JP2018010429A - Method for calculating fiber accumulation content in high pressure tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a calculation method capable of improving calculation accuracy of a fiber accumulation content of a fiber-reinforced resin layer formed on the outer periphery of a liner.SOLUTION: A method for calculating a fiber accumulation content includes: a step of multiplying a theoretical cross section area of a fiber-reinforced resin layer 50 in a dome portion 30 from a first point to a second point which are separated with a predetermined length in a radial direction from a central axis of a high pressure tank 10 in the fiber-reinforced resin layer 50 by a design value Vfor designof the previously set fiber accumulation content to calculate a used fiber amount; a step of measuring the cross section area of the fiber-reinforced resin layer 50 from the first point to the second point; and a step of dividing the used fiber amount by the measured cross section area to calculate a fiber accumulate content Vfor design.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for calculating fiber deposition content in a high-pressure tank.

  In recent years, tanks for storing high-pressure gas used in fuel cell systems and the like have been developed. In particular, in automotive fuel cell systems, the outer periphery of the liner (inner container) is reinforced with a fiber reinforced plastic (Fiber Reinforced Plastics) layer (hereinafter referred to as a fiber reinforced resin layer) from the viewpoint of ensuring strength and reducing weight. The tank is considered promising. The high-pressure tank has a substantially cylindrical cylindrical portion and dome-shaped dome portions located on both sides of the cylindrical portion, and a base is connected to the opening of the dome portion.

  The high-pressure tank is manufactured using, for example, a filament winding method (hereinafter referred to as “FW method”). In the FW method, a resin-impregnated fiber impregnated with a thermosetting resin (hereinafter also simply referred to as “fiber”) is wound around a plurality of layers around a liner, and then heated to thermally cure the resin and a fiber-reinforced resin layer. Form.

  Since the high-pressure tank manufactured in this way is required to be strong enough to withstand a high filling pressure, particularly when mounted on a vehicle, it is necessary to accurately grasp whether or not the strength is ensured. Therefore, for example, Patent Document 1 below proposes a method of analyzing the strength of the high-pressure tank by obtaining the thickness and cross-sectional area of the fiber reinforced resin layer using a finite element method.

JP 2011-248394 A

  By the way, the Young's modulus may be obtained from the fiber deposition content as a physical property value of strength. However, in reality, the resin oozes out by winding the fiber bundle, and the actual fiber deposition content may be different from the design value (designed fiber deposition content). Then, physical property values such as Young's modulus are different from actual physical property values, and it is difficult to accurately grasp the strength of the manufactured high-pressure tank.

  This invention is made | formed in view of such a subject, The objective is providing the calculation method which can improve the calculation precision of the fiber deposition content rate of the fiber reinforced resin layer formed in the liner outer periphery. It is in.

  In order to solve the above problems, a method for calculating a fiber accumulation content in a high-pressure tank according to the present invention includes a liner having spherical dome portions on both sides of a cylindrical cylinder portion, and a fiber wound around the outer periphery of the liner. And a fiber-reinforced resin layer formed in a high-pressure tank, wherein the fiber deposition content rate in the high-pressure tank is a predetermined distance in the radial direction from the central axis of the high-pressure tank among the fiber-reinforced resin layer in the dome portion Calculating the amount of fiber used by multiplying the theoretical cross-sectional area of the fiber reinforced resin layer from the first point to the second point and the preset design value of the fiber accumulation content, from the first point, A step of measuring a cross-sectional area of the fiber reinforced resin layer up to the second point, and a step of dividing the amount of used fiber by the measured cross-sectional area to calculate a fiber deposition content.

  In the present invention, the calculation is performed based on the actually measured cross-sectional area (the cross-sectional area of the fiber reinforced resin layer from the first point to the second point spaced apart from the central axis of the high-pressure tank by a predetermined length in the radial direction). The actual fiber deposition content can be calculated. By calculating the Young's modulus using the fiber deposition content calculated in this way, the strength property value can be accurately obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the calculation method which can improve the calculation precision of the fiber deposition content rate of the fiber reinforced resin layer formed in the liner outer periphery can be provided.

It is sectional drawing which shows schematic structure of a high pressure tank. It is process drawing which shows the calculation method of the fiber accumulation content of the high pressure tank in this embodiment. It is explanatory drawing for comparing the thickness of the fiber reinforced resin layer in a dome part. It is explanatory drawing explaining the mode of calculation of the element thickness of the dome part by the existing technique.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. It should be noted that the following description of the preferred embodiment is merely an example, and is not intended to limit the present invention, its application, or its use.

  First, the configuration of the high-pressure tank will be described. FIG. 1 is a cross-sectional view showing a schematic configuration of a high-pressure tank.

  As shown in FIG. 1, the high-pressure tank 10 includes a liner 40, a fiber reinforced resin layer 50 that covers the surface of the liner 40, and two base parts 14. Note that the high-pressure tank 10 may be configured to include only one of the two cap portions 14.

  The high-pressure tank 10 includes a substantially cylindrical cylindrical portion 20 and dome-shaped dome portions 30 located on both sides of the cylindrical portion 20. The dome portion 30 is reduced in diameter with increasing distance from the cylindrical portion 20 in the tank central axis AX direction of the cylindrical portion 20. The portion with the smallest diameter is opened, and the base portion 14 is inserted into the opening.

  The liner 40 is a portion also referred to as an inner shell or an inner container of the high-pressure tank 10, and has a space 25 for storing a fluid therein. The liner 40 suppresses permeation of gas such as hydrogen gas to the outside. The material of the liner 40 is not particularly limited. For example, a synthetic resin such as a nylon resin or a polyethylene resin is used.

  The fiber reinforced resin layer 50 is formed by winding fibers around the surface of the liner 40 by a filament winding method (hereinafter also referred to as “FW method”), and has a configuration in which a plurality of fibers are laminated. The FW method is a method in which reinforcing fibers impregnated with a thermosetting resin are wound around a liner 40 to thermoset the thermosetting resin. For example, an epoxy resin is used as the thermosetting resin.

  By the way, it is normal that the thickness of the fiber reinforced resin layer increases around the base portion of the dome portion, and a theoretical formula for modeling this thickness is known. FIG. 4 is a diagram for explaining the calculation (theoretical formula) of the thickness of the fiber reinforced resin layer 50 in the dome portion in the existing technology.

  As shown in FIG. 4, when assuming a bundle of fibers in which fibers are wound around the outer periphery of the liner, the amount of fibers in the bundle of fibers is the same in the cylinder portion and the dome portion. However, the fiber wrapping angle is that the cylinder part is hoop-wound and the dome part is helically wound (especially low-angle helical winding near the caps at both ends of the tank), so the fiber angle α0 of the cylinder part and the dome part Is different from the fiber angle α. When the area of one fiber bundle when the fiber bundle is cut at right angles to the fiber, that is, at a fiber angle of 0 °, is S, the fiber layer thickness h0 of the fiber bundle in the cylinder portion having the radius R0 from the tank center axis AX The following relational expression is established between the tank center axis AX and the fiber layer thickness hx of one bundle of fibers in the dome portion having the radius Rx by using the area S and the respective fiber angles α0 and α and the radii R0 and Rx. It is known to do.

  Formula 1 shows the ratio of the layer thickness of one bundle of fibers in the cylinder portion and the dome portion shown in FIG. 4, and from Formula 2, the fiber layer of one bundle of fibers in the dome portion having a radius Rx from the tank center axis AX. The thickness hx is calculated. That is, the “theoretical cross-sectional area (theoretical thickness)” in the present specification can be calculated based on Formula 1 and Formula 2.

  As shown in Equations 1 and 2, a theoretical equation for calculating the fiber layer thickness hx (hereinafter also referred to as layer thickness) of one bundle of fibers in the dome is known. Ooze out and the layer thickness deviates from the theoretical value calculated by Equation 1 and Equation 2. The deviation between the theoretical fiber layer thickness hx and the layer thickness of an actual high-pressure tank (hereinafter referred to as an actual tank) is indicated by the symbol G in the graph shown in FIG. It is represented by Thus, the layer thickness around the base portion 14 in the dome portion 30 is the theoretical value (the layer thickness of “theoretical” shown in FIG. 3) and the actual tank (the layer thickness of the “actual tank” shown in FIG. 3). And a shift occurs.

  When the deviation occurs as described above, the fiber accumulation content of the actual tank may be different from the initial fiber accumulation content (design value of the fiber accumulation content). If it does so, the calculation precision of the Young's modulus calculated using fiber accumulation content will fall.

Therefore, in the present embodiment, the calculation accuracy of the Young's modulus is improved by calculating the actual fiber deposition content V _{f (for calculation)} and calculating the Young's modulus based on this V _{f (for calculation)} . . A method _{for calculating the} fiber deposition content V _{f (for calculation)} will be described in detail below.

  FIG. 2 is a process diagram showing a calculation process of the fiber accumulation content of the high-pressure tank in the present embodiment. FIG. 3A is an enlarged cross-sectional view showing the configuration around the base portion of the dome portion shown in FIG. FIG. 3B is a graph showing the theoretical value of the layer thickness of the fiber reinforced resin layer, and FIG. 3C is a graph showing the measured value of the layer thickness of the fiber reinforced resin layer. The horizontal axis of FIG. 3 (B) and FIG. 3 (C) shows a radial position (refer FIG. 3 (A)), and the vertical axis | shaft of FIG. 3 (B) and FIG. 3 (C) is a fiber reinforced resin layer. The layer thickness (see FIG. 3A) is shown.

(Step S10)
First, as shown in FIG. 2 and FIG. 3 (B), the fiber reinforced resin from the first point to the second point that is separated from the tank center axis AX in the radial direction by a predetermined length in the fiber reinforced resin layer 50 in the dome portion 30. The amount of fiber used is calculated by multiplying the theoretical cross-sectional area of the layer 50 (the area of the hatched portion shown in FIG. 3B) by the preset design value V _{f (for design) of} the fiber accumulation content _(use) Fiber amount calculation step).

(Step S20)
Next, as shown in FIG. 2 and FIG. 3 (C), the same range as the range used when the theoretical cross-sectional area was calculated in step S10 in the actual tank (the center of the tank in the fiber reinforced resin layer 50 in the dome portion 30). The cross-sectional area (area of the hatched portion shown in FIG. 3C) of the fiber reinforced resin layer 50 is measured (from the first point to the second point spaced apart from the axis AX by a predetermined length in the radial direction) (cross-sectional area measuring step). .

(Step S30)
Next, as shown in FIG. 2, the fiber accumulation content V _{f (for calculation)} is calculated by dividing the used fiber amount calculated in step S10 by the cross-sectional area measured in step S20 (fiber accumulation content calculation). Process).

The Young's modulus is calculated using the fiber deposition content calculated through steps S10 to S30 shown in FIG. The calculation method of Young's modulus is described in the following formula.
1 / E _T = V _{f (for calculation)} / E _f + (1−V _{f (for calculation)} ) / E _m
V _f : Fiber deposition content ratio E _T : Young's modulus in the thickness direction E _f : Young modulus of fiber simple substance E _m : Young modulus of single resin

In order to verify the calculation accuracy of the fiber deposition content according to this embodiment described above, the Young's modulus calculation result using the conventional method and the Young's modulus calculation result using the calculation method of the present embodiment (hereinafter, this calculation method) The experiment which compares was conducted. As experimental conditions, the design value V _{f (for design)} of the fiber accumulation content is 0.67, the Young's modulus E _{f of the} fiber is 260 [GPa], the Young's modulus of the resin is E _m = 2 [GPa], and the theoretical cross section And the ratio of the cross-sectional area of the actual tank to 1 / 0.95.

The thickness direction Young's modulus E _T in this calculation method was calculated by the following procedures (1-1) to (1-3).
(1-1) Calculate the amount of fiber used from the theoretical cross-sectional area and the design value (V _{f (for design)} ) of the fiber accumulation content.
(Amount of fiber used) = 1 x 0.67 = 0.67
(1-2) The actual fiber accumulation content V _{f (for calculation)} is calculated from the amount of fiber used and the cross-sectional area of the actual tank.
V _{f (for calculation)} = 0.67 / 0.95 = 0.705
(1-3) The Young's modulus is calculated using the _calculated fiber deposition content V _{f (for calculation)} .
1 / E _T = V _{f (for design)} / E _f + (1−V _{f (for design)} ) / E _m = 0.705 / 260 + (1-0.705) / 2
E _T = 6.66 [GPa] (Calculation result (1))

As a comparative example, the Young's modulus E _T in the thickness direction according to the conventional method was calculated by the following procedures (2-1) and (2-2).
(2-1) Design value V _f of fiber accumulation content _{(for design)} Calculate thickness direction Young's modulus E _T at 67%.
1 / E _T = V _{f (for design)} / E _f + (1-V _{f (for design)} ) / E _m = 0.67 / 260 + (1-0.67) / 2
E _T = 5.97 [GPa]
(2-2) The calculated Young's modulus is corrected by multiplying the ratio of the theoretical cross section and the actual tank cross section.
E _T = 5.97 x 1 / 0.95 = 6.28 [GPa] (Calculation result (2))

As shown in the calculation results (1) and (2), an error of 6% occurred between the Young's modulus value calculated by this calculation method and the Young's modulus value calculated by the conventional method. As described above, this error is caused by the fact that the resin leaks out due to the influence of the manufacturing in the actual tank, and the deviation of the layer thickness (see the symbol G shown in FIG. 3) occurs. In the present embodiment, the calculation is performed based on the actually measured cross-sectional area (the cross-sectional area of the fiber reinforced resin layer 50 from the first point to the second point spaced apart from the tank center axis AX by a predetermined length in the radial direction). Therefore, the actual fiber deposition content V _{f (for calculation)} can be calculated. By calculating the Young's modulus using the fiber deposition content V _{f (for calculation)} calculated in this way, the strength property value can be obtained accurately.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention.

10: High-pressure tank 14: Base part 20: Cylindrical part (cylinder part)
25: Space part 30: Dome part 40: Liner 50: Fiber reinforced resin layer E _f : Fiber simplex Young's modulus E _m : Resin simplex Young's modulus E _T : Thickness direction Young's modulus G: Deviation

Claims (1)

Method for calculating fiber deposition content in a high-pressure tank comprising: a liner having spherical dome portions on both sides of a cylindrical cylinder portion; and a fiber reinforced resin layer formed by winding fibers on the outer periphery of the liner Because
The theoretical cross-sectional area of the fiber reinforced resin layer from the first point to the second point that is spaced apart from the central axis of the high-pressure tank by a predetermined length in the fiber reinforced resin layer in the dome part, and a preset fiber deposition content Multiplying the design value of the rate to calculate the amount of fiber used,
Measuring the cross-sectional area of the fiber reinforced resin layer from the first point to the second point;
Dividing the used fiber amount by the measured cross-sectional area to calculate a fiber deposition content,
Calculation method of fiber accumulation content in high-pressure tank.