CN109030171B - Method for determining concrete fracture toughness by two-point straight line method - Google Patents

Method for determining concrete fracture toughness by two-point straight line method Download PDF

Info

Publication number
CN109030171B
CN109030171B CN201810727792.0A CN201810727792A CN109030171B CN 109030171 B CN109030171 B CN 109030171B CN 201810727792 A CN201810727792 A CN 201810727792A CN 109030171 B CN109030171 B CN 109030171B
Authority
CN
China
Prior art keywords
point
test piece
concrete
straight line
ini
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201810727792.0A
Other languages
Chinese (zh)
Other versions
CN109030171A (en
Inventor
管俊峰
姚贤华
陈记豪
李长永
李长明
陈珊珊
黄坡
郭慧敏
腾权
何双华
曲福来
李晓克
赵顺波
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
North China University of Water Resources and Electric Power
Original Assignee
North China University of Water Resources and Electric Power
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by North China University of Water Resources and Electric Power filed Critical North China University of Water Resources and Electric Power
Priority to CN201810727792.0A priority Critical patent/CN109030171B/en
Publication of CN109030171A publication Critical patent/CN109030171A/en
Application granted granted Critical
Publication of CN109030171B publication Critical patent/CN109030171B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • 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
    • G01N2203/0058—Kind of property studied
    • G01N2203/006—Crack, flaws, fracture or rupture
    • G01N2203/0062—Crack or flaws
    • G01N2203/0064—Initiation of crack

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Abstract

The invention discloses a method for determining the fracture toughness of concrete by a two-point linear method, which mainly comprises the following steps: manufacturing a group of test pieces with the same size, obtaining a crack initiation load by static loading, determining a straight line from two points and solving the slope of the straight line, wherein the slope is the crack initiation toughness of the concrete without the size effect. The invention avoids the fitting analysis work of a large amount of test data, has comprehensive consideration factors, has enough precision of the prediction result and is easy to judge the reasonability of the result.

Description

Method for determining concrete fracture toughness by two-point straight line method
Technical Field
The invention relates to the technical field of civil engineering material detection, in particular to a method for determining concrete fracture toughness by a two-point linear method.
Background
Stress intensity factor corresponding to the initiation load of the test piece with crack, called initiation toughness Kini. Fracture toughness of concrete under laboratory conditionsAnd (3) obvious size effect exists, and if the fracture toughness independent of the size of the test piece is to be obtained, the fracture toughness of the concrete without the size effect is determined by adopting a boundary effect theory. However, this method must be based on a large amount of experimental data and can be implemented by fitting regression analysis. And the test piece adopted must satisfy the following conditions: the seam height ratio is different with the same size; or the same seam height ratio and different sizes; or a combination of the two forms. In addition, the fracture toughness of the concrete is determined at present based on a continuous medium mechanics theory, and the important influence of concrete aggregate particles cannot be contained in the theory.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a method for determining the fracture toughness of concrete by a two-point straight line method; the method overcomes the size effect existing in the existing concrete fracture toughness measurement, and does not consider the influence of aggregate particles.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for determining the fracture toughness of concrete by a two-point straight line method is designed, and comprises the following steps:
(1) pouring a group of concrete test pieces with H multiplied by B multiplied by W and alpha seam height ratio, wherein H is the height of the test piece, B is the thickness of the test piece, W is the effective span of the test piece, and the initial crack length of the test piece is a0The seam height ratio α ═ a0/H；
(2) Loading the test piece in the step (1) to be damaged by adopting a wedged split type or a three-point bending type according to a static loading test method, and recording the crack initiation load P of each test piece in the loading processini,iCalculating the average value of the test piece crack initiation load and recording the average value as Pini；
(3) Calculating the average value K of the fracture toughness of the group of test pieces based on a method for determining a straight line from two pointsini: wherein the first point is the origin (0,0), and the ordinate Y of the second point is equal to the average value P of the crack initiation loads of the group of concrete samplesini；
For a wedge split type specimen, the abscissa X of the second point is
Figure GDA0002610869140000021
For a three-point bending specimen, the abscissa X of the second point is
Figure GDA0002610869140000022
In the formulas (1) and (2), B is the thickness of the test piece, alpha is the seam height ratio, H is the height of the test piece, dmaxIs the maximum particle diameter of the aggregate of concrete, ae1、ae2Is a geometric parameter;
the slope of a straight line formed by the first point (0,0) and the second point (X, Y) is the average value K of the fracture initiation toughness of the test pieceini；
(4) Calculating the fracture toughness K of each test piece of the group based on a method for determining a straight line from two pointsini,i: wherein the first point is the origin 0 point (0,0), and the ordinate Y of the second pointiEqual to the crack initiation load P of a single concrete sampleini,i；
For a wedge split type specimen, the abscissa X of the second pointiThe abscissa X of the second point is obtained from the formula (2) for the three-point bending type test piece according to the formula (1);
a first point (0,0) and a second point (X)i，Yi) The slope of the straight line is the fracture toughness K of a single test pieceini,i。
Further, in steps (3) to (4), the geometric parameter a of formula (1)e1The following formula is used to calculate,
Figure GDA0002610869140000031
in the formula (3), α is the slit height ratio of each test piece, a0As the length of the initial crack,
Figure GDA0002610869140000032
formula (2)) Geometric parameter a ofe2The following formula is used to calculate,
Figure GDA0002610869140000033
in the formula (4), α is the slit height ratio of each test piece, a0As the length of the initial crack,
Figure GDA0002610869140000034
furthermore, the height H of the test piece is 150 mm-1200 mm, and the range is wide.
Further, the seam height ratio alpha is 0.4-0.5.
Furthermore, 3-5 concrete samples are provided, and the test workload is small.
Compared with the prior art, the invention has the positive and beneficial technical effects that:
1. the invention only adopts a group of samples with the same size and the same seam height ratio, thereby avoiding the fitting analysis of a large amount of test data.
2. The invention considers the influence of concrete aggregate particles on crack initiation and is more practical.
3. The method is simple and practical, and the slope of the straight line passing through the origin is the fracture toughness.
4. The invention only needs two coordinate points, and one of the two coordinate points is fixed as an origin (0,0), so that the data volume is small; and the other point can be used for obtaining the average value of the material parameters by taking the average value of the initiation load of a group of test pieces, or obtaining each individual value of the material parameters by taking the single value of the initiation load of a single test piece in the group, so that the discreteness of the initiation toughness determination result of the rock heterogeneous material can be displayed.
5. The invention can adopt a wedge split or three-point bending type, and is not limited by the size and the type of a test piece; the size of the selected test piece is in a selection range (the height H of the test piece can be any value between 150mm and 1200 mm), and the method is wider than that of other test pieces.
6. In the test process, only the crack initiation loads of 3-5 test pieces need to be measured, other test quantities do not need to be measured, the workload is small, and the test process is simple.
Drawings
FIG. 1 is a schematic diagram of the determination of the average value of the fracture toughness of concrete by a two-point straight line method according to the present invention;
FIG. 2 is a diagram illustrating the determination of discrete values of the fracture toughness of concrete by a two-point straight line method according to the present invention.
Detailed Description
The following examples are intended to illustrate the present invention in detail and should not be construed as limiting the scope of the present invention in any way.
Some of the steps or methods involved in the following examples are conventional in the art, unless otherwise specified, and all of the materials involved are commercially available, unless otherwise specified.
Example 1: the method for determining the fracture toughness of the concrete by a two-point straight line method comprises the following steps:
pouring a group of concrete test pieces with H multiplied by B multiplied by W and alpha seam height ratio, wherein H is the height of the test piece, B is the thickness of the test piece, W is the effective span of the test piece, and the initial crack length of the test piece is a0The seam height ratio α ═ a0H; loading the test piece to be damaged by adopting a wedged split type or a three-point bending type according to a static loading test method, and recording the crack initiation load P of each test piece in the loading processini,iCalculating the average value of the test piece crack initiation load and recording the average value as Pini(ii) a Determining a straight line based on two points, wherein the first point is an original point (0,0), and the ordinate Y of the second point is equal to the average value P of the crack initiation loads of the group of concrete samplesini；
For a wedge split type specimen, the abscissa X of the second point is
Figure GDA0002610869140000051
For a three-point bending specimen, the abscissa X of the second point is
Figure GDA0002610869140000052
Wherein B is the thickness of the specimen, alpha is the seam height ratio, H is the height of the specimen, dmaxIs the maximum particle diameter of the aggregate of concrete, ae1、ae2Is a geometric parameter;
Figure GDA0002610869140000053
Figure GDA0002610869140000054
Figure GDA0002610869140000055
the slope of the straight line formed by the first point (0,0) and the second point (X, Y) is the average value K of the fracture initiation toughness of the test pieceiniSee, fig. 1; if the ordinate Y of the second pointiEqual to the crack initiation load P of a single concrete sampleini,i(ii) a For a wedge split type specimen, the abscissa X of the second pointiThe X-axis coordinate of the second point is still obtained by the formula (2) for the three-point bending type test piece; at this time, a first point (0,0) and a second point (X)i，Yi) The slope of the straight line is the fracture toughness K of a single test pieceini,i. See fig. 2.
Example 2: method for determining concrete fracture toughness by two-point straight line method
In the embodiment, the wedged split type concrete sample is adopted, and the maximum particle size d of the aggregatemax10 mm. The test pieces are divided into five groups according to the size:
the first group H × B × W is 1200 × 200 × 1440mm, and the seam height ratio α is a0The total of 3 specimens was 0.5/W. By adopting the method, the crack initiation load is based on 3 test piecesThe fracture initiation toughness determined by the 3 test pieces and the average value of the fracture initiation load of the first group of test pieces can be respectively obtained, and the results are shown in table 1.
The second group H × B × W is 1000 × 200 × 1200mm, and the seam height ratio α is a0And W is 0.5, and the total number of the test pieces is 4. By adopting the method, the fracture initiation toughness determined by 4 test pieces and the average value of the fracture initiation load of the second group of test pieces can be respectively obtained based on the fracture initiation loads of the 4 test pieces, and the result is shown in table 1.
The third group H × B × W is 800 × 200 × 960mm, and the slit height ratio α is a0And W is 0.5, and the total number of the test pieces is 4. Based on the crack initiation loads of the 4 test pieces, the crack initiation toughness determined by the 4 test pieces and the average value of the crack initiation loads of the third group of test pieces can be respectively obtained, and the result is shown in table 1.
A fourth group H × B × W is 600 × 200 × 720mm, and a seam height ratio α is a0And W is 0.5, and the total number of the test pieces is 4. By adopting the method, the cracking toughness determined by the 4 test pieces and the average value of the cracking toughness obtained by the average value of the cracking loads of the fourth group of test pieces can be respectively obtained based on the cracking loads of the 4 test pieces, and the result is shown in table 1.
A fifth group H × B × W is 150 × 200 × 150mm, and the seam height ratio α is a0The total of 3 specimens was 0.5/W. By adopting the method, the cracking toughness determined by 3 test pieces and the average value of the cracking toughness obtained by the average value of the cracking load of the fifth group of test pieces can be respectively obtained based on the cracking load of the 3 test pieces, and the result is shown in table 1.
As can be seen from Table 1, the fracture initiation toughness determined by five groups of different test pieces respectively is more consistent by adopting the method, and the effectiveness and the rationality of the method provided by the invention are proved.
Table 1 cracking toughness of concrete determined in example 1
Figure GDA0002610869140000071
Fracture initiation and fracture of the concrete given by the double-K fracture modelRange of variation of toughness Kini＝0.65-0.77MPa·m1 /2. Therefore, the fracture initiation toughness determined by the method provided by the invention is well consistent with the calculation of the double-K fracture model, the calculation precision of the method is slightly better than that of the double-K fracture model, the calculation result is not changed along with the size of the test piece, and the size effect is avoided.
Example 3: method for determining concrete fracture toughness by two-point straight line method
In the experiment of this example, a three-point bending loading type is adopted, and the maximum particle size d of the concrete aggregatemax10 mm. The test pieces are divided into four groups according to the size:
the first group H × B × W is 500 × 200 × 2000mm, and the seam height ratio α is a0The total of 3 specimens was 0.5/W. By adopting the method, the cracking toughness determined by 3 test pieces and the average value of the cracking toughness obtained by the average value of the cracking load of the first group of test pieces can be respectively obtained based on the cracking load of the 3 test pieces, and the result is shown in table 2.
The second group H × B × W is 400 × 200 × 1600mm, and the seam height ratio α is a0And W is 0.5, and the total number of the test pieces is 4. By adopting the method, the cracking toughness determined by the 4 test pieces and the average value of the cracking toughness obtained by the average value of the cracking load of the second group of test pieces can be respectively obtained based on the cracking loads of the 4 test pieces, and the result is shown in table 2.
The third group H × B × W is 300 × 200 × 1200mm, and the seam height ratio α is a0The total of 5 specimens was 0.5/W. Based on the crack initiation loads of the 5 test pieces, the crack initiation toughness determined by the 5 test pieces and the average value of the crack initiation loads of the third group of test pieces can be respectively obtained, and the result is shown in table 2.
A fourth group H × B × W is 150 × 200 × 600mm, and a seam height ratio α is a0And W is 0.5, and the total number of the test pieces is 4. By adopting the method, the cracking toughness determined by the 4 test pieces and the average value of the cracking toughness obtained by the average value of the cracking loads of the fourth group of test pieces can be respectively obtained based on the cracking loads of the 4 test pieces, and the result is shown in table 2.
As can be seen from Table 2, the fracture initiation toughness determined by four different test pieces is consistent with that determined by the method, and the effectiveness and the reasonability of the method are proved.
Table 2 fracture initiation toughness of concrete determined in example 2
Figure GDA0002610869140000091
The fracture initiation fracture toughness variation range K of the concrete is given by a double-K fracture modelini＝0.40-0.67MPa·m1 /2. Therefore, the fracture initiation toughness determined by the method provided by the invention is well consistent with the calculation of the double-K fracture model, and the calculation result of the method provided by the invention does not change along with the size of the test piece and has no size effect.
Example 4: method for determining concrete fracture toughness by two-point straight line method
The test of this embodiment adopts a wedge split-pull loading type, and the maximum particle diameter d of the concrete aggregatemax25 mm. The test piece is divided into three groups according to the size of the test piece:
the first group H × B × W is 300 × 200 × 360mm, and the seam height ratio α is a0The total of 4 specimens was 0.4/W. By adopting the method, the fracture initiation toughness determined by 4 test pieces and the average value of the fracture initiation load of the first group of test pieces can be respectively obtained based on the fracture initiation loads of the 4 test pieces, and the result is shown in table 3.
The second group H × B × W is 800 × 240 × 960mm, and the seam height ratio α is a0The total of 4 specimens was 0.4/W. By adopting the method, the fracture initiation toughness determined by 4 test pieces and the average value of the fracture initiation load of the second group of test pieces can be respectively obtained based on the fracture initiation loads of the 4 test pieces, and the result is shown in Table 3.
The third group H × B × W is 1000 × 250 × 1200mm, and the seam height ratio α is a0The total of 5 specimens was 0.4/W. Based on the crack initiation loads of the 5 test pieces, the crack initiation toughness determined by the 5 test pieces and the average value of the crack initiation loads of the third group of test pieces can be respectively obtained, and the result is shown in table 3.
As can be seen from Table 3, the fracture initiation toughness determined by three different test pieces is more consistent with the method of the present invention, and the effectiveness and the rationality of the method of the present invention are proved.
Table 3 cracking toughness of concrete determined in example 3
Figure GDA0002610869140000101
While the present invention has been described in detail with reference to the drawings and the embodiments, those skilled in the art will understand that various specific parameters in the above embodiments can be changed without departing from the spirit of the present invention, and a plurality of specific embodiments are formed, which are common variation ranges of the present invention, and will not be described in detail herein.

Claims (4)

1. A method for determining the fracture toughness of concrete by a two-point straight line method is characterized by comprising the following steps:
(1) pouring a group of concrete test pieces with H multiplied by B multiplied by W and alpha seam height ratio, wherein H is the height of the test piece, B is the thickness of the test piece, W is the effective span of the test piece, and the initial crack length of the test piece is a0The seam height ratio α ═ a0/H；
(2) Loading the concrete test piece in the step (1) to be damaged by adopting a wedged split type or a three-point bending type according to a static loading test method, and recording the crack initiation load P of each test piece in the loading processini,iCalculating the average value of the crack initiation load of the concrete sample and recording the average value as Pini；
(3) Calculating the average value K of the fracture toughness of the group of concrete samples based on a method for determining a straight line at two pointsini: wherein the first point is the origin (0,0), and the ordinate Y of the second point is equal to the average value P of the crack initiation loads of the group of concrete samplesini；
For a wedge split type specimen, the abscissa X of the second point is
Figure FDA0002868645200000011
For a three-point bending specimen, the abscissa X of the second point is
Figure FDA0002868645200000012
In the formulas (1) and (2), B is the thickness of the test piece, alpha is the seam height ratio, H is the height of the test piece, dmaxIs the maximum particle diameter of the aggregate of concrete, ae1、ae2Is a geometric parameter;
the slope of a straight line formed by the first point (0,0) and the second point (X, Y) is the average value K of the fracture initiation toughness of the test pieceini；
(4) Calculating the fracture toughness K of each test piece of the group based on a method for determining a straight line from two pointsini,i: wherein the first point is the origin 0 point (0,0), and the ordinate Y of the second pointiEqual to the crack initiation load P of a single concrete sampleini,i；
For a wedge split type specimen, the abscissa X of the second pointiThe abscissa X of the second point is obtained from the formula (2) for the three-point bending type test piece according to the formula (1);
a first point (0,0) and a second point (X)i，Yi) The slope of the straight line is the fracture toughness K of a single test pieceini,i(ii) a In the steps (3) to (4), the geometric parameter a of the formula (1)e1The following formula is used to calculate,
Figure FDA0002868645200000021
in the formula (3), α is the slit height ratio of each test piece, a0As the length of the initial crack,
Figure FDA0002868645200000022
geometric parameter a of formula (2)e2The following formula is used to calculate,
Figure FDA0002868645200000023
in the formula (4), α is the slit height ratio of each test piece, a0As the length of the initial crack,
Figure FDA0002868645200000024
2. the method for determining the fracture toughness of concrete by the two-point straight line method according to claim 1, wherein the height H of the test piece is 150 mm-1200 mm.
3. The method for determining the fracture toughness of concrete by the two-point straight line method according to claim 1, wherein the seam height ratio α is 0.4-0.5.
4. The method for determining the fracture toughness of concrete by the two-point straight line method according to claim 1, wherein the number of the test pieces is 3-5.
CN201810727792.0A 2018-07-03 2018-07-03 Method for determining concrete fracture toughness by two-point straight line method Active CN109030171B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810727792.0A CN109030171B (en) 2018-07-03 2018-07-03 Method for determining concrete fracture toughness by two-point straight line method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810727792.0A CN109030171B (en) 2018-07-03 2018-07-03 Method for determining concrete fracture toughness by two-point straight line method

Publications (2)

Publication Number Publication Date
CN109030171A CN109030171A (en) 2018-12-18
CN109030171B true CN109030171B (en) 2021-03-23

Family

ID=65521807

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810727792.0A Active CN109030171B (en) 2018-07-03 2018-07-03 Method for determining concrete fracture toughness by two-point straight line method

Country Status (1)

Country Link
CN (1) CN109030171B (en)

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4672805B1 (en) * 2010-06-08 2011-04-20 有限会社Ｉ・Ｒ・Ｔ Pillar base isolation structure
CN102519805A (en) * 2011-12-01 2012-06-27 三峡大学 Method and system for testing fracture toughness of incompact soil body
JP6224346B2 (en) * 2013-05-09 2017-11-01 太平洋マテリアル株式会社 Concrete floor repair method
CN105910899B (en) * 2016-04-14 2018-09-14 华北水利水电大学 Measure the tensile strength of rock material and the method for fracture toughness simultaneously
CN105973701B (en) * 2016-04-29 2018-10-23 华北水利水电大学 Measure the yield strength of Hi-Stren steel and the method for fracture toughness simultaneously
CN105865896B (en) * 2016-05-19 2019-01-18 华北水利水电大学 The fracture toughness of quasi-brittle material and the method for tensile strength are determined by two o'clock loading specimen
CN107063792A (en) * 2017-03-14 2017-08-18 华北水利水电大学 The method that the concrete initiation angle of no dimensional effect is determined by small-size test piece

Also Published As

Publication number Publication date
CN109030171A (en) 2018-12-18

Similar Documents

Publication Publication Date Title
Liu et al. An improved semi-analytical solution for stress at round-tip notches
Li et al. Effect of interaction between corrosion defects on failure pressure of thin wall steel pipeline
Ayatollahi et al. Tensile fracture in notched polycrystalline graphite specimens
Lee et al. Experimental study on the convective heat transfer coefficient of early-age concrete
Ayatollahi et al. Mixed mode brittle fracture of sharp and blunt V-notches in polycrystalline graphite
Yang et al. Nozzle criteria for enhancing extrudability, buildability and interlayer bonding in 3D printing concrete
Ranganathan et al. Fatigue crack initiation at a notch
Volk et al. Prediction of formability for non-linear deformation history using generalized forming limit concept (GFLC)
CN105910899B (en) Measure the tensile strength of rock material and the method for fracture toughness simultaneously
Fantilli et al. Synergy assessment in hybrid ultra-high performance fiber-reinforced concrete (UHP-FRC)
CN105181492A (en) Measuring method for surface strengthening member fatigue crack expansion rate
Ducoulombier et al. “The slug test”: inline assessment of yield stress for extrusion-based additive manufacturing
Vargas et al. Comparison of two full-field identification methods for the wedge splitting test on a refractory
CN105823686A (en) Method for measuring tensile strength and fracture toughness of cement mortar or concrete
Tisza et al. Springback analysis of high strength dual-phase steels
Chen et al. A study on evaluation method of crack tip reverse plastic zone size for the center cracked steel plate model under tension–compression cyclic loading
Zhu et al. Surface fatigue crack growth under variable amplitude loading
Ouinas et al. Numerical modelling of the interaction macro–multimicrocracks in a plate under tensile stress
CN109030171B (en) Method for determining concrete fracture toughness by two-point straight line method
Dong et al. Marker load-aided bidirectional fatigue crack growth rate measurement via a semi-elliptical surface crack
Malipatil et al. Damage tolerance behavior of a nickel-based super-alloy GTM718 under cold-TURBISTAN variable amplitude loads
CN105865896B (en) The fracture toughness of quasi-brittle material and the method for tensile strength are determined by two o'clock loading specimen
Zhang et al. In-situ microscopy testing of plasticity variation ahead of fatigue crack tip in AL2024-T3
Xing et al. A method for establishing a continuous constitutive model of welded metals
Olson et al. Determination of residual stress intensity factor in the compact tension coupon

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant