KR20160124839A - Ship body structure with excellent crashworthiness, and ship body structure designing method - Google Patents

Abstract

The hull structure shall be such that, in the shell plating or in the inner plates facing each other on the sides of the ship, some or all of the members of one or more of the members are of full height as defined in the Unified Requirements W11 Rev. 8 2014 of the International Classification Society (IACS) And a total elongation of 1.4 times or more of the value of the high-ductility steel sheet. Further, it is preferable to use the high-ductility steel sheet for the stiffener adhering to the portions (outer plates, inner plates) using the steel sheet.

Description

[0001] SHIP BODY STRUCTURE WITH EXCELLENT CRASHWORTHINESS AND SHIP BODY STRUCTURE DESIGNING METHOD [0002]

The present invention relates to a hull structure having excellent collision resistance and a design method of the hull structure capable of suppressing the break of a hull in a large-sized ship collided with a side portion.

In bulk carriers such as ore carriers and coal carriers, a single-row hull structure (single hull) is employed up till now. Although it does not pollute the offshore oceans from these vessels, fuel oil etc. are also loaded on the vessels, and the outflow of fuel oil causes marine pollution. Therefore, it is necessary to suppress wave fronts due to collision or the like.

In addition, oil spills from tankers are becoming an international problem, as they cause more marked marine pollution. BACKGROUND ART In recent years, a double hull structure (double hull) has been underway to prevent oil leakage due to a collision accident or the like. Double hulls have a lower rate of oil leakage than single hulls, but the effect is insufficient.

It is possible to improve the collision resistance of the hull structure by increasing the number of cargo oil tanks, increasing the height of the double bottom, and increasing the double side spacing. However, these countermeasures cause an increase in the drying cost, the operation cost, and a drop in the mounting efficiency. On the other hand, the value of the product of the yield stress and the uniform elongation, the energy absorption amount to the uniform elongation, or the yield stress is equal to or more than that of the side shell plating, the side shell plating attached to the inner plate, There has been proposed a hull structure using a steel material having increased strength (see, for example, Patent Document 1). Further, a steel sheet for a ship has been proposed in which the strength and ductility are improved to increase the absorbed energy with respect to impact at the time of impact (see, for example, Patent Documents 2 to 6).

Japanese Patent Application Laid-Open No. 2002-87373 Japanese Patent Laid-Open No. 11-193438 Japanese Patent Application Laid-Open No. 11-193441 Japanese Patent Application Laid-Open No. 11-193442 Japanese Patent Laid-Open No. 11-246934 Japanese Patent Application Laid-Open No. 11-246935

It is not clear whether or not the amount of energy absorption up to the occurrence of the wave in the inner plate is controlled by the uniform elongation and it is also difficult to determine the amount of energy absorbed by the members of the members other than the side steel plates (upper deck, bilge, transformer, stringer) The contribution to inhibition is also unclear.

Therefore, the hull structure of Patent Document 1 has a problem that it is impossible to design a rational hull. Considering the suppression of the final wave generated in the impacted ship by collision of the impact vessel with the side of the impacted vessel, it is necessary to consider the total elongation to the breaking rather than the uniform elongation as disclosed in Patent Document 1 .

In Patent Document 1, the steel material quantitatively defined on the basis of the uniform elongation, that is, the value of the product of the yield stress and the uniform elongation, the energy absorption amount to the uniform elongation, or the yield stress is equal to or more than the uniform elongation itself A steel material having an increase of 20% or more has been proposed. However, even with a 20% increase in the homogeneous elongation, the total elongation, which is the sum of the homogeneous elongation and the local elongation, is only about 20%, since the local elongation does not seem to change much. Therefore, it does not reach the entire elongation specification of the present invention to be described later, and the wave break can not be suppressed.

In addition, Patent Document 1 aims at significantly increasing the amount of energy that can be absorbed until a wave break occurs in a hull of a double hull structure (double hull structure). Therefore, The description does not describe a condition in which there is no substrate and a condition in which a wave of a single-hull structure (single hull) is not generated.

In the case of using the steel sheets described in Patent Documents 2 to 6, it is possible to increase the absorbed energy at the time of impact, but as in the case of the hull structure of Patent Document 1, without considering the total elongation at which the steel sheet is broken, There is room for improvement.

Patent Literatures 2 to 6 disclose that when a collision accident occurs between ships, it is possible to prevent a hole from being broken due to breakage of the hull, or to reduce the breaking area as compared with the case of a conventional steel plate. However, Shock absorptive performance is described only, and there is no description about the relationship with the actual hull structure or the conditions that do not cause wave breaks.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a hull structure excellent in collision resistance, in which the energy absorbable for absorbing members is increased so as to suppress the break of the hull, .

The gist of the present invention is as follows.

(1) A total elongation of not less than 1.4 times the value of the total elongation specified in the Unified Requirements W11 Rev. 8 2014 of the International Association of Classification Societies (IACS) And a hull structure using a high ductility steel sheet which has been confirmed to satisfy the above requirements and which is attached as a spec. The collision resistance referred to herein means a property that, for example, even if a side collision of another ship is performed at a predetermined velocity, the wave front can be suppressed.

(2) The steel sheet according to the above (1), wherein the high-ductility steel sheet has a hull structure using the high-ductility steel sheet on a part of the inner plate facing the outer plate or all the inner plates. Hull structure.

(3) A total elongation of at least 1.4 times the value of the total elongation specified in the Unified Requirements W11 Rev. 8 2014 of the International Association of Classification Societies (IACS) And a hull structure using a high ductility steel sheet which has been confirmed to satisfy the above requirements and which is attached as a spec.

(4) The steel sheet according to any one of (3) to (3), wherein the high-ductility steel sheet is used in a part of the outside sheathing facing the inner sheath or the entirety of the outside sheathing, Hull structure.

(5) The hull structure according to any one of (1) to (4) above, characterized in that the high-ductility steel sheet is used for part or all of the stiffener adhering to the region where the high- . The reinforcing material in the present invention is a generic term for all members for suppressing warpage and deformation of a plate material constituting a hull including an outer plate and an inner plate. For example, in the case of double hull, Refers to a member (aggregate) for suppressing warpage of the outside sheathing, in addition to a member for suppressing warpage outside the plane, for example, in the case of a single hull.

(6) The hull structure according to any one of (1) to (5), wherein the high-ductile steel sheet is used for part or all of the stringer.

(7) The hull structure according to any one of (1) to (6), wherein the high ductile steel sheet is used for part or all of the upper deck.

(8) The hull structure according to any one of (1) to (7), wherein the high ductile steel sheet is used for part or all of the bilge.

(9) The hull structure according to any one of (1) to (8), wherein the high-ductility steel sheet is used for part or all of the transformer.

(10) The hull structure according to any one of (1) to (9), wherein the plate thickness of the high ductility steel sheet is more than 12 mm but not more than 50 mm.

(11) In the shell plating on the side of the ship, specify the area where it is necessary to suppress the wave, and apply to the steel plate used for the site the requirements specified in the Unified Requirements W11 Rev. 8 2014 of the International Classification Society (IACS) Characterized in that a high-ductility steel sheet having a total elongation of 1.4 times or more of the value of the total elongation as a specification and confirmed to satisfy the above-mentioned specification is used.

(12) Further, among the inner plates opposed to the outer sheath in which the high ductility steel sheet is used, a portion required to suppress the corrugation is specified, and the high ductility steel sheet is used for the steel sheet used in the portion (11). ≪ / RTI >

(13) In the inner plate on the side of the ship, specify the area where it is necessary to suppress the wave, and specify the steel plate to be used for the site as specified in the Unified Requirements W11 Rev. 8 2014 of the International Classification Society (IACS) Characterized in that a high-ductility steel sheet having a total elongation of 1.4 times or more of the value of the total elongation as a specification and confirmed to satisfy the above-mentioned specification is used.

(14) The steel sheet for use in a high-ductility steel sheet according to any one of the preceding claims, wherein the high-ductility steel sheet is characterized in that, (13). ≪ / RTI >

(15) The steel sheet according to any one of (11) to (14), wherein the high-ductility steel sheet is used for a steel sheet used for part or all of the stiffener adhered to the region where the high- A method of designing a hull structure as set forth in any one of the preceding claims.

(16) The method for designing a hull structure according to any one of (11) to (15), wherein the steel sheet used for part or all of the stringer is the high ductility steel sheet.

(17) The method of designing a hull structure according to any one of (11) to (16), wherein the steel sheet used for part or all of the upper deck is the high ductility steel sheet.

(18) The method of designing a hull structure according to any one of (11) to (17), wherein the steel sheet used for part or all of the bilge is the high ductile steel sheet.

(19) The method of designing a hull structure according to any one of (11) to (18), wherein the steel sheet used for part or all of the transformer is the high ductility steel sheet.

Industrial Applicability According to the present invention, it is possible to provide a hull structure excellent in collision resistance, in which occurrence of wave fronts due to collision of a large ship, for example, is suppressed without a significant increase in cost, .

Fig. 1 is a view for explaining members of a double-hull structure. Fig.
Fig. 2 is an enlarged view of a bottom portion of the line side portion in Fig.
3 is a diagram for explaining a collision scenario of the analysis by the finite element method.
Fig. 4 is a view for explaining an example of the absorption energy analysis result of each member by the finite element method. Fig. 4 is a diagram showing the absorbed energy ratio of each member in the case where all members of the double-hull structure are conventional steels. STR: STRINGER, UPDK: Upper Deck, BILGE: Bilge, T.BHD: Trans Bulk Head: Reinforcing material flange surface, Trans: , S.BHD: SuSi bulkhead. Here, the stiffener web is a portion of the stiffener which is perpendicular to the shell or inner plate to which the stiffener is attached. The stiffener flange face generally refers to a portion of the stiffener that is parallel to the shell or inner plate .
Fig. 5 is a view for explaining an example of the absorption energy analysis result of each member by the finite element method. Fig. 5 is a diagram showing the absorbed energy ratio of each member in the case where the outer plate, the inner plate and the reinforcing member of the double-
Fig. 6 is a view for explaining an example of the absorption energy analysis result of each member by the finite element method, and shows a ratio of absorbed energy of each member when all the members of the hull are high-ductility steel sheets.
Fig. 7 is a view for explaining the absorption energy analysis result of a collided ship by the finite element method. In Fig. 7, This is a comparison of the maximum value of the energy amount.
Fig. 8 is a view for explaining an example of the analysis result of the damage of the inner plate by the finite element method, and shows the damage of the inner plate when it is 1.3 times the value of the total elongation of the unified standard.
Fig. 9 is a view for explaining an example of the analysis result of the damage of the inner plate by the finite element method, and shows the damage of the inner plate when it is 1.4 times the value of the total elongation of the unified standard.
Fig. 10 is a view for explaining an example of the analysis result of the damage of the inner plate by the finite element method, and shows the damage of the inner plate when it is 1.5 times the value of the total elongation of the unified standard.
Fig. 11 is a view for explaining an example of the analysis result of the inner plate damage by the finite element method. The analysis result of the damage of the inner plate when the outer plate, the inner plate and the stiffener of the double-hull structure are 1.5 times the value of the total elongation of the unified standard Fig.
Fig. 12 is a schematic diagram for explaining a collision scenario of an analysis by the finite element method in a single-axis hull structure. Fig.
Fig. 13 is a view for explaining the absorption energy analysis result of the bulk carrier by the finite element method, and is a comparative diagram of an absolute value of the amount of energy absorbed by the bulk carrier until a wave is generated in the shell plate.
Fig. 14 is a view for explaining an example of the analysis result of the damage of the outer sheath by the finite element method, and shows the damage of the sheathing after 1.4 seconds from the start of collision when the outer sheath and aggregate of the bulk carrier are conventional steels.
Fig. 15 is a view for explaining an example of the analysis result of the damage to the sheathing by the finite element method, and shows damage of the sheathing after 1.4 seconds from the start of collision when the outer sheath and aggregate of the bulk carrier are high- .
Fig. 16 is a view for explaining an example of the analysis result of the damage to the outer sheath by the finite element method, and shows the damage of the outer sheath after 6 seconds from the collision when the outer sheath and aggregate of the bulk carrier are conventional steels.
Fig. 17 is a view for explaining an example of the analysis result of the damage to the outer sheath by the finite element method, and shows the damage of the outer sheath after 6 seconds after the collision when the outer sheath and the aggregate of the bulk carrier are high-
18 is a comparative diagram of a critical impact velocity (a critical velocity at which no wave is generated in a bulk carrier) of a VLCC colliding with a bulk carrier.
Fig. 19 is a view for explaining an example of the analysis result of the damage to the outer sheath by the finite element method, and shows the damage of the outer sheath at the end of the collision when the outer sheath and aggregate of the bulk carrier are conventional steels.
Fig. 20 is a view for explaining an example of the analysis result of the damage of the outer sheath by the finite element method, and shows damage of the outer sheath at the end of the collision in the case where the outer sheath and the aggregate of the bulk carrier are high ductility steel sheets.

As shown in Figs. 1 and 2, the main components constituting the double hull structure of the oil tank are a side member 10 and an inner member 11, a stiffener 12 attached to the outer member 10 and the inner member 11, 13, a transformer 14, a stringer 15, an upper deck 16, and a bilge 17. The present inventors have found that, by the large oil tankers (V ery L arge C rude oil C arrier, VLCC ") finite element method (FEM) energy that is absorbed assumed collision, and by the absence modifications and variations of the double hull structure of Respectively.

In the analysis by the FEM, as shown in Fig. 3, when the collision vessel assumes a scenario in which the collision vessel collides at 90 degrees from the side of the center of the hull of the collided ship (V _A = 0㏏) Respectively. The analysis was carried out until the velocity (㏏) of the vessel to be impacted and the velocity V _B (㏏) of the vessel were constant. Here, 1 ㏏ is the speed at which one nautical mile (1,852 m) advances in one hour.

This 12 ㏏ is the speed limit on the Nakano Sea Route of Tokyo Bay enacted as the Enforcement Regulations of the Maritime Traffic Safety Act of Japan (March 27, 1973, Transportation Ordinance No. 9). In addition, the collision ship was made to have the same VLCC as that of the ship to be collided, and the load state of the collision ship was set to the full state where the initial kinetic energy was the largest and the influence of the inertia force was large. This is one of the most serious crash scenarios for the affected vessel. The shell, the inner plate, and the stiffener (the outer shell-attached stiffener and the inner shell-attached stiffener, hereinafter the same) of the impacted ship are the same as the case of the conventional steel (17% of the total elongation) (Case 2). In the case of the high ductility steel plate (case 3), all members of the hull of the object to be impacted were analyzed by FEM, and the absorbed energy ratio of each member was obtained. The total elongation of 17% in Case 1 is determined as follows. That is, the steel sheet which is frequently used for ships has a plate thickness of 15 mm to 20 mm, and the strength classification in the unified standard (Unified Requirement W11 Rev. 8 2014) of the International Association of Classification Societies (IACS) , 17% of the total height specified by the unified standard is used as a representative value of the conventional lecture. In order to grasp the absorption energy of the ship using the high-ductility steel sheet, in case 2 and case 3, the deviation of the manufacture of the high-ductility steel sheet is not limited to 23.8%, which is 1.4 times the total elongation of 17% , The analysis was carried out assuming that the average overall elongation of the high ductility steel sheet was 27%.

Figs. 4, 5 and 6 show the ratios of the energy absorbed by member deformation of the double-hull structure in the case 1, case 2 and case 3, respectively. As shown in Figs. 5 and 6, when a high ductility steel sheet is applied to at least the outer plate, the inner plate, and the stiffener, it can be seen that the sum of these absorbed energy ratios (OS + IS + Longi Web + Longi Face) exceeds 50% have. On the other hand, as shown in Fig. 4, when all the members are the conventional steel, the sum of the absorbed energy ratios of the outside sheathing, the inner sheathing and the stiffener is 50% or less. Therefore, in the case of efficiently absorbing energy by the high ductility steel sheet, it is considered desirable to apply a high ductility steel sheet to at least the outer plate, the inner plate and the reinforcing material. 4 to 6, the reinforcing materials among the outside sheathing, the inner sheathing and the reinforcing materials are Longi Web and Longi Face. The sum of the absorbed energy ratios of the shell, the inner plate, and the stiffener represents the sum of the energy absorbed by OS, IS, Longi Web, and Longi Face. By applying the high ductility steel sheet, the occurrence of the wave plate of the outer plate and the inner plate is greatly delayed due to the high ductility effect. When a wave breaks on the inner plate, the cargo oil flows out into the ocean and becomes a large-scale ocean pollution. Therefore, it is important to absorb as much collision energy as possible until the inner plate wave occurs. Fig. 7 shows a comparison of absolute values of the energy absorbed by the vessel to be impacted until the occurrence of the inner plate wave, or the end of the impact, in the case 1, case 2 and case 3. Fig. In Case 3, no wave was generated in the inner plate, and thus it represents the energy absorbed by the vessel to be collided until the end of the collision. It can be seen from Fig. 7 that the amount of energy absorption up to the cargo oil outflow can be greatly improved along with the expansion of the application member of the high ductility steel sheet.

Here, the product (908 MJ) of the absorbed energy ratio (50% = 0.50) between the absorbed energy difference (1816 MJ) between the case 3 and the case 1 and the outer plate, inner plate and stiffener to which the high- The absorbed energy (478 MJ) is added, and the absorbed energy of Case 2 is estimated to be 1386 MJ. This value is almost the same as the absorption energy (1393 MJ) (absorbed energy of case 2 in Fig. 7) obtained by the analysis by the finite element method. In this regard, the analysis by the finite element method shows that the absorbed energy of 100% and 0% of the high ductility steel sheet and the absorbed energy ratio of each member of the high ductility steel sheet 0% (conventional steel 100%) as shown in FIG. 4 It can be understood that the absorbed energy when the application member of the high-ductility steel sheet is changed can be predicted.

The application ratio of the high-ductility steel sheet is often determined in advance from the cost of drying the ship. In such a case, by analyzing by the finite element method, if the ratio of the absorbed energy for each member to the weight ratio of the member in the case where the conventional steel as shown in Fig. 4 is used is obtained in advance, The priority (economical) of the applied member of the ductile steel sheet can be evaluated. That is, by applying a high ductility steel sheet from a member having a high ratio (ratio of absorbed energy / weight), it is possible to easily determine the member to which the high ductility steel sheet is applied.

Next, the value of the total elongation specified in the Unified Requirements W11 Rev. 8 2014 of the International Association of Classification Societies (IACS) for stiffeners, trusses, stringers, upper decks, Fig. 8, Fig. 9 and Fig. 10 show the results of analysis of the damage of the inner panel in the case of using a steel sheet having a total elongation of 1.3 times, 1.4 times and 1.5 times as large as that of the steel sheet. Figs. 8 to 10 are views after 6 seconds from the start of the collision. Fig. Figs. 8 to 10 are views showing the inner plate from the inside of the cargo oil tank inside the hull, and half of the starboard half of the collided ship is shown as non-displayed. As shown in Fig. 8, when the value of the total elongation was 1.3 times, a wave (crack penetrating the inner plate vertically) occurred in the inner plate. On the other hand, as shown in Figs. 9 and 10, when the value of the total elongation is 1.4 times or more, no peeling occurs in the inner plate. In Fig. 8, there are a plurality of cracks and damages in the lower part of the tank. In Fig. 9 and Fig. 10, however, it can be confirmed that these plural cracks and damages did not occur.

In addition, the total elongation values specified in the Unified Requirements W11 Rev. 8 2014 are shown in Table 1. Table 1 specifies the minimum elongation to be satisfied by the hull material used, depending on plate thickness and grade. The alphabets (A, B, D, E, and F) in Grade indicate the difference in test temperature required in the Charpy Impact test and the numbers (32, 36 and 40) The high-ductility steel sheet satisfies the unified standard because it has an elongation exceeding the standard value of the total elongation shown in Table 1 above.

In view of the above-described analysis result, manufacturing cost, and productivity, the embodiment of the hull structure of the present invention is as follows.

The present invention is characterized in that a total elongation of at least 1.4 times the value of the total elongation specified by the IACS uniform standard is imposed as a specification on the part of the outside plate of the side portion or the entire portion of the outside plate as the specification, It is a hull structure using a ductile steel plate. In addition, it is preferable to use the high ductility steel sheet on a part of the inner plate facing the outer sheath in which the high ductility steel sheet is used, or on the entire portion of the inner sheath.

In the present invention, it is confirmed that a total elongation of not less than 1.4 times the value of the total elongation specified by the IACS uniform standard is imposed as a specification on the part of the inner plate of the side portion or the entire portion of the inner plate, It is a hull structure using a ductile steel plate. In addition, it is preferable to use the high ductility steel sheet at a part of the outside sheathing facing the inner sheath where the high ductility steel sheet is used, or at the entire part of the outside sheathing.

Further, it is more preferable to use the high-ductility steel sheet on a part or all of the stiffeners adhered to the portions (outer plates, inner plates) where the high-ductility steel sheet is used. Further, it is more preferable to use the high ductility steel sheet on part or all of the stringer. Further, it is more preferable to use the high ductility steel sheet for part or all of the upper deck. Further, it is more preferable to use the high ductility steel sheet in part or all of the bilge. Further, it is more preferable to use the above-described high ductility steel sheet for part or all of the transformer.

It can be seen from Fig. 7 that as the number of members to which the high ductility steel sheet is applied increases, the absolute value of the energy absorption amount increases. From the above, it is preferable to apply the high-ductility steel sheet to a large number of members. However, from the viewpoints of economical efficiency and efficient energy absorption, it is preferable to first apply to outer shell, inner shell and reinforcement. In this case, there may be a deformation applied to the outer plate, the inner plate and the stiffener adhered to the outer plate, and a deformation applying the high-ductility steel plate to the outer plate and inner plate. In the case where only one of the shell plate and the inner plate is made of the high ductility steel sheet, it is more preferable that the shell plate is made of the high ductility steel sheet because the energy absorption amount of the shell plate is higher than the absorbed energy amount of the inner plate. However, the use of the high ductility steel sheet is not limited to only the inner steel sheet. Also, a high ductility steel plate may be used for the bottom structure, the bow structure, and the stern structure. Further, a high ductile steel sheet may be used for the upper structure (bridge or the like).

Since the energy absorption is large even after the uniform elongation in the stress-strain curve, in the present invention, the total elongation of the steel material used in the member is considered in order to suppress the final wave. When the high-ductility steel sheet is applied to a shell plate, an inner plate and a stiffener, a side impact at a speed limit of 12 knots in a general harbor does not cause a break in the inner plate. As described above, it is economically reasonable to limit the application member of the high ductility steel sheet.

As described above, the present invention uses a high-ductility steel sheet having a total elongation of 1.4 times or more of the total elongation specified by the unified standard of IACS as a specification and confirmed to satisfy the above specifications. However, , The actual production target of the high ductile steel sheet may be 1.5 times or 1.5 times or more. The total elongation average of the high ductility steel sheet can be regarded as about 1.5 times or 1.5 times the value of the total elongation specified in the unified standard of IACS. In the embodiments described later, the present invention uses 1.5 times as an example. Further, as the specification of the total elongation of the high-ductility steel sheet, it may be set to a higher value, for example, 1.5 times or more or 27% or more, not 1.4 times or more than the value of the total elongation specified by the unified standard of IACS .

It is also known that the value of the total elongation depends on the test piece. The values of the total elongation specified by the IACS unified standard are based on the equilibrium test specimens with GL (intergrowth distance) = 200 mm and w (width) = 25 mm. In the case of using the test specimens other than the test specimens, the conversion formula of the following formula (1) may be used from a known method, for example, from 2.2.2 and Table K.2.2 of Part 2 of Part 2,

Where n is the total elongation when an arbitrary test piece is used, E is the total elongation when a balanced test piece of GL = 200 mm and w (width) = 25 mm is used, A is the cross sectional area , L is the distance between the centers of the test specimens.

The present invention can be applied to a small-sized ship in addition to a large-sized ship, but is particularly effective when applied to a large-sized ship. The steel sheet used for such a large-sized ship has a thickness of more than 12 mm and not more than 50 mm. For example, steel plates of more than 12 mm and not more than 50 mm are often used for the shell and inner plates, and steel plates of more than 12 mm and not more than 30 mm are often used for the reinforcement. Therefore, it is preferable that the thickness of the high-ductility steel sheet used in the present invention is more than 12 mm and not more than 50 mm. In particular, the steel sheet used in these large ships (particularly, the outer sheet) has a particularly large thickness of more than 20 mm, and the steel sheet for use in the present invention is applied to a member having a sheet thickness exceeding 20 mm May be limited. In principle, the steel plates shall have a yield strength of 235 MPa or more (IACS Normal Strength Steel), 315 MPa or more (IACS strength classification 32), 355 MPa or more (IACS strength classification 36) and 390 MPa or more (IACS strength classification 40). As a general rule, the tensile strength of the steel sheet is 400 MPa or more and 660 MPa or less.

Although the effect of the present invention is specifically shown by a VLCC having a particularly large effect, for example, as shown in Fig. 5, even if only the outer plate is secured, the absorption energy at the time of collision is secured to be close to 30% Considering the absolute value of the amount of energy, even when applied to a single-hull structure (single hull) such as a bulk carrier (ore carrier) in which collision safety is strictly problematic, It is effective. In addition, in the claims of the present invention, two members, i.e., an outer plate and an inner plate, are distinguished. In the case of a single-row hull structure, since the shell plate is also considered to be the inner plate (conversely, the inner plate is also considered to be the shell plate), the case of a single-row hull structure is also within the technical scope of the present invention. Needless to say, it is needless to say that even in the fuel oil tank portion where the leakage of oil is likely to occur due to the collision of the bulk carriers in the event of collision, even in the case where the hull is basically a one- (Local) double-hull structure surrounded by the inner plate and the inner plate), the waveguide is suppressed and the oil leakage is suppressed. Further, even in the case of a ship having a sunshade angle, in the case of using the high ductility steel sheet, there is a high possibility of not generating a wave at the time of collision, depending on the speed and the angle of impact. In other words, it is possible to raise the collision speed without generating a wave at the angle of view. Or even if a wave break occurs at the time of collision, the wave break can be made very small. As a result, the collision safety can be improved.

The total elongation, which is 1.4 times or more the value of the total elongation specified by the unified standard of IACS, is a very high value and can not be satisfied unless a steel sheet is manufactured by a special manufacturing method that satisfies this high elongation. However, the value of total elongation has some variation. As a result, when a steel sheet is produced by a common manufacturing method, a steel sheet having an overall elongation property which is 1.4 times or more as large as the value of the total elongation stipulated by the unified standard of IACS is produced, and the steel sheet is (unintended) A case used for the hull structure is considered. However, such a case does not fall within the technical scope of the present invention. In order to carry out the present invention, it is necessary to specify the side steel plate members which need to suppress the corrugation, and to use the above-mentioned high ductility steel plates for the steel plates to be used for the members. Particularly, in the case of the outer plate or inner plate, it is necessary to specify the area where it is necessary to suppress the wave breaking, and to use the high ductility steel sheet for the steel plate to be used in the area. Specifically, a value of the total elongation, which is 1.4 times or more the value of the total elongation specified by the unified standard of IACS in the steel sheet specification, is required, and the total elongation (manufactured by conforming to the specification and measured by the subsequent tensile test) It is intended to use only steel plates that are at least 1.4 times the value of the total elongation specified in the IACS unified standard. Namely, it is specified that a steel plate used for the side steel plate member has a total elongation of not less than 1.4 times the value of the total elongation specified by the IACS unified standard, The design of the hull structure using the high ductile steel sheet confirmed to satisfy the specification is intended. As a result of such intentional design of the hull structure, only the steel plate which has been confirmed to be 1.4 times or more of the total elongation value specified by the IACS standard of uniformity is required to have the hull structure specified as a side steel plate member Member having a hull structure used in the hull structure.

In addition, the steel sheet used in the hull structure needs to satisfy the standards of each classification society in conformity with the unified standard of IACS. As a result, the tensile test is performed at the frequency specified by the standards of each classification society. Normally, it is determined that only the steel sheet whose test results satisfy the steel material specification, etc. is passed to the inspection by each steelmaker, and the results of the tensile test and the like are described in the steel material inspection certificate and the like. Steel inspection certificate, etc., are received by the surveyor of each classification society and then delivered to the shipbuilding company from the steel company.

In the present invention, " 1.4 times the value of the total elongation specified by the IACS uniform standard is imposed as a specification " means that the total elongation of 1.4 times or more the value of the total elongation specified in the unified standard of IACS, Lt; / RTI > Computer processing of steel products such as shipbuilding companies and steelmakers is proceeding, and there are many cases where a written specification such as steel plate specifications is not sent. In the present invention, it may be imposed as a specification by a method other than a written method such as data transfer. Also, the expression " can confirm that the above specification is satisfied " means that tensile test is performed at a frequency specified by at least the standards of each classification society, and the inspection of each steelmaker measures the value of the total elongation Is at least 1.4 times the value of the total elongation specified in the IACS unified standard. This confirmation is generally performed by a computer system in each steelmaking company (for example, whether or not the test result satisfies a required value such as a steel plate specification or the like is determined by the computer system).

The side steel plate members which need to suppress the corrugation (the portions where the corrugation is to be suppressed in the shell or inner plate) depend on the type of vessel, depending on the way of thinking about the collision safety of the designer of the hull structure . For example, in the case of a bulk carrier, it is specified that a shell, not a ballast tank, is a shell plate in which a portion of a shell plate (that is, a portion without an inner plate) May be used. Alternatively, the portion where the shell plate to be a part of the fuel tank is present may be specified as the shell plate which needs to suppress the wave plate, and the high ductility plate may be used for the shell plate of the portion.

Further, for example, in the case of a tanker, the outer plate facing the portion (the inner plate portion) where the tank storing the product oil (crude oil in the case of the crude oil tanker) is stored is specified as the outer plate do. In this case, the portion is almost entirely in the height direction and the longitudinal direction of the outside sheathing, and the high-ductility steel sheet is used for the outside sheathing portion. The high ductility steel sheet may be used for the inner plate facing the outer sheath using the high ductility steel sheet, or a portion or all of the sheathing attached to the outer sheath and the inner sheath, The high ductility steel sheet may be used.

Further, for example, in the case of a rectangular tank type LNG carrier, the portion of the side shell plating nearest to the spherical tank in which the LNG is stored may be specified as an outer shell which needs to suppress the waveguide. In this case, since the tank is spherical, the portion is not necessarily the portion covering the entire tank when viewed from the side and viewed from the side, and may be only the portion closest to the tank. The high ductile steel sheet may be used for the outer plate of the specified portion. If necessary, the peripheral portion of the side shell plating nearest to the spherical tank may also be specified as the shell plating, which needs to suppress the wave tightness.

In addition to the outer plate, the inner plate, and the stiffener, part or all of the stringer, part or all of the upper deck, part or all of the bilge, part or all of the trans, Steel plates may be used.

The above method is a method of specifying a member which needs to suppress the wave from the design drawing of the angle of view. The absorption energy analysis of each member by the finite element method may be performed to specify a member that needs to suppress the waveguide. For example, by using Fig. 4 showing the ratio of absorbed energy to each member in the case of conventional steel, the outer plate having the highest absorption energy is defined as a member which needs to suppress the wave breaking, and even if the above- do. In addition, from the comparison between the analysis results of Figs. 4 to 7 and the respective drying costs, it is also possible to specify the outer and inner plates as the members which need to suppress the wave, and the outer and inner plates may be made of the high ductility steel sheet. Similarly, from the comparison between the results of analysis shown in Figs. 8 to 10 and Fig. 11 to be described later and the respective drying costs, the outer plate and the inner plate are specifically specified as the members required to suppress the wave plate, And it is also possible to use the high ductility steel sheet for the shell plate, the inner plate, and the stiffener attached to each of the shell plate and the inner plate.

While the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to these examples. Those skilled in the art will recognize that various changes and modifications within the spirit and scope of the appended claims will be apparent to those skilled in the art and they are also within the technical scope of the present invention.

≪ Example 1 >

First, the effect of applying the present invention to a double-hull structure (double hull) will be described. 1, a steel plate having a total elongation of 1.5 times the value of the total elongation specified by the Unified Requirement W11 of the International Association of Classification Societies (IACS) is attached to the shell plate, the inner plate, , And the damage of the inner plate was analyzed as FEM in the crash scenario shown in Fig. As a result, as shown in Fig. 11, it was clear that the inner plate did not reach crack growth or large cracks.

≪ Example 2 >

Next, the effect of applying the present invention to a single-row hull structure (single hull) will be described. The present inventors assumed an accident that a VLCC collided with a bulk carrier of a single hull, and the energy absorbed by member deformation and deformation of the bulk carrier was obtained by FEM.

In the FEM analysis, as shown in Fig. 3, a serious scenario in which the VLCC collides with 12 에서 at 90 degrees immediately adjacent to the central portion of the hull of a suspended bulk carrier (V _A = 0 하였다) is assumed . Specifically, as shown in Fig. 12, the bow of the VLCC was collided with the outer plate 20 of the bulk carrier of the one-sided hull structure, and the analysis was performed up to 6 seconds after the collision. This collision point is assumed to be a strict collision position with respect to the wave plate of the outside sheathing. In Fig. 12, the right half of the bulk carrier is shown as non-display.

The aggregate 21 adhered to the outer plate 20 and the outer sheath 20 of the bulk carrier is a high-softness steel sheet (entire elongation 17%), 27%) (Case 5) were analyzed by FEM. The aggregate 21 is attached to the outside sheathing 20 and is a reinforcing material for suppressing warpage outside the outside sheathing 20. The total elongation of 17% in Case 4 is the lower limit of the total elongation specified by the unified standard of IACS. The total elongation of 27% in the case 5 corresponds to 1.5 times of the total elongation of 17% in the case 4.

In the analysis of Case 4 and Case 5, a comparison of the absolute value of the energy absorbed by the bulk carrier up to the occurrence of the outside sheathing is shown in Fig. It is apparent from Fig. 13 that by applying the high ductility steel sheet to the outer plate and the aggregate (reinforcement) of the bulk carrier, the amount of energy absorption up to the occurrence of the wave plate can be greatly improved.

Figs. 14 to 17 show the analysis results of the damage of the outer sheath in the analysis of the case 4 and the case 5. Fig. 14 to 17 are views showing the outside sheathing from the outside of the bulk carrier.

14 and 15 are views of Case 4 and Case 5 after 1.4 seconds from the start of the collision. As shown in Fig. 14, when conventional steel was used for the outer plate and the aggregate (reinforcing material), a wave (crack penetrating the outer plate vertically) occurred in the outer plate. On the other hand, as shown in Fig. 15, when a high ductility steel sheet is used for the outer panel and the aggregate (reinforcing material), the outer panel does not have a wave break.

Fig. 16 and Fig. 17 are diagrams when the speed of the bulk carrier (V) and the speed V _B (V) of the VLCC become equal speeds, and in this analysis, the figure is six seconds after the start of the collision. As shown in Fig. 16, when conventional steel is used for the outer plate and the aggregate (reinforcement), the outer plate is largely damaged. On the other hand, as shown in Fig. 17, when a high ductility steel sheet is used for the outer shell and the aggregate (reinforcing material), the outer shell is broken, but the degree of damage of the outer shell is small as compared with the case of using the conventional steel. From the above, it is apparent that the occurrence of the wave plate of the outer plate can be greatly reduced and the wave plate can be made small by applying the high ductility steel sheet to the outer plate and the aggregate (reinforcement) of the bulk carrier.

Further, the inventors of the present invention calculated the limit collision speed of VLCC based on the energy absorbed in the bulk carrier shown in Fig. The critical impact velocity is a velocity at which a wave is generated in the outer shell of the bulk carrier. In other words, the critical impact velocity is a velocity at which the waves do not occur in the outer shell.

18 shows estimated values of the critical impact velocity of the VLCC in the case 4 and the case 5. Fig. In Case 4, if the velocity of the VLCC exceeds 3 kPa, the outer plate of the bulk carrier generates a wave, but in Case 5, the velocity of the VLCC increases to 5 kPa. It has been found that by applying a high ductility steel sheet to the outer plate and aggregate (reinforcing material) of the bulk carrier, the critical collision speed is greatly improved.

In this regard, the present inventors assumed a scenario in which the VLCC collides with 5 에서 at 90 degrees immediately adjacent to the center of the hull of a suspended bulk carrier (V _A = 0㏏), and analyzed by FEM . In this analysis, in comparison with the analysis performed in the above-described analysis of Figs. 12 to 17, the VLCC speed is different, but the other conditions are the same.

18 and 19 are diagrams at the time of the bulk carrier velocity V _A of the speeds (㏏) and VLCC V _B (㏏) has been a constant speed, a view after 6 seconds from the start of collision in the present analysis. As shown in Fig. 19, in the case where the outer plate and the aggregate of the bulk carrier were conventional steel (total elongation 19%), the outer plate was corrugated. On the other hand, as shown in Fig. 20, when the outer plate and the aggregate of the bulk carrier were high-ductility steel sheets (total elongation 28.5%), no breakage occurred in the outer plates. In the outer plate of the bulk carrier subjected to the analysis, IACS had a strength of 36 and a thickness of 25 to 30 mm. As a result, according to Table 1, the total elongation of the conventional steel was 19%, and the total elongation of the high-ductility steel sheet was 28.5% of 1.5 times that of the conventional steel.

When the application range of the high ductility steel sheet is limited to the member having a sheet thickness exceeding 20 mm, it is preferable that the total elongation of the high ductility steel sheet exceeds 27% in consideration of manufacturing variations. This also applies to the double-hull structure.

For example, according to the data described in the Journal of the Japan Society of Naval Architects and Ocean Engineers, No. 17, No. 2013A-GS10-4, "Establishment of Ship Collision Incident Database on the Korean Coast Based on the Decision of the Refereeing Officer and Its Typing" The frequency of occurrence of a collision when the speed of the ship is 5. Or less is about 20% of the total collision accident. This data includes types of vessels other than the bulk carriers. On the whole, assuming the same frequency of occurrence for large-sized bulk carriers, by applying the high-ductility steel sheets to the outer plates and aggregates (reinforcing materials) of the bulk carriers, It was found that the occurrence of a wave in the outside sheathing can be suppressed in a collision of about 20% of an accident involving a carrier as a collided ship. This is sufficient for economic rationality, considering the protection of marine environment, prevention of damage by human life and loading by collision.

Next, Yasuhira Yamada, Hisayoshi Endo, and Preben Terndrup Pedersen et al., "Effect of Buffer Bow Structure in Ship-Ship Collision", International Journal of Offshore and Polar Engineering, Vol. 18 No. 2, 2008, p. 1-9, the above-described calculation method of the critical impact speed will be described with reference to the following equations (2) to (4). As a calculation condition, it is assumed that the collision ship (B ship) collides with 90 degrees immediately adjacent to the central portion of the hull of the collided ship (A ship) stopped, as shown in Fig. The respective parameters in the calculation of the critical impact speed are as follows.

V _A : Speed of impacted ship (= 0)

V _B : Collision ship speed

M _A : displacement of the ship to be impacted (including additional water mass)

M _B : Displacement of collision ship (including additional water mass)

E _s is the energy absorbed by the vessel to be impacted, other than the hull motion,

And, just before and after the collision, kinetic energy conservation law and momentum conservation law are applied. Here, in the case of collision at the critical collision speed, it is assumed that the velocities of both ships after collision become equal to V '. Further, it is assumed that there is no rigid body rotation motion of the hull. In this case, the following expression (2) is derived from the kinetic energy conservation law, and the following expression (3) is derived from the momentum conservation rule.

V 'is eliminated from the above equations (2) and (3), and V _B is solved to obtain Equation (4). Then, if the E _s according to the equation (4), in the case of collision in the limit impact speed, impact end to a blood collision vessels absorbed by the non-hull kinetic energy E _{s, cr,} based on the art E _{s, cr} , The limit collision speed V _{B , cr} is calculated.

Also, when it comes to calculating the limit impact velocity shown in Figure 18. In the present invention, to secure the blood collision vessel and simplified to (M _A = ∞), to the Equation (4) Equation (5), limit the impact velocity V _{B , and cr} are calculated.

INDUSTRIAL APPLICABILITY The present invention is useful for a ship in which good collision resistance is important in the hull structure.

10: Exterior
11: inner plate
12: Stiffener attached to shell
13: Stiffener attached to inner plate
14: Trans
15: Stringer
16: Upper deck
17: Bilge
20: Exterior
21: Aggregate (reinforcing material)
22: Upper Deck
23: Stiffener
24: Bilge
25: Trans

Claims (19)

A total elongation of not less than 1.4 times the value of the total elongation specified in the Unified Requirements W11 Rev. 8 2014 of the International Association of Classification Societies (IACS) is applied as part of the shell plating, And has a hull structure using a high-ductility steel sheet which is confirmed to satisfy the above-mentioned specifications. The method according to claim 1,
The hull structure according to any one of the preceding claims, further comprising a hull structure using the high ductility steel sheet on a part of the inner plate facing the outer sheath in which the high ductility steel sheet is used or on the entire inner plate. A total elongation of not less than 1.4 times the value of the total elongation specified in the Unified Requirements W11 Rev. 8 2014 of the International Association of Classification Societies (IACS) is imposed as a specification on a part of the inner plate of the side part or the whole part of the inner plate. And has a hull structure using a high-ductility steel sheet which is confirmed to satisfy the above-mentioned specifications. The method of claim 3,
The hull structure according to any one of claims 1 to 3, further comprising a hull structure using the high ductility steel sheet on a part of the outside sheathing facing the inner sheath in which the high ductility steel sheet is used or the entirety of the outside sheathing. 5. The method according to any one of claims 1 to 4,
Further, the hull structure is characterized in that the high-ductility steel sheet is used for part or all of the stiffener adhering to the portion where the high-ductility steel sheet is used. 6. The method according to any one of claims 1 to 5,
Further, the hull structure is characterized in that the high-ductile steel sheet is used for part or all of the stringer. 7. The method according to any one of claims 1 to 6,
Further, the hull structure is characterized in that the high ductile steel sheet is used for part or all of the upper deck. 8. The method according to any one of claims 1 to 7,
Further, the hull structure is characterized in that the high-ductile steel sheet is used for part or all of the bilge. 9. The method according to any one of claims 1 to 8,
Further, the hull structure is characterized in that the high-ductility steel sheet is used for part or all of the transformer. 10. The method according to any one of claims 1 to 9,
Wherein the high ductility steel sheet has a thickness of more than 12 mm and not more than 50 mm. The steel plate to be used in the area is specified by specifying the area where it is necessary to suppress the waveguide from the outside plate of the side portion and the total elongation specified in Unified Requirement W11 Rev. 8 2014 of the International Classification Society (IACS) Wherein a high-ductile steel sheet having a total elongation of 1.4 times or more of the value of the high-ductility steel sheet is attached as a specification and confirmed to satisfy the above-mentioned specifications. 12. The method of claim 11,
The steel sheet for use in a steel sheet according to any one of claims 1 to 3, wherein the steel sheet used for the steel sheet is characterized in that the steel sheet used for the steel sheet is a high- Design method of structure. It is necessary to identify the parts of the inner plate on the side of the ship which need to be suppressed and to apply to the steel plate used for the part the total elongation specified in the Unified Requirements W11 Rev. 8 2014 of the International Classification Society (IACS) Wherein a high-ductile steel sheet having a total elongation of 1.4 times or more of the value of the high-ductility steel sheet is attached as a specification and confirmed to satisfy the above-mentioned specifications. 14. The method of claim 13,
The steel sheet according to any one of claims 1 to 3, wherein the steel plate used for the area is specified by specifying a portion of the outer plate facing the inner plate using the high-ductility steel sheet, Design method of structure. 15. The method according to any one of claims 11 to 14,
The method of designing a hull structure according to claim 1, wherein the high ductility steel sheet is used for a steel sheet used for part or all of a stiffener attached to the portion where the high ductility steel sheet is used. 16. The method according to any one of claims 11 to 15,
The method of designing a hull structure according to claim 1, wherein the steel sheet used for part or all of the stringer is the high ductility steel sheet. 17. The method according to any one of claims 11 to 16,
The method of designing a hull structure according to claim 1, wherein the steel sheet used for part or all of the upper deck is the high ductility steel sheet. 18. The method according to any one of claims 11 to 17,
The method of designing a hull structure according to claim 1, wherein the steel sheet used for part or all of the bilge is the high ductility steel sheet. 19. The method according to any one of claims 11 to 18,
The method of designing a hull structure according to claim 1, wherein the steel sheet used for part or all of the transformer is the high ductility steel sheet.

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