CN113176142A - Method for calculating axial-radial crack stress intensity factor of outer wall of ultrahigh pressure container barrel - Google Patents
Method for calculating axial-radial crack stress intensity factor of outer wall of ultrahigh pressure container barrel Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/006—Crack, flaws, fracture or rupture
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0075—Strain-stress relations or elastic constants
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
The invention relates to the technical field of design and development of an ultrahigh pressure container and fatigue failure evaluation and calculation, in particular to a calculation method for stress intensity factors of axial-radial cracks on the outer wall of a cylinder body of the ultrahigh pressure container. The invention comprises the following steps: determining structural parameters of the ultrahigh pressure container, measuring shape parameters of the axial-radial cracks, and determining the load working condition of the cylinder; fitting the stress distribution vertical to the plane of the crack; calculating a required fitting coefficient; calculating another fitting coefficient under the current crack shape; calculating the crack shape coefficients at the deepest point of the current crack and at the position close to the free surface; calculating the stress intensity factor KI. The method can realize the calculation of the axial-radial semielliptical crack stress intensity factor of the outer wall of the cylinder body quickly, simply and conveniently by a formula while ensuring the accuracy of the calculation result, does not need to rely on finite element calculation software and professional mathematical analysis software, and is more suitable for engineering application.
Description
Technical Field
The invention relates to the technical field of design and development of an ultrahigh pressure container and fatigue failure evaluation and calculation, in particular to a calculation method for stress intensity factors of axial-radial cracks on the outer wall of a cylinder body of the ultrahigh pressure container.
Background
The axial-radial surface cracks on the outer wall of the cylinder body are common cracks in the manufacturing and running use of the ultrahigh pressure vessel, mainly take the shape of a semi-ellipse, namely E-shaped cracks in typical cracks described in GB 34019-2017 ultrahigh pressure vessel. From the point of view of damage tolerance of the pressure vessel, it is necessary to accurately calculate the stress intensity factor of the crack tip, since it is a key parameter for residual strength evaluation and residual life prediction based on fatigue crack propagation of crack-containing pressure vessels. Therefore, in practical engineering application, it is very important to find a fast and simple calculation method for the stress intensity factor of the axial-radial semi-elliptical crack of the outer wall of the cylinder.
The traditional crack tip stress intensity factor calculation method mainly comprises a mathematical analysis method, a finite element method, a boundary configuration method, a photoelastic method and the like, and most of researchers and researchers use the mathematical analysis method (mainly a weight function method) and the finite element method mostly at present. For the calculation of typical crack stress intensity factors of the ultrahigh Pressure container, non-mandatory annexes D in ASME BPVC, VIII, 3-2019 < Alternative Rules for Construction of high Pressure Vessels > in the United states and annexes F in GB 34019-2017 < ultrahigh Pressure vessel > in China are mentioned, and the contents of the two standards are similar. The method has detailed calculation steps for the axial-radial cracks (A-type cracks) of the inner wall of the cylinder in the standardAnd two methods are respectively given. However, for the axial-radial crack (E-type crack) on the outer wall of the cylinder, no specific calculation formula is given in the standard, and only the calculation can be performed by adopting a similar method, namely: elastic analysis is carried out to obtain stress distribution data vertical to the plane of the crack; performing related cubic polynomial fitting on the stress distribution data, and solving a fitting coefficient of a cubic polynomial; thirdly, according to the actual shape parameters of the crack, based on G in the tableiAnd (4) value data, and finally obtaining stress intensity factors at the deepest point of the crack and the free surface.
From the above, the key point of the calculation of the stress intensity factor of the axial-radial crack on the outer wall of the cylinder is to obtain a stress distribution curve perpendicular to the plane of the crack, and solve the fitting coefficient of the cubic polynomial thereof. However, in the elastic analysis process, we generally need to make mathematical derivation or perform calculation analysis by using finite element calculation software; in the data fitting process, the fitting is generally performed by a least square method by using special mathematical analysis software such as Maple, MATLAB, MathCAD, Mathematica and the like or special calculation programs. Therefore, the calculation processes are too tedious and complicated, and are not suitable for quick and concise calculation needs in engineering.
In addition, the existing calculation method generally only considers the working condition that the container bears the internal pressure load. However, the engineering may also be subjected to the working conditions that the container bears external pressure load or both the external pressure load and the internal pressure load, for example: a container in a ten thousand meter deep sea environment, an inner container in a multi-layer shrink sleeve ultrahigh pressure container and the like. The prior art is insufficient for the special situation.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a calculation method for the axial-radial crack stress intensity factor of the outer wall of the cylinder of the ultrahigh pressure container, which can realize the calculation of the axial-radial semi-elliptical crack stress intensity factor of the outer wall of the cylinder in a quick, simple and written manner only by a formula while ensuring the accuracy of the calculation result, does not need to rely on finite element calculation software and professional mathematical analysis software, and is more suitable for engineering application.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for calculating the stress intensity factor of axial-radial cracks on the outer wall of an ultrahigh pressure vessel cylinder is characterized by comprising the following steps:
s1, determining structural parameters of the ultrahigh pressure container, measuring shape parameters of the axial-radial cracks, and determining the load working condition of the cylinder;
s2, fitting the stress distribution perpendicular to the plane of the crack according to the following formula:
σ＝A′0+A′1(x/t)+A′2(x/t)2+A′3(x/t)3x is more than or equal to 0 and less than or equal to t (formula 1)
Wherein:
sigma is the stress perpendicular to the plane of the axial-radial crack on the outer wall of the cylinder body and is in unit of MPa;
x is the distance measured from the free surface of the crack in mm;
t is the thickness of the cylinder wall of the container and is unit mm;
s3, calculating the desired fitting coefficient A 'in equation 1 from the following equation'i：
Wherein:
a00∈[0.9，1]、a01∈[0.01，0.02]、a02∈[0.1，0.2]、a03∈[0.1，0.2]；a10∈[3.3，3.4]、a11∈[3.7，3.8]、a12∈[1.2，1.3]、a13∈[0.6，0.7]；a20∈[2.5，2.6]、a21∈[5.0，5.1]、a22∈[1.6，1.7]、a23∈[0.7，0.8]；a30∈[0.2，0.3]、a31∈[1.3，1.4]、a32∈[1.1，1.2]、a33∈[0.5，0.6]；
k is the ratio of the outer diameter to the inner diameter of the cylinder;
pothe external pressure load of the cylinder is in unit MPa;
pithe internal pressure load of the cylinder is in MPa;
s4, calculating another fitting coefficient A under the current crack shape according to the following formulai：
A0＝A′0
A1＝A′1(a/t)
A2＝A′2(a/t)2
A3＝A′3(a/t)3(formula 3)
Wherein:
a is the crack depth in mm;
s5, calculating the crack shape coefficient Q at the deepest point of the current crack and the position close to the free surface according to the following formula:
Q＝1+4.593(a/l)1.65-qy(formula 4)
Wherein:
l is the crack length in mm;
Gitaking interpolation values between values given in tables according to the values of the tables F.1 and F.2 in GB 34019-2017 ultrahigh pressure container;
s6, obtaining fitting coefficient A under the current crack shapeiAnd after the crack shape coefficient Q is obtained, calculating the stress intensity factor K at the deepest point of the current crack and the position close to the free surface according to the following formulaI：
Preferably, for a container cylinder with a diameter ratio K between 1.2 and 3.0, formula 2 in the step S3 is specifically:
preferably, in the step S1, the structural parameters of the ultra-high pressure vessel include: outer radius r of cylinderoInner radius r of cylinderiThe cylinder body is made of materials; the shape parameters of the axial-radial crack include: crack depth a, crack length l; the loading condition of the cylinder comprises the following steps: internal pressure load piExternal pressure load poA design temperature; searching the performance parameters of the material to obtain the yield strength of the material at the design temperature
The invention has the beneficial effects that:
1) the calculation method is quick, simple and accurate. The calculation method provided by the invention can calculate the fitting coefficient in the stress distribution cubic polynomial perpendicular to the plane of the crack by simply utilizing an algebraic formula without using finite element calculation software and professional mathematical analysis software, solves the current situation that the calculation of the stress intensity factors at the axial-radial crack deepest point and the free surface of the outer wall of the cylinder of the ultrahigh pressure vessel is complicated, and is more suitable for engineering application. Meanwhile, the calculation process is simple and quick, the calculation result has higher accuracy, and the application calculation in the engineering is greatly facilitated.
2) The load working condition is considered comprehensively. The calculation method provided by the invention considers the working condition that the inner wall and the outer wall of the ultrahigh pressure container bear pressure load, and improves the applicability in engineering. Particularly, a specific calculation formula of the ultrahigh pressure vessel with the diameter ratio K between 1.2 and 3.0 is provided, and the calculation requirements of most vessels can be met.
Drawings
FIG. 1 is a structural diagram of the existence and stress of axial-radial cracks on the outer wall of a cylinder body of an ultrahigh pressure vessel with pressure loads on the inner wall and the outer wall;
FIG. 2 shows the stress at the deepest point of the crack and the stress at the free surface in the second embodimentDegree factor KIThe calculation result graph of (2);
FIG. 3 is a comparison of a fitted curve of example three with a reference curve;
FIG. 4 is a graph showing the stress intensity factor K at the deepest point of a crack and at the free surface of a crack using the method of the present invention and a general complex method in the third embodimentIComparing the calculated results with the graph;
FIG. 5 is a graph comparing a fitted curve of the fourth example with a reference curve;
FIG. 6 is a graph comparing the stress intensity factor KI at the deepest point of the crack and at the free surface by applying the method of the present invention and the general complex method in the fourth embodiment.
Detailed Description
For ease of understanding, the specific construction and operation of the invention is described further herein as follows:
for an ultrahigh pressure container with pressure load bearing on the inner wall and the outer wall, the following function formula can be obtained through mathematical derivation of a stress distribution function of a plane where an axial-radial crack is positioned perpendicular to the outer wall of the cylinder:
in the above formula, σ is the stress perpendicular to the plane of the axial-radial crack on the outer wall of the cylinder body, and is MPa; p is a radical ofiThe internal pressure load of the cylinder is MPa; p is a radical ofoThe external pressure load of the cylinder is MPa; k is the ratio of the outer diameter to the inner diameter of the cylinder; r isoIs the outer radius of the cylinder body, mm; x is the distance measured from the free surface of the crack, mm; t is the wall thickness of the cylinder of the container, mm. From the functional expression, it can be seen that as the value of x increases, the stress value σ also increases.
Axial-radial cracks of the external wall of the cylinder, usually semi-elliptical cracks, with a stress intensity factor K at the deepest point and close to the free surfaceIIt can be calculated by the following steps:
1) determining structural parameters of the ultra-high pressure vessel, comprising: outer radius r of cylinderoInner radius r of cylinderiThe cylinder body is made of materials; measuring shape parameters of axial-radial cracks, including: crack depth a, crack length l; determining the loading condition of the cylinder, comprising: internal pressure load piExternal pressure load poDesign temperature, etc.; searching the performance parameters of the material to obtain the yield strength of the material at the design temperature
2) The stress distribution perpendicular to the plane of the crack is fitted as follows:
σ＝A′0+A′1(x/t)+A′2(x/t)2+A′3(x/t)3,0≤x≤t
3) calculating a fitting coefficient:
the fitting coefficient A 'required in the above formula was calculated from the following formula'i：
In the formula, a00∈[0.9，1]、a01∈[0.01，0.02]、a02∈[0.1，0.2]、a03∈[0.1，0.2]；a10∈[3.3，3.4]、a11∈[3.7，3.8]、a12∈[1.2，1.3]、a13∈[0.6，0.7]；a20∈[2.5，2.6]、a21∈[5.0，5.1]、a22∈[1.6，1.7]、a23∈[0.7，0.8]；a30∈[0.2，0.3]、a31∈[1.3，1.4]、a32∈[1.1，1.2]、a33∈[0.5，0.6]。
For a container cylinder with a diameter ratio K between 1.2 and 3.0, in particular:
A′1＝(3.324-3.7307K+1.5975K2-0.22578K3)·(pi-po)
A′2＝(-2.6072+5.099K-2.841K2+0.4358K3)·(pi-po)
A′3＝(0.2798-1.3831K+1.2603K2-0.2138K3)·(pi-po)
4) calculating another fitting coefficient A under the shape of the crack according to the following formulai：
A0＝A′0
A1＝A′1(a/t)
A2＝A′2(a/t)2
A3＝A′3(a/t)3
5) The crack shape coefficient Q at the deepest point of the crack and near the free surface is calculated as follows:
Q＝1+4.593(a/l)1.65-qy
in the formula, qyCalculated as follows:
6) the stress intensity factor K at the deepest point of the crack and near the free surface is calculated as followsI：
In the formula, GiCan be pressed into GB 34019-2017 & lt & ltultrahigh pressure containerTables f.1 and f.2 in table ″, take values, and an acceptable interpolation between the values given in the tables.
Due to the container with the diameter ratio K between 1.2 and 3.0, the use requirement of most ultrahigh pressure containers can be met. Thus, to facilitate a further understanding of the invention, the following specific example is described herein, taking as an example equation 6 for calculating a vessel having a ratio K between 1.2 and 3.0:
example one
Assuming that an ultra-high pressure vessel is subjected to only internal pressure load piThe pressure is 130MPa, the design temperature is normal temperature, and the selected material is 35CrNi3 MoVR; the outer radius of the cylinder body is roIs 400mm, and the inner radius r of the cylinder bodyi200mm, the crack depth a of the oval crack measured was 15.5mm and the crack length l was 46.5 mm. The stress intensity factor K at the deepest point of the crack and the free surface is calculated by the calculation methodIThe specific implementation steps of the calculation comprise:
1. and obtaining the diameter ratio K of the cylinder body to be 2 according to the outer radius and the inner radius of the cylinder body, and according with the requirement in the formula 6.
2. A 'required in formula 1 is calculated according to formula 6'iTo give A'0、A′1、A′2、A′3Respectively as follows: 86.15, 58.03, -37.28, 109.77.
3. Calculating according to formula 3 to obtain fitting coefficient AiTo obtain A0、A1、A2、A3Respectively as follows: 86.15, 4.50, -0.22, 0.051.
4. The shape coefficients Q at the deepest point of the crack and at the free surface were calculated to be 1.748 and 1.748, respectively, according to equation 4.
5. Calculating the stress intensity factor K at the deepest point of the crack and the free surface according to the formula 5IRespectively at 15.90MPa m1/2、13.80MPa·m1/2。
The first embodiment shows that the calculation method provided by the invention can be used for obtaining the calculation result by substituting the calculation formula without other finite element calculation software, professional mathematical analysis software and the like, is simple and quick, and is suitable for engineering application. Thus, the advantages of the present invention are demonstrated.
Example two
Assuming internal pressure load p of an ultra-high pressure vesseli130MPa and bears external pressure load poThe pressure is 30MPa, the design temperature is normal temperature, and the selected material is 35CrNi3 MoVR; the outer radius of the cylinder body is roIs 400mm, and the inner radius r of the cylinder bodyi200mm, the crack depth a of the oval crack measured was 15.5mm and the crack length l was 46.5 mm. The stress intensity factor K at the deepest point of the crack and the free surface is calculated by the calculation methodIThe specific implementation steps of the calculation comprise:
1. the diameter ratio K of the cylinder is obtained according to the outer radius and the inner radius of the cylinder and is 2, and the requirement in the formula 6 is met;
2. a 'required in formula 1 is calculated according to formula 6'iTo give A'0、A′1、A′2、A′3Respectively as follows: 36.27, 44.64, -28.68, 84.44.
3. Calculating the fitting coefficient A according to equation 3iTo obtain A0、A1、A2、A3Respectively as follows: 36.27, 3.46, -0.17, 0.039.
4. The shape coefficients Q at the crack deepest point and at the free surface were calculated as 1.749, 1.749, respectively, according to equation 4.
5. Calculating the stress intensity factor K at the deepest point of the crack and the free surface according to the formula 5IAre respectively 12.23 MPa.m1/2、10.61MPa·m1/2。
Example two shows that under otherwise identical conditions, the application of external pressure load to the vessel reduced the stress intensity factor at the crack deepest point and at the free surface. The calculation method provided by the invention not only considers the working conditions of the internal load and the external load, but the calculation method under the coexistence of the external load and the internal and external loads is not generally provided by the domestic and foreign related standards. Therefore, from the perspective, the comprehensiveness of the invention in consideration of the working condition is also shown.
In fact, in the case where the crack depth-to-length ratio a/l was 1/3, it was easily obtained in the second example that, at each value of the crack depth a,stress intensity factor K at the deepest point of axial-radial crack and free surface of outer wall of cylinder body of ultrahigh pressure vesselIThe calculation results of (2) are shown in fig. 2. Thus, the calculation superiority of the invention is reflected again.
In summary, the core innovation point of the present invention is that the fitting coefficient a 'required in equation 1 can be obtained by simple algebraic operations of equations 2 and 6'iAnd other professional mathematical analysis software or special programs are not needed to be used for calculation and solving, so that the method is very suitable for calculation by engineering application and has higher precision. The reliability of the results is verified by the following examples.
EXAMPLE III
Assuming internal pressure load p of an ultra-high pressure vesseli130MPa and bears external pressure load poIs 30 MPa; the outer radius of the cylinder body is roIs 400mm, and the inner radius r of the cylinder bodyiIs 200 mm. Comparing the fitting curve obtained by calculation with the curve obtained by a general complex method, and calculating the stress intensity factor K by the methodICompared with the calculation result obtained by a general complex method, the method comprises the following specific implementation steps:
1. the diameter ratio K of the cylinder is 2, between 1.2 and 3.0, obtained according to the outer radius and the inner radius of the cylinder, and meets the requirement in the formula 6;
2. a 'required in formula 1 is calculated according to formula 6'iTo give A'0、A′1、A′2、A′3Respectively as follows: 36.27, 44.64, -28.68, 84.44.
3. The stress distribution curves of the system 1 and the conventional calculation formula are plotted, as shown in fig. 3, in which the stress distribution curve of the conventional calculation formula is a reference curve, and the stress distribution curve of the formula 1 of the present invention is a fitting curve.
FIG. 3 shows that the fitted curve substantially coincides with the reference curve, the coefficient of certainty R of the fitted curve2The (statistic for measuring the goodness of fit) is 0.9996, and the fitting precision is high.
4. When the depth-to-length ratio a/l of the crack is 1/3, the crack calculated by the method of the invention and the general complex method is used under the value of a of each crack depthStress intensity factor K at the deepest point of the grain and at the free surfaceIThe results of the calculations of (a) are compared, as shown in fig. 4.
FIG. 4 shows the stress intensity factor K at either the crack deepest point or the free surfaceIThe calculation results of the two methods are very consistent, and the absolute error delta between the two methods is +/-0.1 MPa.m1/2In the meantime.
Example four
Assuming internal pressure load p of an ultra-high pressure vesseli130MPa and bears external pressure load poIs 30 MPa; the outer radius of the cylinder body is ro300mm, the inner radius r of the cylinder bodyiIs 100 mm. Comparing the fitting curve obtained by calculation with the curve obtained by a general complex method, and calculating the stress intensity factor K by the methodICompared with the calculation result obtained by a general complex method, the method comprises the following specific implementation steps:
1. the diameter ratio K of the cylinder is 3, which is between 1.2 and 3.0, according to the outer radius and the inner radius of the cylinder, and meets the requirement in the formula 6;
2. a 'required in formula 1 is calculated according to formula 6'iTo give A'0、A′1、A′2、A′3Respectively as follows: -5.13, 41.33, -111.26, 170.06.
3. The stress distribution curves of the system 1 and the conventional calculation formula are plotted, as shown in fig. 5, in which the stress distribution curve of the conventional calculation formula is a reference curve, and the stress distribution curve of the formula 1 is a fitting curve.
FIG. 5 shows that the fitted curve is substantially close to the reference curve, and the coefficient of solution R of the fitted curve2The (statistic for measuring the goodness of fit) is 0.9918, and the fitting precision is high.
4. When the crack depth-length ratio a/l is 1/3, under each crack depth a value, the stress intensity factor K at the deepest point of the crack and the free surface is calculated by the method of the invention and the general complex methodIThe results of the calculations of (a) are compared, as shown in fig. 6.
FIG. 6 shows the stress intensity factor K at either the crack deepest point or the free surfaceITwo kinds ofThe calculation results of the methods are relatively consistent, and the absolute error delta between the two methods is +/-0.5 MPa.m1/2In the meantime.
In summary, the crack stress intensity factor K of the present invention is shown in the third and fourth examplesIExcellent reliability of the calculation results.
It will, of course, be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
The techniques, shapes, and configurations not described in detail in the present invention are all known techniques.
Claims (3)
1. A method for calculating the stress intensity factor of axial-radial cracks on the outer wall of an ultrahigh pressure vessel cylinder is characterized by comprising the following steps:
s1, determining structural parameters of the ultrahigh pressure container, measuring shape parameters of the axial-radial cracks, and determining the load working condition of the cylinder;
s2, fitting the stress distribution perpendicular to the plane of the crack according to the following formula:
σ＝A′0+A′1(x/t)+A′2(x/t)2+A′3(x/t)3,0≤x≤t (formula 1)
Wherein:
sigma is the stress perpendicular to the plane of the axial-radial crack on the outer wall of the cylinder body and is in unit of MPa;
x is the distance measured from the free surface of the crack in mm;
t is the thickness of the cylinder wall of the container and is unit mm;
s3, calculating the desired fitting coefficient A 'in equation 1 from the following equation'i：
Wherein:
a00∈[0.9，1]、a01∈[0.01，0.02]、a02∈[0.1，0.2]、a03∈[0.1，0.2]；a10∈[3.3，3.4]、a11∈[3.7，3.8]、a12∈[1.2，1.3]、a13∈[0.6，0.7]；a20∈[2.5，2.6]、a21∈[5.0，5.1]、a22∈[1.6，1.7]、a23∈[0.7，0.8]；a30∈[0.2，0.3]、a31∈[1.3，1.4]、a32∈[1.1，1.2]、a33∈[0.5，0.6]；
k is the ratio of the outer diameter to the inner diameter of the cylinder;
pothe external pressure load of the cylinder is in unit MPa;
pithe internal pressure load of the cylinder is in MPa;
s4, calculating another fitting coefficient A under the current crack shape according to the following formulai：
A0＝A′0
A1＝A′1(a/t)
A2＝A′2(a/t)2
A3＝A′3(a/t)3(formula 3)
Wherein:
a is the crack depth in mm;
s5, calculating the crack shape coefficient Q at the deepest point of the current crack and the position close to the free surface according to the following formula:
Q＝1+4.593(a/l)1.65-qy(formula 4)
Wherein:
l is the crack length in mm;
Gitaking interpolation values between values given in tables according to the values of the tables F.1 and F.2 in GB 34019-2017 ultrahigh pressure container;
s6, obtaining fitting coefficient A under the current crack shapeiAnd after the crack shape coefficient Q is obtained, calculating the stress intensity factor K at the deepest point of the current crack and the position close to the free surface according to the following formulaI：
2. The method for calculating the axial-radial crack stress intensity factor of the outer wall of the cylinder of the ultrahigh-pressure vessel according to claim 1, wherein the method comprises the following steps: for a container cylinder with the diameter ratio K between 1.2 and 3.0, the formula 2 in the step S3 is specifically as follows:
3. the ultra-high pressure vessel cylinder outer wall axial-radial crack according to claim 1 or 2The stress intensity factor calculation method is characterized by comprising the following steps: in the step S1, the structural parameters of the ultra-high pressure vessel include: outer radius r of cylinderoInner radius r of cylinderiThe cylinder body is made of materials; the shape parameters of the axial-radial crack include: crack depth a, crack length l; the loading condition of the cylinder comprises the following steps: internal pressure load piExternal pressure load poAnd a design temperature.
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| CN117057166B (en) * | 2023-10-11 | 2023-12-26 | 合肥通用机械研究院有限公司 | Calculation method of stress intensity factor at crack free surface of stress concentration part |
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| CN117195608B (en) * | 2023-11-08 | 2024-01-12 | 合肥通用机械研究院有限公司 | Calculation method of stress intensity factor at deepest point of crack under any stress distribution |
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| CN117236069B (en) * | 2023-11-08 | 2024-02-02 | 合肥通用机械研究院有限公司 | Method for calculating stress intensity factor at crack free surface under arbitrary stress distribution |
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| CN117521417A (en) * | 2024-01-02 | 2024-02-06 | 合肥通用机械研究院有限公司 | Calculation method of crack stress intensity factor of inner wall of high-pressure thick-wall spherical shell |
| CN117494482B (en) * | 2024-01-02 | 2024-03-19 | 合肥通用机械研究院有限公司 | Calculation method of high-pressure thick-wall spherical shell outer wall crack stress intensity factor |
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