TWELVE-CORNERED STRENGTHENING MEMBER
A crush can to an automotive vehicle has a twelve-cornered cross section comprising sides and corners creating internal angles and external angles. A geometry of the cross section varies between a front section and a rear section of the crush can. The geometry of the cross section is optimized using a plurality of control parameters including a lateral width, a vertical width, a taper ratio, a front scaling factor, and a rear scaling factor.
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This application is a divisional of U.S. patent application Ser. No. 12/891,801, filed Sep. 27, 2010, which is a continuation-in-part of U.S. patent application Ser. No. 12/233,808, filed Sep. 19, 2008 (now U.S. Pat. No. 8,539,737), the entire content of each of which is incorporated herein by reference.
INTRODUCTIONThe present teachings relate generally to a strengthening member for a vehicle body or other structures. The present teachings relate more specifically to a strengthening member having a twelve-cornered cross section.
BACKGROUNDIt is desirable, for vehicle strengthening members, to maximize impact energy absorption and bending resistance while minimizing mass per unit length of the strengthening member.
When a compressive force is exerted longitudinally on a strengthening member, for example a force due to a front impact load on a vehicle's front rail or other strengthening member in the engine compartment, the strengthening member can crush in a longitudinal direction to absorb the energy of the collision. In addition, when a bending force is exerted on a strengthening member, for example a force due to a side impact load on a vehicle's front side sill, B-pillar or other strengthening member, the strengthening member can bend to absorb the energy of the collision.
U.S. Pat. No. 6,752,451 discloses a strengthening member having concave portions at the four corners of a basic rectangular cross section, resulting in four U-shaped portions forming an angle of 90 degrees with each other. To avoid cracks at the concave portions at the four corners and to increase strength, the concave portions have increased thickness and hardness. Increased thickness and hardness of the corner portions is disclosed to be achievable only by drawing or hydroforming, and therefore decreases manufacturing feasibility while increasing the mass per unit length of the strengthening member.
U.S. Pat. No. 6,752,451 makes reference to Japanese Unexamined Patent Publication No. H8-337183, which also discloses a strengthening member having concave portions at the four corners of a basic rectangular cross section, resulting in four U-shaped portions forming an angle of 90 degrees with each other. U.S. Pat. No. 6,752,451 states that its thickened concave portions provide improved crush resistance and flexural strength over H8-337183.
It may be desirable to provide a strengthening member configured to achieve the same or similar strength increase as provided by the thickened corners, while minimizing mass per unit length of the member and maintaining a high manufacturing feasibility.
It may further be desirable to provide a strengthening member that can achieve increased energy absorption and a more stable axial collapse when forces such as front and side impact forces are exerted on the strengthening member. Additionally, it may be desirable to provide a strengthening member that possesses improved noise-vibration-harshness performance due to work hardening on its corners.
In various applications, a strengthening member can be used as a crush can attached directly to a bumper beam in alignment with a vehicle's front rails. Crush cans may, for example, manage impact energy and intrusion during a frontal collision. To protect a vehicle's occupants in high speed crash events, a crush can (as part of a vehicle's front end) acts as an energy absorber to absorb a maximum amount of impact energy within a limited crush distance (i.e., a crush can must absorb a high amount of impact energy over a short crush distance). To minimize vehicle repair costs in low speed crash events, however, a crush can must both absorb energy with a limited stroke and be sequentially collapsible within a low speed protection zone to avoid damage to costly vehicle components.
It may be desirable, therefore, to provide a method of optimizing a strengthening member to provide crush cans that are progressive, stable, and energy efficient in both high and low speed frontal impact events.
SUMMARYIn accordance with certain embodiments, the present teachings provide a method for optimizing a twelve-cornered strengthening member comprising: modeling a vehicle assembly including a strengthening member having a twelve-cornered cross section; parameterizing a geometry of the strengthening member with a plurality of control parameters; defining a design of experiment using the plurality of control parameters; modeling a vehicle using the vehicle assembly; simulating a frontal impact event with the vehicle; generating a response surface based on the frontal impact event; and determining a set of optimized control parameters for the strengthening member based on the response surface.
The present teachings additionally or alternatively provide a crush can for an automotive vehicle, the crush can having a twelve-cornered cross section comprising sides and corners creating internal angles and external angles, wherein a geometry of the cross section varies between a front section and a rear section of the crush can and is optimized using a plurality of control parameters including a lateral width, a vertical width, a taper ratio, a front scaling factor, and a rear scaling factor.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present teachings, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present teachings and together with the description, serve to explain certain principles of the teachings.
At least some features and advantages of the present teachings will be apparent from the following detailed description of exemplary embodiments consistent therewith, which description should be considered with reference to the accompanying drawings, wherein:
Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. The various exemplary embodiments are not intended to limit the disclosure. To the contrary, the disclosure is intended to cover alternatives, modifications, and equivalents.
The present teachings contemplate providing a strengthening member with a twelve-cornered cross section having a substantially increased stiffness throughout the sides and corners without increasing thickness within the corners. The strengthening member can achieve increased energy absorption and a more stable axial collapse when forces such as front and side impact forces are exerted on the strengthening member. The strengthening member can also possess improved durability and noise-vibration-harshness (NVH) performance due to work hardening on the twelve corners. The degrees of the internal and external angles of the present teachings can achieve the same strength increase as thickened corners, while minimizing mass per unit length of the member and maintaining a high manufacturing feasibility because the member can be formed by bending, rolling, stamping, pressing, hydro-forming, molding, extrusion, cutting, and forging.
An exemplary embodiment of a twelve-cornered cross section for a strengthening member in accordance with the present teachings is illustrated in
In certain embodiments of the present teachings, a thickness of the sides and corners can range from about 0.7 mm to about 6.0 mm. In certain embodiments, the thickness of the sides is substantially the same as the thickness of the corners.
Conventional strengthening members having square or rectangular cross sections are widely used due to their high manufacturing feasibility. Because a strengthening member with a twelve-cornered cross section in accordance with the present teachings has substantially increased strength and stiffness without requiring thicker corner portions, it has a higher manufacturing feasibility than previously-contemplated twelve-cornered members that have thickened 90° corners. While still providing a desired strength, a strengthening member in accordance with the present teachings can be formed in one or multiple sections by, for example, bending, rolling, stamping, pressing, drawing, hydro-forming, molding, extrusion, cutting, and/or forging. Thus-formed sections can be joined via welding, adhesive, fastening, or other known joining technologies.
In accordance with certain exemplary embodiments of the present teachings, the thickness of the strengthening member may vary, for example, within one side or from side to side to optimize the overall axial crush and bending performance. Examples of such varied thickness embodiments are illustrated in
In comparing crash energy absorption of strengthening members of varying shapes having the same thickness and perimeter, as illustrated in
A twelve-cornered cross section in accordance with the present teachings is contemplated for use with a number of structural members such as a front rail, a side rail, a cross member, roof structures, and other components that can benefit from increased crash energy absorption. In addition, the present teachings can be applied to both body-on-frame and unitized vehicles, or other types of structures.
The embodiments of
For a front rail comprising SAE1010 material, a front rail as illustrated in
The embodiments of
For a convoluted front rail comprising SAE1010 material, a front rail as illustrated in
Strengthening members having a variety of cross sections are illustrated in
As can further be seen, the exemplary strengthening members with twelve-cornered cross sections having external angles of 108° and 124° show an overall increase in axial crush strength over twelve-cornered cross sections having external angles of 90°. In fact, deviation of the angles from 90° such that each internal angle is about the same as other internal angles and ranges from about 100° to about 110°, and each external angle is about the same as other external angles and ranges from about 105° to about 130°, increases strength without negatively affecting the stability of a crush mode of the strengthening member. Such an increase in strength obviates the need for reinforcing (e.g., thickening) the concave portions at the four corners of the strengthening member, decreasing weight and cost and increasing manufacturing feasibility.
Strengthening members in accordance with the present teachings can comprise, for example, steel, aluminum, magnesium, fiberglass, nylon, plastic, a composite, or any other suitable materials. Exemplary implementations of the strengthening member can comprise, for example, a high strength steel such as, for example, DP590, DP590R, or HSLA350. These three steels have similar yield strengths, but DP590 and DP590R have a higher tensile strength than HSLA350. DP590R has a ferrite-bainite microstructure and a slightly higher yield-to-tensile strength ratio than DP590.
In various applications, strengthening members, as detailed above, can be used as crush cans to manage impact energy and intrusion during a frontal collision.
In accordance with certain embodiments of the present teachings, when using a twelve-cornered strengthening member as a crush can, the design of the crush can may be optimized to provide a desired crush result (i.e., with respect to energy absorption and crush distance) for both high and low speed frontal impact events.
As used herein, the term high speed frontal impact event refers to a crash wherein the front end of a vehicle impacts an object at a high speed, such as, for example, a crash wherein the front end of a vehicle impacts an object while the vehicle is going at least 30 mph. As those of ordinary skill in the art would understand, such events may be simulated, for example, by various high speed frontal crash modes tests) designed to meet occupant injury metrics. Such modes, may include, for example, a 35 mph, 100% overlap, frontal rigid barrier mode (i.e., running a vehicle into a solid barrier at 35 mph); a 40 mph, 40% offset, deformable barrier mode (i.e., running a vehicle into a deformable barrier at 40 mph with a 40% offset so that only 40% of the front end of the vehicle impacts the barrier); and a 25-30 mph, 30° angular, rigid barrier mode (i.e., running a vehicle into a solid barrier at 25-30 mph and a 30° angle).
As used herein, the term low speed frontal impact event refers to a crash wherein the front end of a vehicle impacts an object at a low speed, such as, for example, a crash wherein the front end of a vehicle impacts an object while the vehicle is going 10 mph or less. As those of ordinary skill in the art would understand, such events may be simulated, for example, by various low speed frontal crash modes (i.e., tests) designed with objectives of minimizing the repair costs of a vehicle. Such modes may include, for example, a 15 kph (9.32 mph), 40% offset, 10° angular, rigid barrier mode (i.e., running a vehicle into a solid barrier at 15 kph and a 10° angle, with a 40% offset so that only 40% of the front end of the vehicle impacts the barrier).
In certain exemplary embodiments of the present teachings, the geometry of a cross section of a crush can be optimized using a plurality of control parameters. The control parameters may be generated, for example, using a parametric model of the crush can. As would be understood by those of ordinary skill in the art, any type of 3-dimensional structural modeling software and/or tools may be used to create the parametric model.
As shown below in Table 1 and illustrated in
As illustrated in
As illustrated in
As illustrated in
At step 201, the crush can 102 is parameterized using a parametric modeling tool. The present teachings contemplate using any known methods and/or techniques as would be understood by those of ordinary skill in the art to build a parametric model of the crush can 102. Certain exemplary embodiments of the present teachings consider, for example, building the parametric model using MeshWorks developed by Detroit Engineered Products Inc. (DEP) or Pro/ENGINEER developed by FTC®.
As explained in detail above, the geometry of the crush can 102 can be parameterized with a plurality of control parameters. In certain embodiments, for example, the geometry of the crush can 102 may be parameterized by generating a lateral width (Width_y), a vertical width (Width_z), a taper ratio, a front scaling factor, and a rear scaling factor. As above, the lateral width and the vertical width may generate dimensions for a front section 106 of the crush can 102 (see
As shown at step 202 of
At step 204, a vehicle is modeled, for example, using a finite element model based on the DOE (e.g., a vehicle subsystem or a full vehicle is modeled using a bumper/crush can assembly). As above, the present teachings contemplate using any known methods and/or techniques as would be understood by those of ordinary skill in the art to build a finite element model of the vehicle.
As shown at step 205 of
At step 207, a response surface is generated based on the performance output from the simulation. As those of ordinary skill in the art would understand, response surface methods (RSMs) are generally used to examine the “surface” or the relationship between a simulated response and the factors affecting the response. Regression models are used, for example, to analyze the response, focusing on the nature of the relationship between the response and the input factors rather than identification of important input factors. Accordingly, an RSM tries to interpolate available test data in order to locally or globally predict the correlation between the control parameters and the optimization objectives (i.e., the optimization problem). The present teachings contemplate using any known methods and/or techniques as would be understood by those of ordinary skill in the art to generate the response surface. Certain exemplary embodiments of the present teachings consider, for example, generating the response surface using a multi-objective optimization application, such as ModeFRONTIER™.
As would be understood by those of ordinary skill in the art, a set of optimized control parameters (i.e., for the crush can 102) may be determined based on the response surface. As indicated at step 208 of
In accordance with certain exemplary embodiments of the present teachings, as shown at step 210, the determined set of optimized control parameters may be validated, for example, by performing a confirmation run. As above, a crush can 102 may be modeled using the optimized control parameters, a frontal impact event may be simulated with a vehicle model including the crush can 102, and a performance output may be measured for the crush can 102. If the crush can's performance is acceptable, the optimization application may generate an optimum design for the crush can 102, as indicated by the last step 211, shown in the flow diagram of
As those of ordinary skill in the art would understand, the above method is exemplary only and not intended to be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred. Furthermore, the present teachings and claims are not intended to be limited to the above recited steps, and may include various additional steps and/or combinations of steps as would be understood by those of ordinary skill in the art.
ExampleTo further demonstrate the above optimization method, an exemplary crush can was modeled and experimental test runs were conducted, as shown and described below with reference to Table 2 and
As illustrated in Table 2, to optimize a twelve-cornered crush can, a bumper/crush can assembly was modeled and the geometry of the crush can was parameterized, establishing a set of baseline control parameters (Width_y=0, Width_z=0, taper ratio=1, front scaling factor=1.0, and rear scaling factor=1.0). To create a complete crush model, a vehicle subsystem, including the bumper/crush can assembly, was modeled as a rigid body (i.e., a body having nothing to deform behind it) with a lumped mass of 401 Kg at the vehicle's center of gravity. To establish a set of baseline performance outputs (a 1.32 Kg crush can with an 86.3 KN average crush force and 15381 J of energy absorption), a frontal impact event was simulated using a 35 mph, 100% overlap, frontal rigid barrier mode (i.e., the vehicle was run into a wall at an initial velocity (I.V.) of about 35 mph) to completely crush the crush cans.
Based on the defined DOE (see Table 1), the frontal impact event was then simulated using various combinations of the five control parameters (i.e., the bumper/crush can assembly was updated with various combinations of control parameters) to generate a response surface. To optimize the crush can dimensions, an optimization problem was defined to minimize the mass of the crush can, while providing energy absorption of greater than about 15 KJ for each can, and an average crush force of greater than about 100 KN and less than about 110 KN per can.
As illustrated in
There was, however, an imposed force constraint of 110 KN (e.g., to prevent deformation of rails behind the crush cans). Accordingly, as shown in
As shown in
In accordance with certain embodiments, to reduce complexity and save computation time, a sub-system model can be utilized to track crush can performance in a high speed frontal impact event by imposing derived constraints from a low speed frontal impact event (e.g., accounting for the carry-over strength from a vehicle's side-rails). For example, using an average side rail strength of about 130 KN, the strength of the crush can may be set at a lower level (e.g., 110 KN or less) to insure that the crush can crushed first (prior to the side rails). Accordingly, the crush or stroke during a low speed frontal impact event can be inherently minimized by maximizing the crush strength for the crush can (e.g., within the designated constraint). Thus, although both low speed and high speed crashes may be simulated using the above method (e.g., through simultaneous optimizations), a simple high speed model may track the high speed response and optimize the design to maximize energy absorption through the entire crush distance with a reduced crush can weight. The improved performance of the crush can may then be verified by spot checking a low speed event (i.e., since the low speed requirements were backed into the optimization problem in the form of constraints to the force level attained).
Thus, the method illustrated above with regard to Table 2 and
Although various exemplary embodiments shown and described herein relate to methods for optimizing a twelve-cornered crush can in an automobile bumper assembly, those having ordinary skill in the art would understand that the methodology described may have a broad range of application to strengthening members useful in a variety of applications. Ordinarily skilled artisans would understand, for example, how to modify the exemplary methods described herein to optimize the geometry of a strengthening member used in an application other than a bumper assembly.
Accordingly, while the present teachings have been disclosed in terms of exemplary embodiments in order to facilitate a better understanding, it should be appreciated that the present teachings can be embodied in various ways without departing from the scope thereof. Therefore, the present teachings should be understood to include all possible embodiments which can be embodied without departing from the scope of the teachings set out in the appended claims.
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the written description and claims are approximations that may vary depending upon the desired properties sought to be obtained by the present teachings. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.
It will be apparent to those skilled in the art that various modifications and variations can be made to the devices and methods of the present disclosure without departing from the scope of its teachings. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the teachings disclosed herein. It is intended that the specification and embodiment described herein be considered as exemplary only.
Claims
1. A crush can for an automotive vehicle, the crush can having a twelve-cornered cross section comprising sides and corners creating internal angles and external angles,
- wherein a geometry of the cross section varies between a front section and a rear section of the crush can and is optimized using a plurality of control parameters including a lateral width, a vertical width, a taper ratio, a front scaling factor, and a rear scaling factor.
2. The crush can of claim 1, wherein the internal angles of the front section of the crush can are not the same as the internal angles of the rear section of the crush can, and the external angles of the front section of the crush can are not the same as the external angles of the rear section of the crush can.
3. The crush can of claim 1, wherein the lateral width of the front section of the crush can is not the same as the lateral width of the rear section of the crush can and the vertical width of the front section of the crush can is not the same as the vertical width of the rear section of the crush can.
4. The crush can of claim 3, wherein the taper ratio raises or lowers a height ratio between the front section and a rear section of the crush can.
5. The crush can of claim 4, wherein the front scaling factor scales coordinates of inner corner points of the front section of the crush can and the rear scaling factor scales coordinates of inner corner points of the rear section of the crush can.
6. The crush can of claim 1, wherein the plurality of control parameters are generated using a parametric model of the crush can.
7. The crush can of claim 6, wherein the geometry of the cross section is optimized using an optimization algorithm for an optimal crush can performance with respect to energy absorption and crush distance for both high and low speed frontal impact events.
8. A method for optimizing a twelve-cornered strengthening member, the method comprising:
- modeling a vehicle assembly including a strengthening member having a twelve-cornered cross section;
- parameterizing a geometry of the strengthening member with a plurality of control parameters;
- defining a design of experiment using the plurality of control parameters;
- modeling a vehicle using the vehicle assembly;
- simulating a frontal impact event with the vehicle;
- generating a response surface based on the frontal impact event; and
- determining a set of optimized control parameters for the strengthening member based on the response surface.
9. The method of claim 8, wherein modeling the vehicle assembly comprises modeling a bumper and a crush can having a twelve-cornered cross section.
10. The method of claim 8, wherein parameterizing the geometry with a plurality of control parameters comprises generating a lateral width, a vertical width, a taper ratio, a front scaling factor, and a rear scaling factor.
11. The method of claim 10, wherein generating the lateral width and the vertical width comprises generating dimensions for a front section of the strengthening member.
12. The method of claim 11, wherein generating the taper ratio comprises generating a height ratio between the front section and a rear section of the strengthening member.
13. The method of claim 12, wherein generating the front scaling factor comprises generating a factor which scales coordinates of inner corner points of the front section of the strengthening member and generating the rear scaling factor comprises generating a factor which scales coordinates of inner corner points of the rear section of the strengthening member.
14. The method of claim 8, wherein defining a design of experiment comprises defining an upper bound value and a lower bound value for each of the plurality of control parameters.
15. The method of claim 8, wherein modeling a vehicle using the vehicle assembly comprises modeling a vehicle subsystem or a full vehicle based on the design of experiment.
16. The method of claim 8, wherein simulating a frontal impact event with the vehicle comprises measuring a performance output of the strengthening member during a high speed frontal impact event and/or a low speed frontal impact event.
17. The method of claim 16, wherein measuring a performance output of the strengthening member comprises measuring energy absorption, an average crush force, and a mass of the strengthening member.
18. The method of claim 17, wherein determining the set of optimized control parameters comprises defining an optimization problem including design objectives, design constraints, and design variables for the strengthening member.
19. The method of claim 18, wherein determining the set of optimized control parameters comprises searching for a solution to the optimization problem based on the response surface.
20. The method of claim 8, further comprising validating the set of optimized control parameters by simulating a frontal impact event with the set of optimized control parameters.
Type: Application
Filed: Dec 30, 2016
Publication Date: Apr 20, 2017
Applicant: FORD GLOBAL TECHNOLOGIES, LLC (Dearborn, MI)
Inventors: Tau TYAN (Northville, MI), James Chih CHENG (Troy, MI), Raj JAYACHANDRAN (Canton, MI), Ching-Hung CHUANG (Northville, MI), Yiping XIE (Ann Arbor, MI), Yuan WANG (Novi, MI), Leonard Anthony SHANER (New Baltimore, MI), Yu-Kan HU (Ypsilanti, MI)
Application Number: 15/395,524