GB2598094A

GB2598094A - Drive shaft

Info

Publication number: GB2598094A
Application number: GB2012416.0A
Authority: GB
Inventors: Dewhirst Michael; Lewis Paul
Original assignee: Lentus Composites Ltd
Current assignee: Lentus Composites Ltd
Priority date: 2020-08-10
Filing date: 2020-08-10
Publication date: 2022-02-23
Also published as: GB202012416D0

Abstract

A drive shaft comprises a tubular member of multi-layered filament wound composite material form, wherein the reinforcing fibre 10 of the composite material within at least one layer thereof is wound at a varying winding angle. Preferably, the angle varies from a fixed notional winding angle by less than ±5°, such as ±2°; the winding angle varying in a continuous sinuous, wavy manner of fixed length or frequency 18. A method of manufacture of a drive shaft comprising winding fibres at a varying winding angle is also provided. The incorporation of viscoelastic elements within a drive shaft is also described. Such arrangements may be of enhanced vibrational damping characteristics.

Description

DRIVE SHAFT

This invention relates to a drive shaft, and in particular to a drive shaft of a composite material.

The use of composite materials in the fabrication of drive shafts is increasingly common, the composite materials allowing weight savings to be made whilst maintaining desired levels of strength and stiffness, and so enabling low weight drive shafts of good torque transmitting capability to be produced. Increasingly, such drive shafts are being used in high speed applications, and it has been found that in such applications, the drive shafts may be subject to harsh vibrational loadings, in use. This is also true where traditional materials are used.

Composite materials are usually inherently of better damping properties than traditional materials, in part due to the use of viscoelastic resin materials in the manufacture thereof, but the levels of vibrations that are experienced, especially in high speed applications, are such that it is desirable for the drive shaft to be manufactured in such a manner as to have enhanced vibrational damping properties.

It is an object of the invention, therefore, to provide a drive shaft of a composite material and which is of enhanced damping properties.

According to a first aspect of the invention there is provided a drive shaft comprising a tubular member of multi-layered filament wound composite material form, wherein the reinforcing fibre of the composite material within at least one layer thereof is wound at a varying winding angle.

Such an arrangement has been found to be advantageous, compared to arrangements in which the winding angle at which the reinforcing fibre is wound is fixed, in that the resulting drive shaft is of enhanced damping capability, and so is better suited for use in high speed applications in which significant levels of vibrations are experienced, the drive shaft being better able to damp such vibrations.

Preferably, the varying winding angle varies from a fixed notional winding angle by less than ±5°. More preferably, the varying winding angle varies from a fixed notional winding angle by less than ±2°. It conveniently varies in a continuous manner, for example in a sinuous, wavy manner, preferably of fixed wavelength or frequency.

It will be appreciated that the reinforcing fibre thus extends along a sinuous, wavy path and so is not wound in a truly helical manner, rather than a straight path and in a truly helical manner.

As winding of the reinforcing fibre in this manner may negatively impact upon at least certain of the mechanical properties of the drive shaft, where the drive shaft is of multi-layered form, the varying winding angle may be employed in a subset of the layers rather than in all of the layers. As a consequence, the enhanced damping benefits may be achieved without impacting upon the other mechanical properties of the drive shaft to an unacceptable degree.

The invention also relates to a method of manufacture of a drive shaft comprising winding a reinforcing fibre onto a mandrel, wherein the reinforcing fibre of the composite material is wound at a varying winding angle, and curing or allowing to cure a resin material incorporated in or applied to the reinforcing fibre.

Preferably, the varying winding angle varies from a fixed notional winding angle by less than ±5°. More preferably, the varying winding angle varies from a fixed notional winding angle by less than ±2°.

According to another aspect of the invention there is provided a drive shaft comprising a tubular member of multi-layered filament wound composite material form, wherein at least one element of a viscoelastic material is sandwiched between at least two of the layers of the reinforcing fibre of the composite material.

By incorporating at least one viscoelastic element sandwiched between layers of the reinforcing fibre, it has been found that the damping properties of the drive shaft are enhanced.

Preferably, a plurality of viscoelastic elements are provided, spaced apart with one another in the axial direction of the drive shaft. By way of example, five or more such elements may be provided, spaced apart from one another, adjacent an end of the drive shaft. A further series of such elements may be provided adjacent an opposite end of the drive shaft. Additional elements may be provided, sandwiched between a different adjacent pair of the layers. The additional elements may be axially positioned between the first mentioned ones of the elements. Further elements may be provided, sandwiched between a different adjacent pair of the layers and axially aligned with the first mentioned ones of the elements.

Conveniently, the elements are located adjacent low-angle wound fibre layers.

At least one of the fibre layers may be wound with a varying winding angle as outlined hereinbef ore.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic illustration of part of a drive shaft in accordance with an embodiment of the invention; Figure 2 is a diagrammatic view illustrative of the invention; Figures 3 to 6 are views of further embodiments of the invention; and Figure 7 is a graph illustrating the enhanced damping achieved with the embodiments of Figures 3 to 6.

Referring firstly to Figures 1 and 2, one embodiment of the invention takes the form of a drive shaft of filament wound composite material form. The drive shaft is fabricated by winding a reinforcing fibre 10, for example of carbon fibre form, in a generally helical pattern upon a mandrel 12. The fibre 10 is wound in a series of layers, and within each layer, the winding angle is substantially uniform. However, whereas traditionally the winding angle would be truly uniform throughout each layer, for example at an angle of 45° for a torque transmitting drive shaft, and so the fibre 10 would follow a truly helical path represented by the straight line 16 in Figure 2, in accordance with the invention the winding angle is varied continuously by an angle of less than ±5°, and preferably by less than ±2°, during winding, with the result that the fibre 10 does not follow a truly helical path, but rather deviates therefrom in a sinuous, wavy or cyclical manner, as denoted by the line 18 in Figure 2. The variation is preferably of fixed wavelength or frequency, and of fixed amplitude.

The reinforcing fibre 10 may be of pre-impregnated form, containing a quantity of a resin material. Alternatively, it may be passed through a resin containing bath before winding, or resin may be impregnated into the fibre assembly once wound. After curing or allowing the resin to cure, it will be appreciated that a rigid tubular body of a composite material, reinforced by the filament wound reinforcing fibres 10, is formed which, after completion of any desired finishing operations, can be used as a drive shaft. In use, the composite material comprising the resin and the fibre serves to transmit torque loadings along the length of the shaft. The resin material is typically of polymeric form, and the elasticity thereof is able to absorb or damp at least some vibrational loadings to which the drive shaft is exposed.

By incorporating one or more layers of windings that are wound in the manner set out hereinbefore to be of wavy, not truly helical form, it will be appreciated that at least within those layers, vibrational loadings can be absorbed or damped to an enhanced degree, and so the drive shaft as a whole may be of enhanced damping performance.

As the provision of the layers of wavy, not truly helically wound fibres will be of reduced load transmitted performance compared to truly helically wound layers, in order to maintain the load transmitting characteristics of the drive shaft at an acceptable level, it is preferred for only a subset of the layers to be wound in the wavy, not truly helical fashion set out hereinbefore, rather than for all of the layers to be wound in this manner.

Referring next to Figure 3, an alternative embodiment of the invention is illustrated. In the arrangement of Figure 3, during the winding process, after winding of at least some layers but before winding of a low winding angle layer, elements 20 of a viscoelastic material are wrapped around the mandrel. After positioning of the elements 20, the winding process is completed. It will be appreciated that, in this manner, upon completion of the fabrication of the drive shaft, the drive shaft will include regions in which the elements 20 are sandwiched between adjacent layers of the reinforcing fibre material.

The presence of the elements 20 allows a small amount of elastically damped shearing movement to occur between the layers between which the elements 20 are sandwiched, in use, and as a result, the drive shaft has enhanced vibrational damping characteristics.

In the arrangement of Figure 3, five elements 20 are provided close to each end of the shaft, the elements 20 being spaced apart from one another in the axial direction of the shaft.

Figure 4 illustrates an arrangement in which, after positioning of the elements 20 and winding one or more fibre layers thereon, additional elements 22 are provided at locations between the elements 20. After winding further fibre layers over the elements 22, further elements 24, axially aligned with the elements 20, are provided and further fibre layers are wound over the elements 24. In this manner, the elements 20 may be located beneath a low winding angle layer, the elements 22 may be sandwiched between two low winding angle layers, and the elements 24 may be located to the exterior of a low winding angle layer. In such an arrangement the elements 20, 24 may be located above and below a low winding angle section of the drive shaft, with the elements 22 located centrally within the thickness of the low winding angle section.

Figure 5 illustrates an arrangement in which elements 20 of relatively large axial extent are sandwiched between two low winding angle layers, further elements 22 are positioned over the elements 20, again sandwiched between two low winding angle layers. In this arrangement, the elements 20 are equally spaced within the thickness of a low winding angle region of the drive shaft.

Figure 6 illustrates an arrangement similar to Figures, but in which the elements 20, 22 are of greater axial extent.

In each of the arrangements of Figures 3 to 6, enhanced damping may be achieved for the reasons set out hereinbefore.

Figure 7 is a graph illustrating the effect of the provision of the elements 20, 22, 24 upon the Q value of the drive shafts, and hence upon their ability to damp vibrations, Figure 7 clearly demonstrating that the incorporation of significant levels of viscoelastic material sandwiched between winding layers achieves marked reduction in the Q value, and hence represents a marked improvement in the vibrational damping performance of the drive shafts.

The arrangements of Figures 3 to 6 may be modified, if desired, to include one or more layers of fibres wound in a wavy manner as described hereinbefore to achieve further enhancements in vibrational damping.

Whilst specific embodiments of the invention are described herein, it will be appreciated that a wide range of modifications and alterations may be made to the arrangements without departing from the scope of the invention as defined by the appended claims.

S

Claims

CLAIMS: 1. A drive shaft comprising a tubular member of multi-layered filament wound composite material form, wherein the reinforcing fibre of the composite material within at least one layer thereof is wound at a varying winding angle.
2. A shaft according to Claim 1, wherein the varying winding angle varies from a fixed notional winding angle by less than ±5°.
3. A shaft according to Claim 2, wherein the varying winding angle varies from a fixed notional winding angle by less than ±2°.
4. A shaft according to any of the preceding claims, wherein the varying winding angle varies in a continuous manner.
5. A shaft according to Claim 4, wherein the varying winding angle results in fibres being
6. A shaft according to Claim 5, wherein the varying winding angle results in fibres being wound in sinuous, wavy manner of fixed wavelength or frequency.
7. A shaft according to any of the preceding claims, wherein the varying winding angle is employed in only a subset of the layers.
8. A method of manufacture of a drive shaft comprising winding a reinforcing fibre onto a mandrel, wherein the reinforcing fibre of the composite material is wound at a varying winding angle, and curing or allowing to cure a resin material incorporated in or applied to the reinforcing fibre.
9. A drive shaft comprising a tubular member of multi-layered filament wound composite material form, wherein at least one element of a viscoelastic material is sandwiched between at least two of the layers of the reinforcing fibre of the composite material.
10. A shaft according to Claim 9, wherein a plurality of viscoelastic elements are provided, spaced apart with one another in the axial direction of the drive shaft.
11. A shaft according to Claim 9 or Claim 10, wherein the elements are located adjacent low-angle wound fibre layers.
12. A shaft according to any of Claims 9 to 12, wherein at least one of the fibre layers is wound with a varying winding angle.