JP5015349B2 - Bow structure - Google Patents

Description

The present invention relates to a bow structure that has a buffering effect that can prevent damage to a partner ship that collides due to deformation of itself during a collision, thereby improving collision safety.
This application claims priority on August 24, 2009 based on Japanese Patent Application No. 2009-193475 for which it applied to Japan, and uses the content here.

  Today's large ships are equipped with a Barbasse bow (spherical bow) under the bowline to reduce any energy loss due to wave resistance during navigation. In order to produce a curved plate having a large curvature used for this Barbasse bow, bending by linear heating, that is, linear heating, is frequently used in the molding process.

  This linear heating process is a processing method in which the steel sheet surface is locally heated in a linear manner using a gas burner or the like so that the highest temperature on the heating side surface is about 600 ° C. to 1100 ° C. In this linear heating process, a phenomenon is used in which the heated portion is thermally expanded and plastically deformed by restraint from the surroundings. In this linear heating process, water cooling is generally performed immediately after heating in order to increase work efficiency, and the steel sheet after the linear heating process is baked into the heated part and locally The yield strength has increased.

  For this reason, the Barbasu bow using such a curved plate has nonuniform strength along the surface and is not easily deformed. When a ship equipped with such a barbus bow collides with another ship, for example, as shown in FIG. 10A, the bow 200a of the own ship 200 bites into the ship 201a of the other ship 201 to destroy the ship 201a, and further, the destruction part 201b. There was a risk that the hull would expand and there would be a hole in the hull (the hull would break).

  Conventionally, as a means (structure) for improving the collision safety of a ship, studies have been made mainly from the aspect of a hull structure such as a double hull structure. However, in recent years, it has been studied to apply a steel material excellent in energy absorption performance at the time of collision.

  As an example, in Patent Document 1 below, the product of the yield stress σy and the uniform elongation εu (σy × εu) is given to the outer skin of the ship, etc., compared to the conventional standard material of the International Classification Society Association (IACS). Steel that has been increased by 20% or more, or steel that has increased the amount of energy absorption up to the uniform elongation εu by 20% or more in the tensile test, or the yield stress σy is equal to or greater and the uniform elongation εu is increased by 20% or more. A hull structure to which a steel material is applied is disclosed. With this configuration, it is possible to increase the amount of energy that can be absorbed before a breakage occurs in the hull, while maintaining the hull structure that is not different from the conventional one.

  However, if the ship's bow collides with the other ship's hull, even if the ship's bow does not deform, even if the ship uses a steel plate that has improved its energy absorption by 50% or more, There is a risk of penetrating the ship's hull. In that case, there is a problem that the increase in the amount of absorbed energy cannot be expected.

In order to solve such a problem, it is also considered to design a bow portion that exhibits a buffering effect even when the bow of the ship collides with another ship.
For example, Patent Literature 2 below discloses a bow portion having a flexible structure in which the bow portion is constructed using a material softer than a steel material used for general hull construction.
However, this Patent Document 2 only shows an aluminum material that is difficult to apply to a large ship as a soft material, and does not particularly disclose obtaining a flexible structure using a steel material.

  Further, Patent Document 3 below discloses a bow structure in which a low strength portion made of a low yield point steel having a yield stress of 235 MPa or less is provided on the outer plate of the base portion of a spherical protrusion (valve portion) in Barbus Bau. Yes. In this structure, the bending strength in the lateral direction of the base portion is reduced and the bow portion is bent by the reaction force of the collision, so that the bow portion of the collision ship is prevented from biting into the flank of another ship.

  In this Patent Document 3, the horizontal portion strength of the Barbus Bau is reduced while reducing the structural strength in the horizontal direction of the Barbus Bau while ensuring a sufficient strength in the vertical direction of the Barbus Bau, as shown in FIG. To easily increase the contact area of the collision part 300c. This structure prevents the breakage (generation of holes) of both the collision ship (own ship) 300 and the collision ship (other ship) 301 due to the increase in the contact area. However, the bending of the root portion 300b is caused by local deformation of the portion using the low yield point steel, and the collision energy is not sufficiently absorbed by the bending of the root portion 300b.

Further, when the barbus bow 300a is bent, the own ship 300 and the other ship 301 come closer to each other, and the distance between the two becomes smaller without sufficiently absorbing energy. As a result, as shown in FIG. 10B, the tip portion 300d of the collision ship 300 may come into contact with the collision ship 301 and penetrate into the hull 301a of the collision ship 301, which may further increase the damage due to the collision accident. There is also sex.
Therefore, it is necessary to increase the absorption amount of the collision energy after the barbus bow 300a is deformed and until the tip portion 300d of the own ship 300 comes into contact with the hull of the other ship 301.
The dotted line portion in FIG. 10B indicates the position of the Barbus bow 300a before the collision ship 300 collides with the collision ship 301.

JP 2002-087373 A Japanese Patent Laid-Open No. 7-329881 JP 2004-314825 A

  The present invention has been made in view of the above circumstances, and the portion of the bow of the bassus bow is linearly heated under normal heating conditions (maximum heating temperature on the heating side: 600 to 1100 ° C.) and has a predetermined curvature. The conditions of the bow structure that can realize a large amount of energy absorption at the time of deformation of the valve part of the Barbus Bau as much as possible when the ship collides. The purpose is to clarify. It is another object of the present invention to provide a bow structure having a buffering effect that can effectively prevent damage to other ships in the event of a collision without changing the hull structure design.

In order to solve the above-described problem, in one aspect of the present invention, the following bow structure is provided.
(1) The bow structure with excellent collision energy absorption capability is such that the outer shell member of Barbusbau is given a curvature by being linearly heated at a maximum surface temperature on the heating side of 600 ° C. or higher. Before, it consists of a steel plate whose yield strength at room temperature is 120 MPa to less than 200 MPa, and whose yield strength at 600 ° C. is not more than 0.6 times the yield strength at room temperature.
(2) In the bow structure with excellent collision energy absorption capability as described in (1) above, the steel plate constituting the outer shell member of the Barbasse bow has a maximum surface temperature on the heating side of 600 ° C or higher and a bending angle of 120 ° C. Is obtained by dividing the yield strength YP (LH, RT) of the linear heating portion at room temperature by the yield strength YP (AR, RT) of the non-linear heating portion at room temperature. A steel sheet having a yield strength ratio α of 1.2 or less may be used.
(3) In the bow structure excellent in the collision energy absorption capability according to the above (1) or (2), the outer shell member and the inner component member constituting the Barbus bow are 45 degrees or less with respect to the horizontal direction of the hull longitudinal direction. The yield strength of the L member having an angle of may be lower than the yield strength of the W member having an angle greater than 45 degrees with respect to the horizontal direction of the hull.

  According to the present invention, when a situation occurs in which the bow of the own ship having the Barbus bow collides with the hull of another ship, the valve side surface of the Barbus bow on the collision ship side (own ship side) is more uniformly buckled and deformed. Thus, the collision energy can be greatly absorbed. In addition, by colliding the collision surface while absorbing the collision energy, it is possible to reduce the damage of the ship to be collided (other ships) as much as possible, thereby contributing to the prevention of marine pollution due to the sinking of the ship and the oil spill. be able to.

It is a figure which shows the relationship between the yield strength of a steel plate, and test temperature. It is a figure which shows the steel plate bent to the bending angle of 120 degree | times by linear heating. It is a figure which shows the test piece produced from the said steel plate bent to the bending angle of 120 degree | times by linear heating. It is a figure which shows the relationship between (alpha) and ratio YP (AR, 600 degreeC) / YP (AR, RT) of the yield strength in 600 degreeC of a steel plate, and the yield strength in room temperature of a steel plate. It is a figure explaining the test method for investigating the buckling property of the steel plate which received the linear heating. It is a figure which shows the relationship between the magnitude | size P of the load at the time of applying a load to the steel plate which received the linear heating, and the displacement (DELTA) of a block. It is a figure which shows the relationship between EA ratio (ratio with the absorption energy in case (alpha) is 1.0) and the value of (alpha) in the test shown in FIG. It is a figure which shows the structural model of the ship side in the collision simulation of a bow structure and a ship side structure. It is a figure which shows transition of the amount of penetration and the relative energy absorptivity absorbed by Barbus Bau when a bow structure penetrates into a ship side structure. It is a figure which shows the relationship between (alpha) and the ratio of the energy absorptivity divided by the energy absorptivity of the steel plate in the case of a reference example ((alpha) = 1). It is a schematic diagram which shows each deformation | transformation of a collision ship and a ship to be collided when the ship which does not have a buffering effect collides with the bow structure. It is a schematic diagram which shows each deformation | transformation of a collision ship and a ship to be collided when the ship which has a buffer effect collides with the bow structure. It is a schematic diagram which shows a deformation | transformation of each of a collision ship and a ship to be collided when the ship which has the buffer effect of this invention collides with the bow structure. It is a longitudinal cross-sectional view which shows the outline of the internal structure of the bow which has a Barbus bow. It is a perspective view which shows the outline of the internal structure of the bow which has a Barbus bow.

  The present inventors have fully studied the case where an accident occurs in which the bow of a ship having a Barbus bow collides with the hull of another ship, and as shown in FIG. 10C, the valve portion 100b of the Barbus bow 100a is made more uniform. It was found that more buckling energy can be absorbed if buckling deformation is possible. As shown in FIG. 10C, the impact force due to the collision is alleviated by the buckling deformation of the Barbus bow 100a of the collision ship 100. As a result, local breakage and breakage of the hull 101a of the ship 101 can be avoided, and the occurrence of breakage can be prevented. The dotted line portion in FIG. 10C indicates the position of the Barbus bow 100a before the collision ship 100 collides with the collision ship 101.

  The valve portion of the Barbus Bau is configured using a steel plate that has been linearly heated and provided with a curvature as described above. By this linear heating process, the yield strength is increased in the portion where the heat of the steel sheet is received. As a result, the yield strength of the steel sheet is non-uniform between the part to which heat is locally applied and the part to which heat is not applied.

  When such a steel plate is used, the Barbasse bow deforms unevenly during a collision. Therefore, there is a concern that the energy absorption capacity of the structural member using the steel plate is lower than that of the structural member using the steel plate whose yield strength is uniform inside the steel plate. Therefore, it may not be possible to expect a sufficient amount of collision energy absorption to avoid local breakage or breakage of the ship to be collided in the event of a collision.

  Therefore, it is necessary to prevent bending due to bending deformation as shown in FIG. 10B. Therefore, the inventors examined a structure in which the Barbus bow 100a is buckled uniformly along the horizontal direction of the hull as shown in FIG. 10C.

  In order for the Barbus bow to be deformed at the time of a collision, the member arranged along the hull longitudinal horizontal direction, which is the collision direction, needs to be made of a steel material that is easily deformed. In order for the Barbus bow to buckle uniformly, the deformation of the members arranged along the longitudinal direction of the hull is restrained by the members arranged in the direction intersecting with the longitudinal direction of the hull to prevent the Barbus bow from being bent. It is effective.

  Although the shape and internal structure of the Barbus bow are various, it is comprised by the outer shell member and internal structure member which have a curvature. Furthermore, this internal structural member forms the skeleton of Barbus Bau and is generally constituted by a combination of longitudinal ribs and lateral ribs.

  FIG. 11A and FIG. 11B schematically show an example of the structure of the Barbasse bow. The internal structural member 111 that constitutes the Barbassau has a plurality of members arranged parallel to or perpendicular to the hull longitudinal horizontal direction with respect to the hull longitudinal horizontal direction, which is the hull collision direction, and a predetermined angle with respect to the hull longitudinal direction. It is comprised by the one part member arrange | positioned by.

  Specifically, the plurality of members constituting the internal structural member are classified as either a member arranged parallel to the hull longitudinal horizontal direction or a member arranged perpendicularly. That is, the internal structural member 111 constituting the Barbus bow is classified into an L member 111b and a W member 111a defined as follows. The L member 111b is a member having an angle of 45 degrees or less with respect to the hull longitudinal horizontal direction. The W member 111a is a member having an angle larger than 45 degrees with respect to the horizontal direction of the hull.

The L member 111b is a member that deforms at the time of a collision, and the W member 111a is a member that restrains deformation of the L member 111b. In order to deform the L member 111b, it is preferable to use a steel material having a yield strength lower than the yield strength of the W member 111a for the L member 111b. As a result, it is possible to prevent the W member 111a from being easily deformed with respect to the L member 111b.
Furthermore, this structure can prevent local deformation of the L member 111b such as simple bending, and the Barbus bow is deformed along the horizontal direction of the hull longitudinal direction.
Similarly, the outer shell member 110 can also be classified into an L member and a W member, and a steel material having a yield strength lower than the yield strength of the W member is preferably used for the L member. As described above, regarding the outer shell member and the internal structural member constituting the Barbasse bow, the yield strength of the L member having an angle of 45 degrees or less with respect to the hull longitudinal horizontal direction is larger than 45 degrees with respect to the hull longitudinal horizontal direction. It is preferable to design so that it may become lower than the yield strength of W member which has these.

Further, in order for the Barbasu bow to be uniformly buckled and deformed, the outer shell member 110 constituting the outer shell needs to be buckled and deformed in a bellows shape. In addition, since the outer shell member 110 needs to be uniformly deformed, it is necessary to use a steel plate whose yield strength does not change greatly even after linear heat processing.
In the following description, it is assumed that the yield strength of the L member is lower than that of the W member.

  Changes in the yield strength of the linear heating part due to linear heating when using a steel plate with a curvature that is obtained by linear heating at a heating surface maximum surface temperature of 600 ° C. or more at the part having the curvature of Barbasse bow It is desirable to use a steel plate having as small a size as possible. As a result, since the amount of energy that can be absorbed by the outer shell member 110 increases, the Barbasse bow can absorb a sufficient amount of collision energy. In order to minimize the change in the yield strength of the linear heating portion that accompanies the linear heating, a steel plate that can be processed into a predetermined curvature with the application of as little heat as possible is desirable.

Therefore, the yield strength of the steel sheet at high temperatures was examined in order to examine the ease of processing (linear heat processing characteristics) by applying local heat.
Although the yield strength at room temperature is a steel material of the same class, a steel plate as a sample was prepared using two types of steels A and B having different yield strengths at high temperatures. The difference in yield strength of these steel plates at high temperatures is because the content of stable fine precipitates is different even at high temperatures. Using these steel plates, tensile tests were performed at various temperatures.
FIG. 1 shows the relationship between the yield strength of the steel sheet and the test temperature at which the tensile test was performed. For the yield strength at each test temperature, the yield point or 0.2% proof stress value was used. Furthermore, instead of the yield strength of the steel sheet, a value obtained by dividing the measured value YP (AR, test temperature) at the test temperature by the measured value YP (AR, RT) at room temperature was used.

As shown in FIG. 1, when the test temperature increases, the yield strength becomes zero at a certain temperature. That temperature is defined as the mechanical melting temperature.
In ordinary linear heating processing with a maximum temperature of about 1000 ° C., it is considered that the mechanical melting temperature affects the linear heating characteristics. However, the mechanical melting temperature cannot be easily measured.

  From FIG. 1, it was confirmed that the yield strength value at 600 ° C., which is lower than the mechanical melting temperature of both steels A and B, correlates with the mechanical melting temperature. Therefore, paying attention to the yield strength at 600 ° C. as an index for evaluating workability by linear heating, the following experiment was conducted.

  In mass%, C: 0.1%, Si: 0.3%, Mn: 1.0%, Al: 0.005%, P and S as impurities, P: 0.03% or less , S: Various steel plates 1 with varying yield strength at room temperature and 600 ° C. were prepared by adjusting the contents of Cr and Nb, which increase the high temperature strength, to steel limited to 0.01% or less. These steel plates 1 had a substantially square shape, and the dimensions were about 500 mm on a side and about 10 mm in thickness. In addition, also in FIG. 1, the steel plate produced by the same method (steel plate composition and dimension) is used. As shown in FIG. 2A, linear heating processing (maximum heating temperature 1000 ° C. on the heating side) was repeated on the steel plates until the bending angle reached 120 degrees.

As shown in FIG. 2B, each of the part (linear heating part) 2 that has undergone linear heating of the bent steel sheet 1 and the part (non-linear heating part) 3 that has not undergone linear heating have a line as shown in FIG. The test piece 4 including the steel plate surface was cut out from the steel plate surface on the side subjected to the shape heating. By this processing, the NKU No. 1 tensile test piece (Nick Nippon Kaiji Kyokai) (Nippon Kaiji Kyokai) Steel Ship Rules and Inspection Procedures (K-knitted materials), which is half the thickness of the steel plate 1, is 5 mm thick. U1 test piece).
Each test piece was subjected to a tensile test at room temperature to determine the yield strength. The yield strength of the linear heating part at room temperature is YP (LH, RT), and the yield strength of the non-linear heating part at room temperature is YP (AR, RT). The ratio α was α = YP (LH, RT) / YP (AR, RT), and the difference in yield strength between the linear heating part and the non-linear heating part was evaluated. Moreover, about the non-linear heating part, the yield strength YP (AR, 600 degreeC) in 600 degreeC was also calculated | required.

FIG. 3 shows a ratio YP (AR, 600 ° C.) of the yield strength ratio α between the linear heating portion and the non-linear heating portion of the steel plate and the yield strength of the steel plate at 600 ° C. and the yield strength at room temperature of the steel plate. ) / YP (AR, RT).
As a result, as shown in FIG. 3, when the yield strength at 600 ° C. is not more than 0.6 times the yield strength at room temperature, the value of α indicating the difference in yield strength between the linear heating portion and the non-linear heating portion. Can be suppressed to 1.2 or less.

Next, the condition of α for the barbasse bow to buckle uniformly when using a steel plate at the bow was examined.
Using various steel plates having different values of α (about 500 mm on a side and about 10 mm in thickness), test pieces having a bending angle of 120 degrees made in the same manner as described above were prepared, as shown in FIG. The load P was applied from one side while restraining with the block 5. The relationship between the magnitude of the load and the block displacement Δ was measured. FIG. 5 shows a measurement example of three test pieces having α values of 1.0, 1.18, and 1.4.
In addition, in order to eliminate the influence of plastic deformation after α-1.0 steel plate is mechanically bent to a bending angle of 120 degrees without applying linear heating. Tempering is performed to such an extent that the yield strength does not change.

When α was 1.4, since the yield strength of the linearly heated portion of the steel sheet was high, strain was concentrated just outside the region. Since bending occurred at the strain concentration portion, the displacement Δ increased without the load P sufficiently rising. Therefore, as shown in FIG. 5, the energy absorption capacity of the steel sheet was lowered.
When α was 1.18, the steel sheet showed a load-displacement curve similar to that when α was 1.0. Therefore, as shown in FIG. 5, the steel sheet had sufficient energy absorption capability.

  The area formed by the load P and the displacement Δ shown in FIG. 5 (the area formed by the load curve and the displacement axis) is defined as absorbed energy EA (TP), and the value of EA (TP) when α is 1.0. Was used as a reference value. The relationship between α and EA (TP) is shown in FIG. From this figure, if the α of the steel sheet is 1.2 or less, the yield strength is high even if a portion having a non-uniform yield strength is formed on the steel sheet by linear heating with the maximum surface temperature on the heating side of 600 ° C or higher. High energy absorption ability can be expected as well as uniform deformation of the steel sheet. Therefore, α is preferably 1.2 or less when linear heating is performed until the maximum surface temperature on the heating side is 600 ° C. or higher and the bending angle is 120 degrees.

  From the results of FIG. 3 and FIG. 6 described above, when producing a steel plate (curved plate) with a curvature for Barbasse bow by linear heating at a temperature of 600 ° C. or higher, the yield strength at 600 ° C. is at room temperature. A steel plate having a yield strength of 0.6 times or less is used. If a curved plate having the α value of 1.2 or less is produced from such a steel plate, the curved plate has less uneven yield strength in the curved plate. It was recognized that the Barbasse bow composed of such curved plates can be buckled uniformly during a collision and can exhibit a large impact energy absorption ability.

In the above, the conditions of the steel plate for uniformly buckling deformation of the bow on the collision ship side have been described. In order for the bow on the collision ship side to buckle and deform, basically, it is necessary to make the yield strength of the steel plate used for the bow smaller than the yield strength of the ship to be collided.
However, the yield strength of steel plates used in ships must meet the unified standard of the International Classification Societies Association (IACS). In addition, in a bow structure having a conventional inner bone structure, the steel sheet needs to have strength to withstand wave shock. Furthermore, if the strength of the steel sheet is lowered too much, a large energy absorption effect during deformation cannot be expected.

Considering the above points, the yield strength of the steel sheet needs to be 120 MPa or more. Further, in order for the Barbasu bow to be surely buckled and deformed at the time of collision, the yield strength of the steel plate needs to be 220 MPa or less. In order to further ensure the buckling deformation of the Barbasse bow, less than 200 MPa is desirable.
Therefore, a steel plate having a yield strength at room temperature of 120 MPa or more and 220 MPa or less is used as a portion (outer shell member) having a Barbasse bow curvature before linear heat processing. For this reason, the yield strength of the site | part (non-linear heating part) which has not received the linear heating of the steel plate which gave the curvature by linear heating processing is also the yield strength similar to the above.

  Although the embodiments of the present invention have been described above, the effects of the present invention will be specifically described by way of examples.

  As a steel plate used for the bow structure, a steel plate having a component composition shown in Table 1 and having a side of about 500 mm and a plate thickness of about 10 mm was prepared. About each steel plate, the room temperature tensile test and the 600 degreeC tensile test were implemented, and the yield strength YP (AR, RT) in room temperature and the yield strength YP (AR, 600 degreeC) in 600 degreeC were calculated | required. Further, the linear heating process was repeated for each steel plate until the bending angle reached 120 degrees under the condition that the maximum heating temperature on the heating side surface was 1000 ° C. Test pieces similar to those described above were cut out from the portions of these bent steel sheets that had undergone linear heating. That is, the NKU No. 1 tensile test piece having a thickness of 5 mm, which is half the thickness of the steel sheet so as to include the steel sheet surface on the side subjected to the linear heating, is cut out for the linear heating part (Japan Maritime Association) (NK; Nippon Kaiji Kyokai) A U1 test piece defined in the steel ship regulations and inspection procedures (K knitting material) was produced. These test pieces were subjected to a tensile test at room temperature, and yield strengths YP (LH, RT) were obtained.

Table 2 shows YP (AR, RT), YP (LH, RT), YP (AR, 600 ° C.) and the steel plates of Reference Examples 1 to 3 , Examples 1 to 3 and Comparative Examples 1 to 6. The ratio α = YP (LH, RT) / YP (AR, RT) and β = YP (AR, 600 ° C.) / YP (AR, RT) are shown.
The steel plates of Reference Examples 1 to 3 and Examples 1 to 3 had YP (AR, RT) of 120 to 220 MPa, α of 1.2 or less, and β of 0.6 or less. Moreover, in Comparative Examples 1 to 6, β was more than 0.6.

Next, the energy absorptivity in the case where Barbusbau was constituted using the steel plates shown in Tables 1 and 2 was determined by simulation.
FIG. 7 shows a 1/4 simulation model in the center in the longitudinal direction of the ship side structure of the crude oil tanker. A transverse partition wall 12 corresponding to the partition structure of the oil cargo portion is disposed along the BB ′ portion in the ship side structure. Since the collision positions A and D in the ship side structure are set at the center position of the oil cargo portion, the model is symmetric with respect to the collision center 13 in the longitudinal direction of the hull. A portion along the CC ′ portion is a heel side thick plate portion 11 which is the most important member in the hull structure. The AA ′ portion indicates the vertical direction of the collision position, and the DD ′ portion indicates the horizontal direction of the collision position.

  When the deformation caused by the collision increases, plastic deformation occurs not only in the D-D 'and A-A' portions close to the collision portion but also in the C-C 'portion far from the collision center 13. Therefore, the heel side thick plate portion 11 which is the most important member of the hull structure is plastically damaged. As a result, the fracture resistance of the steel material is significantly reduced, and there is a risk of causing large-scale damage to the hull structure. Therefore, using the above model, the energy absorption capacity of Barbusbau when the entire collision part deformed and collided was calculated. The energy absorption ability is originally indicated by the unit (J) indicating energy, but is a non-dimensional value here for numerical calculation.

FIG. 8 shows the collision between the bow penetration amount and the Barbus bow when the bow structure including the Barbus bow constructed using the steel plates of Reference Examples 1 and 2 and Comparative Example 1 is collided with the ship side structure of the model of FIG. The relationship with the relative energy absorption capacity of the hour is shown. The amount of penetration of the bow indicates the amount of penetration of Barbusbau after deforming in the horizontal direction of the hull after colliding with the ship side of the ship to be collided.
In both Reference Example 1 and Reference Example 2, α of the steel plate used in the bow structure is 1.18, and the steel plate is displaced as shown in FIG. 10C. In Reference Example 1, the yield strength of the outer shell member of Barbus Bau was set to 200 MPa corresponding to 50% of the yield strength of the steel material used in the ship side structure. In Reference Example 2, the yield strength of the outer shell member of Barbus Bau was 214 MPa, corresponding to 53.5% of the yield strength of the steel used in the ship side structure.
Regarding Comparative Example 1, it was assumed that the characteristics of the steel sheet used in the bow structure were the strength characteristics shown in Table 2.
In the simulation, the calculation result of the relative energy absorption capacity under the condition that both the yield strength of the linearly heated portion and the yield strength of the non-linearly heated portion is 220 MPa was used as a reference example (ref). . The reduction ratio from the reference example with respect to the relative energy absorption capacity of each of the examples and comparative examples is shown by EA / EA (ref) in Table 2.

When the α of the steel plate on the bow structure side is 1.2 or less and the yield strength of this steel plate is lower than the yield strength on the boat side structure side, the bow structure buckles as shown in FIG. 10C. Therefore, in Reference Example 1, the collision surface with the ship-side structure and the energy absorption amount of the outer shell member are larger than those in Comparative Example 1, so that the energy absorption capability is dramatically improved as shown in FIG. Even in the case of Reference Example 2, the collision area is smaller than that of Example 1, but the energy absorption capacity of the outer shell member is increased, so that the energy absorption capacity is increased as compared with Comparative Example 1.

Similarly, with respect to the steel plates of Examples 1 to 3 and Comparative Examples 2 to 6, the relative energy absorption capacity up to the bow penetration of 6 m shown in FIG. 8 was calculated. As shown in Table 2, in the bow structure using the steel plates of Examples 1 and 2 , YP (AR, RT) is 120 to 220 MPa, and β is 0.6 or less. It had sufficient energy absorption capability. On the other hand, in the bow structure using the steel sheets of the comparative examples 2~6, YP (AR, RT) is Deattari 220MPa greater, since β is Deattari than 0.6, these bow structures, Example 1 Compared with the steel sheets of ~ 3 , the energy absorption ability was greatly reduced.

  Furthermore, the information in Table 2 is summarized and FIG. 9 shows the relationship between α and EA / EA (ref). As shown in FIG. 9, when α is greater than 1.2, EA / EA (ref) is greatly reduced. This large decrease in the energy absorption capability is considered to be due to the transition of the deformation mode of Barbusbau from FIG. 10C to FIG. 10A or FIG. 10B. Therefore, even if a portion having a non-uniform yield strength is formed on a steel sheet by linear heating at 600 ° C. or higher, a high energy absorption capacity can be obtained by using a steel sheet having α of 1.2 or less for the outer shell member of Barbusau. The bow structure which has can be comprised.

  From the above, a steel plate with a yield strength of 120 MPa or more and 220 MPa or less and a yield strength at 600 ° C. before linear heating processing of 0.6% or less of the yield strength at room temperature is removed from the barbasse bow. By using it as a shell member, the energy absorption capacity on the bow side at the time of collision can be increased, and serious damage to the partner ship can be prevented. Further, such a steel sheet has a yield strength ratio α between the linear heating portion and the non-linear heating portion after linear heating processing and imparting curvature under normal heating conditions (600 ° C. or higher) is 1. 2 or less. The bow structure using such a steel plate as an outer shell member has a buffering effect due to buckling deformation without causing a change in the hull structure design.

  It is possible to provide a bow structure having a buffering effect that can effectively prevent damage to a partner ship in the event of a collision without causing a change in the hull structure design.

1 Steel plate 2 Part subjected to linear heating (linear heating part)
3 Parts not receiving linear heating (non-linear heating part)
4 specimens 5 blocks

Claims (3)

The outer shell of Barbus Bau
Curvature is imparted by linear heating processing at a maximum surface temperature on the heating side of 600 ° C. or higher, and the yield strength at room temperature is 120 MPa to less than 200 MPa before the linear heating processing, and yield at 600 ° C. It consists of a steel plate whose strength is 0.6 times or less of the yield strength at room temperature,
A bow structure with excellent collision energy absorption capability. The steel plate constituting the outer shell member of the Barbus Bau,
When linear heating is performed until the maximum surface temperature on the heating side is 600 ° C. or higher and the bending angle is 120 degrees,
The yield strength ratio α obtained by dividing the yield strength YP (LH, RT) of the linear heating portion at room temperature by the yield strength YP (AR, RT) of the non-linear heating portion at room temperature is 1.2. Is
Bow structure which is excellent in impact energy absorbing ability according to claim 1, characterized in that. Regarding the outer shell member and the internal structural member constituting the Barbus bow, the yield strength of the L member having an angle of 45 degrees or less with respect to the hull longitudinal horizontal direction has an angle greater than 45 degrees with respect to the hull longitudinal horizontal direction. Lower than the yield strength of the W member,
3. A bow structure having excellent collision energy absorption capability according to claim 1 or 2 .

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