GB2593444A

GB2593444A - Improvements in and relating to road-vehicle parts

Info

Publication number: GB2593444A
Application number: GB2003461.7A
Authority: GB
Inventors: Basil Chimon Yves
Original assignee: Advanced Mfg Development Services Ltd
Current assignee: Advanced Mfg Development Services Ltd
Priority date: 2020-03-10
Filing date: 2020-03-10
Publication date: 2021-09-29
Also published as: GB202003461D0

Abstract

A method of improving a mechanical property of a road-vehicle part. A reinforcing element 12 is positioned in/on a first blank 10, preferably comprising aluminium, to form a reinforced blank 16. The reinforcing element comprises a second material, preferably steel. For a property of the materials, preferably stiffness or elastic modulus, the value for the reinforcing element material is greater than the value for the blank material. The reinforced blank is deformed, preferably by forging, to form the road-vehicle part, preferably a steering knuckle. Preferably, a first deformation step joins the reinforcement element with the first blank and a second step forms the shape of the part. The reinforcing element may be positioned in the hole 14 in the blank. The reinforcing element may be encased by the first blank in the deformed condition. The reinforcing element may be placed at weakness of the part. A method for determining the placement is claimed comprising: making a model of the road-vehicle part; generating mechanical vulnerability location data; and determining a position for deformatively incorporating the reinforcing element. A general method of improving mechanical properties is also claimed.

Description

Improvements in and Relating to Road-Vehicle Parts The present invention relates to a method of improving a mechanical property of a product, in particular to a method of improving a mechanical property of a road-vehicle part for a road vehicle. The invention further relates to a deformafively-manufactured road-vehicle part for a road vehicle and a method of developing a manufacturing parameter for a road-vehicle part.

It is desirable to reduce the weight of road vehicles, such as cars, lorries or buses, so as to reduce the carbon emissions emitted by the travel of such road vehicles. This is particularly the case for road vehicles powered by conventional fossil fuel combustion engines. Light-weight materials, such as cast aluminium alloys, have been used for some road-vehicle parts or components to reduce the weight of the road vehicle.

Additionally, reducing the weight of the unsprung mass of a road vehicle also helps to improve the general handling dynamics and braking of the vehicle. The unsprung mass is the mass of the components which are directly connected to the suspension, such as 15 the parts of the suspension itself and the wheels.

However, parts formed from such light-weight materials may not have sufficient or desirable mechanical properties to be used in some applications. This is particularly the case for parts used in the suspension of the road vehicle, more particularly the case for parts in the suspension system architecture (SSA), and most particularly for steering knuckles. For example, it is important for steering knuckles to have a high stiffness as the part transfers a steering force to the wheels as well as transferring the forces acting on the wheels to the rest of the suspension. Thus, the steering knuckle undergoes high levels of dynamic and static forces.

Increasing the cross-sectional area of such a part can result in improved mechanical 25 properties, but this requires adding more material to the part and so increases the weight and expense to the part.

The present invention seeks to provide a solution to these problems.

According to a first aspect of the present invention, there is provided a method of improving a mechanical property of a road-vehicle part for a road vehicle, the method 30 comprising the steps: a) providing a first blank comprising a first material, a material property of the first material having a first value; b) providing a reinforcing element comprising a second material, said material property of the second material having a second value being greater than the first value; c) positioning the reinforcing element at or in the first blank to form a reinforced blank; and d) deforrning the reinforced blank, the reinforcing element being positioned relative to the first blank in a deformed condition so as to improve said mechanical property, said mechanical property being associated with said material property.

The first material would typically be a low-density metal, such as aluminium. Use of such a material may reduce a weight of the part. The first material would have a material property, for example Young's modulus, which provides a sufficient mechanical property, such as stiffness, for portions of the part which undergo relatively low stress in use. However, such a low-density material may have an insufficient material property to provide a sufficient mechanical property for portions of the part which undergo high stress in use. The use of the reinforcing element which is formed from a second material which would typically have a higher density, such as steel, with a greater or improved material property as compared to the first material, at such high-stress portions of the part provides a sufficient mechanical property for those portions.

Therefore, the part formed by this method has an improved performance, such as stiffness to weight ratio, over parts formed entirely from the first material. The cost of the 20 hybrid material part may be lower as a required volume of expensive lightweight material is reduced.

Deforming, such as forging, the reinforced blank causes plastic deformation of at least the first material which helps to join the reinforcing element and the first blank.

Additionally, deformation increases the strength and stiffness of the blank via work hardening. As such, the deforming process improves the performance of the part. Additionally, by deforming the blank with the reinforcing element, the deforming process can fix the blank relative to the reinforcing element. Furthermore, the deforming process can shape the reinforced blank into the form of the part, or a predecessor thereof. Deformation of the reinforced blank therefore provides significant advantages over fastening the reinforcing element to the blank via fasteners.

The first blank is termed as such so as to differentiate this element from the reinforced blank.

Preferably, the first material has a value of a further material property, such as density, which is different, for example being lower, to that of the second material. Additionally or alternatively, the volume of the first material is greater than that of the second material.

Preferably, the first material may comprise a first metal. Due to its relative ductility, a 5 metal assists with deformative manufacture, as well as providing sufficient strength and stiffness for road vehicle applications.

Beneficially, the first metal may comprise aluminium. Aluminium has a low density and is suited to deformative manufacture and extrusion due to its ductility. Aluminium is relatively cost-effective compared to other low-density metals such as magnesium or 10 titanium.

Advantageously, the second material comprises a second metal. Metals provide high strength, elastic modulus and toughness, suitable for road vehicle applications.

In a preferable embodiment, the second metal may comprise steel. Steel has a high elastic modulus, as well as being tough and cost effective.

Preferably, the mechanical property may be stiffness. Stiffness, especially multi-axial stiffness, is important for road vehicle applications, in particular in steering knuckles. For example, a steering knuckle with a low stiffness may provide undesirable vehicle dynamics.

Additionally, the material property may be the elastic modulus. Stiffness of a part is 20 dependent on the elastic modulus of the material, for example the Young's modulus or the shear modulus of the material.

Preferably, during step d) the deforming of the reinforced blank joins the reinforcement element with the first blank. In this way the reinforcing element is prevented from being displaced relative to the first blank in the deformed condition.

Optionally, during step c) deforming may comprise forging. Forging forms the reinforced blank into the shape of the part, or a predecessor thereto, as well as potentially work-hardening the material.

Advantageously, during step d) the reinforcing element may be positioned relative to the road-vehicle part so as to be encased. Encasement of the reinforcing element may help 30 to prevent corrosion. This is particularly the case if the reinforcing element and the first blank are formed from different metals, since galvanic coupling of the metals may increase a corrosion rate and so preventing exposure of at least one of the metals to the atmosphere is especially important.

Preferably, during step d) the reinforcing element is positioned relative to a post-deformation first blank so as to be at or adjacent to an external surface thereof. For example, the reinforcing element may be considered to be close to an internal wall of the first blank in the deformed condition. This may assist with improving the mechanical properties at or adjacent to the surface of the first blank in the deformed condition.

Beneficially, the first blank may comprise a hole therein and during step c) the reinforcing element is positioned in the hole. If the first blank is formed via extrusion, the hole may be considered to be a cavity in the extrusion profile. Positioning the reinforcing element in the hole allows for the reinforcing element to be easily encased by the first blank in the deformed condition.

Optionally, the cross-section of the reinforcing element matches or substantially matches the cross-section of the hole so that the reinforcing element forms an interference fit with the first blank. The hole could be tapered to assist with creating such an interference fit. The interference fit allows for the reinforcing element to be at least weakly secured to the first blank so as to prevent relative displacement during handling of the reinforced blank. In this instance, the reinforcing element may be required to be forced into the hole.

In a preferable embodiment, the reinforcing element does not fill the hole and during step 20 d) the first blank is deformed into the hole. The hole allows for the reinforcing element to be positioned in the first blank, for example, away from the edge of the first blank. By at least in part filling the hole, voids in the part are prevented or limited.

Advantageously, during step d) the reinforced blank undergoes at least two deformation events, a first deformation event which prevents or limits relative movement of the reinforcement element relative to the first blank, and a second deformation event which shapes the exterior of the reinforced blank to form an exterior shape of the part. The first deformation event may set the position of the reinforcing element. Two deformation events may be preferable so that less pressure is required to deform the reinforced blank.

Beneficially, the reinforcing element may be positioned relative to the post-deformation part blank at or adjacent to a location of mechanical vulnerability during typical application of the part. Selective reinforcement of the first blank allows for a smaller volume of reinforcing element to be used and so, in the instance that the second material is denser than the first material, the part is lighter.

Optionally, the method further comprises the step e) prior to step c) wherein a model of the part is analysed to determine the location of mechanical vulnerability during typical application of the part.

Additionally, the model may be analysed via finite element computational methods.

Preferably, the road-vehicle part may have a non-uniform cross-section, the reinforcing element being positioned at or adjacent to a narrowing of the road-vehicle part. A narrowing of a part is associated with concentrating of mechanical stress. As such, the narrowing of the part is a mechanical vulnerability.

Advantageously, the reinforcing element may have a non-uniform cross-section. This 10 may allow for the reinforcing element to provide greater reinforcement at or adjacent to particular portions of the part.

Optionally, there are a plurality of separate reinforcing elements. This allows for separate and spaced apart reinforcement of the blank or part body.

In a preferable embodiment, the road-vehicle part may be for a suspension system 15 architecture of the road vehicle.

Additionally, the road-vehicle part may comprise a steering knuckle.

According to a second aspect of the present invention, there is provided a deformativelymanufactured road-vehicle part for a road vehicle, the road-vehicle part comprising: a part body comprising a first material, a material property of the first material having a first value; a reinforcing element comprising a second material, said material property of the second material having a second value; the part body having been deformed with the reinforcing element, whereby the reinforcing element is positioned relative to the part body to improve a mechanical property of the road-vehicle part, said mechanical property associated with said material property.

According to a third aspect of the present invention, there is provided a method of developing a manufacturing parameter for a road-vehicle part including a part body comprising a first material having a first value of a material property, the method comprising the computer implemented steps of: a) providing a model of the road-vehicle part; analysing said model to generate mechanical vulnerability location data of typical application of the road-vehicle part; b) determining a position for deformafively incorporating a reinforcing element with said part body based on said mechanical vulnerability location data to reduce a location-specific mechanical vulnerability of the road-vehicle part, the reinforcing element comprising a second material having a second value of said material property and the said material property associated with a mechanical property which causes the mechanical vulnerability.

According to a fourth aspect of the present invention, there is provided a method of 5 improving a mechanical property, the method comprising the steps: a) providing a first blank comprising a first material, a material property of the first material having a first value; b) providing a reinforcing element comprising a second material, said material property of the second material having a second value being greater than the first value; c) positioning the reinforcing element at or in the first blank to form a reinforced blank; 10 and d) deforming the reinforced blank so as to form the part, the reinforcing element being positioned relative to a post-deformation first blank so as to improve said mechanical property, said mechanical property being associated with said material property.

The invention will now be more particularly described, by way of example only, with 15 reference to the accompanying drawings, in which: Figure 1 shows a blank and a reinforcing element separate from each other and being provided in accordance with steps a) and b) of a first aspect of the invention; Figure 2 shows the reinforcing element of Figure 1 received within the blank of Figure 1 in accordance with step c) of the first aspect of the invention; Figure 3 shows the arrangement of Figure 2 having been deformed in accordance with at least part of step d) of the first aspect of the invention; Figure 4 shows a cutaway view of a first embodiment of a steering knuckle formed from the arrangement of Figure 3 having been deformed in accordance with at least part of step d) of the first aspect of the invention; Figure 5 shows a second embodiment of a steering knuckle having been manufactured according to the first aspect of the invention; Figure 6 shows a first embodiment of a further suspension part having been manufactured according to the first aspect of the invention; Figure 7 shows a second embodiment of a further suspension part having been 30 manufactured according to the first aspect of the invention; Figures 8a to 8d shows various cross-sections of reinforcement elements for use with the method according to the first aspect of the invention; Figure 9a shows a model of a third embodiment of a steering knuckle in a first position being analysed to determine a location of mechanical vulnerability of the 5 suspension component; and Figure 9b shows said model of Figure 9a in a second position.

A method of improving a mechanical property of a road-vehicle part for a road vehicle is described hereinbelow. The method is particularly applicable for components of a road-vehicle suspension system architecture, or a road-vehicle suspension. The invention is most particularly applicable for steering knuckles, for example a steering knuckle of a car, although steering knuckles for other road-vehicles may also be considered. The method is additionally or alternatively particularly applicable for automotive or car parts.

Referring to Figure 1, the method first comprises the step of providing a first blank 10, first billet or first body comprising a first material, a material property of the first material having a first value. The method then comprises the step of providing a reinforcing element 12 comprising a second material, said material property of the second material having a second value. At least the first material preferably comprises metal, and more preferably both the first and the second materials comprise metal.

In this case, the first material comprises aluminium, and the second material comprises steel. More specifically, the first blank 10 comprises an alloy of aluminium. The material property is preferably the elastic modulus, which may be given as the Young's modulus. Aluminium has a first value of elastic modulus and steel has a second value of elastic modulus. The second value is greater than the first value, for example a typical engineering alloy of steel may have a Young's modulus of approximately 200 GPa, whilst a typical engineering alloy of aluminium may have a Young's modulus of approximately 70 GPa.

However, it will be appreciated that other materials may be considered. The first material may comprise other materials with a lower density that steel. For example, the first material may comprise titanium, magnesium or alloys thereof, and may even comprise plastics or polymers. The second material may comprise a material with a higher elastic modulus than aluminium, for example, metal matrix composites, such as those containing ceramics, carbon, such as a carbon fibre composite, ceramic or titanium. Various other combinations of materials may be considered.

The first material preferably has a lower yield stress than that of the second material, so that the first blank 10 is plastically deformed at lower stresses than the reinforcing 5 element 12.

Additionally, whilst stiffness is discussed, it will be appreciated that other material properties may be considered for the reinforcing element to improve. These may include strength, for example the tensile strength, shear strength, compressive strength, toughness or fatigue limit or resistance.

The first blank 10 preferably has a greater mass and/or cross-sectional area than the reinforcing element 12. Here the first blank 10 is cylindrical or substantially cylindrical and/or has a circular cross-section. The reinforcing element 12 is preferably similarly shaped to the first blank 10. However, it will be appreciated that other shapes may be considered, and the reinforcing element 12 and the first blank 10 may have different shapes.

The reinforcing element 12 preferably has a shorter longitudinal extent than that of the first blank 10 so that the reinforcing element does not extend all the way through the first blank 10. For example, the first blank 10 may be at least twice as long as the reinforcing element 12. In this way, the reinforcement provided by the reinforcing element 12 is localised and excess weight created by excessive length of the reinforcing element 12 is avoided. However, it will be appreciated that this may not be the case for more uniformly reinforced parts.

Preferably, the first blank 10 has a hole 14 therein to receive the reinforcing element 12. The hole 14 may be a continuous aperture through the first blank 10, although the hole 14 may alternatively be a recess. The hole 14 may additionally be considered to be a cavity within the first blank 10; however, it will be appreciated that such a cavity is not entirely closed. The cross-section of the hole 14 is preferably similar or identical to a cross-section of the reinforcing element 12. For example, the diameter of the hole 14 may be similar or identical to the diameter of the reinforcing element 12. This may allow for the reinforcing element 12 to form an interference fit with the first blank 10 which may prevent the reinforcing element 12 from being displaced from the first blank 10 during handling thereof.

The hole 14 may be directly formed in the first blank 10, for example extruding the first blank 10 so that the extrusion profile defines the hole 14 or a cavity. If extrusion is used, a length of the first material is extruded with the desired extrusion profile, and first blanks 10 of the required dimension are cut from the length. Alternatively, the first blank 10 may be cast so that there is the hole 14 therein. In the instance of casting, the hole or cavity 14 may be formed by the use of a core, which may for example be sand or metal, in the mould. Despite being casted, the blank 10 with the reinforcing element 12 would still be deformed or forged after casting. This deformation process may occur whilst the casted material is semi-solid. It will be appreciated that the hole 14 in the first blank 10 may be formed in the first blank 10 after formation of the first blank 10. For example, the first blank 10 without the hole may be cast or otherwise formed, and then the hole 14 may be machined, for example drilled, into the first blank 10. Alternatively, 3D printing or additive manufacture may be used to form the first blank 10. It will even be appreciated that multi-material 3D printing or additive manufacture may be used to form the first blank 10 with the reinforcing element 12 therein or thereat. After forming the first blank 10 and reinforcing element 12 via 3D printing, these components are preferably forged or otherwise deformed.

Whilst the hole 14 is shown as being at the centre of the first blank 10, it will be appreciated that the hole 14 may be closer to one side of the first blank 10 than another 20 side, in other words being off-set from the centre of the blank 10. For example, the hole 14 may preferably be close to an internal wall of the first blank 10.

Referring to Figure 2, the method comprises the step of positioning the reinforcing element 12 at or in the first blank 10, and as such a reinforced blank 16 is formed. In this case, the reinforcing element 12 is positioned in the hole 14 of the first blank 10. The reinforcing element 12 positioning, and the location of the hole 14, is preferably predetermined via analysis. As such, the reinforcing element 12 is positioned relative to the first blank 10 so that the location of the reinforcing element 12 within the final part is at or adjacent to a location of mechanical vulnerability of the part. Such analysis and positioning will be further described hereinbelow.

Referring to Figure 3, the method further comprises the step of deforming the reinforced blank 16. Here the reinforced blank 16 is deformed via a first deformation process. Thus, the first blank 10 is deformed with the reinforced blank 16 therein or thereat. The deformation process is preferably forging; however, it will be appreciated that other deformation processes may be considered such as rolling, stamping, pressing or hydroforming.

The deformation is preferably hot or warm and therefore the reinforced blank 16 is preheated so as to be at an elevated temperature. However, cold deformation may also 5 be considered and so the reinforced blank 16 may be at or close to room temperature. A hydraulic press and closed die tooling are used to produce the desired part shape.

The first deformation process causes the reinforced blank 16 to be formed into a post-deformation reinforced blank 18. The post-deformation reinforced blank may otherwise be termed the reinforced blank in a deformed condition, or a precursor for the part. The post-deformation reinforced blank 18 has a shape which roughly or approximately, but not exactly, corresponds to the shape of the finished first part. Such deformation of the reinforced blank 16 is preferably due to deformation of the first blank 10 by the first deformation process. The first blank 10 is formed into a post-deformation first blank 20. The post-deformation first blank may otherwise be termed as the first blank in a deformed condition, or a precursor for the part body.

The deformation is plastic deformation. In other words, the first material yields and may be considered to flow to form the post-deformation reinforced blank 18. Whilst the hole is shown in Figure 3, such deformation preferably causes the hole 14 or cavity in which the reinforcing element 12 is positioned to be at least in part closed or filled. As such, the first deformation process may prevent or limit relative movement between the reinforcing element 12 and the post-deformation reinforced blank 18. For example, the or each opening of the hole may be closed and/or the diameter of the hole may be narrowed It will be appreciated that the reinforcing element 12 may not deform, or at least may not plastically deform, during the deformation process, given that it is preferably formed from a material with a greater yield point than that of the first material. However, it will be appreciated that the reinforcing element could yield and plastically deform in some instances, if a high forging or other deforming pressure were used.

Referring to Figure 4, the post-deformation reinforced blank 18 may undergo a second deformation process. The second deformation process is preferably also a forging process or event, and the post-deformation reinforced blank 18 may be required to be reheated. In this way, the post-deformation reinforced blank 18 is deformed into the part 22. The post-deformation first blank 20 is thus deformed into a part body 24 of the part 22. The reinforcing element 12 may still be undeformed, or at least plastically undeformed, by the second deformation process. It will be appreciated that after the second deformation process, further manufacturing processes may be required. For example, heat treatment, sand blasting, machining, painting and assembly of additional components may be required.

It will be appreciated that two separate deformation events or processes may not be required, and the reinforced blank may only undergo a single deformation event or process.

The part 22, which is here a steering knuckle, includes the part body 24 which comprises the first material and the reinforcing element 12 which comprises the second material. The part body 24 has been deformed with the reinforcing element 12. The reinforcing element 12 is positioned relative to the part body 24 to improve a mechanical property of the road-vehicle part 22 and as such is positioned at or adjacent to a location of mechanical vulnerability of the part 22. The steering knuckle 22 includes a wheel connection point 22a, or wheel bearing socket, for connecting to a wheel or hub of the wheel, as well as further connection points 22b for connecting to other automotive parts such as the track or tie rods.

The road vehicle part is preferably recyclable. In the instance that the part contains aluminium and steel, or other materials with different melting points, the part would be raised above the melting point of aluminium. The aluminium of the part would melt leaving the steel as a solid since the melting point of steel or iron is greater than that of aluminium. The liquid aluminium can then be separated from the steel, for example by pouring the aluminium into a container away from the steel.

Referring now to Figure 5, there is shown a second embodiment of a steering knuckle 122. Similar or identical reference numerals are used for the second embodiment as for the first embodiment, with 100 added. The second embodiment of the steering knuckle comprises a reinforcing element 112 which has a non-uniform longitudinal extent. As such, a first portion 126 of the reinforcing element 112 is wider than a second portion 128 of the reinforcing element 112. Such an arrangement may provide greater reinforcement to a portion of the part 122 which has a greater cross-section and/or undergoes greater stress. The reinforcing element 112 may be non-planar, and it will be appreciated that the reinforcing element 12 could be plastically deformed during the or each deformation processes so as to approximately or substantially follow the contours of the part body 124. The reinforcing element 112 has a rectangular cross-section, although it will be appreciated that other shaped cross-sections will be considered.

It can be seen that the reinforcing element 12 is positioned at a location of narrowing or tapering 130 of the part body 124. A narrowing or tapering may be associated with 5 increased stress concentration and therefore such a location may be associated with a mechanical vulnerability of the part 122.

Figure 6 shows a first embodiment of a further suspension part 222. Similar or identical reference numerals are used for the further suspension part first embodiment as for the first embodiment of the steering knuckle, with 200 added. The further suspension part 222 comprises a plurality of reinforcing elements 212. The further suspension part 222 comprises two arms 232 having a connection point 234 at or adjacent to an end of each arm 232. The arms join at a joining point 236. Each arm comprises one reinforcing element 212. Such an arrangement may be formed, for example, by positioning two aligned and spaced apart reinforcing elements 212 in a straight blank, deforming the blank via forging, and bending the blank to form the required shape. The reinforcing elements 212 may be the same, as shown here, or different, for example to provide different structural reinforcement.

Figure 7 shows a second embodiment of a further suspension part 322. Similar or identical reference numerals are used for the further suspension part second embodiment as for the first embodiment of the steering knuckle, with 300 added. The second embodiment comprises one reinforcing element 312, which is here shown to be similar or identical to the reinforcing elements of the preceding embodiment.

Figure 8a shows a cross-section of a fourth embodiment of a reinforcing element 412. The cross-section of the second embodiment of the reinforcing element 412 is cross-25 shaped or substantially cross-shaped.

The reinforcing element 412 comprises two arms, a first arm 438 preferably being wider or thicker than a second arm 440. Such an arrangement may provide additional stiffness or strength in a particular direction of a part.

Figure 8b shows a cross-section of a fifth embodiment of a reinforcing element 512. The 30 cross-section of the third embodiment is square shaped or substantially square-shaped and has a square shaped or substantially square-shaped hole 542 therein.

Although shown as being square shaped, it will be appreciated that other shaped reinforcing elements with at least one hole therein may be considered. Similarly, the holes may be of other shapes.

The walls of the reinforcing element may collapse when compressed during the 5 deformation. Alternatively, the hole of the reinforcing element may be filled with a liquid and then sealed which prevents collapse of the walls of the reinforcing element.

Figure 8c shows a cross-section of a sixth embodiment of a reinforcing element 612. The reinforcing element 612 is L-shaped or substantially L-shaped. Such an arrangement may provide additional strength or stiffness at or adjacent to particular edges of a part.

The L-shaped cross-section has two arms. A first arm 644 is thicker or wider than a second arm 646, which may provide additional stiffness or strength in a particular direction of a part.

Figure 8d shows a cross-section of a seventh embodiment of a reinforcing element 712. The reinforcing element 712 is star shaped or substantially star shaped.

The aforementioned method of improving a mechanical property of a road-vehicle part for a road vehicle may further comprise the step of determining a location of mechanical vulnerability of the part, said mechanical vulnerability occurring during typical application or loading of the part.

Such a step may be achieved via providing a model of the part. For example, the model may be computer generated, although it will be appreciated that it may be a physical model. The model may be analysed by finite element computational methods. The model may be put under conditions, for example loading conditions, which are typical during application of the part. Finite element analysis may be carried out on the model to determine the location of highest stress and/or strain of the part and/or model. As such, a location of mechanical vulnerability is determined.

Alternatively, modal analysis may be used on the model. This may be achieved by oscillating the model and measuring the amplitude of vibrations at different locations of the part in response to the oscillations. The amplitude of vibrations can be used to determine the stiffness of locations of the part, with greater amplitudes of vibration corresponding to less stiffness. The locations of lowest stiffness may be considered to be mechanical vulnerabilities.

Figures 9a and 9b show a model 848 of the part being oscillated and being deformed from one position to another position. Locations of greatest amplitude of vibration are indicated in red 850 and locations of least amplitude of vibration are in dark blue 852. Locations of intervening amplitudes of vibration are indicated by intervening colours and shades of orange 854, yellow 856, green 858 and lighter blue 860, in descending order of amplitude of vibration.

As such, a location of particular mechanical vulnerability, in other words a location of least or low stiffness, of the model 848 or part can be seen to be the locations which are red, orange and/or yellow 850, 852, 854. The reinforcing element should therefore be positioned at or adjacent to any or all of these locations 850, 852, 854. To achieve this, an appropriately shaped blank will be formed with a hole into which the reinforcing element can be positioned so as to be at or adjacent to the location of particular mechanical vulnerability once the part has been formed. Computer simulation software, such as Deform (RTM), for forging or other deformation processes may be useful for this purpose.

Although the method is described for steering knuckles in particular, the method may be used to form parts for other suspension components such as suspension links, steering link arms, drive shafts, suspension dampers, lower and upper control arms. Alternatively, the method may be used for other parts of the subframe.

Additionally, road-vehicle parts which are not part of the suspension of a road-vehicle could also be made in accordance with the described method. For example, parts in the body in white structures, particularly those fabricated predominantly from extruded aluminium alloys, may also be made in accordance with the described method. Examples are sills, A and B pillars, instrument panel frames and closures with side impact panels of automobiles.

Whilst the method is described as being for road-vehicle parts, it will be appreciated that other parts or components may be formed in accordance with the described method. For example, parts for other vehicles, such as aerospace vehicles or rail vehicles.

It is therefore possible to provide a method of improving a weight to stiffness ratio of a 30 part by providing a blank of a lighter but less stiff material and forging the blank with a reinforcement of a higher stiffness but less dense material. This allows for the strategically targeted reinforcement of the part and therefore for the creation of a high-performance part, or in other words a part with a high stiffness to weight ratio.

Although deformation of the reinforced blank is described, it will be appreciated that in some instances this may not be necessary. For example, if the first blank and reinforced 5 blank are co-formed via multi-material 3D printing, the deformation step may be omitted and the co-formed first blank and reinforced blank may instead be sintered.

The words 'comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of 10 one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

Claims 2. 3. 4. 5. 6. 7.
A method of improving a mechanical property of a road-vehicle part for a road vehicle, the method comprising the steps: a) providing a first blank comprising a first material, a material property of the first material having a first value; b) providing a reinforcing element comprising a second material, said material property of the second material having a second value being greater than the first value; c) positioning the reinforcing element at or in the first blank to form a reinforced blank; and d) deforming the reinforced blank, the reinforcing element being positioned relative to the first blank in a deformed condition so as to improve said mechanical property, said mechanical property being associated with said material property.
A method as claimed in claim 1, wherein the first material comprises a first metal.
A method as claimed in claim 2, wherein the first metal comprises aluminium.
A method as claimed in any one of the preceding claims, wherein the second material comprises a second metal.
A method as claimed in claim 4, wherein the second metal comprises steel.
A method as claimed in any one of the preceding claims, wherein the mechanical property is stiffness.
A method as claimed in any one of the preceding claims, wherein the material property is elastic modulus A method as claimed in any one of the preceding claims, wherein during step d) the deforming of the reinforced blank joins the reinforcement element with the first blank.
9. A method as claimed in any one of the preceding claims, wherein during step c) deforming comprises forging.
10. A method as claimed in any one of the preceding claims, wherein during step d) the reinforcing element is encased by the first blank in the deformed condition.
11. A method as claimed in any one of the preceding claims, wherein during step d), the reinforcing element is positioned relative to a post-deformation first blank so as to be at or adjacent to an external surface thereof.
12. A method as claimed in any one of the preceding claims, wherein the first blank comprises a hole therein and during step c) the reinforcing element is positioned in the hole
13. A method as claimed in claim 12, wherein the cross-section of the reinforcing element matches or substantially matches the cross-section of the hole so that the reinforcing element forms an interference fit with the first blank.
14.A method as claimed in claim 12 or claim 13, wherein the reinforcing element does not fill the hole and during step d) the first blank is deformed into the hole.
15. A method as claimed in any one of the preceding claims, wherein during step d) the reinforced blank undergoes at least two deformation events, a first deformation event which prevents or limits relative movement of the reinforcement element relative to the first blank, and a second deformation event which shapes the exterior of the reinforced blank to form an exterior shape of the part.
16. A method as claimed in any one of the preceding claims, wherein the reinforcing element is positioned relative to the post-deformation part blank at or adjacent to a location of mechanical vulnerability during typical application of the part.
17. A method as claimed in claim 16, further comprising the step e) prior to step c) wherein a model of the part is analysed to determine the location of mechanical vulnerability during typical application of the part.
18. A method as claimed in claim 17, wherein the model is analysed via finite element computational methods.
19. A method as claimed in any one of the preceding claims, wherein the road-vehicle part has a non-uniform cross-section, the reinforcing element being positioned at or adjacent to a narrowing of the road-vehicle part.
20. A method as claimed in any one of the preceding claims, wherein the reinforcing element has a non-uniform cross-section.
21. A method as claimed in any one of the preceding claims, wherein the road-vehicle part is for a suspension system architecture of the road vehicle.
22. A method as claimed in any one of the preceding claims, wherein the road-vehicle part comprises a steering knuckle.
23 A deformafively-manufactured road-vehicle part for a road vehicle, the road-vehicle part comprising: a part body comprising a first material, a material property of the first material having a first value; a reinforcing element comprising a second material, said material property of the second material having a second value; the part body having been deformed with the reinforcing element, whereby the reinforcing element is positioned relative to the part body to improve a mechanical property of the road-vehicle part, said mechanical property associated with said material property.
24 A method of developing a manufacturing parameter for a road-vehicle part including a part body comprising a first material having a first value of a material property, the method comprising the computer implemented steps of: a) providing a model of the road-vehicle part; b) analysing said model to generate mechanical vulnerability location data of typical application of the road-vehicle part; c) determining a position for deformatively incorporating a reinforcing element with said part body based on said mechanical vulnerability location data to reduce a location-specific mechanical vulnerability of the road-vehicle part, the reinforcing element comprising a second material having a second value of said material property and the said material property associated with a mechanical property which causes the mechanical vulnerability.
25. A method of improving a mechanical property, the method comprising the steps: a) providing a first blank comprising a first material, a material property of the first material having a first value; b) providing a reinforcing element comprising a second material, said material property of the second material having a second value being greater than the first value; c) positioning the reinforcing element at or in the first blank to form a reinforced blank; and d) deforming the reinforced blank so as to form the part, the reinforcing element being positioned relative to a post-deformation first blank so as to improve said mechanical property, said mechanical property being associated with said material property.