KR20010091758A - Tensile and bending tester in temperature gradient field - Google Patents
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- G01N1/02—Devices for withdrawing samples
- G01N1/10—Devices for withdrawing samples in the liquid or fluent state
- G01N1/14—Suction devices, e.g. pumps; Ejector devices
- G01N2001/1418—Depression, aspiration
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/22—Devices for withdrawing samples in the gaseous state
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Abstract
Description
본 발명은 온도경사장에서 재료의 기계적 성질을 측정하기 위한 인장 및 굽힘시험기에 관한 것이다. 공업재료가 산업현장에서 사용될 때에 사용조건에 따라 큰 온도경사장(temperature gradient field) 즉 재료의 어떤 한 부분의 온도가 다른 부분의 온도와 크게 다른 상황에 놓일 수 있다. 예를 들면, 자동차의 실린더 불록은 내부온도(피스톤과 접촉하고 있는 쪽) 와 외부온도(물로 냉각되어 지는쪽)가 크게 다른 상황에 놓인다. 또한 제철소에서 철강재료를 만드는 과정중 한 분야인 연속주조시 주형의 내측(응고각의 고상/액상의 계면과 접하고 있는 부분)의 온도는 매우 높은 반면(약 1723K) 응고를 촉진하고 구리(Cu) 주형을 보호하기 위하여 수냉 되는 외측(응고각/주형 계면 과 접촉하고 있는 부분)의 온도는 상대적으로 낮다(약 1273K). 이와 같은 상황을 재료내에 온도경사가 있다고 한다.The present invention relates to tensile and bending testers for measuring the mechanical properties of materials at temperature gradients. When an industrial material is used in an industrial field, depending on the conditions of use, a large temperature gradient field, i.e., the temperature of one part of the material, may be significantly different from the temperature of the other part. For example, the cylinder block of a car is in a situation where the internal temperature (the side in contact with the piston) and the external temperature (the side to be cooled by water) are significantly different. In addition, the temperature inside the mold (parts in contact with the solid / liquid interface of the solidification angle) during the continuous casting, which is one of the processes of making steel materials in steel mills, is very high (about 1723 K), which promotes solidification and improves copper (Cu). In order to protect the mold, the temperature outside the water-cooled (part in contact with the solidification angle / mould interface) is relatively low (about 1273 K). This situation is said to be a temperature gradient in the material.
그런데 과거에는 연속주조 주형내와 같은 온도경사장에서의 재료의 응력-변형거동을 연구하기 위해서 먼저 어떤 일정 온도 간격으로(예를들면 50K 또는 100K 간격) 각각의 온도에서 인장 및 굽힘시험편의 온도가 전체적으로 똑같은 상황, 즉 균일 온도장에서 일축인장을 실시하고, 이 실험으로 얻어진 응력-변형곡선들을 가지고 각 온도에서의 재료의 항복응력, 영율, 가공경화지수등을 구하고 다시 이 값들을 유한요소법(Finite Element Method ; FEM)에 의한 컴퓨터 계산을 하여 온도경사가 있는 재료의 응력-변형거동을 예측하였다. 따라서 재료의 양쪽의 온도차이가 심한 경우 인장시험의 횟수가 많아지고 컴퓨터에 의한 FEM분석에 많은 시간과 경비가 소요되며 컴퓨터 계산이 포함되므로 정확한 기계적 성질을 측정할 수 없다. 따라서 온도경사장에서 재료의 기계적 성질을 보다 경제적이고 간편하면서 정확하게 측정하기 위하여 새로운 인장 및 굽힘 시험기의 발명이 요구된다.In the past, however, in order to study the stress-strain behavior of a material at a temperature gradient such as in a continuous casting mold, the temperature of the tensile and bending test specimens at each temperature at a certain temperature interval (eg 50K or 100K interval) Perform uniaxial tension in the same situation, namely, uniform temperature field, calculate the yield stress, Young's modulus, work hardening index, etc. of the material at each temperature with the stress-strain curves obtained from this experiment. Computational calculations using the Element Method (FEM) predict the stress-strain behavior of materials with temperature gradients. Therefore, when the temperature difference between the two materials is severe, the number of tensile tests increases, the time-consuming and expensive expense of FEM analysis by computer, and computer calculations are included. Therefore, accurate mechanical properties cannot be measured. Thus, the invention of a new tensile and bending tester is required to more economically, simply and accurately measure the mechanical properties of materials at temperature gradients.
또한 철강재조 과정중의 연속주조시 주형내에서 철강재료의 응고각이 파단되어 응고되지 않은 용탕이 흘러나와 주형벽면에 달라붙으면 주조작업이 중단되고, 이것을 수리하여 다시 조업이 재개되는데는 수개월이 걸리며 경비도 많이 들기 때문에 이와 같은 사태가 일어나지 않도록 조업하는 것은 매우 중요하다. 따라서 연속주조시 응고각의 파단 여부를 판단하기 위해서는 주형내 응고각의 파단강도의 측정이 필수적이다. 그래서 주형내의 응고각의 파단강도를 가능한한 정확히 측정하기 위한 방법이 끊임없이 연구되어 왔으며 최근 연속주조 몰드내에서 응고각의 파단강도를 좀더 정확히 측정하기 위하여 P.Ackermann 등과 M.Suzuki등은 분해칠주형침적 (Submerged Split Chill Tensile ; SSCT) 시험을 실시하였다, 분해칠주형침적인장 시험 방법은 대형 용해로에서 약 10톤 이상의 용탕을 만들고 이속에 분리 가능한 주형을 삽입하고 일정시간(2초-20초)이 흐른 뒤 주형을 상하분리시켜 주형주위에 생성된 응고각의 파단강도를 측정하는 것이다. 현재까지 이 방법으로 측정된 응고각의 파단강도가 가장 정확하고 신뢰성이 있는 것으로 인정받고 있다. 그러나 이 시험방법은 시험장치가 매우 복잡하고 비용도 많이 들며 시험이 어렵다. 따라서 응고각의 파단에 관련된 기계적 성질을 보다 간편하고 정확하게 측정할 수 있는 시험장치의 개발이 요구되어 왔다.In addition, during the continuous casting during the steel manufacturing process, the solidification angle of the steel material is broken in the mold, and the unsolidified molten metal flows out and sticks to the mold wall. The casting operation is stopped, and it takes several months to repair and resume the operation again. It's very expensive, so it's very important to operate it so that this doesn't happen. Therefore, it is essential to measure the breaking strength of the solidification angle in the mold to determine whether the solidification angle is broken during continuous casting. Therefore, methods for measuring the breaking strength of the solidification angle in the mold as accurately as possible have been constantly studied. In order to more accurately measure the breaking strength of the solidification angle in the continuous casting mold, P. Ackermann and M. Suzuki et al. Submerged Split Chill Tensile (SSCT) tests were conducted. The cracked test method for depositing immersion field is to make a molten metal of about 10 tons or more in a large furnace, insert a detachable mold at a time, and allow a fixed time (2 to 20 seconds). After flow, the mold is divided up and down to measure the breaking strength of the solidification angle generated around the mold. To date, the breaking strength of the solidification angle measured by this method is recognized as the most accurate and reliable. However, this test method is very complex, expensive, and difficult to test. Therefore, there has been a demand for the development of a test apparatus that can more easily and accurately measure the mechanical properties related to the fracture of the solidification angle.
따라서 본 발명의 목적은 온도경사장에서의 재료의 기계적 성질측정시 종래의 균일 온도장에서 인장시험 한후 컴퓨터 계산을 해야하는 복잡하고 부정확한 방법을 개선하기 위하여 사각단면의 인장 및 굽힘 시험편 하나의 좌우 양쪽면에 서로 다른 온도를 부여하고, 그 상태에서 인장 및 굽힘시험을 실시함으로써 한번에 보다 편리하고 정확하게 재료의 기계적 성질을 측정할 수 있는 장치를 개발하는 것이다.Therefore, an object of the present invention is to measure the mechanical properties of a material at a temperature gradient, and to improve the complicated and inaccurate method of performing computer calculations after a tensile test in a conventional uniform temperature field. By applying different temperatures to the surface and performing tensile and bending tests in that state, a device that can measure the mechanical properties of the material more conveniently and accurately at once is developed.
제1도는 온도경사장 인장시험기 주요부분의 개략도.1 is a schematic view of the main portion of the temperature gradient tension tester.
제2도는 시험편을 가열하기 위한 고주파 유도코일의 사진.2 is a photograph of a high frequency induction coil for heating a test piece.
제3도는 온도경사장 굽힘시험기 장치 주요부분의 개략도.3 is a schematic view of the main part of the temperature gradient bending tester apparatus.
제4도는 온도경사장 인장시험기로 얻어진 응력-변형곡선과 기존 방법으로 얻어진 응력-변형곡선의 비교도.4 is a comparison diagram of the stress-strain curve obtained by the temperature gradient tension tester and the stress-strain curve obtained by the conventional method.
제5도는 온도경사장 인장시험 장치로 얻어진 파단강도와 분해칠주형침적시험으로 얻어진 파단강도의 비교도.5 is a comparison of the breaking strength obtained by the temperature gradient tensile tester and the breaking strength obtained by the decomposition molding mold deposition test.
< 도면의 주요부분에 대한 부호의 설명><Description of the reference numerals for the main parts of the drawings>
1. 시험편 2. 시험편의 가열면1. Test piece 2. Heating surface of the test piece
3. 시험편의 냉각면 4. 상부지그(Upper gig)3. Cooling surface of test piece 4. Upper gig
5. 하부지그(Lower gig) 6. 고주파유도가열 코일5. Lower gig 6. High frequency induction heating coil
7. 냉각용 가스노즐 8. 열전대7. Cooling gas nozzle 8. Thermocouple
9. 하중측정기(Load cell)9. Load cell
이하 첨부된 도면을 참조하여 본 발명의 실시 예를 설명하도록 한다.Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings.
제 1도는 본 발명에 의한 온도경사장 인장시험기의 주요부분에 대한 개략도이고, 제2도는 온도경사장 시험기에서 가장 중요한 고주파가열 코일의 형상을 나타낸 사진이다. 또한 제 3도는 온도경사장 인장시험에 사용했던 고주파유도 가열코일과 개스노즐의 새로운 배치에 의한 온도경사장 굽힘시험기의 개략도를 나타낸 것이며 제 4도는 본발명품의 타당성을 검증하기 위하여 온도경사장 인장시험기로 측정한 응력-변형곡선과 기존의 균일온도장 인장시험 후 컴퓨터 계산을 실시한 응력-변형 곡선을 비교한 것이다. 그리고 제 5도는 본 발명품의 실용화를 위한 적용성 검토로 온도경사장 인장시험과 분해칠주형침적시험으로 얻어진 연속주조주형내 응고각의 파단강도를 비교한 것이다.Figure 1 is a schematic diagram of the main part of the temperature gradient tension tester according to the present invention, Figure 2 is a photograph showing the shape of the most important high-frequency heating coil in the temperature gradient tester. In addition, Figure 3 shows the schematic diagram of the temperature gradient bending tester by the new arrangement of the high frequency induction heating coil and the gas nozzle used in the temperature gradient tension test, and Figure 4 shows the temperature gradient tensile tester to verify the validity of the present invention. The stress-strain curve measured by is compared with the stress-strain curve obtained by computer calculation after the conventional uniform temperature field tension test. 5 is a comparison of the breaking strength of the solidification angle in the continuous casting mold obtained by the temperature gradient tension test and the decomposition casting mold deposition test by examining the applicability for the practical application of the present invention.
먼저 제 1도는 시험편의 상하를 지그(5,6)으로 고정하고 하부지그(5)을 밑으로 이동시켜 시험편을 인장하는 고온 일축 인장시험기의 챔버 내부만을 나타낸 것이다.First, Figure 1 shows only the inside of the chamber of the high temperature uniaxial tensile tester for fixing the test piece by fixing the top and bottom of the test piece with the jig (5,6) and moving the lower jig 5 downward.
본 발명의 특징은 시험편(1)의 한면(2)은 고주파 유도코일(6)로 가열하고 다른면(3)은 가스 노즐(7)을 통해 순수한 아르곤 가스를 분사시켜 냉각되어진다. 길이 8mm,폭 10mm 면적 내에서 원하는 온도를 얻기 위한 유도가열 코일이 고안되었다. 즉, 시편의 두께 방향으로 직선적인 온도경사를 얻기 위해서는 유도가열(과전류의 깊이와 밀도), 코일들 사이의 간섭, 시편의 길이 방향과 두께방향으로의 열전도 그리고 주위로의 열전달과 복사 등이 균형을 이루게 하였다. 시편내의 요구되는 온도와 온도경사를 얻기 위한 유도코일은 제 2도와 같이 복잡한 형상을 가지게 되었다. 유도가열코일의 재료는 구리이고 구리 파이프내부는 냉각수가 흐르게 되어 있다. 또한 시험편의 다른 쪽을 균일하게 냉각시키기 위해서 시험편(1)과 가스 노즐(7) 사이의 거리(10mm), 가스 노즐의 직경(15 )과 홀수(8개), 그리고 가스유량(온도경사에 따라 다름;1~50ℓ/min)을 적절히 조정하였다.A feature of the present invention is that one side 2 of the test piece 1 is heated by a high frequency induction coil 6 and the other side 3 is cooled by injecting pure argon gas through the gas nozzle 7. Induction heating coils are designed to achieve the desired temperature within an area of 8 mm length and 10 mm width. That is, in order to obtain a linear temperature gradient in the thickness direction of the specimen, induction heating (depth and density of overcurrent), interference between coils, thermal conduction in the longitudinal and thickness directions of the specimen, and heat transfer and radiation to the surroundings are balanced. To achieve. The induction coil to obtain the required temperature and temperature gradient in the specimen has a complex shape as shown in FIG. The material of the induction heating coil is copper, and cooling water flows inside the copper pipe. In addition, in order to uniformly cool the other side of the test piece, the distance between the test piece 1 and the gas nozzle 7 (10 mm), the diameter of the gas nozzle 15 and the odd number (8 pieces), and the gas flow rate (depending on the temperature gradient) 1-50 L / min) was adjusted appropriately.
제 3도에 나타낸 바와 같이 온도경사장 인장시험기(제 1도)에서 사용된 것과 똑같은 유도코일과 가스 노즐의 배치를 인장시험기와 다르게 배치하여 온도 경사장 굽힘 시험기를 만들었다. 제작된 고주파 유도코일과 가스 노즐을 가지고 인장 및 굽힘 시험편에 큰 온도경사를 부여 할 수 있으며 두께 방향으로 거의 직선적인 온도 경사를 얻어 수 있었다.As shown in FIG. 3, the same arrangement of induction coil and gas nozzle as the one used in the temperature gradient tension tester (FIG. 1) was arranged differently from the tension tester to make the temperature gradient bending tester. With the fabricated high frequency induction coil and gas nozzle, it was possible to give a large temperature gradient to the tensile and bending specimens and to obtain a nearly linear temperature gradient in the thickness direction.
본 발명에 의한 온도경사장 인장 및 굽힘 시험기의 타당성을 검증하기 위하여 온도 경사장에서의 응력-변형 곡선을 균일 온도장 인장시험 후 상용화되어있는 유한요소법 컴퓨터 프로그램(MARC 프로그램)에 의한 열탄소성 응력-변형 해석을 하였다. 이때 계산에 사용된 재료의 영률, 항복강도, 가공경화지수 등은 균일 온도장 인장 시험으로부터 얻어진 응력-변형곡선을 이용하여 측정하였다. 열탄소성 응력-변형 계산은 먼저 시험편에 2차원적인 온도 분포를 부여한 다음 시험편의 왼쪽 끝을 고정하고. 오른쪽을 온도 경사장 인장 시험시 사용한 아래척(5) 이동속도(1×10-21/s)와 같은 속도로 인장 하였다. 0.105 mass%C의 탄소강에 대하여 계산된 응력-변형 곡선을 온도경사장 인장시험으로 얻어진 것을 제 4도에 비교하여 나타내었다. 대략적으로 두 곡선이 서로 잘 일치하고 있다. 이와 같이 두곡선이 일치하는 것으로부터 본 발명에 의한 온도 경사장 인장기로 과거에 행하여진 많은 수의 균일 온도장 인장시험과 복잡하고 시간이 많이 소요되는 FEM 해석을 대신하여 간편하고 정확하게 온도경사장에서의 재료의 기계적 성질을 측정할 수 있는 것이 입증 되었다.Thermoelastic stress by the finite element method computer program (MARC program), which is commercialized after the uniform temperature field tension test, in order to verify the validity of the temperature gradient tension and bending tester according to the present invention. Deformation analysis was performed. The Young's modulus, yield strength, and work hardening index of the materials used for the calculations were measured using the stress-strain curves obtained from the uniform temperature field tensile test. Thermoelastic stress-strain calculations first give the specimen a two-dimensional temperature distribution and then fix the left end of the specimen. The right side was pulled at the same speed as the lower chuck 5 moving speed (1 × 10 −2 1 / s) used in the temperature gradient test. The stress-strain curves calculated for 0.105 mass% C carbon steel are shown in FIG. 4 as obtained by the temperature gradient tension test. Roughly the two curves are in good agreement with each other. In this way, the two curves coincide with each other, instead of the large number of uniform temperature field tension tests conducted in the past with the temperature gradient field tensioner according to the present invention and the complicated and time-consuming FEM analysis. It has been proven that the mechanical properties of materials can be measured.
또한 온도경사장 인장 시험기의 실용화를 위한 적용을 검토하기 위하여 폭 10mm,두께 20mm, 길이 140mm의 직사각형의 인장 시험편을 연속주조 슬라브 표면에 평행하고. 시험편의 주축이 주상정 의 성장방향과 수직이 되도록 채취하였다. 온도경사장 시험에서 한쪽면은 각종 탄소강의 강도가 영으로 되는 온도(Zero Strength Temperature: ZST)로 가열하였으며 다른 쪽면은 계산된 연속주조 몰드내의 표면온도로 냉각하였다. 인장시험은 변형속도 1×1O-2/s으로 실시하였다. 최대인장강도 Fmax/Ao를 시험편의 파단강도로 하였으며, 여기서 Fmax는 최대하중이고 Ao는 인장시험하기 전 시편 중앙부에서의 단면적이다.In addition, a rectangular tensile test piece of width 10mm, thickness 20mm and length 140mm is parallel to the surface of continuous casting slab to examine the application for the practical application of the temperature gradient tension tester. The specimen's spindle was taken perpendicular to the growth direction of the column head. In the temperature gradient test, one side was heated to zero strength temperature (ZST) of various carbon steels and the other side was cooled to the surface temperature in the calculated continuous casting mold. Tensile tests were conducted at a strain rate of 1 × 10 −2 / s. The maximum tensile strength, Fmax / Ao, is the breaking strength of the specimen, where Fmax is the maximum load and Ao is the cross-sectional area at the center of the specimen before tensile testing.
0.10/5mass%C 탄소강에 온도경사장( 한쪽면의 온도는 1733K, 다른 쪽면의 온도1273K로 조절) 에서 측정된 파단강도와 균일온도장에서 측정한 파단강도를 비교한 결과 균일온도장 시험편 양쪽의 평균 온도(1503K)에 해당하는 파단강도 보다 약간 낮은 값을 나타내었다.The fracture strength measured at 0.10 / 5mass% C carbon steel at the temperature slope (adjustable temperature on one side is adjusted to 1733K and the temperature on the other side 1273K) and at the uniform temperature field are compared. It showed a value slightly lower than the breaking strength corresponding to the average temperature (1503K).
제 5도에 여러 가지 탄소강에 대하여 온도경사장 인장시험과 SSCT시험으로 측정된 파단 강도를 비교하였다. SSCT시험에서는 용질들이 주상정 사이에 편석되어 있는 상태에서(in-situ측정) 응고각의 파단강도를 측정할 수 있으나 응고각과 몰드의 계면 온도 측정이 어렵고 응고각의 불균일 성장에 의해 응고각의 단면적 측정이 어려워 약간의 시험오차가 나게된다. 한편 온도경사장 인장시험에서는 계면온도가 정확하게 조절되고 시험편의 단면적이 정확하게 측정되지만 이것은 in-situ측정이 아니다. 그러나 온도경사장 인장시험으로 측정된 저탄소강 및 중탄소강의 초기 응고각의 파단강도는 SSCT시험으로 얻어진 것과 잘 일치한다. 그러므로 새롭게 개발된 온도경사장 시험장치는 연속주조 주형내의 응고각의 파단강도를 보다 간단하고 편리하게 측정하는데 사용 될 수 있음을 검증하였다.In FIG. 5, the fracture strengths measured by the temperature gradient tensile test and the SSCT test were compared for various carbon steels. In the SSCT test, the fracture strength of the solidification angle can be measured while the solutes are segregated between columnar tablets (in-situ measurement), but it is difficult to measure the interfacial temperature between the solidification angle and the mold and the cross-sectional area of the solidification angle due to uneven growth of the solidification angle. Difficult to measure leads to slight test errors. On the other hand, in the temperature gradient tension test, the interface temperature is precisely controlled and the cross-sectional area of the specimen is accurately measured, but this is not an in-situ measurement. However, the breaking strengths of the initial solidification angles of the low and medium carbon steels measured by the temperature gradient tensile test agree well with those obtained by the SSCT test. Therefore, the newly developed temperature gradient test apparatus proved that it could be used to measure the breaking strength of solidification angle in continuous casting mold more simply and conveniently.
종래의 균일온도장에서 인장 및 굽힘을 실시하여 얻어진 응력-변형곡선으로부터 각 온도에서 구한 재료의 항복응력, 영율, 가공경화지수등의 값들을 이용하여 다시 컴퓨터 계산을 하므로 시간과 경비가 많이 소요되었으나, 본 발명으로 인하여 한번에 온도경사장 인장 및 굽힘 시험으로 보다 편리하고 정확하게 온도경사장에서 재료의 기계적 성질을 구할 수 있게 된다. 따라서 본 발명으로 개발된 온도경사장 인장 및 굽힘시험기는 철강 및 비철재료의 연속주조기의 주형내의 응고각의 고온 응력-변형거동을 쉽고 정확하게 측정할 수 있다. 그 결과 여러 작업조건에서 연속주조 주형내의 응고각의 파단강도가 정확히 측정되면 주조된 재료의 표면에 발생하는 균열을 방지할 수 있고 응고각의 파단에 따른 조업중단이나 수리등을 예방 할수 있게되어 철강재료 및 기타재료의 생산성향상과 에너지 절감에 큰 효과가 있을 것으로 기대된다.It was very time and costly because computer calculations were again made using the values of yield stress, Young's modulus, work hardening index, etc., obtained at each temperature from the stress-strain curves obtained by tensioning and bending at conventional uniform temperature fields. Due to the present invention, it is possible to obtain the mechanical properties of the material at the temperature gradient more conveniently and accurately by the temperature gradient tension and bending test at once. Therefore, the temperature gradient tension and bending tester developed by the present invention can easily and accurately measure the high temperature stress-strain behavior of the solidification angle in the mold of the continuous casting machine of steel and nonferrous materials. As a result, if the breaking strength of the solidification angle in the continuous casting mold is accurately measured under various working conditions, it is possible to prevent cracks on the surface of the cast material and to prevent operation interruption or repair due to the breaking of the solidification angle. It is expected to have a great effect on productivity and energy saving of materials and other materials.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR100948035B1 (en) * | 2006-06-30 | 2010-03-19 | 경상대학교산학협력단 | Method of Acquisition of True Stress-Strain Curves over Large Strain by the Tensile Test and its Finite Element Analysis, and Tensile Test Device using it |
| KR101295333B1 (en) * | 2011-11-28 | 2013-08-08 | 한국과학기술연구원 | Jig for measuring a bending deformation |
| KR102605631B1 (en) * | 2022-12-28 | 2023-11-23 | 목포대학교산학협력단 | A Method for Bending Fatigue Test Procedure of Primary Barrier in LNG Cryogenic Cargo |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100948035B1 (en) * | 2006-06-30 | 2010-03-19 | 경상대학교산학협력단 | Method of Acquisition of True Stress-Strain Curves over Large Strain by the Tensile Test and its Finite Element Analysis, and Tensile Test Device using it |
| KR101295333B1 (en) * | 2011-11-28 | 2013-08-08 | 한국과학기술연구원 | Jig for measuring a bending deformation |
| KR102605631B1 (en) * | 2022-12-28 | 2023-11-23 | 목포대학교산학협력단 | A Method for Bending Fatigue Test Procedure of Primary Barrier in LNG Cryogenic Cargo |
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