JP2003202280A - Fracture toughness characteristic evaluating method and device for non-homogeneous material ct test piece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily evaluate the fracture toughness characteristic of a CT test piece composed of a non-homogeneous material without performing FEM analysis. <P>SOLUTION: This device comprises a ζ<SB>0</SB>calculating part 3 for calculating a coefficient ζ<SB>0</SB>on the basis of a crack length a and a ligament length b generated on a welding material 16, a variable calculating part 4 for calculating variables α, β to minimize the ultimate load PL of the CT test piece 14 on the basis of the coefficient ζ<SB>0</SB>, a η<SB>(i</SB>-<SB>1)</SB>calculating part 5 for calculating a coefficient η<SB>(i</SB>-<SB>1)</SB>on the basis of the variables α, β, a width W of the CT test piece 14, the crack length a, the ligament length b, a load step i, and a welding half width h of the welding material 16, a γ<SB>(i</SB>-<SB>1)</SB>calculating part 6 for calculating a coefficient γ<SB>(i</SB>-<SB>1)</SB>as the coefficient on the basis of the ligament length b, the load step i and the width W, a toughness term calculating part 7 for calculating a toughness term of the fracture toughness characteristic, an elasticity term calculating part 8 for calculating the elasticity term, and a fracture toughness characteristic acquiring part 9 for acquiring the fracture toughness characteristic by adding the elasticity term and the toughness term. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaluation method and an evaluation apparatus for easily evaluating the fracture toughness characteristics of a CT test piece composed of a heterogeneous material such as a dissimilar material joint or a welded joint.

[0002]

2. Description of the Related Art In the current fracture toughness standards such as ASTM,
Fracture toughness formulas have been developed that can easily obtain fracture toughness characteristics on the assumption that the entire test piece is a homogeneous material. For this reason, the fracture toughness characteristics cannot be evaluated by a simple method from the current fracture toughness equation for a specimen composed of a non-homogeneous material such as a welded joint or a dissimilar joint.

Therefore, C composed of a non-homogeneous material
In order to evaluate the fracture toughness characteristics of the T (Compact) test piece, it is necessary to perform detailed evaluation by FEM analysis.

On the other hand, even for a test piece composed of a non-homogeneous material, an evaluation formula for easily evaluating fracture toughness characteristics is provided for a three-point bending (3PB: 3 point bending) test piece. , Joch (J. Joch, RAAinsworth and THHyd
e, LIMITED LOAD AND J-ESTIMATES FOR IDEALISED PROB
LEMS OF DEEPLY CRACKED WELDED JOINTS IN PLANESTRAI
N BENDING AND TENSION, Fatigue Fracture. Engng Mas
ter. Struct. Vol.16, No.10, 1993, p1061-1079.), Hor
net (P.Hornet and C.Eripret, EXPERIMENTALJ EVALUAT
ION FROM A LOAD DISPLACEMENT CURVE FOR HOMOGENEOUS
AND OVERMATCHED SENB OR CCT SPECIMENTS, Fatigue Fr
acture. Engng Master. Struct. Vol.18.No.6, 1995,
p679-692.), (E.Roos, U.Eisele and H.Silcher, A Pro
cedurefor the Experimental Assessment of the J-int
egral by Means of Specimensof Different Geometrie
s, Int. J. Pres. Ves. & Piping 23, 1986, p81-93.), E
ripret (C.Eripret and P.Hornet, FRACTURE TOUGHNESS
TESTING PROCEDURES FOR STRENGTH MIS-MATCHED STRUC
TURES, Mis-matching of Interfaces and Welds, Edited
by KHSchwalbe and M. Kocak, 1997, p17-34).

According to the above, the fracture toughness characteristics of a 3PB test piece composed of a non-homogeneous material composed of a base material and a welding material for welding the base materials together show the crack length a generated in the welding material. And the ligament length b of the welding material,
The coefficient ζ ₀ is calculated using the formula shown below.

[0006]

[Equation 17]

The ultimate load P _L of the _3PB test piece is a coefficient ζ ₀ , a yield stress σ _yB of the welding material, a plate thickness B of the 3PB test piece B, a width W of the 3PB test piece, a crack length a, and a yield of the base material. stress sigma is the ratio of the yield stress sigma _yB welding material for _yA mismatch degree _{M (σ yB / σ yA)} , the first variable alpha, using a second variable beta, expressed by the equation shown below It

[0008]

[Equation 18]

Further, the width W of the 3PB test piece, the crack length a,
It is the following formula which shows the relationship between the 1st variable (alpha) and the 2nd variable (beta) using the welding half width h of a welding material.

[Formula 19]

Using, the first variable α and the second variable β that minimize the value of the limit load P _L are calculated.

Then, the calculated first variable α and second variable β, the width W of the 3PB test piece, the crack length a, the ligament length b, the load step i, and the width W of the 3PB test piece,
This is an expression using the welding half width h of the welding material and the degree of mismatch M.

[Equation 20]

The coefficient η _(i-1) obtained from
It is an expression using the effective plate thickness B _N of the test piece and the area A _pl relating to plasticity under the load displacement curve.

[Equation 21]

The plastic term J _{pl (i) at} the load step i of the fracture toughness property J obtained from the above, the stress intensity factor K of the 3PB test piece, the Young's modulus E of the 3PB test piece, and the Poisson ratio ν of the 3PB test piece It was a ceremony

[Equation 22]

The elastic term J _{el (i) at} the load step i of the fracture toughness characteristic J obtained from the above is calculated respectively.

Further, the plastic term J _{pl (i)} and the elastic term J
_The fracture toughness characteristic J is obtained by adding _{el (i)} based on the following formula.

[0016]

[Equation 23]

The fracture toughness property J thus obtained
The fracture toughness characteristics of the 3PB test piece are easily evaluated by using.

On the other hand, as described above, with respect to the CT test piece, an evaluation formula for simply evaluating the fracture toughness characteristics has not been obtained. Therefore, in order to accurately evaluate the fracture toughness characteristics of the CT test piece composed of the non-homogeneous material, FEM analysis is performed.

[0019]

The CT test piece is 3 PB.
The volume of the test piece is smaller than that of the test piece. As a result, when irradiation is performed as in a surveillance test, not only the cost but also the irradiation dose can be reduced, and the equipment such as the constant temperature bath and the heater can be downsized even in the normal test. For example, for a specimen with a thickness of 25 mm, 3P
The B test piece requires a plane area of 50 mm × 200 mm, whereas the CT test piece requires a plane area of 60 mm × 62.5 mm. Furthermore, when measuring the fracture toughness characteristic curve, it is necessary to measure the load point displacement, but the CT test piece has the advantage that the measurement range can be made wider and the measurement becomes easier.

Therefore, it is very important and necessary to evaluate the fracture toughness characteristics of the CT test piece having the above advantages over the 3PB test piece.

However, when the fracture toughness characteristics are evaluated by FEM analysis, a huge amount of calculation time is required, and there is a problem that the evaluation result cannot be obtained quickly.

The present invention has been made in view of the above circumstances, and it is possible to easily evaluate the fracture toughness characteristics of a CT test piece made of a non-homogeneous material without performing FEM analysis. It is an object of the present invention to provide a fracture toughness property evaluation method and a fracture toughness property evaluation device for a CT test piece of a non-homogeneous material.

[0023]

In order to achieve the above object, the present invention takes the following means.

That is, the non-homogeneous material CT of the invention of claim 1
In the fracture toughness evaluation method of a test piece, the fracture toughness characteristics of a CT test piece composed of a non-homogeneous material composed of a base material and a welding material that welds the base materials together, cracks generated in the welding material Using the length a and the ligament length b of the welding material, the coefficient ζ ₀ is calculated based on the formula shown below.

[0025]

[Equation 24]

The ultimate load P _L of this CT test piece has a coefficient ζ
₀ , yield stress σ _{yB of} welded material, plate thickness B, C of CT test piece
Width W of T specimen crack length a, degree of mismatch is the ratio of the yield stress sigma _yB welding material for yield stress sigma _yA of the base material _{M (σ yB / σ yA)} , the first variable alpha, the second It is expressed by the following equation using the variable β of

[0027]

[Equation 25]

Further, using the width W of the CT test piece, the crack length a, and the welding half width h of the welding material, it is the following equation showing the relationship between the first variable α and the second variable β.

[Equation 26]

Using, the first variable α and the second variable β such that the value of the limit load P _L is minimized are calculated.

Then, the calculated first variable α and second variable β, the width W of the CT test piece, the crack length a, the ligament length b, the load step i, the welding half width h of the welding material, and the degree of mismatch It is an expression using M

[Equation 27]

It is an expression using the coefficient η _(i-1) obtained from, the ligament length b, the load step i, and the width W of the CT test piece.

[Equation 28]

It is an expression using the coefficient γ _(i-1) obtained from the above, the effective plate thickness B _N of the CT test piece, and the area A _pl relating to the plasticity under the load displacement curve.

[Equation 29]

The plasticity term J _{pl (i) at} the load step i of the fracture toughness property J obtained from the above, the stress intensity factor K of the CT test piece, the Young's modulus E of the 3PB test piece, and the Poisson's ratio ν of the CT test piece are used. It was a ceremony

[Equation 30]

The elastic term J _{el (i) at} the load step i of the fracture toughness characteristic J obtained from the above is calculated respectively.

Furthermore, the plastic term J _{pl (i)} and the elastic term J _pl
The fracture toughness characteristic J is obtained by adding _{el (i)} based on the following formula.

[0036]

[Equation 31]

The fracture toughness characteristic evaluation apparatus for non-homogeneous CT specimens according to the second aspect of the present invention is a C composed of a non-homogeneous material composed of a base material and a welding material for welding the base materials together.
A fracture toughness characteristic evaluation device for calculating the fracture toughness characteristic of a T test piece and evaluating the fracture toughness characteristic of a CT test piece, comprising:
Coefficient calculating means, variable calculating means, second coefficient calculating means, third coefficient calculating means, elastic term calculating means, plastic term calculating means, fracture toughness characteristic acquiring means, and fracture toughness characteristic evaluation. And means.

The first coefficient calculating means calculates the fracture toughness characteristics of a CT test piece composed of a non-homogeneous material composed of a base material and a welding material for welding the base materials together, and A fracture toughness characteristic evaluation device for evaluating fracture toughness characteristics, which is an expression using a crack length a generated in a welding material and a ligament length b of the welding material.

[Equation 32] The coefficient ζ ₀ determined by is calculated.

The variable calculating means includes the coefficient ζ ₀ calculated by the first coefficient calculating means and the yield stress σ _yB , C of the base material.
The thickness of the T test piece B, the width W of the CT test pieces, the crack length a, which is the ratio of yield stress sigma _yB welding material for yield stress sigma _yA of the base material mismatch degree M, the first variable alpha, and It is an expression for obtaining the ultimate load P _L of the CT test piece using the second variable β.

[Expression 33]

Is a formula showing the relationship between the first variable α and the second variable β using the width W of the CT test piece, the crack length a, and the welding half width h of the welding material.

[Equation 34]

Using, the first variable α and the second variable β that minimize the value of the limit load P _L are calculated.

The second coefficient calculating means is the first variable α and the second variable β calculated by the variable calculating means, the width W of the CT test piece, the crack length a, the ligament length b, and the load step i. , The welding half width h of the welding material, and the mismatch degree M.

[Equation 35]

The coefficient η _(i-1) obtained from the above is calculated.

The third coefficient calculating means is an equation using the ligament length b, the load step i, and the width W of the CT test piece.

[Equation 36] The coefficient γ _(i-1) obtained from is calculated.

The plasticity term calculation means calculates the coefficient η _(i-1) calculated by the second coefficient calculation means, the coefficient γ _(i-1) calculated by the third coefficient calculation means, and the validity of the CT test piece. It is a formula using a plate thickness B _N and an area A _pl regarding plasticity under a load displacement curve.

[Equation 37]

The plastic term J _{pl (i)} at the load step i of the fracture toughness characteristic J obtained from is calculated.

The elastic term calculating means is an equation using the stress intensity factor K of the CT test piece, the Young's modulus E of the CT test piece, and the Poisson's ratio ν of the CT test piece.

[Equation 38]

The elastic term J _{el (i)} at the load step i of the fracture toughness characteristic J obtained from is calculated.

The fracture toughness characteristic obtaining means adds the addition of the plastic term J _{pl ( i)} calculated by the plastic term calculating means and the elastic term J _{el (i)} calculated by the elastic term calculating means.

[Formula 39] Fracture toughness characteristic J is obtained based on

The fracture toughness property evaluation means uses the fracture toughness property J acquired by the fracture toughness property acquisition means to calculate C
The fracture toughness characteristics of the T test piece are evaluated.

The fracture toughness characteristic of the CT test piece of the non-homogeneous material thus simply calculated can obtain a solution almost equivalent to the fracture toughness characteristic calculated in detail by the FEM analysis. Therefore, according to the inventions of claims 1 and 2, even if the FEM analysis is not performed,
Fracture toughness characteristics of non-homogeneous CT specimens can be quickly obtained.

[0052]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an example of a non-homogeneous material CT test piece fracture toughness property evaluation apparatus 1 to which a fracture toughness property evaluation method for a non-homogeneous material CT test piece according to an embodiment of the present invention is applied. is there.

FIG. 2 shows a CT made of a non-homogeneous material.
It is sectional drawing which shows an example of a test piece. This CT test piece 14
Is formed by welding two base materials 15, which are plate materials, with a welding material 16. The welding thickness of the welding material 16 is 2 h, that is, the welding half width is h. a is the crack length of the welding material 16, b is the ligament length b of the welding material, W is the width of the CT test piece 14,
B is the plate thickness of the CT test piece.

That is, the non-homogeneous material C according to the embodiment.
Non-homogeneous material C to which the fracture toughness evaluation method of T test piece is applied
The T-test piece fracture toughness property evaluation apparatus 1 includes a base material 15 and a base material 1.
A device for calculating the fracture toughness characteristics of a CT test piece 14 composed of a non-homogeneous material composed of a welding material 16 for welding 5 pieces together, and evaluating the fracture toughness characteristics of the CT test piece 14. An input unit 2, a ζ ₀ calculation unit 3,
The variable calculation unit 4, the η _{( i−1)} calculation unit 5, and γ
_{(I-1) The} calculation unit 6, the plastic term calculation unit 7, the elastic term calculation unit 8, the fracture toughness property acquisition unit 9, the fracture toughness property evaluation unit 10, and the result output unit 11 are provided.

The parameter input section 2 is a crack length a of the welding material 16, the ligament length b of the welding material 16, the welding half width h of the welding material 16, which are various parameters of the CT test piece 14 as shown in FIG. yield stress of the weld material 16 sigma _yB, the yield stress of the base material 15 sigma _yA, thickness B and the effective thickness _B N of CT specimen 14, the width W of the CT test pieces 14, the stress intensity factor of the CT test piece 14 K , The Young's modulus E of the CT test piece 14, the Poisson's ratio ν of the CT test piece 14, the load step i of the CT test piece 14, the area A _pl related to plasticity under the load displacement curve of the CT test piece 14, The input parameters are calculated by using the ζ ₀ calculation unit 3, the η _(i−1) calculation unit 5, and the γ
_(I-1) Output to the calculation unit 6 and respectively.

The ζ ₀ calculation unit 3 is an equation using the crack length a and the ligament length b based on the parameters output from the parameter input unit 2.

[Formula 40] The coefficient ζ ₀ is calculated by the following, and the calculated ζ ₀ is output to the variable calculation unit 4.

The variable calculation unit 4 calculates the coefficient ζ ₀ calculated by the ζ ₀ calculation unit 3 and the yield stress σ _yB , CT of the base material 15.
Thickness B of the test piece 14, the width W of the CT test pieces 14, the crack length a, which is the ratio of yield stress sigma _yB of the welding material 16 with respect to the yield stress sigma _yA of the base member 15 mismatch degree M, variables alpha, and This is an expression for obtaining the ultimate load P _L of the CT test piece 14 using the variable β.

[Formula 41]

Is the width W of the CT test piece 14, the crack length a,
And a welding half width h of the welding material 16 is a formula showing a relationship with variables α and β.

[Equation 42]

Using, the variables α and β are calculated so that the value of the limit load P _L is minimized, and the calculated result is η
_(I-1) Output to the calculation unit 5.

The η _(i-1) calculation unit 5 outputs the result from the variable calculation unit 4 as a result, the width W of the CT test piece, the crack length a, the ligament length b, the load step i, and the welding half width of the welding material. It is an expression using h and the degree of mismatch M.

[Equation 43] The coefficient η _(i-1) obtained from the above is calculated, and the calculation result is output to the plastic term calculation unit 7.

The γ _(i-1) calculation unit 6 is an expression using the ligament length b, the load step i, and the width W of the CT test piece 14 among the parameters output from the parameter input unit 2.

[Equation 44]

The coefficient γ _(i-1) obtained from
The calculation result is output to the plasticity term calculation unit 7.

The plasticity term calculation unit 7 calculates each calculation result output from the η _(i-1) calculation unit 5 and the γ _(i-1) calculation unit 6 and the effective plate thickness B _N of the CT test piece 14, And an expression using the area A _pl regarding plasticity under the load displacement curve

[Equation 45]

The plastic term J _{pl (i)} in the load step i of the fracture toughness characteristic J obtained from is calculated, and the calculation result is output to the fracture toughness characteristic acquisition unit 9.

The elastic term calculator 8 calculates the stress intensity factor K of the CT test piece 14, the Young's modulus E of the CT test piece 14, and the CT.
This is an expression using the Poisson's ratio ν of the test piece 14.

[Equation 46]

The elastic term J _{el (i)} of the fracture toughness characteristic J obtained from the load step i is calculated, and the calculation result is output to the fracture toughness characteristic acquisition unit 9.

The fracture toughness characteristic acquisition unit 9 is a plastic term calculation unit 7.
The addition formula in which the plasticity term J _{pl ( i)} calculated by the above and the elastic term J _{el (i)} calculated by the elastic term calculation unit 8 are added

[Equation 47]

The fracture toughness characteristic J is acquired based on the above, and the obtained fracture toughness characteristic J is output to the fracture toughness characteristic evaluation unit 10.

The fracture toughness characteristic evaluation section 10 uses the fracture toughness characteristic J acquired by the fracture toughness characteristic acquisition section 9 as follows.
The fracture toughness characteristics of the CT test piece 14 are evaluated, and the evaluation result is output to the result output unit 11.

The result output unit 11 is the fracture toughness characteristic evaluation unit 1.
The evaluation result output from 0 is output.

FIG. 3 shows a non-homogeneous material CT according to the same embodiment.
Non-homogeneous CT using the method for evaluating fracture toughness of test pieces
It is the fracture toughness characteristic J with respect to the crack length a acquired by the test piece fracture toughness characteristic evaluation device 1. In addition, in FIG.
Fracture toughness characteristics F1 calculated strictly by FEM analysis
(Plane strain) and F2 (plane stress) are also shown.

As shown in FIG. 3, the fracture toughness property J obtained by the fracture toughness property evaluation device 1 for CT test piece of non-homogeneous material
Is between the curves of the fracture toughness characteristics F1 and F2 calculated strictly by the two-dimensional FEM analysis, and there is a good agreement.

In the case of the evaluation model as shown in FIG. 2, FE
When exact calculation is performed by M analysis, it usually takes 2 to 3 days (about 50 to 70 hours), whereas
The calculation time by the non-homogeneous material CT test piece fracture toughness evaluation apparatus 1 is about 1 hour.

Therefore, in the fracture toughness evaluation apparatus to which the fracture toughness evaluation method for non-homogeneous CT specimens according to the embodiment of the present invention is applied, as shown in the process flow chart of FIG. When the various parameters necessary for the evaluation of the fracture toughness characteristics are input from the input unit 2, the input parameters are input to the ζ ₀ calculation unit 3, the γ _(i−1) calculation unit 6, and the elastic term calculation unit 8, respectively. Output (S
1). Then, the ζ ₀ calculation unit 3 calculates the coefficient ζ ₀ ,
The calculated ζ ₀ is output to the variable calculation unit 4 (S2).

Next, the coefficient ζ ₀ calculated by the ζ ₀ calculator 3, the yield stress σ _{y B of the} base material 15, the CT test piece 14
Thickness B, width W of CT test piece 14, crack length a, base material 1
5 yield stress σ _yA yield stress _WE of weld material 16
Mismatch degree M that is the ratio of _yB , variable α, and variable β
By using a variable α that minimizes the value of the limit load P _L
Then, the variable β is calculated by the variable calculator 4, and the calculation result is output to the η _(i−1) calculator 5 (S3).

In the η _(i-1) calculation unit 5, step S3
Output from the variable calculation unit 4 in
Width W of test piece, crack length a, ligament length b, load step i, welding half width h of welding material, and degree of mismatch M
Based on the above, the coefficient η _{(i−1 )} is calculated, and the calculation result is output to the plastic term calculation unit 7 (S4).

In the γ _(i-1) calculation unit 6, step S1
Among the parameters output from the parameter input unit 2 in step 1, the ligament length b, the load step i, and C
The coefficient γ _(i-1) is calculated based on the width W of the T test piece 14, and the calculation result is output to the plastic term calculation unit 7 (S
5).

In the plasticity term calculation unit 7, the CT test piece 14 and each calculation result output from the η _(i-1) calculation unit 5 in step S4 and from the γ _(i-1) calculation unit 6 in step S5. based on the area a _{p l} on plastic under the effective thickness B _N, and the load displacement curve of the plastic section J _pl of fracture toughness properties J of the load step i _(i)
Is calculated and the calculation result is output to the fracture toughness property acquisition unit 9 (S6).

The elastic term calculation unit 8 calculates the stress intensity factor K of the CT test piece 14, the Young's modulus E of the CT test piece 14, and the CT test piece 14 of the parameters output from the parameter input unit 2 in step S1. The Poisson's ratio ν is used to calculate the elastic term J _{el (i)} of the fracture toughness characteristic J at the load step i, and the calculation result is output to the fracture toughness characteristic acquisition unit 9 (S7).

In the fracture toughness characteristic acquiring section 9, step S6
And the plasticity term J _{pl ( i)} output in step S
The fracture toughness characteristic J is obtained by adding the elastic term J _{el (i)} output in 7. Then, the obtained fracture toughness characteristic J is output to the fracture toughness characteristic evaluation unit 10 (S8).

The fracture toughness characteristic evaluation unit 10 uses the fracture toughness characteristic J output from the fracture toughness characteristic acquisition unit 9 to calculate C
The fracture toughness characteristics of the T test piece 14 are evaluated, and the evaluation result is output to the result output unit 11 (S9). Then, the result output unit 11 outputs an evaluation result, an example of which is shown in FIG. 3 (S10).

The fracture toughness characteristics of the CT test piece of the non-homogeneous material thus simply calculated are F as shown in FIG.
It is possible to obtain a solution almost equivalent to the fracture toughness characteristics calculated in detail by EM analysis. In the case of the evaluation model as shown in FIG. 2, when the strict calculation is performed by the FEM analysis, the calculation time of 2-3 days (about 50 to 70 hours) is usually required, whereas the CT test piece fracture of the non-homogeneous material is required. The calculation time by the toughness evaluation apparatus 1 is about 1 hour. That is, by using the fracture toughness characteristic evaluation apparatus 1 for a non-homogeneous material CT test piece to which the fracture toughness characteristic evaluation method for a non-homogeneous material CT test piece according to the embodiment of the present invention is applied, a precise calculation by FEM analysis is performed. It is possible to easily and quickly obtain the same result as.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such configurations. Within the scope of the technical idea of the invention as claimed in the claims, those skilled in the art can come up with various modifications and modifications, and the modifications and modifications are also within the technical scope of the present invention. Be understood to belong to.

[0085]

As described above, according to the present invention,
A fracture toughness property evaluation method and a fracture toughness property evaluation device for a heterogeneous material CT test piece capable of easily evaluating the fracture toughness property of a CT test piece composed of a non-homogeneous material without performing FEM analysis. Can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a non-homogeneous material CT test piece fracture toughness property evaluation apparatus to which a fracture toughness property evaluation method for a non-homogeneous material CT test piece according to an embodiment of the present invention is applied.

FIG. 2 is a sectional view showing an example of a CT test piece made of a non-homogeneous material.

FIG. 3 is a FE image showing fracture toughness characteristics acquired by the fracture toughness characteristic evaluation apparatus for non-homogeneous material CT test pieces to which the fracture toughness evaluation method for non-homogeneous material CT test pieces according to the same embodiment is applied.
Figure comparing with fracture toughness characteristics by M analysis

FIG. 4 is a process flow chart in a fracture toughness property evaluation apparatus to which a fracture toughness property evaluation method for a heterogeneous CT test piece according to the same embodiment is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Nonhomogeneous material CT test piece fracture toughness property evaluation apparatus 2 ... Parameter input part 3 ... ζ ₀ calculation part 4 ... Variable calculation part 5 ... η _(i-1) calculation part 6 ... γ _(i-1) calculation part 7 ... Plastic term calculation section 8 ... Elastic term calculation section 9 ... Fracture toughness characteristic acquisition section 10 ... Fracture toughness characteristic evaluation section 11 ... Result output section 14 ... CT test piece 15 ... Base metal 16 ... Welding material

Claims (2)

[Claims] 1. A fracture toughness characteristic of a CT test piece composed of a non-homogeneous material composed of a base material and a welding material for welding the base materials together, and a crack length a generated in the welding material. And the ligament length b of the welding material, A coefficient zeta ₀ determined by the yield stress sigma _yB of the welding _material, plate thickness B of the CT test pieces, the width W of the CT test pieces, the crack length a, for yield stress sigma _yA of the base material It is an _expression for _obtaining the ultimate load P _L of the CT test piece using the mismatch degree M which is the ratio of the yield stress σ _yB of the welded material, the first variable α and the second variable β. By using the width W of the CT test piece, the crack length a, and the welding half width h of the welding material, the first variable α and the second variable α
Is a formula showing the relationship with the variable β of Is used to calculate the first variable α and the second variable β such that the value of the ultimate load P _L is minimized, and the calculated first variable α and second variable β, It is an expression using the crack length a, the ligament length b, the load step i, the width W of the CT test piece, the welding half width h of the welding material, and the degree of mismatch M. From the coefficient η _(i-1) , the ligament length b, the load step i, the CT
This is an expression using the width W of the test piece. _Is a formula using the coefficient γ _(i-1) obtained from the above, the effective plate thickness B _N of the CT test piece, and the area A _pl relating to plasticity under the load displacement curve. The plastic term J _{pl (i)} in the load step i of the fracture toughness property J obtained from the above, the stress intensity factor K of the CT test piece, the Young's modulus E of the CT test piece, and the Poisson's ratio ν of the CT test piece are The formula used is [Equation 7] The addition formula [Equation 8] obtained by adding the elastic term _{Jel (i) at the} load step i of the fracture toughness characteristic J obtained from the above and the plastic term _{Jpl (i)} and the elastic term _{Jel (i).} The fracture toughness property J is obtained by using
A fracture toughness property evaluation method for a non-homogeneous CT test piece, wherein the fracture toughness property of the CT test piece is evaluated using the fracture toughness property J. 2. A fracture toughness property of a CT test piece composed of a non-homogeneous material composed of a base material and a welding material for welding the base materials together is calculated, and the fracture toughness property of the CT test piece is calculated. It is a fracture toughness characteristic evaluation device for evaluating, and is an expression using a crack length a generated in the welding material and a ligament length b of the welding material. And a coefficient ζ calculated by the first coefficient calculating means, the first coefficient calculating means calculating a coefficient ζ ₀ determined by
₀ , the yield stress σ _{yB of the} base material, the plate thickness B of the CT test piece, the width W of the CT test piece, the crack length a, the yield stress of the welded material with respect to the yield stress σ _yA of the base material σ
_Using the mismatch degree M, which is the ratio of _yB , the first variable α, and the second variable β, the ultimate load P _{L of the} CT test piece is used.
Is an expression for obtaining Is a formula showing the relationship between the first variable α and the second variable β using the width W of the CT test piece, the crack length a, and the welding half width h of the welding material. 11] Using a variable calculation means for calculating the first variable α and the second variable β such that the value of the limit load P _L is minimized, and the first variable calculated by the variable calculation means. α and the second variable β, the crack length a, the ligament length b,
It is an expression using the load step i, the width W of the CT test piece, the welding half width h of the welding material, and the degree of mismatch M. Is a formula using the second coefficient calculating means for calculating the coefficient η _(i-1) obtained from the above, the ligament length b, the load step i, and the width W of the CT test piece. And a coefficient η calculated by the second coefficient calculating means, the third coefficient calculating means calculating the coefficient γ _(i-1) obtained from
_(I-1) , the coefficient γ _(i-1) calculated by the third coefficient calculating means, the effective plate thickness B _N of the CT test piece, and the area A _pl relating to plasticity under the load displacement curve were used. Which is an expression Plasticity term calculation means for calculating the plasticity term J _{pl (i)} of the fracture toughness characteristic J obtained from the above, the stress intensity factor K of the CT test piece, the Young's modulus E of the CT test piece, and the This is an expression using the Poisson's ratio ν of the CT test piece. Elastic term calculation means for calculating the elastic term _{Jel (i)} of the fracture toughness characteristic J obtained from the load step i, and the plastic term J calculated by the plastic term calculation means.
_{pl (i)} and the elastic term J _{el (i)} calculated by the elastic term calculating means are added to obtain the addition formula: Fracture toughness characteristic obtaining means for obtaining the fracture toughness characteristic J on the basis of the fracture toughness characteristic J, and fracture toughness characteristic J obtained by the fracture toughness characteristic obtaining means for evaluating the fracture toughness characteristic of the CT test piece. An apparatus for evaluating fracture toughness characteristics of a CT test piece of a non-homogeneous material, comprising an evaluation means.