JP5047865B2 - Bow structure with excellent collision safety - Google Patents

Description

  The present invention relates to a bow structure of a ship having a buffering effect capable of preventing damage to a partner ship that has been deformed and collided at the time of a collision, and has improved collision safety.

  Today's large ships are equipped with a Barbassau (spherical bow) under the bowline to reduce energy loss due to wave resistance. 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 uses a phenomenon in which a steel plate surface is locally heated in a linear manner using a gas burner, etc., and the heated portion is thermally expanded and plastically deformed by restraint from its surroundings. In order to increase the temperature, water cooling is performed immediately after heating, and the steel sheet after the linear heating process is baked into the heated portion, and the yield strength is locally increased.

  Therefore, the barbassau using such a curved plate is not uniform in strength and is not easily deformed. When a ship equipped with this barbassau collides with another ship, as shown in FIG. There is also a high risk that the bow of the damaged ship will bite into the hull of the collided ship, destroy the hull, and further expand the destruction area to break the hull.

  Conventionally, as a means to improve the collision safety of ships, the main focus has been on the hull structure such as the double structure of the hull, but in recent years steel materials with excellent energy absorption performance at the time of collision have been used. Application is also being considered.

  As an example, Patent Document 1 discloses that the product (σy × εu) of yield stress σy and uniform elongation εu (σy × εu) is 20% compared to a conventional standard material of the International Association of Classification Societies (IACS), such as a ship side skin. Steel materials that have been increased above, or steel materials that have increased the amount of energy absorption up to the uniform elongation εu by 20% or more in the tensile test, or steel materials that have the same or higher yield stress σy and have the uniform elongation εu increased by 20% or more. It is shown about a hull structure that can increase the amount of energy that can be absorbed before a breakage occurs in the hull while applying the above.

  However, if the bow of a ship collides with the hull of another ship, even if a steel plate with an energy absorption of 50% or more is used, if the bow does not deform, there is a risk of penetrating the hull. There is a problem that the effect cannot be expected.

In order to solve such a problem, it is also considered to make the bow a structure having a buffering effect when colliding with another ship.
For example, Patent Document 2 shows that the bow portion is constructed using a soft material compared to the steel material used for hull construction, and the bow portion has a flexible structure.
However, 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 indicate a flexible structure using a steel material. In addition, there is no particular indication as to how a soft material is incorporated into the outer skin or internal structure of the bow.

  Further, Patent Document 3 describes that the internal structure of the spherical protrusion (valve) portion of the Barbasse bow is a structure using a ring-shaped lateral rib member, and yields on the side outer plate between the lateral rib members of the valve root portion. Providing a low-strength portion made of low-yield point steel with a stress of 235 MPa or less, lowering the bending strength in the lateral direction of the root portion, and bending the bow portion by the reaction force of the collision. The bow structure is shown to prevent the part from getting stuck.

  In Patent Document 3, as shown in FIG. 2 (b), the base portion of the barbasse bow is reduced in the width of the hull as shown in FIG. It is a structure that easily deforms in the direction and increases the contact area of the collision part to prevent breakage of both the collision ship and the collision ship, but the bending of the valve part uses low yield point steel. This is due to local deformation of the used part, and the energy absorption at the time of bending is not large.

  Furthermore, when the Barbasu bow is bent, the collision ship and the ship to be collided come closer, and the distance between the two becomes smaller without significant energy absorption. As a result, as shown in FIG. 2 (b), the tip portion of the collision ship may come into contact with the ship to be collided, so that damage due to the collision accident may increase.

  Therefore, in the event of a collision, it is necessary to greatly absorb the collision energy between the time when the barbus bow is deformed and the tip of the hull comes into contact with the ship to be collided, and a bow structure having such a buffering effect is desired.

JP 2002-87373 A Japanese Patent Laid-Open No. 7-329881 JP 2004-314825 A

  Therefore, the present invention can realize a bow structure having a buffering effect that can realize a large energy absorption when the valve portion of the bow's Palbus bow is deformed as uniformly as possible at the time of a collision of a ship, using a steel material. The challenge is to do so.

In order to solve the above problems, the present invention has the following bow structure.
(1) A bow structure having a barbus bow, wherein the outer shell member and the inner shell member constituting the barbus bow are:
L member: a member having an angle of 45 degrees or less with respect to the longitudinal direction of the hull,
W member: A bow structure characterized by using a steel material having a yield strength lower than the yield strength of the W member as the L member when the member has an angle greater than 45 degrees with respect to the horizontal direction of the hull longitudinal direction.
(2) The yield strength of at least 60% or more of the steel materials used for the L member is lower than the yield strength of the steel materials used for the W member. Bow structure.
(3) The bow structure according to (1) or (2), wherein the yield strength of the L member lower than the yield strength of the W member is 120 to 240 MPa.
(4) The bow structure according to (1) or (2), wherein the yield strength of the L member lower than the yield strength of the W member is 240 to 400 MPa.
(5) A bow structure having a barbus bow, wherein the outer shell member and the inner shell member constituting the barbus bow are:
L member: a member having an angle of 45 degrees or less with respect to the longitudinal direction of the hull,
W member: When the member has an angle greater than 45 degrees with respect to the horizontal direction of the hull, the L member of the outer shell member and the inner shell member is a steel material whose yield strength is lower than the yield strength of the W member of the inner shell member. A bow structure characterized by its use.

  According to the present invention, when an accident occurs such that the bow of a ship having a Barbus bow collides with the hull of another ship, the side face of the valve part of the Barbus bow in the colliding ship is more uniformly buckled and deformed. As well as absorbing the collision energy, the collision surface is crushed so that damage to the impacted ship can be reduced as much as possible, thereby preventing marine pollution caused by sinking of the impacted ship and oil spills. Can contribute.

When a ship with a Barbasse bow collides with the hull of another ship, the case where the greatest damage or damage is assumed is as shown in Fig. 2 (a). This is a case where it hits the ship side vertically.
Even in such a case, as shown in FIG. 2 (c), the valve portion of the Barbus Bau is deformed so as to collapse while absorbing energy at the time of collision, and further, the contact area of the collision portion is increased by the deformation. It is desirable that the bow of the collision ship does not penetrate into the ship side of the collision ship.
In particular, if the valve part can buckle and deform more uniformly, more collision energy can be absorbed, so the impact force caused by the collision is mitigated, and local breakage and breakage of the impacted ship are avoided. it can.

For this purpose, it is necessary that the valve portion of the valve bath does not bend due to bending deformation as shown in FIG.
Therefore, a structure in which the bow portion is buckled uniformly in a bellows shape as shown in FIG.

  In order for the Barbus bow to be deformed at the time of a collision, the members arranged along the longitudinal direction of the hull, which is the collision direction, must 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 from the members arranged in the direction intersecting with the longitudinal direction of the hull so that the Barbus bow does not bend. It is considered effective to do so.

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, and the internal structure member generally consists of the combination of a longitudinal rib or a lateral rib.
1 (a) and 1 (b) schematically show an example, but the outer shell member and the internal structural member constituting the Barbasse bow are considered to be based on the hull longitudinal horizontal direction which is the hull collision direction. It is composed of many members arranged parallel to or perpendicular to each other and some members arranged at an angle with respect to the horizontal direction of the hull.

Therefore, the members arranged at an angle with respect to the horizontal direction of the hull longitudinally are classified as either the parallel or vertical members described above, and the outer shell member and the inner structural member (inner shell member) constituting the Barbus bow. Is divided into an L member and a W member defined as follows, and the L member is given deformation at the time of collision, and the W member is given a function of restraining the deformation.
L member: a member having an angle of 45 degrees or less with respect to the hull longitudinal horizontal direction W member: a member having an angle greater than 45 degrees with respect to the hull longitudinal horizontal direction

And in order to give deformation to L member, the steel material of yield strength lower than the yield strength of W member is used as L member, and W member shall be hard to change to L member.
As a result, the L member is prevented from being deformed so as to collapse due to hip breakage, and the barbath bow is deformed without being largely disengaged in the axial direction, so that the energy of collision can be absorbed.
Since the W member of the outer shell member may use a steel material having a low yield stress, such as the tip of a Barbus bow, in such a case, the outer shell member and the W member of the outer shell member are excluded except for the W member. As the L member of the inner shell member, a steel material having a lower yield stress than the W member of the inner shell member is used.

  The arrangement direction of the outer plate constituting the outer shell is determined by the angle formed by the intersection of the horizontal plane and the outer plate with the horizontal direction of the hull. The outer plate may have a different curvature in the plate. In such a case, a portion having an angle of 45 degrees or less with respect to the horizontal direction of the hull and a portion having an angle larger than 45 degrees in the plate. The area ratio is determined and determined by either ratio.

  According to the inventor's study, it is more effective if the yield strength of at least 60% of the steel used for the L member is lower than the yield strength of the steel used for the W member. I found out.

The present inventor first discovered that as a steel material used for the L member, all steel materials having a lower yield strength than the W member were used, so that deformation in the axial direction of the Barbasse bow was facilitated and a predetermined effect could be exhibited. . However, since deformation occurs at the site where yielding is likely to occur, the yield strength of the W member is not necessarily lower than that of the L member in all regions. The experiment was conducted with the same.
As a result, even when 50% of the L member is made of a steel material whose yield strength is lower than that of the W member, the deformation in the axial direction is easier than when the yield strength of the steel material of the L member and the W member is all set to the same level. However, in order for the effect to be remarkable, the ratio of the L member was 60% or more.

  The above examination assumes that the plate thickness of the W member and the L member is almost the same level, but if the plate thickness is extremely different, the design requirement is based on the relationship between the yield strength and the plate thickness. In some cases, the yield strength of each member is changed, but such a case is within the scope of the present invention. A specific example as such a design requirement will be shown in an embodiment described later.

  Next, preferable conditions, such as the yield strength of the steel materials used for a bow part, are demonstrated.

In order for the bow on the collision ship side to buckle and deform, it is necessary to make the yield strength of the steel material such as the steel sheet used for the L member smaller than the yield strength of the steel sheet used on the ship side of the impacted ship.
However, the yield strength of the steel sheet used in the ship needs to meet the unified standard of the International Classification Association (IACS), and the bow as a whole needs to be strong enough to withstand wave shocks. Furthermore, if the strength is lowered too much, a large energy absorption effect accompanying deformation cannot be expected.

From such a point, the yield strength of the L member is desirably 120 MPa or more. In addition, the upper limit of the yield strength is preferably 400 MPa or less in view of the yield strength of the steel plate usually used on the ship side of the ship. In order to be surely buckled and deformed at the time of collision, it is preferably 240 MPa or less, and more preferably less than 200 MPa.
Therefore, the L member is preferably a steel material having a yield strength at room temperature of 120 MPa or more and 240 MPa or less, but a steel material of 240 MPa or more and 400 MPa or less may be used in relation to the strength of the W member.

  As such a steel material, a steel material for an existing welded structure member may be used as long as the yield strength condition is satisfied. Of course, a low yield point steel as disclosed in Patent Document 3 may be used.

  Moreover, the steel material used for the W member may be an existing steel material and is not particularly limited. However, in order to make the Barbus bow easy to deform as a whole, the yield of the steel plate used on the ship side is the same as that of the L member. Steel material is desirable smaller than strength.

  By the way, as described above, the valve portion of the barbasse bow is subjected to thermal deformation by applying local heat, such as linear heating, to the steel plate, and thereby processed to have a curvature (linear heating processing). It is manufactured using. At that time, since the yield strength is high in the portion that has received heat from the steel plate, there is a difference in the yield strength of the steel plate between the portion that has received local heat and the portion that has not received heat.

  When such a steel plate is used, when the Barbasse bow is deformed by a collision, it becomes a non-uniform deformation, and the energy absorption capacity as a structural member is lower than that of a steel plate with no difference in yield strength in the plate. Therefore, it is desirable to use a steel plate having a small difference in yield stress within the steel plate as the L member that is the outer plate of the Barbasse bow.

  As a steel plate having a small difference in yield stress in the steel plate, a steel plate processed to have a predetermined curvature with a small amount of heat applied, that is, a steel plate having a large amount of bending deformation by one linear heating process is suitable.

  There are a method of performing linear heat processing at a high temperature of 600 ° C. or higher and a method of executing at a relatively low temperature of lower than 600 ° C. As described in Japanese Patent No. 56348, in mass%, C: 0.02 to 0.2%, Si: 0.03 to 1%, Mn: 0.3 to 2%, Al: 0.002 It has a basic composition containing 0.1%, P and S as impurities limited to P: 0.03% or less, S: 0.01% or less, and 20 to 95% of the microstructure at room temperature Further, there is a steel sheet that has a ferrite structure in which dislocations are introduced by processing or transformation strain, and the total ratio of bainite and martensite is less than 70%.

  Moreover, as a steel plate in the case of implementing at comparatively low temperature of less than 600 degreeC, as described in Unexamined-Japanese-Patent No. 2006-205181, for example, it is the mass%, C: 0.01-0.20%, Si: 0.02-1.0% or less, Mn: 0.2-2.5% or less, P: 0.025% or less, S: 0.020% or less, Al: 0.002-0.10% Below, and N: 0.0010 to 0.0080% or less of the basic composition, a steel plate having a ferrite fraction of 20% or more, and the yield point is lowered by straightening at a temperature of 250 ° C. or less at which no aging occurs. There are steel plates.

  If the steel plate as exemplified above is used as the curved plate used for the outer shell member of Barbus Bau, it can be uniformly deformed when buckling, and more absorbed energy can be expected. A greater effect can be obtained.

  Although the embodiment of the present invention has been described above, the feasibility and effect of the present invention will be further described with reference to examples.

A real model test body corresponding to the Barbus Bau member is prepared, and the Barbus Bau member is deformed by pressing a rigid body in the axial direction of the Barbus Bau. The deformation mode and the absorbed energy value EA obtained from the area of the load-displacement diagram are obtained. Table 1 shows the relative values to the absorbed energy value EA (ref) in the case of Comparative Example 1.
The deformation modes corresponded to FIGS. 2B and 2C, and the case deformed in a bellows shape is represented as (c), and the case that buckled and deformed in the middle and could not be deformed sufficiently is represented as (b).

  As the inner shell member, steel plates having different plate thicknesses and steel plates having different yield strengths may be used. In that case, the average plate thickness and average yield point (strength) of the W member used are also indicated. In addition, the average in this case carried out the weighted average to the usage-amount of the member.

Next, the plate thickness and yield point of the L member are shown in Table 1. At this time, the relative yield point converted to the average plate thickness of the W member was defined as follows.
Relative yield point = (yield point of L member) x (thickness of L member) / (average thickness of W member)
By comparing this relative yield point with the average yield point of the W member, the ratio of the L member that is below the average yield point of the W member to the entire L member is expressed as a member ratio (%) below the YP (W) av. It was shown in 1.

Inventive Examples 1 to 6 are cases where the ratio (%) of YP (W) av or less is 60% or more, and the absorbed energy value is larger than that of Comparative Example 1.
In invention examples 7-8, since the W member and the L member are the same for the outer shell member, the member ratio (%) below YP (W) av is 0% in the L member, but the inner member W The yield strength is lower than that of the member, and the member ratio (%) of YP (W) av or less in the L member of the inner shell member is secured to 60% or more, so the absorbed energy value is larger than that of Comparative Example 1, The deformation mode is also (c).
In Comparative Examples 2 to 3, since the member ratio (%) of YP (W) av or less in the L member is not a sufficient value, the absorbed energy is larger than that of Comparative Example 1, but it is satisfactory compared with the invention example. Not a value.

It is a figure which shows the outline of the internal structure of the bow which has a Barbus bow. It is a schematic diagram which shows the deformation | transformation at the time of the collision of a ship, (a) is the case of the bow structure which does not have a buffer effect, (b) and (c) is the case of the bow structure which has a buffer effect. It is a figure which shows the outline | summary of the deformation | transformation model test of Barbusbau.

Claims (5)

A bow structure having a barbus bow, wherein the outer shell member and the inner shell member constituting the barbus bow are:
L member: a member having an angle of 45 degrees or less with respect to the longitudinal direction of the hull,
W member: A bow structure characterized by using a steel material having a yield strength lower than the yield strength of the W member as the L member when the member has an angle greater than 45 degrees with respect to the horizontal direction of the hull longitudinal direction.   2. The bow structure according to claim 1, wherein the yield strength of at least 60% of the steel material used for the L member is lower than the yield strength of the steel material used for the W member.   The bow structure according to claim 1 or 2, wherein the yield strength of the L member lower than the yield strength of the W member is 120 to 240 MPa.   The bow structure according to claim 1 or 2, wherein the yield strength of the L member lower than the yield strength of the W member is 240 to 400 MPa. A bow structure having a barbus bow, wherein the outer shell member and the inner shell member constituting the barbus bow are:
L member: a member having an angle of 45 degrees or less with respect to the longitudinal direction of the hull,
W member: When the member has an angle greater than 45 degrees with respect to the horizontal direction of the hull, the L member of the outer shell member and the inner shell member is a steel material whose yield strength is lower than the yield strength of the W member of the inner shell member. A bow structure characterized by its use.

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