JPH0335756Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a stiffening plate used in the structure of ship hulls and various tanks, which is lightweight while having sufficient strength.

[Conventional technology]

For example, in the hull structure, a structure called a stiffening plate is used to prevent deflection and vibration in the bulkhead between the outer holds that form the hull, the bulkhead between the living quarters and the engine room, or the deck. It is being Conventionally, as shown in FIG. 1, this stiffening plate has a plurality of rib members 2 extending in parallel on one side of a stiffening plate main body 1 made of, for example, steel and having a flat plate shape (equal thickness plate). It is set up and configured.

[Problem to be solved by the invention] By the way, in the stiffening plate main body 1, the strength required at the bone member attachment part (point N in the figure) is determined by the strength required at the central part between the adjacent bone members 2 (point N in the figure). Therefore, the plate thickness d of the stiffening plate main body 1 is determined from the required strength at the N point. However, in such a structure, aggregate 2,
For example, for a stiffening plate of a general hull structure with an aspect ratio of 2 or more, the required strength at point M is 68% of the required strength at point N. As a result, a considerable amount of material constituting the stiffening plate body was wasted.

The present invention was developed under these circumstances, and it is an object of the present invention to provide a stiffening plate that has sufficient strength and can reduce the weight of materials, thereby saving materials. The purpose is to

[Means to solve the problem]

This idea is to form both sides of the stiffening plate main body into continuous curved surfaces that are symmetrical to each other and have a wave shape in which a plurality of thick parts extend in parallel, and at least one side of the stiffening plate main body A plurality of bone members are provided so as to extend along the tops of the plurality of thick walled portions, and the wall thickness of the stiffening plate main body between the bone members gradually decreases according to the waveform shape. It is characterized by being formed so that it is smallest at the center.

[Effect]

According to this idea, the main body of the stiffening plate is formed with a wave-shaped cross-section, and the wall thickness is large in the part where the required strength is high (the part where the bone members are installed), and the wall thickness is thick in the part where the required strength is low. Since it is smaller, it is possible to reduce the weight of materials while maintaining sufficient strength, and it is possible to reduce costs and save materials.

In addition, the surface of the stiffening plate main body is formed as a continuous wave-shaped curved surface, and the wall thickness between the bone members is formed so that it gradually decreases according to the wave shape and becomes the minimum at the center. Because of this, there are no parts where the wall thickness changes suddenly, and the strength changes are continuous, compared to when the thick wall parts are locally formed as rectangular or mountain-shaped protrusions on a flat plate. Since there is no stress concentration, it is possible to avoid the occurrence of cracks.

In addition, if the waveform shape is formed only on the flat side of the stiffening plate body, the center of the plate thickness will shift between the thin and thick parts (see Figure 5), so When a load (in-plane load) is applied, a locally eccentric load is applied and a bending moment is generated, which may easily buckle or deform the thin wall part.However, in this invention, the stiffener body Since the corrugated shapes are symmetrically formed on both sides of the plate, the center of the plate thickness is a straight line, and no bending moment is generated under loads parallel to the plate surface, so there is no risk of easy buckling or deformation.

In addition, if the ratio of the thickest part to the thinnest part is constant, there is a difference between forming corrugations on one side only and forming corrugations on both sides as in the present invention. The surface unevenness is smaller, and when used for the deck of a ship or the bottom of a ship's hold, it is difficult for residual cargo, dirt, water, etc. to accumulate in the recesses, and maintenance is easier, such as less rust. Furthermore, the unevenness is small and gentle, making it easier to walk and remove residual cargo.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In the embodiment shown in FIG.
Both surfaces 11 and 12 are each formed in a symmetrical sinusoidal shape, and a plurality of thick portions 3 extend in parallel. A plurality of bone members 2 are attached to one side surface 12 of the stiffening plate main body 1 so as to extend along the tops of the plurality of thick portions 3, respectively.

If the undulation direction of the waves and the length direction of the plate are the same, the stiffening plate main body 1 can be made into a wave shape on both sides by, for example, feeding the plate at a constant speed in a rolling mill and periodically operating the roll interval. It can be easily made.

Here, the weight of the stiffening plate main body, for example, a steel plate, will be compared between the stiffening plate of the present invention and a conventional stiffening plate.
FIG. 3 is a plan view schematically showing an example of the stiffening plate of the present invention, and the chain lines indicate bone members. When considering a rectangular member surrounded by longitudinally extending bone members (the area surrounded by diagonal lines), the stiffening plate of the hull structure is treated as a peripheral fixed plate that receives an evenly distributed load, and the stress applied to the main body of the stiffening plate is σ becomes σ=K・σ ₀・P・b ₂ /t ₂ . However, P is the uniformly distributed load per unit area, σ ₀ is the standard stress, b is the length of the short side of the rectangular part, t is the thickness of the stiffening plate body,
k is a constant. Therefore, the necessary thickness of the stiffening plate body is determined from the allowable stress determined by the material and the maximum uniformly distributed load. By the way, the above constant k is not a uniform value at each position of the rectangular part,
If the center point A of the long side of the rectangular part, the center point B of the short side, and the center point C are selected as representative points, the ratio a/ Since b is usually larger than 3, k _A =0.500,
k _B =0.343, k _C =0.250. However, k _A , k _B , and k _C are constants k at point A, point B, and point C, respectively. Therefore, if the stresses at points A, B, and C are respectively σ _A , σ _B , and σ _C , then σ _A =k _A・σ ₀・P・b ² /t ² ,
σ _B =k _B・σ ₀・P・b ² /t ² , σ _C =k _C・σ ₀・P・b ² /t ² , and if the stiffener body is a plate of equal thickness, then With respect to the distributed load, the stress at point A is the largest, and the stress at point B,
Point C becomes smaller in order. For this reason, in the past, the thickness t was determined so that the stress at point A did not exceed the allowable stress. The thickness t at this time is (1/6 _S ·k _A ·σ ₀ · P _nax ·b ² )1/2, where σ _S is the allowable stress and P _nax is the maximum uniformly distributed load. However, the required thickness at points B and C is
(1/6 _S・k _B・σ0・P _nax・b ² ) 1/2 and (1/6 _S・k _B・σ ₀・P _nax・b ² ) 1/2, respectively, so point B, At point C, the thicknesses are (k _A /k _B ) 1/2 and (k _A /k _C ) 1/2 times the required thickness, respectively. In other words, at point B it is approximately 20.7
%, and the thickness at point C is approximately 41.4% surplus. On the other hand, in the present invention, the thickness of the long side portion is decreased from the long side toward the center.
As shown in the figure, both surfaces 11 and 12 of the stiffening plate main body 1 are formed into a symmetrical sinusoidal shape so that the thick portions extend in parallel along the direction in which the long sides extend. If the thickness of the part corresponding to T ₁ is the thickness of the part corresponding to the center part T ₂ is T ₂ = 0.83T ₁ , then the weight of the steel material is approximately 10% compared to the conventional one.
This can be reduced.

Further, FIG. 5 compares a case (a) in which a waveform is formed only on one side of the stiffening plate main body 1' and a case (b) in which a waveform is formed on both sides of the stiffener main body 1 according to the present invention.

The stiffening plate body 1 is subject to not only loads perpendicular to the plate surface but also loads parallel to the plate surface. However, when only one side is corrugated as shown in a, the plate thickness center m is undulated (the thinner part (and misalignment in the thick part). Therefore, when a pressing force F is applied from the left and right sides of the stiffening plate main body 1', an eccentric load is applied locally, and a bending moment of F x l is generated, as shown in the figure. Thin parts may easily buckle or deform. On the other hand, when both sides are corrugated as shown in b, the plate thickness center m becomes a straight line, so the pressing force F from the left and right sides of the stiffening plate body 1
Even if a

Further, if the thickness of the thickest part is T ₁ and the thickness of the thinnest part is T ₂ , and if only one side of FIG. 5a is corrugated, the depth of the recess 4 is T ₁
-T ₂ , whereas in the case of double-sided corrugation b, the depth of the recess 4 is halved to T ₁ -T ₂ /2. Therefore, if both sides are corrugated, the unevenness on the surface will be small, and when used on the deck of a ship or the bottom of a ship's hold, it will be difficult for residual cargo, garbage, water, etc. to accumulate in the recesses.
Maintenance is easier due to less rust.
Furthermore, since the unevenness is small and gentle, it becomes easier to walk and carry out tasks such as removing residual cargo.

Moreover, FIGS. 6a to 6d show stiffening plates that have been proposed in the past. All of these have protrusions formed at regular intervals on one side of a flat plate-shaped stiffening plate main body 10. A indicates a projection 13 formed into a rectangular shape. In b, a rectangular protrusion 13 is also formed at the intermediate portion between the bone members 2.
The projection 14 c is formed into a mountain shape. d
A mountain-shaped protrusion 14 is also formed at the intermediate portion between the bone members 2.

Since the surfaces of these are flat between the protrusions 13 or between the protrusions 14, the thickness of the boundary portion P between the protrusions 13 or 14 and this flat portion 15 changes rapidly, and the strength does not change. Stress concentration occurs suddenly in this portion P, and cracks are likely to occur.

In contrast, the stiffening plate main body 1 according to the present invention has a sixth
As shown in Figure e, the surface is formed into a continuous wavy curved surface, and the wall thickness between the bone members 2 is formed so that it gradually decreases in accordance with the wavy shape and becomes minimum at the center. Because of this, there are no parts where the wall thickness changes suddenly, and the strength changes continuously, eliminating stress concentration, so it is possible to avoid the occurrence of cracks.

[Effect of idea]

As explained above, according to this invention, the stiffening plate main body is formed in a wave-shaped cross-section, and the parts where the required strength is large (the parts where the bone members are provided) have a large wall thickness, and the required strength is small. Since the wall thickness of the parts is reduced, it is possible to reduce the weight of the material while maintaining sufficient strength.
It is possible to reduce costs and save materials.

In addition, the surface of the stiffening plate main body is formed as a continuous wave-shaped curved surface, and the wall thickness between the bone members is formed so that it gradually decreases according to the wave shape and becomes the minimum at the center. Because of this, there are no parts where the wall thickness changes suddenly compared to cases where a thick wall is locally formed as a rectangular or mountain-shaped protrusion on a flat plate, and the strength changes continuously. Since there is no stress concentration, the occurrence of cracks can be avoided.

In addition, if the waveform shape is formed only on one side of the stiffener body, the center of the plate thickness will shift between the thin and thick parts, and when a load parallel to the plate surface of the stiffener body is applied, Since a locally eccentric load is applied and a bending moment is generated, thin parts may easily buckle or deform, but in this invention, the waveform shape is formed symmetrically on both sides of the stiffener body. , the center of the plate thickness is a straight line, and bending moments do not occur against loads parallel to the plate surface, so it does not buckle easily.
There is no risk of deformation.

In addition, if the ratio of the thickest part to the thinnest part is constant, there is a difference between forming corrugations on one side only and forming corrugations on both sides as in the present invention. The surface unevenness is smaller, and when used for the deck of a ship or the bottom of a ship's hold, it is difficult for residual cargo, dirt, water, etc. to accumulate in the recesses, and the occurrence of rust is reduced, making maintenance easier. Furthermore, the unevenness is small and gentle, making it easier to walk and remove residual cargo.

[Brief explanation of the drawing]

Fig. 1 is an end view showing a conventional stiffening plate, Fig. 2 is a perspective view showing an embodiment of the present invention, Fig. 3 is a plan view schematically showing the stiffening plate, and Fig. 4 is a second Figure 5 is an enlarged end view showing a part of the stiffening plate shown in the figure, Figure 5 is an end view showing a comparison between single-sided corrugation and double-sided corrugation, and Figure 6 shows the conventionally proposed stiffening plate with ridges and this invention. It is an end view showing comparison with a stiffening board by. 1... Stiffening plate main body, 2... Bone member, 3... Thick part.

Claims (1)

[Scope of utility model registration request] Both sides of the stiffening board main body are formed into mutually symmetrical continuous curved surfaces forming a wave shape such that a plurality of thick parts extend in parallel, and the plurality of A plurality of bone members are provided so as to extend along the top of the thick portion, and the wall thickness of the stiffening plate main body between the bone members gradually decreases according to the waveform shape and reaches a minimum at the center portion. A stiffening plate characterized by being formed so as to be.