurement was performed 10 times, and the crack occurrence probability P was calculated by dividing the number of vertices where cracks occurred by the total number of measured vertices, 40. The above measurement was repeated while changing the load in the order of 50 g, 100 g, 200 g, 300 g, 500 g, 1000 g, and 2000 g until P=100%, and the crack occurrence probability P at each load was obtained. In this way, two adjacent loads WH and WL straddling P=50% and crack occurrence probabilities PH and PL (PH<50%<PL) at that time were obtained. A straight line passing through two points (WH, PH) and (WL, PL) was drawn with the horizontal axis and the vertical axis representing the load and crack generation probability, respectively, and the load at which P = 50% was defined as the crack resistance load.

　Crack resistance is mainly divided into two elements. One is impact resistance. Impact resistance is a factor related to whether glass fibers are susceptible to scratches. These also depend on the shape of the glass fibers, the shape of the strands composed of the glass fibers, and the process by which the glass fibers and strands are manufactured. Another is fracture toughness. Fracture toughness is resistance to fracture when a mechanical load is applied to a material having crack-like defects, and it can be said that the higher the fracture toughness, the higher the crack resistance. The present invention focuses on crack resistance and fracture toughness, particularly the relationship between crack resistance and glass composition.

<2-3. Acid resistance>
In one embodiment of the present invention, the acid resistance performance of glass fibers can be evaluated, for example, by a method based on JOGIS J06-1999. That is, put the specific gravity gram of the pulverized glass fiber in a platinum basket, immerse it in 80 ml of sulfuric acid solution with a specific gravity of 1.2 in the flask, heat it at 99 ° C. for 60 minutes, dry it at 120 ° C., weigh it, and weigh it. measure the rate. As a result, it is desirable that the weight loss rate is 0.2% or less.

<3. Method for producing glass fiber>
The glass fiber as described above is produced by flowing out a viscosity-controlled glass melt from a nozzle and winding it up with a winder. This continuous fiber is cut into appropriate lengths for use. Short glass fibers are produced while blowing off a glass melt with high-pressure air, centrifugal force, or the like.

<4. Glass fiber material>
The glass fiber according to the present invention can be applied to various forms of glass fiber material. For example, a strand can be formed by bundling a plurality of glass fibers. Each strand consists of, for example, 100-10000, typically 200-4000 glass fibers. Chopped strands can also be formed by cutting strands to a predetermined length. The length of the chopped strands is not particularly limited, but can be, for example, 1 to 25 mm, preferably 2 to 11 mm, more preferably 3 to 6 mm.

A yarn can also be formed by twisting a plurality of glass fibers to form a plied yarn. Alternatively, a roving can be formed by bundling a plurality of glass fibers. Furthermore, a plurality of glass fibers can form a woven fabric. In this case, weaving methods such as plain weave, twill weave, leno weave, and braid can be applied. Alternatively, a nonwoven fabric can be formed from a plurality of glass fibers. In addition, a mat having voids in which glass fibers are randomly accumulated can be formed.

<5. Resin-impregnated fiber material>
The glass fibers described above can be applied to resin-impregnated fiber sheets. A resin-impregnated fiber sheet is a sheet obtained by forming a woven fabric, a non-woven fabric, or a fiber bundle from the glass fibers described above and impregnating this with a resin.

The resin impregnated in this resin-impregnated fiber sheet is not particularly limited, but for example, thermosetting resin, thermoplastic resin, and photo-setting resin can be used. Examples of thermosetting resins include resins such as urethane resins, vinyl ester resins, and epoxy resins. Examples of thermoplastic resins include polyethylene resins, polypropylene resins, polypropylene copolymers, nylon resins, polymethacrylic resins, polyvinyl chloride resins, and polycarbonate resins. Examples of photocurable resins include ultraviolet curable resins that are cured by irradiation with ultraviolet rays. As the resin impregnated in the resin-impregnated fiber sheet, one of these resins may be used alone, or a plurality of resins may be mixed and used.

The thickness of the resin-impregnated fiber sheet is not particularly limited, but can be, for example, 1 to 10 mm. In addition to the sheet shape, for example, it can be formed into various shapes such as a block shape by laminating a plurality of sheets.

<6. Applications of resin-impregnated fibrous materials>
<6-1. Blade member>
As the blade member, for example, it can be applied to a blade member of a wind turbine for wind power generation, a blade member of a helicopter propeller, a blade member of a drone propeller, and the like. In the applications of the blade member mentioned here, in addition to the need for a high elastic modulus, since the blade member is always in motion, there is a risk of foreign matter colliding with it, and crack resistance is required.

As shown in FIG. 1, the blade member 5 includes an attachment portion 51 attached to the rotating shaft and a blade main body 52 extending from the attachment portion 5 . The blade main body 52 is formed of an outer skin 521 and a core material 522 arranged in an internal space surrounded by the outer skin 521 . The skin 521 is formed of at least one layer of resin-impregnated fiber sheet. The resin-impregnated fiber sheet may contain carbon fiber, aramid fiber, or the like, in addition to the glass fiber described above. For example, the skin 521 may be formed by laminating at least one resin-impregnated glass fiber sheet and at least one resin-impregnated carbon fiber sheet. At this time, by arranging the resin-impregnated carbon fiber sheet on the inside and the resin-impregnated glass fiber sheet on the outside, it is possible to increase the impact resistance against external impact. Alternatively, the skin 521 can be composed only of a resin-impregnated glass fiber sheet.

Although the configuration of the core material 522 is not particularly limited, it can be composed of, for example, a girder body extending in a rod shape and a foam material arranged around the girder body.

By forming the outer skin 521 as described above, the following effects can be obtained. For example, if the outer skin is composed only of a resin-impregnated carbon fiber sheet, although the high elasticity of the carbon fiber guarantees strength against load, there is a problem that the outer skin is vulnerable to impact. Further, there is a problem that the glass fibers of the conventional resin-impregnated glass fiber sheets do not have high impact resistance. Therefore, by forming the resin-impregnated glass fiber sheet with the glass fiber strands having impact resistance and high elasticity as described above, the strength against load can be ensured and impact resistance can be obtained. is valid as

It should be noted that if the elastic modulus of the glass fiber is high, the resin-impregnated carbon fiber sheet can be made thinner, thereby reducing the cost.

In particular, the outer skin 521 of the blade member 5 is required to have a higher elastic modulus in order to prevent deformation due to its own weight and centrifugal force, as it is becoming thinner for weight reduction. Furthermore, since it is usually used outdoors in many cases, high crack resistance (impact resistance) is also required in order to maintain strength against collisions with foreign objects, including birds. The blade member can achieve both strength and impact resistance.

<6-2. High pressure tank>
The high-pressure gas tank stores high-pressure gas such as compressed hydrogen gas and compressed natural gas. For example, as shown in FIG. . The outer wall of the high-pressure gas tank has a liner 61 made of a resin material such as polyamide, and a reinforcing layer 62 is formed inside the liner 61 . The reinforcing layer 62 is formed by laminating a plurality of resin-impregnated fiber sheets. For example, it may be formed by laminating at least one resin-impregnated glass fiber sheet and at least one resin-impregnated carbon fiber sheet. At this time, the resin-containing carbon fiber sheet is arranged inside to ensure the strength against the internal pressure of the tank. On the other hand, the resin-impregnated glass fiber sheet is placed on the outside and functions to protect the interior of the tank against external impacts on the surface of the tank. Alternatively, the reinforcing layer 62 can be composed only of a resin-impregnated glass fiber sheet.

Especially when storing compressed hydrogen gas, it is advantageous to use glass fibers with excellent low temperature resistance.

<6-3. Others>
The resin-impregnated glass fiber sheet according to the present invention can be applied not only to the vane members and high-pressure gas tanks described above, but also to housings for transportation equipment such as helicopters and drones. In particular, it is preferable to use it for the part corresponding to the floor in the housing.

<7. Features>
As described above, the glass fiber according to the present invention can achieve high crack resistance because the glass skeleton is formed of SiO ₂ . In addition, high elastic modulus and high crack resistance can be achieved by containing MgO. However _, if the content of MgO is increased, it is necessary to reduce the content of _SiO2 , which may reduce the crack resistance. You have to adjust the balance.

For example, when the SiO ₂ content is 55% or more and the MgO content is 30% or less, a glass fiber having a high elastic modulus and a high crack load resistance can be obtained.

Examples of the present invention will be described below. However, the present invention is not limited to the following examples.

Glass fibers having the compositions shown in Table 1 were prepared and evaluated for Young's modulus (bulk modulus) and crack load resistance. The unit of numerical values of the compositions in Table 1 is mol %.

According to Table 1, the Young's modulus increases as the MgO content increases. Moreover, when the content of MgO increases to a certain extent, the crack load resistance also increases. However, as the MgO content increases and the SiO ₂ content decreases, the crack load resistance decreases. In particular, when the content of SiO ₂ is smaller than 55 mol %, the crack load resistance is greatly reduced. Therefore, in order to achieve a high elastic modulus and a high crack resistance, for example, the SiO ₂ content should be 55 mol % or more and 62.5 mol % or less, and the MgO content should be 22.5 mol % or more and 30 mol % or less. preferable. That is, high elasticity and high crack resistance can be achieved by balancing the content of SiO ₂ and the content of MgO.

On the other hand, unlike the comparative example, it differs from the example in that it does not contain MgO. As for physical properties, the Young's modulus and crack load resistance are lower than those of the examples, and in particular, the crack resistance is significantly lower than those of the examples.

Claims

SiO 2 forming a glass skeleton;
Al 2 O 3 and
MgO;
contains
Glass fiber with crack resistance.
The glass fiber according to claim 1, wherein the content of SiO2 is 55 mol% or more.
The glass fiber according to claim 1 or 2, wherein the MgO content is 30 mol% or less.
The glass fiber according to any one of claims 1 to 3, which has an elastic modulus of 90 GPa or more.
The glass fiber according to any one of claims 1 to 4, further containing a rare earth compound.
The glass fiber according to any one of claims 1 to 5, which has a crack resistance of 400 g or more.
Formed from the glass fiber according to any one of claims 1 to 6,
Fiberglass materials in the form of strands, chopped strands, yarns and rovings.
a glass fiber material formed from the glass fiber according to any one of claims 1 to 6 and in the form of either a woven fabric or a non-woven fabric;
a resin with which the glass fiber material is impregnated;
A resin-impregnated fibrous material comprising:
The resin-impregnated fiber material according to claim 8, which is used as a wind turbine blade for wind power generation, a helicopter blade, a drone blade, or a high-pressure tank structure.