KR102545149B1 - Cryogenic tensile test equipment for polyurethane foam materials in lng cryogenic cargo holds - Google Patents

Abstract

The cryogenic tensile test apparatus for the polyurethane foam material of the cryogenic cargo hold according to a preferred embodiment of the present invention is formed in a “c” shape so that one side shoulder of the specimen can be covered up and down, so that the upper and lower sides of the “c” character are formed. Each of the two through-holes includes a coupling part formed at a position corresponding to each other and a tensile jig formed in a size corresponding to the coupling part and including a tensile part to which the tensile force transmission hole is coupled, both the through-hole on the upper side and the through-hole on the lower side A fixture that is inserted so as to span one shoulder of the specimen, a tensile force transmitting unit that is coupled to the tensile part of the tensile jig and transmits tensile force to the specimen via the tensile jig, a power generating unit and power that transmits tensile power to the tensile force transmitting unit It includes a control unit that controls the operation of the generating unit, and the tensile jig is coupled to the left shoulder of the specimen and the right shoulder of the specimen, respectively, and the fixture is formed through each of the through-holes formed in each of the tensile jig coupled to the left and right sides of the specimen, respectively. It is characterized by being inserted into. According to the cryogenic tensile test apparatus of the present invention including the above configuration, a tensile test apparatus for a cryogenic environment capable of performing a tensile test in a cryogenic environment for a polyurethane foam material used in a cryogenic cargo hold, and a cryogenic tensile test apparatus used therein There is an effect of being able to provide a jig for a test device.

Description

Cryogenic tensile test equipment for LNG cryogenic cargo hold polyurethane foam materials {CRYOGENIC TENSILE TEST EQUIPMENT FOR POLYURETHANE FOAM MATERIALS IN LNG CRYOGENIC CARGO HOLDS}

The present invention relates to a tensile test apparatus for a specific material, and more particularly, to a cryogenic tensile test apparatus for a polyurethane foam material used in a cryogenic cargo hold such as an LNG cargo hold.

Liquefied natural gas (LNG) is attracting attention as an alternative fuel to reduce oil dependence and reduce greenhouse gas emissions. Globally, it is expected that LNG demand will continue to increase due to decarbonization policies such as EEDI and changes in the industrial environment (see Figure 1, Source: LNG carrier growth prospects in the shipping sector after the 2030s).

LNG transportation relies heavily on LNG Cargo Containment System (CCS) technology developed over the past 20 years.

Membrane type cargo hold systems are composed of an insulating layer and primary and secondary barriers (Fig. 2). The insulation layer is fixed to the hull to support the primary and secondary barrier membranes and to perform insulation functions. The membrane functions to maintain airtightness during a loaded voyage.

The LNG cargo moves through the membrane to the insulation layer (IBS) in case of leakage. Recently, the Mark-III type, which has higher structural strength than NO96, which uses a thin invar sheet as a membrane material, is preferred in the market. The primary barrier is corrugated 1.2 mm 304L stainless steel. And the secondary barrier has various materials and thicknesses depending on the type of system.

In some cases, 0.7mm composite material is used, and in some cases, 1.2mm stainless steel is applied. Corrugations in stainless steel can act appropriately on thermal loads at cryogenic temperatures to reduce thermal stress. An LNG carrier built in 1971 was the first methane carrier with a cargo capacity of about 20,000 cubic meters using the same stainless steel membranes, and has recently increased its cargo capacity to about 266,000 cubic meters.

In the case of a large-capacity LNG cargo tank, wrinkles in the membrane can cause collapse-type damage due to increased sloshing load. Therefore, the data obtained from the strength evaluation of the primary barrier are utilized and reflected in the structural safety design.

Currently, Korea has a market share of about 90% based on world-class LNG carrier design and construction technology, and now it needs to become technologically independent.

In accordance with such a need, research and development on test and evaluation methods for materials and structures for the development of next-generation LNG insulation systems for CCS is urgently needed.

Japanese Patent Registration No. 6222279 (Name: Exterior material for electrical storage device, Registration date: October 13, 2017 ) Japanese Patent Registration No. 6943045 (Name: External material for electrical storage device and electrical storage device using the same, registration date: September 13, 2021 )

The present invention was invented to improve the above problems, and one object of the present invention is to provide a tensile test apparatus for a cryogenic environment capable of performing a tensile test in a cryogenic environment for a polyurethane foam material used in a cryogenic cargo hold. want to provide

Another object of the present invention is to provide a jig applicable to a tensile test apparatus for a cryogenic environment that can be applied to a tensile test apparatus capable of performing a tensile test in a cryogenic environment for a polyurethane foam material used in a cryogenic cargo hold.

Technical problems of the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

The cryogenic tensile test apparatus for the polyurethane foam material of the cryogenic cargo hold according to a preferred embodiment of the present invention, devised to achieve the above object, is formed in a “c” shape so that one shoulder of the specimen can be covered up and down. The upper and lower sides of the letter “c” include a coupling part formed at the corresponding position of each of the two through-holes, and a tensile jig that is formed in a size corresponding to the coupling part and includes a tensioning part to which the tensile force transmission port is coupled. A fixture that spans the shoulder of one side of the specimen by being inserted through both the through hole and the through hole of the lower side, the tensile force transmitting part coupled to the tensile part of the tensile jig and transmitting the tensile force to the specimen through the tensile jig, and the tensile force transmitting part It includes a power generating unit that transmits power and a control unit that controls the operation of the power generating unit, and the tensile jig is coupled to the left shoulder of the specimen and the right shoulder of the specimen, respectively, and the fixture is coupled to each of the left and right sides of the specimen. It is characterized in that it is inserted into each of the through-holes formed in each of the tensile jigs.

In addition, according to a preferred embodiment of the present invention, the specimen of the cryogenic tensile test apparatus for the polyurethane foam material of the cryogenic cargo hold is formed in a plate shape with a pair of shoulders formed on both left and right sides and having a certain thickness, , It is characterized in that it includes a gauge that extends to between the pair of shoulder parts on the other side with the same width as the distance between the pair of shoulder parts on one side.

In addition, according to a preferred embodiment of the present invention, the control unit of the cryogenic tensile test apparatus for the polyurethane foam material of the cryogenic cargo hold includes a wired/wireless communication function and is capable of controlling the power generation unit by a control signal received from the outside. to be

In addition, according to a preferred embodiment of the present invention, the control unit of the cryogenic tensile test apparatus for the polyurethane foam material of the cryogenic cargo hold includes a wired/wireless communication function and is capable of transmitting values measured in the test process to a designated external terminal. to be

According to one embodiment of the present invention, it is possible to provide a tensile test apparatus for a cryogenic environment capable of performing a tensile test in a cryogenic environment with respect to a polyurethane foam material used in a cryogenic cargo hold.

In addition, according to an embodiment of the present invention, a jig applicable to a tensile test apparatus for a cryogenic environment that can be applied to a tensile test apparatus capable of performing a tensile test in a cryogenic environment for polyurethane foam materials used in a cryogenic cargo hold be able to provide

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a graph showing the forecast for the growth prospects of LNG carriers in the shipping sector after the 2030s.
2 is a photograph showing an example of an LNG Cargo Containment System (CCS).
3 is a conceptual structural diagram illustrating a laminated structure of a membrane type CCS (Cargo Containment System).
4 is a plan view showing the shape and dimensions of each part of a dog bone-type specimen that can be used for a tensile test.
5 is a side cross-sectional view and a plan view showing the shape and dimensions of each part of a specimen that can be used for a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention.
6 is a side view, a plan view, and a photograph of a prototype showing the shape and dimensions of a jig that can be used for a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention. .
7 is a photograph immediately after a test piece is installed in the apparatus to perform a tensile test using the cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention.
8 is a graph showing the temperature monitoring results of specimens measured during a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention.
9 is a graph showing the maximum strength during a tensile test for each specimen used in a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings to the extent that those skilled in the art to which the present invention pertains can easily practice the present invention.

In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present invention pertains and are not directly related to the present invention will be omitted. This is to more clearly convey the gist of the present invention without obscuring it by omitting unnecessary description.

For the same reason, in the accompanying drawings, some components are exaggerated, omitted, or schematically illustrated. Also, the size of each component does not entirely reflect the actual size. In each figure, the same reference number is assigned to the same or corresponding component.

1 is a graph showing the forecast for the growth of LNG carriers in the shipping sector after the 2030s;

2 is a photograph showing an example of an LNG Cargo Containment System (CCS).

1 and 2 are mentioned in the [Background of the invention] column, so repeated descriptions are omitted.

3 is a conceptual structural diagram illustrating a laminated structure of a membrane type CCS (Cargo Containment System).

Referring to FIG. 3 , among various laminated components of a membrane type CCS (Cargo Containment System), R-PUF (PolyUrethane Foam) is the most important material for determining insulation performance.

4 is a plan view showing the shape and dimensions of each part of a dog bone-type specimen that can be used for a tensile test.

Referring to FIG. 4, in the conventional specimen Se, which is a dog bone-shaped specimen according to the prior art, four conventional specimen shoulder portions She are formed at which the width of the specimen begins to narrow. The narrow part extending from between the left conventional specimen shoulders (She) to the right conventional specimen shoulders (She) is a gauge.

● If necessary, process the surface of the specimen without changing the structure, and mark the direction x, y, z of the specimen.

● Conditioning control of the test piece is performed according to KS M ISO 291. For accurate measurement, conditioning should be performed for more than 6 hours under the following conditions.

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Hereinafter, an invention specimen (Si) for replacing the conventional specimen (Se), which is a dog bone-type specimen according to the prior art, will be described.

5 is a side cross-sectional view and a plan view showing the shape and dimensions of each part of a specimen that can be used for a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention.

Referring to FIG. 5, it can be seen a design diagram of an invention specimen (Si) that can be used for a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention.

The invention specimen (Si) is formed in a plate shape with a pair of shoulder parts (invention specimen shoulder part (Shi)) formed on both left and right sides, and having a certain thickness, and one shoulder part (invention specimen shoulder part (Shi)) )) characterized in that it includes a gauge extending to between the pair of shoulder parts on the other side with the same width as the distance between the pairs.

In addition, the additional conditions related to the invention specimen (Si) are as follows.

● Both ends of the specimen for the alternate test are reinforced with metal plates.

● During the test, fix one side of the pin and apply a load to the specimen while moving the other side slowly (5±1mm/min).

● As shown in Figure 5, fix the specimen to the jig with a fixing pin.

● The material of the metal plate is aluminum alloy or aluminum oxide.

● The R-PUF and the metal plate are bonded, and the bonding strength of the adhesive must be greater than the shear strength of the R-PUF itself.

● The adhesive should not affect the properties of R-PUF after curing.

6 is a side view, a plan view, and a photograph of a prototype showing the shape and dimensions of a jig that can be used for a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention. .

Referring to FIG. 6, a tensile jig (J) that can be used for a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold,

It is formed in a “c” shape so that one shoulder of the specimen can be covered up and down, and two through-holes are formed at corresponding positions on the upper and lower sides of the “c” shape, respectively, and the size corresponding to the coupling part It is formed to include a tensile force transmission sphere is coupled to the tension.

The above-described tensile jig J is manufactured according to KS M ISO 1926:2013 Rigid Foam Plastic - Tensile Property Measurement Rules.

7 is a photograph immediately after a test piece is installed in the apparatus to perform a tensile test using the cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention.

Referring to FIG. 7, the upper and lower tensile jigs J are prepared, respectively, and the gauge G of the invention specimen Si is visible between the tensile jigs J placed opposite to each other.

Here, the invention specimen shoulder portion (Shi) of the invention specimen (Si) is overlaid on the tensile jig (J) using the fixture (F), but it is difficult to see it from the outside due to the structure of the tensile jig (J).

test procedure

● Tensile test is a test to know the mechanical properties (tensile strength, modulus of elasticity) of materials. This is an experiment to measure the material's resistance to force by pulling the material in the axial direction at a speed of 2±1 mm/min. A tensile test is conducted at a cryogenic temperature, and the tensile strength and modulus of elasticity can be obtained through each force-deformation curve.

● Elongation (e)

The elongation, expressed as a percentage of the gauge length, is: :

(Equation 1)

In this case, each variable has the following meaning.

L ₀ : Gauge Length (mm)

ΔL ₀ : Increased distance between gauge length (mm)

● Maximum tensile strength (σmax)

The ultimate tensile strength (σmax) is given below.

(Equation 2)

In this case, each variable has the following meaning.

Fmax: Max. load during test (N)

b：Width of the area marked with the gauge length on the specimen before test (mm)

h：Thickness of the area marked with the gauge length on the specimen before test (mm)

● The test is conducted at a speed of 5±1mm/min so that the load is evenly applied to the specimen when necessary.

Test Specimen Installation

● Displacement and load must be zero before installing the specimen in the testing machine.

● When attaching the test piece to the grip jig, make sure it is well aligned so that only axial force is applied.

● Also, be careful not to damage the specimen when mounting the specimen in the jig.

Cooling method and holding time (cryogenic test only)

● Using a cryogenic chamber for cryogenic testing, liquid nitrogen (LN2) is injected into the chamber to maintain a cryogenic state.

● Status. Temperature sensors are attached to the top/bottom/sample of the chamber to check the temperature in real time. For uniform temperature distribution of the specimen, after the temperature sensor attached to the specimen reaches the target temperature and maintains it for more than 60 minutes, a high tensile tensile test is performed.

8 is a graph showing the temperature monitoring results of specimens measured during a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention.

Temperature monitoring (cryogenic testing only)

• Attach the temperature recording device in a way that does not affect the dynamic response of the specimen. The temperature of the specimen is monitored and the frequency should be kept low enough to avoid significant temperature changes unless this is a factor to be studied in the test.

start test

● Sample rate is performed after inputting information for test execution, such as specimen mounting and strain rate, and the test equipment must have the following performance.

● A force sensor must be fixed to one of the machine plates to measure the force produced by the reaction of the test specimen against the plate during testing. The sensor must be able to continuously measure the force at any point in the course of a measurement operation, with self-strain being negligible compared to what is being measured and with an additional ±1% accuracy.

● D Devices that measure and, where appropriate, graphically record the forces and displacements produced by the test rig should be checked periodically. The device shall be tested using a series of standard weights, the mass of which is more accurate than ±1% and corresponds to the force applied during the test. To verify the device, a spacer of known thickness should be used with an accuracy greater than ±0.5% or ±0.1mm, whichever is more restrictive.

● Sampling rate should be able to obtain enough data during the test.

9 is a graph showing the maximum strength during a tensile test for each specimen used in a tensile test using a cryogenic tensile test apparatus for a polyurethane foam material in a cryogenic cargo hold according to a preferred embodiment of the present invention.

Tensile strength test results

※ Since urethane foam has weak physical properties, after installation in the tensile jig, the test can be performed by minimizing the alignment and machining tolerance of the jig so that the load can be applied evenly to the specimen, and compressive and tensile loads due to material shrinkage during cryogenic temperatures Since it is a cryogenic test, it is important to maintain sufficient temperature so that the target temperature can be reached to the inside of the material.

A cryogenic tensile test apparatus for a polyurethane foam material for a cryogenic cargo hold according to a preferred embodiment of the present invention and a jig applicable thereto have been described with reference to FIGS. 1 to 9 .

On the other hand, in the present specification and drawings, preferred embodiments of the present invention are disclosed, and although specific terms are used, they are only used in a general sense to easily explain the technical content of the present invention and help understanding of the present invention. It is not intended to limit the scope of the invention. It is obvious to those skilled in the art that other modifications based on the technical idea of the present invention can be implemented in addition to the embodiments disclosed herein.

F: fixture
G: Gauge
J: Tensile jig
Se: Conventional specimen She: Conventional specimen shoulder
Si: Invention specimen Shi: Invention specimen shoulder

Claims (4)

In the cryogenic tensile test apparatus for polyurethane foam materials used in cryogenic cargo holds such as LNG cargo holds,
It is formed in a “c” shape so as to cover one shoulder of the specimen up and down, and includes a coupling portion in which two through-holes are formed at corresponding positions on the upper and lower sides of the “c” shape, and the coupling portion A tensile jig formed in a corresponding size and including a tensile part to which the tensile force transmission sphere is coupled;
a fixture that is inserted to pass through both the through-hole of the upper side and the through-hole of the lower side, and thus spans the shoulder portion of one side of the specimen;
a tensile force transmitting unit coupled to the tensile unit of the tensile jig and transmitting tensile force to the specimen via the tensile jig;
a power generating unit transmitting tensile power to the tensile force transmitting unit; and
Including; a control unit for controlling the operation of the power generating unit;
The tensile jig is coupled to the left shoulder of the specimen and the right shoulder of the specimen, respectively,
The fixture is inserted into each of the through-holes formed in each of the tensile jigs coupled to the left and right sides of the specimen, respectively.
According to claim 1,
The psalm,
A pair of shoulder parts are formed on each side of the left and right sides,
It is made in a plate shape with a certain thickness,
A cryogenic tensile test apparatus for a polyurethane foam material for a cryogenic cargo hold, characterized in that it comprises a gauge extending to between the pair of shoulder portions on the other side with the same width as the distance between the pair of shoulder portions on one side.
According to claim 1,
The control unit,
Including wired and wireless communication functions,
Cryogenic tensile test apparatus for cryogenic cargo hold polyurethane foam material, characterized in that the power generator can be controlled by a control signal received from the outside.
According to claim 1,
The control unit,
Including wired and wireless communication functions,
Cryogenic tensile test apparatus for cryogenic cargo hold polyurethane foam material, characterized in that it is possible to transmit the values measured in the test process to a designated external terminal.

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