SUPPORTING POLE

Abstract

A supporting pole for supporting objects at an elevated position, such as a supporting pole for supporting cables, wires and/or electrical components. The supporting pole is formed of one or more fiber reinforced plastic resin laminates, wherein the one or more laminates comprise: a first ply, the first ply comprising unidirectional fibers, the unidirectional fibers having a first Young's modulus, and a second ply, the second ply comprising chopped fibers, the chopped fibers having a second Young's modulus; wherein the first Young's modulus is greater than the second Young's modulus, and wherein the unidirectional fibers in the laminate are at least 70 wt % of the fibers in the laminate.

Claims

1. A supporting pole for supporting an object at an elevated position, the supporting pole being formed of one or more fiber reinforced plastic resin laminates, wherein the one or more laminates comprise: a first ply, comprising unidirectional fibers, the unidirectional fibers having a first Young's modulus, and a second ply, comprising chopped fibers, the chopped fibers having a second Young's modulus; wherein the first Young's modulus is greater than the second Young's modulus, and wherein the unidirectional fibers in the laminate are at least 70 wt % of the fibers in the laminate.

2. The supporting pole of claim 1, wherein the first Young's modulus is in the range of 84 GPa to 100 GPa.

3. The supporting pole of claim 1, wherein the unidirectional fibers in the laminate are up to 90 wt % of the fibers in the laminate.

4. The supporting pole of claim 1, wherein the unidirectional fibers are substantially longitudinal along the supporting pole.

5. The supporting pole of claim 1, wherein a fiber content of each laminate is in the range of 45 wt % and 60 wt % of the laminate.

6. The supporting pole of claim 1, wherein the supporting pole has an aspect ratio of at least 10.

7. The supporting pole of claim 1, wherein the one or more fiber reinforced plastic resin laminates includes a first laminate and a second laminate; wherein the first laminate is arranged adjacent to the second laminate; and wherein the second ply of the first laminate is disposed between the first plies of the first and second laminates.

8. The supporting pole of claim 1, the wherein the one or more fiber reinforced plastic resin laminates includes a plurality of fiber reinforced plastic resin laminates, wherein a first fiber reinforced plastic resin laminate forms an outermost layer of the plurality of laminates and forms an outer surface of the supporting pole, and at least some of the other fiber reinforced plastic resin laminates are arranged to the interior of the first fiber reinforced plastic resin laminate, and at least some of the other fiber reinforced plastic resin laminates each extend along part of the length of the supporting pole.

9. The supporting pole of claim 1, wherein the unidirectional fibers comprise glass fibers.

10. The supporting pole of claim 1, wherein a plastic resin of the one or more fiber reinforced plastic resin laminates is a polyester resin.

11. A fiber reinforced plastic resin laminate comprising: a first ply, comprising unidirectional fibers, the unidirectional fibers having a first Young's modulus, and a second ply, comprising chopped fibers, the chopped fibers having a second Young's modulus; wherein the first Young's modulus is greater than the second Young's modulus, and wherein the unidirectional fibers in the laminate are at least 70 wt % of the fibers in the laminate.

12. A method of making a supporting pole formed of one or more fiber reinforced plastic resin laminates, wherein the one or more laminates comprise a first ply comprising unidirectional fibers, the unidirectional fibers having a first Young's modulus, and a second ply comprising chopped fibers, the chopped fibers having a second Young's modulus, wherein the first Young's modulus is greater than the second Young's modulus, and wherein the unidirectional fibers in the laminate are at least 70 wt % of the fibers in the laminate, the method comprising centrifugal casting the one or more laminates to form the supporting pole.

13. The method of claim 12, the method comprising centrifugal casting a first fiber reinforced plastic resin laminate, followed by centrifugal casting at least one further fiber reinforced plastic resin laminate inside the first fiber reinforced plastic resin laminate.

14. The method of claim 12, the method comprising heating a centrifugal casting mold to initiate thermosetting polymerization of a liquid resin precursor to form a plastic resin of the one or more fiber reinforced plastic resin laminates.

15. The method of claim 12, the method comprising centrifugal casting the first ply and the second ply of each of the one or more fiber reinforced plastic resin laminates separately.

16. (canceled)

17. The supporting pole of claim 1, wherein the second Young's modulus is in the range of 70 GPa to 83 GPa.

18. The supporting pole of claim 1, wherein the supporting pole is at least 5 meters long.

19. The supporting pole of claim 1, wherein the chopped fibers comprise glass fibers.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0074] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures.

[0075] FIG. 1 shows a supporting pole.

[0076] FIG. 2 shows an orientation of unidirectional fibers, relative to the supporting pole.

DETAILED DESCRIPTION OF THE FIGURES

[0077] FIG. 1 shows a supporting pole 2. The supporting pole 2 has a base 4 and a top 6. The base 4 has a diameter of 25 cm, and the top 6 has a diameter of 11.5 cm. The supporting pole 2 is eight meters tall, from the base to the top. The supporting pole 2 is buried in the ground 8 to a depth of 150 cm.

[0078] FIG. 2 shows part of a supporting pole 2. The supporting pole 2 has a longitudinal axis 5. The unidirectional fibers in the first ply of each laminate in the supporting pole 2 are aligned along line 7. The unidirectional fibers are aligned at an angle relative to the longitudinal axis 5 of the supporting pole 2. This angle is approximately 5 degrees. It will be understood that when the supporting pole is a tubular member, line 7 will actually form a helix of conical helix around the supporting pole.

Computational Modelling

[0079] Computational modelling was performed to optimise the design of the fiber reinforced plastic resin laminates which form the supporting pole.

[0080] Composite laminate theory (CLT) was used to predict the mechanical performances of the fiber reinforced plastic resin laminate comprising unidirectional fibers and chopped fibers. The mechanical description of the first ply comprising unidirectional fibers was done using micromechanical models available on Helius composite software, and the mechanical description of the second ply comprising chopped fibers (also called the chopped strand mat layer, or CSM) was done using a homogenization model.

[0081] The model of the fiber reinforced plastic resin laminate was built into Abaqus finite element analysis (FEA) solution. The FEA modeling inputs are set up in the following order. [0082] Define the geometry design [0083] Define the laminate properties [0084] Define the stacking sequence [0085] Number of laminates and their thickness [0086] Assignment of properties to each ply of the one or more laminates [0087] Choice of a discrete reference system giving the direction and the orientation of the fiber in the 3D pole structure [0088] Define the mesh [0089] Assign the loadings and boundary conditions.

[0090] For all modeling scenarios a fiber weight fraction of 53% is used.

Geometry Design

[0091] The geometry of the model supporting pole is created as a 3D shell surface model and the thickness will be set in the design phase of the laminate. The model supporting pole is a truncated cone, as shown in FIG. 1.

Definition of Laminate Properties

[0092] Two plies were separately defined, a first ply and a second ply. The first ply comprises unidirectional fibers which are aligned along the longitudinal axis of the supporting pole, and the second ply comprises fibers which are not parallel with the unidirectional fibers, such as chopped fibers or fibers orientated at +/?30?, +/?45? or 90? relative to the unidirectional fibers. For each ply, failure properties which were calculated using Helius were also implemented in the Abaqus FEA code. The properties of the plies are shown in Table 1. In the following table, 12, 13 and 23 relate to shearing modulus in planes defined by the 1, 2 and 3 direction. The 1 direction is parallel with the unidirectional fibers in the first ply. The 2 direction is the transverse direction perpendicular with the unidirectional fibers in the first ply (in laminate plane). The 3 direction is the transverse direction perpendicular with the unidirectional fibers in the first ply (through the thickness of the laminate). In the table below: 12 denotes the shearing modulus in 12 plane (12 is the plane of the laminate); 13 denotes the shearing modulus in 13 plane (13 is a plane orthogonal to the laminate plane); and 23 denotes the shearing modulus in 23 plane (23 is a plane orthogonal to the laminate plane).

TABLE-US-00001 TABLE 1 Longitudinal Transversal Young's Young's Shear Shear Shear modulus modulus Poisson's modulus modulus modulus (MPa) (MPa) Ratio 12 (MPa) 13 (MPa) 23 (MPa) Second ply 11769 15888 0.33333 4413 4413 4413 First ply 27587 6230 0.31 2130 2130 2044

3D Mesh Definition

[0093] To mesh the 3D shell geometry, 14546 quadratic shell elements (S4R) were used with an approximate element size of 20 mm. This allows a good compromise between high mesh refinement quality and computational time. To predict supporting pole deflection with high accuracy, both the 2nd order elements to prevent high mesh distortion and the hourglass control algorithm to better capture the flexural effects were used.

Loading and Boundary Conditions

[0094] A static analysis was used. The boundary conditions were defined by locking the bottom 150 cm of the supporting pole in place (to simulate the bottom 150 cm of the supporting pole being buried in the ground, as shown in FIG. 1) and applying a loading displacement of 2200 N at a reference point located 15 cm from the top of the supporting pole. The failure force and deflection were measured from the reference point.

[0095] Under this loading, the maximum deflection of the supporting pole must not exceed 650 mm. For a failure test, the ultimate force must be at least 3300 N.

Laminate Analysis Results

[0096] The fiber reinforced plastic resin laminates of the supporting pole are one of the key parameters influencing the mechanical performances of the supporting pole. Two kinds of fiber reinforced plastic resin laminates were considered, those comprising Advantex? fibers, and those comprising H glass and Advantex? fibers. The resin in all the laminates was polyester. The mechanical properties of the materials are given in Table 2.

TABLE-US-00002 TABLE 2 Tensile Modulus Strength Density Name E (GPa) ? ? (MPa) ? (g/cm.sup.3) Fibers Advantex? 82 0.3 4050 2.61 H glass 87.5 0.3 4635 2.59 Matrix Polyester 3.24 0.35 76 1.20

[0097] The flexural resistance of the supporting pole is mainly driven by the first ply comprising the unidirectional fibers. The flexural resistance is therefore mainly driven by the longitudinal modulus of the laminate along the fiber direction, denoted Ex. The buckling resistance is mainly driven by the presence of layers with off axis fibers (such as the second ply comprising chopped fibers, or plys comprising+/?30?, +/?45? or 90? fibers, relative to the unidirectional fibers) and therefore by a combination of the transverse modulus, Ey, and Ex components. It is necessary to find a good compromise between Ex values and Ey values that allow for a supporting pole with the necessary specifications.

[0098] Laminate properties (Ex and Ey) of different laminates are given in Table 3. The results showed that a fabric configuration with a 0? layer (a first ply comprising unidirectional fibers) associated with a second ply with chopped fibers presents the best mechanical performance because of the compromise between deflection and buckling resistances. It offers a high value of Ex (defection resistance) and Ey (buckling resistance). Furthermore, the introduction of H glass as the unidirectional fibers allows additional improvement, mainly in the Ex component, for a better flexural resistance.

TABLE-US-00003 TABLE 3 Prior art Example 1 Example 2 Example 3 Example 4 Example 5 [0?/chopped] [0?/chopped] [0?/90?] [0?/+?45?] [0?/+?30?] Fiber Advantex? 0? = H glass H glass H glass H glass Chopped = Advantex? Ex (GPa) 22 26.37 27.57 25.21 25.25 27.78 Ey (GPa) 12.55 12.60 14.79 8.53 7.36 ?x (MPa) 400 580 590

[0099] Supporting poles made from laminates with 0? fibers (unidirectional fibers) and chopped fibers were analysed with FEA. As described above, the FEA model predicts both deflection and failure force. The FEA analysis was used to determine reduced fabric grammage that still meet the performance requirements (ultimate failure force of 3300 N, and less than 650 mm deflection when the supporting pole is subjected to a force of 2200 N 15 cm from the top of the supporting pole). In the FEA analysis, the fiber content of the first ply was fixed at 16.45 kg. The results of the FEA analysis are shown in Table 4.

TABLE-US-00004 TABLE 4 Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 First ply fibers (0?/unidirectional) Advantex? H glass Second ply fibers (chopped) Advantex? Advantex? First ply (0? fibers) grammage (g/m.sup.2) 720 720 Second ply (chopped fibers) grammage 300 249 198 147 300 249 198 147 (g/m.sup.2) Supporting pole weight (kg) 40.7 38.7 36.7 34.6 40.7 38.7 36.7 34.6 Supporting pole weight reduction 0% 5% 10% 15% 0% 5% 10% 15% (relative to weight of Example 1) Deflection under 2200 N (mm) 580 609 642 679 553 582 614 649 Failure force criterion (N) 6321 5670 5044 4473 6422 5752 5130 4551 Cost saving (relative to Ex 1) 0% ?5% ?10% ?15% +4% ?1% ?6% ?11%

[0100] Examples 1?4 use Advantex? fibers in the first ply and the second ply. Examples 2 and 3 both offer a reduction in material cost (relative to Example 1) whilst passing the supporting pole requirements. Example 4 offers greater material cost reduction, but fails the deflection test.

[0101] Examples 5-8 use H glass in the first ply and Advantex? in the second ply. Using H glass in the first ply improves the mechanical performance of the supporting poles (deflection and failure force). This is due to the higher Young's modulus and failure strength of the laminate along the 0? fiber direction. Using H glass in the first ply instead of Advantex? decreases the deflection by 4.7%, from 580 mm in Example 1 to 553 mm in Example 5. Example 8 has a 15% reduction in the total laminate grammage (first ply and second ply) relative to Example 1, but still achieves a deflection value of 649 mm and a failure force of 4551 N, which meet the requirements for the mechanical properties. Example 8 offers an 11% material cost reduction (compared to Example 1) and presents much better mechanical performance comparing to Example 4, which used Advantex? for the first ply and has an equivalent total laminate grammage. Example 8 is the lightest and cheapest supporting pole which meets the required mechanical properties, but it has a deflection value close to the maximum allowed for a supporting pole. Example 7 offers a 6% reduction in material cost, and easily meets the mechanical properties required of the supporting pole. A supporting pole comprising H glass in the first ply, with a second ply fabric grammage between that of Example 7 (198 g/m.sup.2) and Example 8 (147 g/m.sup.2) may provide the highest cost reduction whilst maintaining a margin for error in the mechanical properties.

[0102] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0103] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0104] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0105] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0106] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word comprise and include, and variations such as comprises, comprising, and including will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0107] It must be noted that, as used in the specification and the appended claims, the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent about, it will be understood that the particular value forms another embodiment. The term about in relation to a numerical value is optional and means for example +/?10%.