Design Method for Reducing the Circumferential Winding of the Transition Section of Type Ⅳ Hydrogen Storage Bottles

Abstract

The present invention provides a design method for circumferential winding reduction of the transition section of a type-IV hydrogen storage bottle, belonging to the technical field of composite material forming design. By optimizing the liner structure and designing the reduction amount at both ends of the circumferential winding layer, an arc-shaped reduction structure is formed in the circumferential winding layer at the transition section. This method can avoid fiber slippage of the circumferential layer and strengthen the stress distribution of the winding layer at the transition section. According to the verification results, this circumferential winding reduction design method can improve the fiber stress distribution at the transition section. The arc-shaped reduction structure at the transition section can strengthen the fiber stress at the transition section under the action of lamination, further improving the load-bearing capacity of the type-IV hydrogen storage bottle.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material forming design, and specifically discloses a method for reducing the circumferential winding of the transition section of a type-IV hydrogen storage cylinder. Background Art

[0002] With the increasing shortage of oil resources and the global climate problems caused by carbon emissions, hydrogen energy has become a popular research and application object in the field of secondary energy due to its advantages such as rich resources, high calorific value, cleanliness, and renewability. Various countries have successively introduced hydrogen energy development policies, proposing to actively develop hydrogen energy, and the breakthrough of hydrogen storage technology is the key to breaking through the application limitations of hydrogen energy.

[0003] At present, high-pressure gaseous hydrogen storage technology is a technology for storing hydrogen in a high-pressure form, usually in the pressure range of 20 to 70 MPa. The type-IV high-pressure hydrogen storage cylinder is an important carrier of high-pressure gaseous hydrogen storage technology, and it performs excellently in hydrogen energy storage and transportation due to its characteristics of light weight, high strength, high hydrogen storage density, and avoidance of hydrogen embrittlement. The winding layer of the type-IV high-pressure hydrogen storage cylinder is formed by a "circumferential + helical" winding method, and the main bearing pressure is borne by the winding layer. The plastic inner liner mainly plays a role in isolating hydrogen, and the structural shape of the inner liner determines the contour structure of the winding layer. Therefore, the design of the inner liner structure and the winding layer is an important factor affecting the bearing capacity of the container.

[0004] The plastic inner liner material is a high molecular polymer, and the forming process is mainly injection molding, rotational molding, and blow molding. It can achieve precise forming by relying on the constraint of the inner wall of the mold, which provides a large design space for the inner liner structure. Through the grid theory, the thickness and number of layers of the helical winding layer and the circumferential winding layer can be determined for the fiber winding layer. The number of fiber layers is large and the angle changes are diverse. The design optimization of the winding layer mainly focuses on the optimization of the winding angle and ply sequence of the helical winding layer, without considering the design of the circumferential winding layer. However, in the actual winding process, due to the stacking of the circumferential winding layer in the barrel section, the shoulder of the transition section between the barrel section and the head section presents an angular state, as Figure 7 shown, which causes fiber slippage during the winding process and at the same time causes local stress concentration, seriously affecting the service life. Summary of the Invention

[0005] The present invention provides a method for reducing the circumferential winding of the transition section of a type-IV hydrogen storage cylinder. By optimizing the inner liner structure and designing the reduction amount at both ends of the circumferential winding layer, an arc-shaped reduction structure is formed in the transition section of the circumferential winding layer. This method can avoid fiber slippage of the circumferential layer and at the same time strengthen the stress distribution of the winding layer in the transition section.

[0006] The method for reducing the circumferential winding of the transition section of a type-IV hydrogen storage cylinder provided by the present invention includes the following steps:

[0007] S1. Calculate the thickness and number of layers of the winding layer of the cylinder section of the type-IV hydrogen storage cylinder:

[0008] The winding layer of the cylinder section includes a helical winding layer of the cylinder section and a circumferential winding layer of the cylinder section. Each helical winding layer of the cylinder section includes a preset number of layers of helical single-layer fibers, and each circumferential winding layer of the cylinder section includes a preset number of layers of circumferential single-layer fibers;

[0009] S2. Determine the laying scheme of the winding layer of the type-IV hydrogen storage cylinder;

[0010] S3. According to the laying scheme determined in step S2, calculate the thickness from the first winding layer to the last circumferential winding layer f ;

[0011] S4. Optimize the inner liner head curve:

[0012] Taking the center of the interface between the inner liner head section and the inner liner cylinder section as the origin, and taking the axis of rotation of the inner liner as the x axis, and taking the dividing line between the inner liner head section and the inner liner cylinder section as the y axis to establish a coordinate system, the design equation of the inner liner head curve is expressed as:

[0013] (6);

[0014] a ≠ b When the inner liner head curve is an ellipse, a represents the length of the minor semi-axis of the ellipse, b represents the length of the major semi-axis of the ellipse;

[0015] a = b When the inner liner head curve is a circle, a and b represent the radius of the circle;

[0016] Substitute b in the design equation of the inner liner head curve with b + f to obtain the optimized equation of the inner liner head curve:

[0017] (7);

[0018] Realize the flattening of the inner liner head curve;

[0019] Substitute y in formula (7) and take b , calculate to obtain x which is the increased value of the unilateral length of the optimized inner liner cylinder section m ;

[0020] Keep the inner surface of the inner liner and the diameter of the cylindrical section of the inner liner unchanged, and translate the intersection point of the outer wall of the head section of the inner liner and the outer wall of the cylindrical section of the inner liner towards the head section of the inner liner. m , to obtain the optimized inner liner;

[0021] S5. Calculate the reduction amount at the end of the circumferential winding layer of the i -th layer of the cylindrical section :

[0022] The intersection point of the optimized inner liner head curve and the outer wall of the optimized inner liner head section is denoted as point A, and the intersection point of the optimized inner liner head curve and the y axis is denoted as point C. The arc between point A and point C on the optimized inner liner head curve is denoted as arc AC. Arrange the end of the circumferential winding layer of the cylindrical section along arc AC so that after lamination, the end of the circumferential winding layer of the cylindrical section can achieve a smooth transition with the optimized inner liner head curve;

[0023] = The length of the circumferential winding layer of the i- -th layer of the cylindrical section within arc AC - the length of the circumferential winding layer of the i -th layer of the cylindrical section within arc AC;

[0024] S6. Calculate the landing points of the circumferential winding layer of the i -th layer of the cylindrical section on both sides of the optimized inner liner cylindrical section as and , satisfying the following formula:

[0025] = - (10);

[0026] Calculated according to the ply laying scheme determined in step S2;

[0027] Finally, the end of the circumferential winding layer of the cylindrical section forms an arc-shaped reduction structure in the transition section.

[0028] In step S1, the thickness of the helical winding layer of the cylindrical section and the number of single-layer fiber ply lays M , the thickness of the circumferential winding layer of the cylindrical section and the number of single-layer fiber ply lays N are calculated by the following formulas:

[0029] (2);

[0030] (3);

[0031] (4);

[0032] (5);

[0033] Wherein, R is the outer diameter of the inner liner cylinder section; is the minimum design burst pressure; is the initial winding angle of the cylinder section; is the ultimate tensile strength of the fiber; K The value range is 0.65 - 0.8. Each layer of helical single fiber includes two layers of single fibers, and each layer of circumferential single fiber includes one layer of single fiber. The thickness of the single fiber is obtained through actual measurement.

[0034] The initial winding angle of the cylinder section is calculated by the following formula:

[0035] (1);

[0036] Wherein, r 0 is the polar hole radius.

[0037] In step S2, the laying sequence is determined by empirical design or laying optimization method.

[0038] In step S2, the laying sequence is spiral - ring alternating winding.

[0039] In step S4, a coordinate system is established in the CAD software.

[0040] In step S5, connect point A and point C to make a straight line AC, take the mid - point B of the straight line AC, make the perpendicular bisector of the straight line AC intersect with the y axis, take the intersection point as the center of the circle, and draw a circle passing through point A and point C to obtain a fitting circle. The radius of the fitting circle is r , r obtained by measurement. The vertical distance between the center of the circle and the outer wall of the inner liner cylinder section is n , m , n , r satisfies the following formula:

[0041] (8);

[0042] Wherein, m represents the increased value of the unilateral length of the optimized inner liner cylinder section;

[0043] Taking the fitting circle to replace the optimized inner liner head curve, the reduction amount is calculated by the following formula:

[0044] (9.1);

[0045] (9.2);

[0046] (9.3);

[0047] …

[0048] (9. i )

[0049] Wherein, represents the thickness difference between the circumferential winding layer of the i th layer of the cylinder section and the circumferential winding layer of the i- 1st layer of the cylinder section, and is calculated according to the laying scheme determined in step S2.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] By combining the calculation of the winding layer to optimize the curve of the inner liner head, and further designing the reduction amount of the circumferential winding layer, the present invention makes the end position of the circumferential winding layer form the shape of the inner liner head, improves the stress distribution in the transition region of the type-IV hydrogen storage cylinder, avoids stress concentration in the transition section region, avoids the fiber slipping phenomenon during circumferential winding, strengthens the strength of the winding layer in the transition region. At the same time, the reduction of the circumferential winding layer can also reduce the fiber consumption, reduce the cost while ensuring the strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0053] Figure 1 is a flowchart of the design method for reducing the circumferential winding of the transition section of the type-IV hydrogen storage cylinder;

[0054] Figure 2 is a schematic diagram before optimizing the curve of the inner liner head;

[0055] Figure 3 is a schematic diagram after optimizing the curve of the inner liner head;

[0056] Figure 4 is a schematic diagram of replacing the arc AC with a fitted circle;

[0057] Figure 5 is a schematic diagram of the reduction at the end of the circumferential winding layer of the cylinder section;

[0058] Figure 6 is the landing point of the circumferential winding layer of the cylinder section on one side of the optimized inner liner cylinder section;

[0059] Figure 7 Schematic diagram of a type-IV hydrogen storage bottle designed by traditional methods;

[0060] Figure 8 Schematic diagram of a type-IV hydrogen storage bottle designed by this method;

[0061] Figure 9 Schematic diagram of the comparison of fiber stress distributions between a type-IV hydrogen storage bottle designed by traditional methods and a type-IV hydrogen storage bottle designed by this method under the minimum design burst pressure;

[0062] Figure 10 Schematic diagram of the comparison of the outermost fiber stress between a type-IV hydrogen storage bottle designed by traditional methods and a type-IV hydrogen storage bottle designed by this method under the minimum design burst pressure.

[0063] In the figure: 1 - metal boss structure; 2.1 - inner liner before optimization; 2.2 - inner liner after optimization; 3 - helical winding layer of the cylinder section; 4 - circumferential winding layer of the cylinder section. Specific implementation manners

[0064] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0065] Embodiment 1

[0066] This embodiment provides a method for reducing the circumferential winding of the transition section of a type-IV hydrogen storage bottle, including the following steps.

[0067] S1. Calculate the thickness and number of plies of the winding layer of the cylinder section of the type-IV hydrogen storage bottle:

[0068] The winding layer of the cylinder section includes the helical winding layer 3 of the cylinder section and the circumferential winding layer 4 of the cylinder section. Each helical winding layer 3 of the cylinder section includes a preset number of layers of helical single-layer fibers, and each circumferential winding layer 4 of the cylinder section includes a preset number of layers of circumferential single-layer fibers.

[0069] First, calculate the initial winding angle of the cylinder section through Equation (1):

[0070] (1);

[0071] In the formula, r 0 is the radius of the polar hole, R is the outer diameter of the inner liner of the cylinder section.

[0072] The thickness of the helical winding layer 3 of the cylinder section and the number of plies of the helical single-layer fibersM 、The thickness of the circumferential winding layer 4 of the cylinder section and the number of circumferential single - layer fiber ply N are calculated by formulas (2) - (5):

[0073] (2);

[0074] (3);

[0075] (4);

[0076] (5);

[0077] In the formulas, is the minimum design burst pressure, is the initial winding angle of the cylinder section, is the ultimate tensile strength of the fiber, K The value range is 0.65 - 0.8. Each layer of helical single - layer fiber includes two layers of single - layer fiber, and each layer of circumferential single - layer fiber includes one layer of single - layer fiber. The thickness of the single - layer fiber is obtained through actual measurement.

[0078] S2. Determine the ply scheme of the winding layer of the type - IV hydrogen storage cylinder through empirical design or ply optimization method.

[0079] S3. According to the ply scheme determined in step S2, calculate the thickness from the first winding layer to the last circumferential winding layer f .

[0080] S4. Optimize the liner head curve:

[0081] In the CAD software, with the center of the interface between the liner head section and the liner cylinder section as the origin, and the axis of rotation of the liner as x the axis, and the dividing line between the liner head section and the liner cylinder section as y the axis, establish a coordinate system. The design equation of the liner head curve is expressed as:

[0082] (6);

[0083] a ≠ b When, the liner head curve is an ellipse, a represents the semi - minor axis length of the ellipse, b represents the semi - major axis length of the ellipse;

[0084] a = b When, the liner head curve is a circle, a and b represent the radius of the circle;

[0085] In the design equation of the inner liner head curve, b is replaced with b + f to obtain the optimized equation of the inner liner head curve:

[0086] (7);

[0087] To achieve the flattening of the inner liner head curve;

[0088] In formula (7), y Take b , and calculate to obtain x which is the increased value of the unilateral length of the inner liner cylinder section after optimization m ;

[0089] Keeping the inner surface of the inner liner and the diameter of the inner liner cylinder section unchanged, translate the intersection point of the outer wall of the inner liner head section and the outer wall of the inner liner cylinder section towards the inner liner head section by m to obtain the optimized inner liner 2.2.

[0090] S5. Calculate the reduction amount i at the end of the circumferential winding layer 4 of the th layer of the cylinder section:

[0091] The intersection point of the optimized inner liner head curve and the outer wall of the optimized inner liner head section is denoted as point A, and the intersection point of the optimized inner liner head curve and the y axis is denoted as point C. The arc between point A and point C on the optimized inner liner head curve is denoted as arc AC. Arrange the end of the circumferential winding layer 4 of the cylinder section along arc AC so that the end of the circumferential winding layer 4 of the cylinder section can achieve a smooth transition with the optimized inner liner head curve after lamination;

[0092] Reduction amount = The length of the circumferential winding layer 4 of the i- first layer of the cylinder section within arc AC - The length of the circumferential winding layer 4 of the i th layer of the cylinder section within arc AC.

[0093] Since the optimized inner liner head curve is an ellipse and the calculation is relatively complex, the arc AC is fitted into a circle by the following method to simplify the calculation process.

[0094] Connect point A and point C to make a straight line AC. Take the midpoint B of the straight line AC and make the perpendicular bisector of the straight line AC intersect with the y axis. With the intersection point as the center, draw a circle passing through point A and point C to obtain the fitted circle. The radius of the fitted circle is r , r Obtained by measurement, the vertical distance between the center of the circle and the outer wall of the inner liner cylinder section is n , m , n , r Satisfy the following formula:

[0095] (8);

[0096] Wherein, m represents the increased value of the unilateral length of the optimized inner liner barrel section;

[0097] Replace the arc AC with a fitting circle, and the reduction amount is calculated by the following formula:

[0098] (9.1);

[0099] (9.2);

[0100] (9.3);

[0101] …

[0102] (9. i );

[0103] Wherein, represents the i th layer of the circumferential winding layer 4 of the barrel section and the i- 1st layer of the circumferential winding layer 4 of the barrel section, and is calculated according to the laying scheme determined in step S2.

[0104] S6. Calculate the landing points of the i th layer of the circumferential winding layer 4 of the barrel section on both sides of the optimized inner liner barrel section as and , and satisfy the following formula:

[0105] = - (10);

[0106] Calculated according to the laying scheme determined in step S2;

[0107] Finally, the end of the circumferential winding layer 4 of the barrel section forms an arc-shaped reduction structure in the transition section, as shown in Figure 8 ;

[0108] Example 2

[0109] According to the pressure requirements and safety factor regulations for type-IV high-pressure hydrogen storage cylinders such as GB / T 42612, taking the 35MPa type-IV high-pressure hydrogen storage cylinder as an example, its minimum design burst pressure is equal to 2.3 times the working pressure, and the minimum design burst pressure is 80.5MPa. In this embodiment, the fiber stress distribution of the type-IV hydrogen storage cylinder under the minimum design burst pressure is calculated by combining finite element simulation and hydrostatic burst test.

[0110] S1. Calculate the thickness and number of layers of the winding layer of the barrel section of the 35MPa type-IV high-pressure hydrogen storage cylinder:

[0111] The outer diameter of the inner liner barrel section R is 158mm, and the polar hole radius r 0 is 27.5mm. Based on the grid theory, the initial winding angle is calculated by formula (1) .

[0112] The carbon fiber used in the 35MPa type-IV high-pressure hydrogen storage cylinder is T700, and the ultimate tensile strength of the fiber is 2600, the thickness of a single layer of fiber is 0.2mm, then the thickness of each layer of helical single-layer fiber is 0.4mm, and the thickness of each layer of circumferential single-layer fiber is 0.2mm. Under the minimum design burst pressure of 80.5MPa, the thickness of the helical winding layer 3 of the barrel section , the thickness of the circumferential winding layer 4 of the barrel section are calculated by formulas (2)-(5). The total thickness of the winding layer of the barrel section is 10.4mm, the number of layers of helical single-layer fiber paving is 12, and the number of layers of circumferential single-layer fiber paving is 28.

[0113] S2: Design the paving scheme by experience as spiral-ring alternating winding:

[0114] .

[0115] The helical winding angle of the barrel section is taken as 10°, and there are a total of six layers of helical winding layers 3 of the barrel section. Each layer of helical winding layer 3 of the barrel section includes two layers of helical single-layer fibers, with a thickness of 0.8mm.

[0116] The circumferential winding angle of the barrel section is taken as 90°, and there are a total of seven layers of circumferential winding layers 4 of the barrel section. Each layer of circumferential winding layer 4 of the barrel section includes four layers of circumferential single-layer fibers, with a thickness of 0.8mm.

[0117] Each fiber winding angle appears in pairs of positive and negative angles.

[0118] S3. According to the paving scheme determined in step S2, calculate the thickness from the first winding layer to the last circumferential winding layer .

[0119] S4. Optimize the inner liner head curve:

[0120] The design equation of the inner liner head curve is expressed as: ;

[0121] The optimized equation of the inner liner head curve is expressed as: ;

[0122] The increased value of the unilateral length of the inner liner cylinder section after optimization m = 25.31 mm.

[0123] S5. Calculate the reduction amount at the end of the circumferential winding layer 4 of the i th layer of the cylinder section :

[0124] Draw a fitted circle according to the CAD software to determine r = 41.26 mm, n = 31.65 mm; Calculate according to the laying scheme determined in step S2 to obtain = 0, = 1.6 mm, = 1.6 mm, = 1.6 mm, = 1.6 mm, = 1.6 mm, = 0.8 mm, .

[0125] S6. Calculate according to the above parameters and formulas, and the calculation results are shown in Table 1.

[0126] Table 1 The circumferential laying landing point positions

[0127]

[0128] Figure 9 is a schematic diagram of the comparison of the fiber stress distributions of the type-IV hydrogen storage cylinders designed by the traditional method and the type-IV hydrogen storage cylinders designed by this method under the minimum design burst pressure, where Figure 9 (a) represents the fiber stress distribution diagram of the type-IV hydrogen storage cylinder designed by the traditional method under the minimum design burst pressure, Figure 9 and (b) represents the fiber stress distribution diagram of the type-IV hydrogen storage cylinder designed by this method under the minimum design burst pressure. Figure 10 is a schematic diagram of the comparison of the outermost layer fiber stresses of the type-IV hydrogen storage cylinders designed by the traditional method and the type-IV hydrogen storage cylinders designed by this method under the minimum design burst pressure. It can be seen from the comparison that the fiber stress distribution in the transition section is improved, the outermost layer fiber stress is reduced by about 200 MPa, and the load-bearing capacity is greatly improved.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A circumferential winding reduction design method for the transition section of a type-IV hydrogen storage cylinder, characterized in that Including the following steps: S1. Calculate the thickness and number of layers of the winding layer of the cylinder section of the type-IV hydrogen storage cylinder: The winding layer of the cylinder section includes a helical winding layer of the cylinder section and a circumferential winding layer of the cylinder section. Each helical winding layer of the cylinder section includes a preset number of layers of helical single-layer fibers, and each circumferential winding layer of the cylinder section includes a preset number of layers of circumferential single-layer fibers; S2. Determine the laying scheme of the winding layer of the type-IV hydrogen storage cylinder; S3. Calculate the thickness from the first layer of winding to the last layer of circumferential winding according to the ply layup scheme determined in step S2 f ; S4. Optimize the curve of the inner liner head: Taking the center of the interface between the inner liner head section and the inner liner cylinder section as the origin, and taking the rotation axis of the inner liner as the x axis, and taking the demarcation line between the inner liner head section and the inner liner cylinder section as the y axis to establish a coordinate system, the design equation of the inner liner head curve is expressed as: （6）； a ≠ b When the inner liner head curve is an ellipse, a represents the length of the minor semi-axis of the ellipse, b represents the length of the major semi-axis of the ellipse; a = b When the inner liner head curve is a circle, a and b represents the radius of the circle; In the design equation of the inner liner head curve, b Use b + f to replace and obtain the optimized equation of the inner liner head curve: （7）； Realize the flattening of the curve of the inner liner head; Take y in formula (7) and calculate to obtain b , which is x the increased value of the unilateral length of the optimized inner liner barrel section m ; Keep the inner surface of the inner liner and the diameter of the cylindrical section of the inner liner unchanged, and translate the intersection point of the outer wall of the head section of the inner liner and the outer wall of the cylindrical section of the inner liner towards the head section of the inner liner m , to obtain an optimized inner liner; S5, calculate the reduction amount of the end position of the circumferential winding layer of the i cylindrical body section of the : The intersection point of the optimized inner liner head curve and the outer wall of the optimized inner liner head section is denoted as point A. The intersection point of the optimized inner liner head curve and the y axis is denoted as point C. The circular arc between point A and point C on the optimized inner liner head curve is denoted as arc AC. The end of the circumferential winding layer of the cylinder section is arranged along arc AC, so that after lamination, the end of the circumferential winding layer of the cylinder section can achieve a smooth transition with the optimized inner liner head curve; = The i- Length of the circumferential winding layer of the first-layer cylinder body section within the arc AC - The i Length of the circumferential winding layer of the cylinder body section within the arc AC; In step S5, connect point A and point C to form a straight line AC, take the midpoint B of the straight line AC, draw the perpendicular bisector of the straight line AC and intersect with the y axis, take the intersection point as the center of the circle, and draw a circle passing through point A and point C to obtain a fitting circle. The radius of the fitting circle is r , r obtained by measurement. The vertical distance from the center of the circle to the outer wall of the inner liner cylinder section is n , m , n , r satisfy the following formula: （8）； In the formula, m represents the increased value of the unilateral length of the optimized inner liner cylinder section; The reduction is calculated by replacing the optimized inner liner head curve with a fitted circle. It is calculated by the following formula: （9.1）； （9.2）； （9.3）； … （9. i ）； In the formula, represents the thickness difference between the circumferential winding layer of the i th layer of the cylinder body section and the circumferential winding layer of the i- 1st layer of the cylinder body section, which is calculated according to the ply layup scheme determined in step S2; S6, calculate the i landing points of the circumferential winding layer of the barrel section of the layer on both sides of the optimized inner barrel section are and, satisfying the following formula: = - （10）； Calculated according to the layup scheme determined in step S2; Finally, an arc-shaped reduction structure is formed at the end of the circumferential winding layer of the cylinder section in the transition section.

2. The circumferential winding reduction design method for the transition section of a type-IV hydrogen storage cylinder according to claim 1, wherein In step S1, the thickness of the helical winding layer of the cylinder body and the number of single-layer fiber laying of the helix M , the thickness of the circumferential winding layer of the cylinder body and the number of single-layer fiber laying of the circumference N are calculated by the following formula: （2）； （3）； （4）； （5）； In the formula, R is the outer diameter of the inner lining cylinder section, is the minimum design burst pressure, is the initial winding angle of the cylinder section, is the ultimate tensile strength of the fiber, K The value range is 0.65 - 0.

8. Each layer of helical single-layer fiber includes two layers of single-layer fiber, and each layer of circumferential single-layer fiber includes one layer of single-layer fiber. The thickness of the single-layer fiber is obtained through actual measurement.

3. The circumferential winding reduction design method for the transition section of the type-IV hydrogen storage cylinder according to claim 2, wherein The initial winding angle of the cylinder section is calculated by the following formula: （1）； In the formula, r 0 is the radius of the polar pore.

4. The circumferential winding reduction design method for the transition section of the type-IV hydrogen storage cylinder according to claim 1, wherein In step S2, the laying sequence is determined by empirical design or laying optimization method.

5. The circumferential winding reduction design method for the transition section of the type-IV hydrogen storage cylinder according to claim 4, wherein In step S2, the laying sequence is spiral-ring alternating winding.

6. The circumferential winding reduction design method for the transition section of the type-IV hydrogen storage cylinder according to claim 1, wherein, In step S4, a coordinate system is established in CAD software.

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