KR100557390B1 - Hull Stress Monitoring System and Estimation Method of External Moments of a Ship using it - Google Patents

Abstract

The present invention calculates the strain components in each cross section using eight LBSGs installed in two central cross sections separated by each other d in the longitudinal direction of the hull of the hull, and utilizes them to obtain the slope of the strain between the cross sections to act on the container ship. The present invention relates to a hull stress monitoring device capable of accurately obtaining a torsional moment component and a method of estimating an external working moment of a ship using the same.

According to the present invention, four stress gauges are arranged to be left / right symmetrical at a central cross section inside the hull of the container ship, and four stress gauges are additionally added to the cross section moved by d in the longitudinal direction of the ship from the four stress gauges. It is characterized by the arrangement in the same form.

Hull, stress, torsional moment

Description

Hull Stress Monitoring System and Estimation Method of External Moments of a Ship using it}

1A and 1B are schematic cross-sectional views and schematic perspective views showing a state in which four long base strain gauges (LBSGs) are positioned on a central section of a hull of a container ship according to a conventional external acting moment estimation method;

2 shows an example of warping deformation caused by the torsional moment component applied to the LBSG.

FIG. 3 is a St. Moment generated by the torsional moment component shown in FIG. Drawing showing an example of venant deformation,

4 is a view showing the deformation according to the action of the torsional force of the beam having the boundary condition of the general fixed end-fixed end,

5 is a view showing the deformation according to the action of the torsional force of the beam having the boundary condition of the general free end-fixed end,

6 is a view showing the form of the strain when the hull as shown in Figure 1b receives a pure horizontal moment,

7 is a view showing the shape of the strain when the hull as shown in Figure 1b receives a pure vertical moment,

8A and 8B are schematic cross-sectional views and schematic perspective views showing a state in which a plurality of LBSGs (long base strain gauges) are positioned at the center cross-section of the hull of the container ship to perform the external acting moment estimation method of the present invention.

* Description of Signs of Main Parts of Drawings *

5, 20: hull 1-4: stress gauge-LBSG (long base strain gauge)

11-18: 8 long base strain gauges

The present invention relates to a hull stress monitoring device and a method for estimating an external working moment of a ship using the same, in particular, the strain components in each section are obtained by using eight LBSGs installed at two center sections of the hull apart from each other by d. The present invention relates to a hull stress monitoring device capable of accurately determining the torsional moment component acting on a container ship by obtaining the slope of the strain between sections and a method of estimating the external working moment of a ship using the same.

In general, the hull stress monitor for monitoring the external force applied to the container ship is provided with four LBSGs (long base strain gauge) in the central cross section inside the hull 5 to measure the strain in each sensor as shown in FIG. The system was configured to observe the corresponding stress component.

In the related art, in order to estimate the torsional component of the hull section, the deformation of the container line due to the torsional moment component is assumed as a sine function or the like.

However, since these assumptions cannot always be satisfied, in order to apply a more rigorous estimation method, the present invention has been examined as follows.

That is, a large container ship having a general upper open structure can be briefly described by the geometric cross-sectional structure as shown in FIG. 1, and the components of the external force to be considered are the moment components M _y and M _z acting in the horizontal and vertical directions. It can be classified into T _w (Warping component) and T _p (St. Venn), which are torsional moment components respectively related to cross-sectional distortion and cross-sectional retention.

Among these components, the general governing equation of the torsional moment component is described as follows.

: shear modulus, J: polar moment of inertia)는 순수 비틀림 강성(torsional rigidity)을 의미하는 St.Venant 성분이 된다.The general solution to the torsion angle of Equation 1 above is a function of a hyperbolic function. The EJ _w ( E : Young's modulus, J _w : warping moment of inertia) means a warping constant (Γ), GJ (

shear modulus, J : polar moment of inertia, becomes the St.Venant component, meaning pure torsional rigidity.

As a result, the entire torsional moment component may be obtained by integrating Equation 1 as follows.

On the other hand, the warping component that results in the cross-sectional distortion phenomenon can be represented as shown in Figure 2, which is caused by the torsional moment component, the strain and stress for the torsional component causing the pure warping deformation is warping function U and Equations 3 to 5 have the same relationship.

: Warping normal strain

: Warping normal strain

: Warping normal stress

: Warping normal stress

: Warping variable

Warping variable

The warping function U is described in many literatures based on a simple geometrical form, and in the case of a complicated cross-sectional structure such as a container line, the analysis by finite element modeling is described in detail.

By using the above relationship, Bi-moment Bi is defined, and the torsional moment component can be described from Equation 6 below.

(warping moment of inertia)는 수학식 7과 같고,here,

(warping moment of inertia) is the same as Equation 7,

Equation 8 may be derived through Equations 6 and 7.

As a result, it can be seen that Equation 8 is expressed in terms of the longitudinal slope due to the warping deformation component away from the distance d .

The distance of d is less than 1/2 of the length of hold part in the center of cargo loading space of container ship, and it can be selected in the area more than twice as long as the length of stress gauge. Four LBSGs should be arranged at points d / 2 in the bow / stern direction.

However, in the conventional measurement method, it is assumed that the sine function as shown in Equations 9 and 10 by utilizing the length L _H of the upper open structure.

However, there is an error factor by using the shape of the cross-sectional distortion torsional component of the container ship as a sin function whose length from the bow to the front of the port is set to π or the entire ship length as the sin function.

In addition, since the cross section of the actual container ship changes along the longitudinal direction, there is no problem but a method assuming such a moment curve.

This fact can be seen from the fact that the torsional moment component is made to use a relatively complex empirical formula in the classification data of NK and others, and the results obtained from various calculation data cannot be assumed to be in a certain shape.

On the other hand, the pure twist component received in the LBSG can be displayed as shown in Figure 3, as shown in Figures 4 and 5 will have the following properties depending on the boundary conditions in the longitudinal direction. That is, in the case of fixed-fixing, there is no axial movement of the cross section, but the deformation due to the torsion will be different according to the distance from the shear center, and in the case of the free end-free end, the axial movement of the cross section is the same according to the torsion. The amount of deformation received by the installed LBSGs 1-4 will be negligibly small.

First of all, considering the former condition, the related equation is derived as shown in Equation 11. For this, if the distance from the shear center to the LBSG is defined as r _x , the effect of warping becomes relatively smaller than that of pure torsion. Will be.

Ε _T in Equation 11 is expressed as Equation 12 below,

In addition, the axial stress is described by the following equation (13).

이 되는 것으로 가정할 수 있으며, 따라서 LBSG에 수신되는 변형량은 무시 가능한 정도를 얻게 될 것이다.In the latter free end-free end condition, the axial movement of the cross section is the same, but the LBSG is twisted in the same direction according to the torsion.

It can be assumed that the amount of deformation received in the LBSG will be negligible.

On the other hand, from the viewpoint of the central section of the container ship in which the hull stress monitoring device is installed, it has the constraints of the bulkhead of the accommodation port and the bulkhead of the bow, Is understood in form.

Therefore, it is assumed that the warping is partially constrained, and as a result, the latter condition does not affect the LBSG. something to do.

On the other hand, as shown in Figure 6, the moment component acting in the horizontal direction mainly occurs in waves, wind and currents, etc., it can be simplified into a bending moment component. Therefore, the relationship between the horizontal bending moment M _y component and the strain ε _y can be described using the cross-sectional secondary moment component Z _yy as in Equations 14 and 15.

In addition, as can be seen in Figure 7 the vertical moment M _z In the case of, it can be understood as the bending moment component mainly generated by the effect of cargo arrangement and bow pitching motion. Therefore strain ε _z Using the component and the second moment Z _zz component of the cross section, the equations (16) and (17) are summarized.

In summary, the conventional method utilizes the assumptions about the deformation and moment component of the container ship to estimate the torsional component of the ship's cross section. However, the conventional method reflects the effect of the change in the longitudinal cross section of the container ship. There was a problem that it was practically impossible to do.

Therefore, the present invention obtains the strain component in each cross section using eight LBSGs installed at two center cross sections of the hull by a distance d, and uses the torsional moment component acting on the container line by using these to obtain the slope of the strain between the cross sections. The purpose of the present invention is to provide a hull stress monitoring device that can accurately calculate the and a method of estimating the external working moment of a ship using the same.

In order to achieve the above object, the present invention arranges four stress gauges vertically and symmetrically along a central cross section inside the hull, and lengths of container hold corresponding to the center of the container ship in the longitudinal direction from the four stress gauges. Less than one-half of, and move more than twice as long as the length of the stress gauge (LBSG), additionally four stress gauges are arranged along the central section inside the hull.

In addition, four stress gauges are respectively provided at a distance of d / 2 in the bow and stern directions from the center of the container hold in the longitudinal direction.

The calculation method of the external working moment of the container ship using the hull stress monitoring value of the present invention is as follows.

(여기서,

은 측정된 변형량 벡터이고,

는 측정량과 각 성분과의 관계를 나타내는 행렬로서 단면의 기하하적 특성에 의해First, the outputs of the four stress gauges installed in each of the cross sections are the amount of deformation in the longitudinal direction.

(here,

Is the measured strain vector,

Is a matrix representing the relationship between measurand and each component.

은 서로 독립적인 변형량 성분 벡터인

으로 기술된다. 또한, ε _y 는 수평 모멘트 성분에 의한 변형량, ε _z 는 수직 모멘트 성분에 의한 변형량, ε _w 는 단면 왜곡 비틂 모멘트 성분에 의한 변형량, ε _T 는 순수 비틂 모멘트 성분에 의한 변형량, y _B 및 y _T 는 폭 방향의 중립축으로부터 제1 과 제2 응력게이지 및 제3 과 제4 응력게이지까지의 거리, z _B 및 z _T 는 각각 중립축으로부터 LBSG의 높이 방향 거리이다)와 같이 표현되는 단계와; 상기 각각의 단면에 대한 변형률의 차이를 바탕으로

와 같이 단면 왜곡 비틂 모멘트 성분에 의한 변형량의 차를 구하는 단계와; 상기 변형량의 차이로부터,

와 같이 단면 왜곡 비틂 모멘트 성분을 추정하는 단계로 이루어진다.Described as

Is a vector of strain components independent of each other

Is described. Ε _y is the deformation amount due to the horizontal moment component, ε _z is the deformation amount due to the vertical moment component, ε _w is the deformation amount due to the cross-sectional distortion ratio moment component, ε _T is the deformation amount due to the pure torque moment component, y _B And y _T is the distance from the neutral axis in the width direction to the first and second stress gauges and the third and fourth stress gauges, z _B and z _T Are each the height direction distance of the LBSG from the neutral axis; Based on the difference in strain for each cross section

Obtaining a difference in deformation amount due to the cross-sectional distortion torque moment component as follows; From the difference in the deformation amount,

Estimating the cross-sectional distortion torque moment component as follows.

Therefore, in the present invention as described above, it is possible to exclude the hypothesis curve of the torsional moment component required when the LBSG is provided only on one cross section as in the conventional method, which is very useful for monitoring the external force moment component of the container ship. It is also applicable to the monitoring system of wire moment components, which can be effectively applied even in general cases where the distribution of the torsional moment components along the longitudinal direction cannot be assumed due to the large size and separation of the engine space and the accommodation space.

(Example)

Referring to the accompanying drawings, a method of estimating an external working moment of a container ship using a hull stress monitoring device according to the present invention will be described.

8A and 8B are schematic cross-sectional views and schematic perspective views showing a state in which a plurality of LBSGs (long base strain gauges) are set in the central section of the hull of the container ship to perform the external acting moment estimation method of the present invention.

In the installation form of the LBSG proposed in the present invention, four LBSGs 11 to 14 are respectively installed in the central cross section inside the hull 20 as shown in FIG. 8A, and four LBSGs 11 to 14 are provided as shown in FIG. 8B. Four LBSGs 15-18 are installed in the inner end surface of the ship body 20 by shifting predetermined distance, ie, d as shown in FIG.

으로부터 수학식 19 및 20과 같이 서로 독립인 변형량 성분 벡터

를 구할 수 있다.Here, the output of the four LBSGs 11 to 14 by the external force moment is the deformation amount in the longitudinal direction, and is the measured deformation amount vector expressed by Equation 18 below.

Strain component vectors independent of each other as shown in Equations 19 and 20 from

Can be obtained.

는 측정된 변형량이고,

는 측정량과 각 성분과의 관계를 나타내는 변환 행렬이며,

는 변형량 성분들로서, 제1 LBSG(11)를 기준으로here

Is the measured strain,

Is a transformation matrix representing the relationship between the measurand and each component,

Are strain components, based on the first LBSG (11)

Deformation due to the horizontal moment components: ε _1y = - ε _y

Deformation due to the vertical moment component: ε _1z = ε _z

Strain due to section distortion ratio moment component: ε _1w = ε _w

Deformation due to pure torsional moment component: ε _1T = ε _T

It is defined as

Further, the distances from the neutral axis in the width direction to the upper LBSG (11, 12) and the lower LBSG (13, 14) are respectively y _B. And y _T , z _B and z _T Is the lower and upper height of the LBSG from the neutral axis.

In addition, U ₁ and U ₃ mean warping functions of the upper LBSG (11, 12) and the lower LBSG (13, 14), which is determined from the geometric properties of the cross section.

On the other hand, this relationship is similarly applied to the cross section in which the LBSGs 15 to 18, which are cross-sections moved by d as shown in FIG. 8B, are used for the convenience of symbols, and the value in the adjacent cross section is expressed by using the subscript a. Deriving the difference in the measured value in the cross-section is simplified as shown in Equation 21.

및

은 각각 하기의 수학식 22 및 23과 같이 표현된다.In Equation 21

And

Are represented by Equations 22 and 23, respectively.

는 두 단면에서 동일한 값을 갖는 경우로 정의한다. 따라서 위의 방정식을 풀면, 하기 수학식 24와 같이 단면 왜곡 비틀림 모멘트 성분에 의한 변형량의 차를 구할 수 있다.Where the transformation matrix

Is defined as the case having the same value in both cross sections. Therefore, by solving the above equation, it is possible to obtain the difference of the deformation amount due to the cross-sectional distortion torsional moment component as shown in the following equation (24).

As shown in Equation 24, the cross-sectional distortion torsion moment component can be estimated from Equation 25 from the difference of the deformation amount due to the cross-sectional distortion torsional moment component.

As a result, a relational expression in the form of excluding various assumptions contained in Equations 9 and 10 used in the conventional measurement method can be obtained.

Therefore, the present invention, using the eight LBSG (11 to 18) installed in the two center cross-sections of the hull 20 by the distance d from each other as shown in Figure 8b, to obtain the strain components in each cross-section, using the strain between the cross-sections By obtaining the slope of, the torsional moment component acting on the container line can be accurately determined.

In the present invention described above, the assumption curve of the torsional moment component required when the LBSG is provided in only one end face as in the conventional method can be eliminated, which is very useful for monitoring the external force moment component of the container ship, and the engine as the container is enlarged. According to the separation of space and residence space, there is an advantage that it can be applied to the monitoring system of wire moment component that can be effectively applied even in general case where distribution of torsional moment components along the longitudinal direction cannot be assumed.

Claims (3)

In the hull stress monitoring device for monitoring the stress of the hull through a plurality of stress gauges installed on the hull of the container ship, The four stress gauges are arranged vertically and horizontally symmetrically along the center cross section inside the hull, and are smaller than 1/2 of the container hold length corresponding to the center portion of the container ship in the longitudinal direction from the four stress gauges, and the stress gauge (LBSG The hull stress monitoring device, characterized in that four stress gauges are arranged along the central cross section of the hull by moving more than twice as long. The method of claim 1, And four stress gauges each installed at a distance of d / 2 in the bow and stern directions from the center of the container hold in the longitudinal direction. Four stress gauges are arranged upside down / left-right symmetrically along the center cross-section inside the hull of the container ship, and four stress gauges are additionally arranged by moving d in the longitudinal direction along the central cross-section inside the hull from the four stress gauges. Making a step; The output of the four stress gauges in the midship section is the strain in the longitudinal direction, which is the measured strain vector expressed as

Transformation matrix expressed as shown in Equation 19 showing the relationship between the measurand and each component

By substituting, the strain component vectors independent of each other for each cross section as shown in Equation 20

Obtaining a step; Equation 18

[Equation 19]

[Equation 20]

Where ε _y is the deformation due to the horizontal moment component, ε _z is the deformation due to the vertical moment component, ε _w is the deformation due to the cross-sectional distortion ratio moment component, ε _T is the deformation due to the pure torque moment component, y _B And y _T is the distance from the neutral axis in the width direction to the first / second stress gauge and the third / fourth stress gauge, z _B and z _T Are distances in the height direction of the stress gauge LBSG from the neutral axis, respectively.) Each cross section is a transformation matrix representing a geometric feature.

Is selected as a condition having the same value, and based on this, obtaining a difference in deformation amount due to the sectional distortion torsional moment component as shown in Equation 24; [Equation 24]

Estimating a cross-sectional distortion torque moment component from the difference in deformation amount, as shown in Equation 25: [Equation 25]

Estimation method of external action moment of container ship using hull stress monitoring device, characterized in that made.

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