WO2018132357A1

WO2018132357A1 - Cast aluminum or magnesium foam insert

Info

Publication number: WO2018132357A1
Application number: PCT/US2018/012910
Authority: WO
Inventors: Randy BEALS
Original assignee: Magna International Inc.
Priority date: 2017-01-10
Filing date: 2018-01-09
Publication date: 2018-07-19
Also published as: DE112018000344T5

Abstract

An aluminum or magnesium-based structural component formed by a casting process using a metal foam insert is provided. The metal foam insert is produced by disposing a homogeneous polystyrene-based foam preform having an optimized particle size and statistical distribution of the particles in a mold cavity. The process then includes pouring the molten aluminum or magnesium-based material into the mold cavity to form the metal foam insert having a desired shape and pore size distribution. The highly stable metal foam insert is then used in the casting process to produce the structural component which is lightweight and stiff, for example a hollow core structures formed by High Pressure Vacuum Die Casting (HPVDC) or Noise Vibration Hardness (NVH) sheet body floor panel.

Description

CAST ALUMINUM OR MAGNESIUM FOAM INSERT

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This PCT International Patent Application claims the benefit of U.S.

Provisional Patent Application Serial No. 62/444,553 filed January 10, 2017 entitled "Cast Auminum Or Magnesium Foam Insert," the entire disclosure of the application being considered part of the disclosure of this application and hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0002] The invention relates generally to metal foam inserts for use in casting structural components for automotive vehicles, processes of forming the metal foam inserts, structural components formed by casting using the metal foam inserts, and casting processes to form the structural components using the metal foam inserts.

2. Related Art

[0003] Structural components formed of metal, such as aluminum, for automotive vehicles are oftentimes forming by casting the aluminum around metal foam. The volume of the metal foam is occupied primarily by air, which reduces the weight of the finished metal component that is cast around the foam. The metal foam can also be used to achieve a desired shape of the finished metal component in the casting die. The metal foam insert can also create a type of box design that will increase the over stiffness of the component.

[0004] Conventional aluminum foams are formed by introducing gas, such as argon or nitrogen, into molten aluminum. The conventional aluminum foam utilizes antiquated technology of introducing gas impurities into a molten bath, i.e. introducing gas bubbles and optionally additives into the molten aluminum. The convention aluminum foam formed does not have a homogeneous pore size, structure, and properties. Rather, the conventional aluminum foam has a random or Monte Carlo distribution. Thus, a more stable metal foam insert is desired.

SUMMARY

[0005] The invention provides a metal foam insert for use in casting a structural component, such as a component for an automotive vehicle, and a process for forming the metal foam insert. The metal foam insert is formed by exposing molten metal to a polystyrene-based foam preform. The metal foam insert is stable and has a more homogeneous pore size, structure, and properties compared to the conventional metal foams.

[0006] The invention also provides a structural component formed by casting using the metal foam insert, and a casting process using the metal foam insert. The casting process includes disposing the metal foam insert in a mold cavity, and exposing the metal foam insert to another metal to form the structural component. Due to the stability of the metal foam insert, the structural component has the benefit of reduced weight and increased stiffness, compared to other structural components on the market.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

[0008] Figure 1 illustrates a polystyrene bead cell structure of a polystyrene-based foam preform according to an example embodiment;

[0009] Figure 2 illustrates the polystyrene-based foam preform being ejected from a mold according to the example embodiment;

[0010] Figure 3 illustrates a sprue, runner, and gate attached to the polystyrene- based foam preform according to the example embodiment; [0011] Figure 4 illustrates applying a refractory coating to the polystyrene-based foam preform and attached components according to the example embodiment;

[0012] Figure 5 illustrates drying the refractory coating applied to the polystyrene- based foam preform according to the example embodiment;

[0013] Figure 6 illustrates the example coated polystyrene-based foam preform and attached components ready for casting;

[0014] Figure 7 illustrates introducing molten metal to the polystyrene-based foam preform to form a metal foam insert according to the example embodiment;

[0015] Figure 8 illustrates a casting process to form the metal foam insert according to the example embodiment;

[0016] Figure 9 illustrates an energy balance of the step of casting the metal foam insert according to the example embodiment;

[0017] Figure 10 illustrates cooling the cast metal foam insert and attached components in a refractory ceramic shell according to the example embodiment;

[0018] Figure 11 illustrates degating the metal foam insert from the attached components according to the example embodiment;

[0019] Figure 12 illustrates the metal foam insert of the example embodiment after machining;

[0020] Figure 13 illustrates a typical structure of the finished metal foam insert which includes a relatively or approximately uniform pore size;

[0021] Figure 14 illustrates a conventional lost-foam casting process for purposes of comparison;

[0022] Figure 15 illustrates burning loose sand out of a flask according to the conventional lost-foam casting process for purposes of comparison; [0023] Figure 16 is a statistical distribution of polystyrene bead size according to the example embodiment;

[0024] Figure 17 is an example of an optimized sequence of the polystyrene bead particle size used to form the metal foam insert;

[0025] Figure 18 illustrates bending stiffness relative to height of the metal foam insert (Cosmafoam) in the form of a sheet according to the example embodiment;

[0026] Figure 19 illustrates typical components of a two-part sand casting mold and core print for purposes of comparison;

[0027] Figure 20 illustrates a front engine cradle with the metal foam insert as a core formed by High Pressure Vacuum Die Casting (HPVDC) according to an example embodiment;

[0028] Figure 21 illustrates additional detail of the front engine cradle of Figure 20;

[0029] Figure 22 illustrates a Noise Vibration Hardness (NVH) sheet for an automotive floor application including the metal foam insert according to an example embodiment; and

[0030] Figure 23 illustrates a sheet including the metal foam insert according to an example embodiment for miliary applications.

DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0031] One aspect of the invention provides a metal foam insert for use in casting a structural component, such as a component for an automotive vehicle, and a process for forming the metal foam insert. The metal foam insert has improved stability compared to conventional metal foams used in casting processes. The cast structural component formed using the metal foam insert of the present invention is stable, lightweight and highly stiff, which is beneficial for automotive vehicle applications, such as hollow core structures formed by High Pressure Vacuum Die Casting (HPVDC) and Noise Vibration Hardness (NVH) sheet panels for body floor panels.

[0032] The process used to form the metal foam insert first includes providing a polystyrene-based foam preform having an optimized particle bead size, statistical distribution of the bead particles to form the resultant stable porosity size. The polystyrene- based foam preform is typically homogeneous and includes a uniform bead size throughout. The polystyrene-based foam preform can optionally include additives in addition to the polystyrene. The polystyrene-based foam preform also has a desired size and shape, which depends on the structural component to be formed.

[0033] According to an example embodiment, the polystyrene-based foam preform is formed by making a pattern from polystyrene beads of a certain size and particle distribution. The polystyrene beads are impregnated with a certain amount of

aluminum/magnesium foam stabilizers, such as SiC , AI2O₃, TiB₂, TiC, TiH₂, and/or SiC, etc., to create a modified polystyrene. According to this embodiment, the polystyrene-based foam preform is a 97.5 volume percent (vol. %) air cavity that is packaged into tiny 50 micron cells. Figure 1 illustrates a 50 mm polystyrene bead cell structure of the

polystyrene-based foam preform according to the example embodiment.

[0034] Depending on production volume, the partem of the polystyrene beads of the example embodiment can be created many different ways. For simple geometries and small volume runs, the pattern can be hand cut or machined from a solid block of pre-impregnated polystyrene foam. If the geometry is complex and/or the production volume is large, then the pattern can be mass-produced by a process similar to injection molding. In the injection molding process, pre-expanded beads of polystyrene with foam stabilizers are injected into a preheated aluminum mold at low pressure. Steam is then applied to the polystyrene beads, causing them to expand more and fill the die. The final pattern of the polystyrene-based foam preform is approximately 97.5 vol. % air and 2.5 vol. % polystyrene and foam stabilizers, based on the total volume of the polystyrene-based foam preform. The polystyrene foam pattern will constrict dimensionally, similar to conventional castings. Figure 2 illustrates the polystyrene-based foam preform 10 being ej ected from the mold 12 using an ej ection pin 14. Pre-made polystyrene foam pouring basins, runners, and risers can be hot glued to the polystyrene-based foam preform. As shown in Figure 3, a down sprue 16, runner 18, and gate 20 can glued to two of the polystyrene-based foam preforms 10.

[0035] According to the example embodiment, the polystyrene-based foam preform and attached components are next coated with at least one refractory coating. A variety of refractory coatings can be used, for example a ceramic material, such as AI2O₃, or others. The refractory coating can be applied by dipping, brushing, spraying, showering, or flow coating. In other words, the polystyrene-based foam preform and attached components can be coated many different ways, for example hand dipped for low volume production, or automated by a robot station for high volume production. Figure 4 illustrates an example of the step of applying the refractory coating 22 to the polystyrene-based foam preform 10, in this case by dipping. The refractory coating will create a barrier between the foam surface and surrounding area of a subsequent casting step. The refractory coating can have many layers for thin walls, such as less than 0.8 mm for HPVDC core applications, or thick walls for NVH plate applications. The refractory coating also has zero or minimal permeability, which prevents gas created by the vaporized polystyrene foam pattern from escaping during a subsequent casting process. The foundry should check the refractory slurry(s) used to form the refractory coating before coating the polystyrene-based foam preform and attached components. The refractory slurry(s) should also be continually mixed to maintain properties. The face coat, or the first coating, should be of the slurry to provide the surface finish that is needed in the final condition of the polystyrene-based foam preform. After the polystyrene-based foam preform and attached components are coated, they are allowed to dry. The drying step includes either air cooling for low volume production, or introducing the polystyrene-based foam preform and attached components into a dryer to allow a shorter drying cycle for high volume production. Preferably, the drying step occurs in an oven at 120° F to 140° F (49° C to 60° C) for 3 to 5 hours. Figure 5 illustrates the drying step according to the example embodiment, wherein the refractory coating applied to the polystyrene-based foam preform 10 and attached components is dried with air convection and thermal radiation to form a shell of the refractory coating 22 around the polystyrene- based foam preform 10 and attached components. After the refractory coating dries, the polystyrene-based foam preform and attached components are placed on the foundry floor and are ready for casting. Figure 6 illustrates the example polystyrene-based foam preform 10 and attached components which are ready for casting.

[0036] The process next includes disposing the polystyrene-based foam preform in a mold cavity or another casting area, and then introducing the molten metal used to form the metal foam insert to the polystyrene-based foam preform. The particle size of the polystyrene-based foam preform is preferably sequenced and optimized in its location in the mold cavity before being introduced to the molten metal wave front.

[0037] The molten metal used to form the metal foam insert is typically aluminum- based or magnesium-based material. For example, the molten metal used to form the metal foam insert can be an aluminum alloy, such as A356.2, or a magnesium alloy, such as AZ91E. These two alloys are preferred when the metal foam insert is used to form the HPVDC hollow core. Altematively, aluminum-based material used to form the metal foam insert is 5182 - 0 and/or a 6000 series sheet, and the magnesium-based material is AZ31B. These two alloys are preferred when the metal foam insert is used to form the floor panel applications. The composition of the A356.2 alloy is provided below in Table 1 , and the composition of the AZ91E alloy is provided below in Table 2. The composition of the 5182 - O alloy is provided below in Table 3, and the composition of the AZ31B alloy is provided below in Table 4.

Table 1

Table 2

Table 3

Table 4

[0038] According to the example embodiment, the metal used to form the metal foam insert is a degassed molten aluminum alloy or magnesium alloy. This molten metal 24 is poured into the sprue 16 and flows through the runner 18 and gate 20 to the attached to the polystyrene-based foam preforms 10, as shown in Figure 7. As the molten metal is poured, the molten metal takes the shape of the polystyrene-based foam preform.

[0039] According to the example embodiment, the combination of the controlled metal temperature and filling speed create a molten metal wave which vaporizes the polystyrene beads and introduces a controlled gas to form the metal foam insert. The chemical reaction of the aluminum or magnesium-based material with the stabilizers of the polystyrene-based foam preform creates a unique and stable structure of the metal foam insert. The metal foam insert is a cast aluminum or magnesium-based foam, preferably with homogeneous properties and pore size. The metal foam insert can be cast in many different ways, for example by hand-pouring for low volume production, or by automated pouring for high volume production. Preferably, the pouring process is automated because the fill profile is more significant than in conventional foundry practice. Figure 8 illustrates the casting step used to form the metal foam insert according to the example embodiment. More specifically, Figure 8 illustrates a heat flux between the molten metal and mixture of liquid foam and gas, with a small vapor gap therebetween. Figure 8 also shows a mass flux between the liquid foam and gas, and the polystyrene beads and foam stabilizes. In this case, the liquid foam and gas is referred to as a decomposition breakdown layer (L_b), and the materials are contained in the refractory shell formed of the ceramic material.

[0040] During the step of forming the metal foam insert, the polystyrene burns out upon contact by the molten metal. According to the example embodiment, the modified polystyrene structure decomposes in at least four stages, including a Contact Stage, Gap Stage, Collapse Stage, and Engulf Stage. This process is mostly dependent on the Contact Stage when the molten metal is in direct contact with the polystyrene-based foam preform. The polystyrene-based foam preform decomposes by an Ablation type process. A thin layer of liquid modified polystyrene develops and then some of the modified polymer liquid vaporizes. The gas diffuses into the molten aluminum or magnesium-based material in a controlled manner. The amount of gas released related to the average polystyrene particle size affects the final stable aluminum or magnesium-based foam bubble size, and thus the pore size and porosity of the metal foam insert. Basic assumptions for the step of casting the metal foam insert include: homogeneous liquid polystyrene and foam stabilizers;

uniform rate of ablation of polystyrene; mass flux decreases linearly toward metal; gas vaporization and foam stabilization at x = 0; and the presence of the decomposition breakdown layer L_b as shown in Figure 8. Figure 9 illustrates an energy balance of the step of casting the metal foam insert according to the example embodiment. The energy balance of the example embodiment is provided by the following equation 1: k_D(d²q/6x²) + tpC_Dux/L_B) dq_/dx = 0 equation 1

Boundary Conditions

q (0) = q_M , q i_B) = qp

-k_D dq/dx (L_B) = r_peou

[0041] The following equation 2 is used to arrive at the Arrhenius Model for the gas production and thus the production of the aluminum or magnesium-based foam created inside the refractory shell. The following equation 2 can also provide the liquid foam temperature, Peclet number, and the heat flux from metal. r_v = r_v (q_M ,x_v) = a exp (-E/R q_M ) (1- x_v)ⁿ equation 2 where:

r_v = gas production rate

q_{M =} production rate

x_v = gas fraction

a = reaction rate (kg/m²-s)

E = activation energy (J/mole)

R = universal gas constant

n = reaction order

[0042] According to the example embodiment, the cast metal foam insert 26 and attached components are next allowed to cool in the refractory shell 22 for a predetermined period of time, as shown in Figure 10. Preferably, the cooling step includes a forced air quench on the refractory shell. The metal foam insert solidifies inside the refractory shell, refractory shell around the metal foam insert helps to protect the metal foam insert from damage. The refractory shell is then taken to a shakeout table, and the refractory ceramic shell is removed. Once the metal foam insert is solidified and removed from the refractory shell, the metal foam insert is degated from the additional components. In the example embodiment, the metal foam insert is removed from the gates, runners, and sprues by machining. The final metal foam insert is then machined and cleaned and is ready for the final application(s). Figure 11 illustrates the degating step, and Figure 12 illustrates the machined metal foam insert 26 of the example embodiment. Figure 13 illustrates the typical structure of the finished metal foam insert 26 which includes a relatively or approximately uniform pore size.

[0043] The process used to form the metal foam insert can be similar to a "lost-foam casting process," such as the process shown in Figure 14, but also varies from the conventional lost-foam casting in several significant ways. For example, the method of the present invention includes forming the hard outer refractory shell around the metal foam, without any permeation, for example an alumina (AI2O₃) based hard, non-permeable shell. The lost-foam slurry, however, has a great deal of permeability, which allows the gas created by the vaporized foam pattern to escape through the coating and into the sand. The slurry used to form the refractory shell on the polystyrene-based foam preform of the present invention provides for little or no permeability. In the conventional lost-foam casting process, controlling permeability is a crucial step to avoid sand erosion. It is also noted that the refractory shell of the present invention resembles an investment casting shell more than a lost-foam coating because no permeability is required. Under lost-foam casting conditions, the gases formed at the metal front escape out of the mold and casting, so there is no substantial gas layer ahead of the flowing melt. In the process of the present invention, a vaporized gas layer is generated so that the gas bubbles are trapped in a controlled manner and create the stable aluminum or magnesium-based foam structure. Also, in the lost-foam casting process, there are no foam stabilizers, such as S1O2, AI2O₃, TiB₂, TiC, TiH₂, or SiC, etc., embedded in the polystyrene. In addition, the lost-foam casting process utilizes a flask that is backed up with un-bonded silica sand. The sand is usually rained into the flask from an overhead sand bin and then compacted. The unbonded sand is usually compacted from approximately 90 lbs/ft³ to 100 lbs/ft³. The process of the present invention does not require the flask or the sand. Finally, once the lost-foam casting has been poured, the process utilizes a gas flame with forced air over the sand in order to burn off the residual gas escaping from the flask, unlike the process used to form the metal foam insert of the present invention. Figure 15 illustrates the lost-foam casting flask with the loose sand being burned out.

[0044] According to the present invention, once the molten metal of the metal foam insert is solidified, the metal foam insert can be removed from the mold and used in a subsequent casting process. The metal foam insert is typically highly stable and homogeneous. The particle size, particle size distribution, and porosity of the finished metal foam insert are typically determined by experimental data. Generally, the finer the pore size, the more enhanced the properties. The polystyrene beads themselves are typically quantified with a statistical analysis that would look similar to Figure 16. The polystyrene beads could be separated into different sizes, by floating, etc., in order to obtain the best polystyrene size for the optimum metal foam insert pore size. An optimized sequence of the polystyrene bead particle size of the polystyrene-based foam preform could be achieved by modeling the metal foam insert and determining how the modified polystyrene beads vaporize and how the gas is released based on bead size. An example of an optimized sequence of the polystyrene bead particle size used to form the metal foam insert is shown in Figure 17. The size and distribution of the polystyrene beads could be arranged as to different sizes during the vaporization sequence to create different metal foam pore sizes and/or tailored mechanical properties for light weighting in different areas of the metal foam insert. For example, larger metal foam pore size provides for reduced weight but diminished mechanical properties, and smaller metal foam pore size provides for a heavier product but increased mechanical properties. The gas entering the metal wave front could be customized by using different nominal polystyrene bead sizes in order to create the smallest relatively or approximately uniform metal foam insert pore size. Also, complex 3D patterning of the metal foam insert can be achieved through multiple and interfacial layering.

[0045] Preferably, the metal foam insert has a closed section, and thus the vertical stiffness for each section is larger compared to an open section design. At twice the section thickness, the stiffness of the metal foam insert would decrease by 54%. The weight of the metal foam insert is also reduced by around 30% due to decreased density, compared to the conventional metal foams. Figure 18 illustrates the specific bending stiffness compared to height of the metal foam insert in the form of a sheet according to an example embodiment. As indicated above, the metal foam insert achieves a more uniform pore size compared to the conventional metal foams. The conventional methods used to create metal foam have issues creating an approximately or relatively uniform a pore size. If the pore size is not relatively or approximately uniform, it becomes very difficult to model and thus very difficult to predict the properties of the material. The metal foam insert of the present invention has a stable and relatively or approximately uniform pore size, primarily due to the unique and novel way that the foam is created directly from modified polystyrene beads.

[0046] The invention also provides the structural component formed by casting using the metal foam insert, and the casting process using the metal foam insert. The casting process includes disposing the metal foam insert in a mold cavity, which may or may not contain sand. The metal foam insert provides a surface roughness needed for the stability to print into an actual HPVDC HI 3 tooling of the example embodiment and prevent gas from escaping. As shown in Figure 19, core-prints are used, which are impressions in the tooling 28 allowing the metal foam insert 10, also referred to as the core, to be set and retained in a proper position in the mold during casting of the structural component. The core print allows the metal foam insert to stay in place and not be displaced by the forced and/or velocity of the molten metal entering the tool. Figure 19 also illustrates the other components typically used in the tooling 28, in this case a two-part sand casting mold.

[0047] The process further includes pouring another molten metal into the mold cavity around the metal foam insert to form the structural component. The molten metal conforms to the shape of the metal foam insert, which is typically a desirable shape depending on the application of the structural component. For example, the metal foam insert forms a metallurgical bond with the molten metal during the HPVDC filling cycle. When the metal foam insert is used to form the structural component for the floor panel application, the metal foam insert is introduced as a ribbon between two solidifying sheets or thin plates of metal.

[0048] The stability of the metal foam insert is especially beneficial for structural components of two applications, including the hollow core structure formed by HPVDC and the NVH sheet panels for body floor panels. It has been found that the lightweight and highly stiff thin walled body structure of the finished structural component is superior to anything currently in the market. The structural component formed using the metal foam insert could also be used in chassis applications and floor pan structures. Figure 20 illustrates a front engine cradle 30 in grey with the metal foam insert 26 as the core in blue formed by HPVDC. Figure 21 illustrates additional detail of the front engine cradle 30 of Figure 20. Figure 22 illustrates a NVH sheet of the metal foam insert 26 for autobody floor applications. Figure 23 illustrates a sheet of the metal foam insert 26 for miliary applications. [0049] Many modifications and variations of the present disclosure are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the invention.

Claims

Claim 1. A method for manufacturing a metal foam insert for use in casting of a structural component, comprising the steps of: providing a foam preform, the foam preform including beads with pores therebetween, the beads being polystyrene-based; applying at least one refractory coating formed of ceramic to the foam preform; and casting metal onto the coated foam preform to form the metal foam insert, the metal being aluminum-based or magnesium-based.

Claim 2. A method according to Claim 1, wherein the polystyrene-based beads of the foam preform are impregnated with an aluminum and/or magnesium stabilizer selected from the group consisting of SiC , AI2O₃, TiB₂, TiC, TiH₂, and/or SiC.

Claim 3. A method according to Claim 1, wherein the polystyrene-based beads of the foam preform have an approximately uniform particle size.

Claim 4. A method according to Claim 1 , wherein the step of casting metal onto the coated foam preform is conducted according to the following equation 2: r_v = r_v (<¾ , x_v) = a exp (-E/R <¾ ) (1- x_v)ⁿ equation 2 where:

r_v = gas production rate

q_M = production rate

x_v = gas fraction

a = reaction rate (kg/m²-s)

E = activation energy (J/mole)

R = universal gas constant

n = reaction order

Claim 5. A method according to Claim 1, wherein the foam preform has a pattern formed by hand cutting, machining from a solid block of pre-impregnated polystyrene foam, or injection molding.

Claim 6. A method according to Claim 1, wherein the foam preform is formed of approximately 97.5 vol. % air and 2.5 vol. % of polystyrene and the stabilizers, based on the total volume of the foam preform.

Claim 7. A method according to Claim 1, wherein the foam preform decomposes during the casting step.

Claim 8. A metal foam insert formed by the method of Claim 1.

Claim 9. A metal foam insert according to Claim 8, wherein the metal foam insert includes pores and has an approximately uniform pore size.

Claim 10. A method for manufacturing a structural component, comprising the steps of:

providing a foam preform, the foam preform including beads with pores therebetween, the beads being polystyrene-based;

applying at least one refractory coating formed of ceramic to the foam preform; casting a first metal onto the coated foam preform to form the metal foam insert, the metal being aluminum-based or magnesium-based; and casting a second metal onto the metal foam insert.

Claim 11. A method according to Claim 10, wherein the step of casting the second metal onto the metal foam insert includes high pressure vacuum die casting.

Claim 12. A method according to Claim 10, wherein the step of casting the first metal onto the coated foam preform is conducted according to the following equation 2: r_v = r_v (<¾ ,x_v) = a exp (-E/R <¾ ) (1- x_v)ⁿ equation 2 where:

r_v = gas production rate

q_M = production rate

x_v = gas fraction

a = reaction rate (kg/m²-s)

E = activation energy (J/mole)

R = universal gas constant

n = reaction order

Claim 13. A structural component formed by the method of Claim 10.

Claim 14. A structural component according to Claim 13, wherein the structural component is a component of an automotive vehicle.

Claim 15. A structural component according to Claim 14, wherein the structural component is a front engine cradle or a sheet of a body floor panel of an automotive vehicle.