Method for testing strength for rear bumper equivalent to test conducted on actual vehicle, calculation document obtained by the same, and strength test system for rear bumper equivalent to test conducted on actual vehicle

Abstract

To provide a method for a strength test for a rear bumper equivalent to a test conducted on an actual vehicle, a calculation document obtained by the method, and a strength test system for a rear bumper equivalent to a test conducted on an actual vehicle.SOLUTION: The method for a strength test for a rear bumper equivalent to a test conducted on an actual vehicle includes: the step of selecting a specific chassis frame from among a plurality of chassis frames; the step of selecting a specific plate-shaped stay from among a plurality of types of stays; the step of attaching a rear bumper prepared as a test target; and the measurement step of measuring the displacement amount of the rear bumper. The method includes the step of identifying the weakest frame in strength, and the step of selecting the specific stay including selecting the largest stay from among the plurality of types of stays.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for testing the strength of a rear bumper equivalent to a test conducted on an actual vehicle, a calculation sheet obtained by the method, and a system for testing the strength of a rear bumper equivalent to a test conducted on an actual vehicle. [Background technology]

[0002] Regarding automobile equipment, obtaining an "equipment type designation (E mark)" omits the technical review of the equipment. "Equipment type designation (E mark)" is a system that verifies in advance whether an automobile's equipment complies with national standards for safety, the environment, etc. Equipment that has been certified with this type designation is exempt from full inspection.

[0003] The automobile type designation system is a system in which the government inspects new vehicles before they are sold to see if they meet safety standards for braking performance, quality control systems, etc. Vehicles that pass the inspection are given a type designation by the government, which allows manufacturers to omit inspections of each mass-produced vehicle.

[0004] Regarding rear bumpers, by obtaining an "equipment type designation (E mark)" in advance, technical inspections relating to the rear bumper can be omitted for various automobiles to which the rear bumper is attached, thereby streamlining the inspection process for automobile sales.

[0005] In September 2021, safety standards were revised to strengthen safety standards for intrusion prevention devices, of which the rear bumper is a part.

[0006] As a result, rather than just checking the strength of the conventional plate-shaped stays and rear bumper, we decided to check the strength of the attachment to the chassis frame as well.

[0007] Therefore, when conducting a strength test on a rear bumper, it was necessary to perform the strength test on the rear bumper while it was attached to an actual vehicle. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-117957 Summary of the Invention [Problem to be solved by the invention]

[0009] However, it is extremely complicated and practically impossible to carry out strength tests on the same rear bumper for each vehicle model (type) while it is attached to an actual vehicle.

[0010] Therefore, there was a need for a method that could rationally omit inspections for rear bumpers, that is, a method that would allow "intrusion prevention devices" attached to substitutes for the rear bumpers of actual vehicles to comply with vehicle inspections.

[0011] An object of the present invention is to provide a strength testing method for rear bumpers equivalent to tests conducted on an actual vehicle, a calculation sheet obtained by the method, and a strength testing system for rear bumpers equivalent to tests conducted on an actual vehicle. [Means for solving the problem]

[0012] The invention according to claim 1 is a strength test method for a rear bumper equivalent to a test performed on an actual vehicle, the strength test method comprising: (I) preparing a rear bumper to be subjected to a strength test; (II) selecting a specific chassis frame from a plurality of chassis frames that vary by vehicle manufacturer and model, the specific chassis frame being selected from the plurality of chassis frames based on shape, size, and strength characteristics published by the vehicle manufacturer; (III) selecting a specific plate stay from a plurality of types of plate stays that are published and used by vehicle manufacturers; (IV) attaching the two chassis frames selected in step (II) to a stand in parallel with each other, attaching the plate-shaped stays selected in step (III) to the vicinity of the free ends of each of the two chassis frames, and attaching the rear bumper prepared as a test subject in step (I) to the chassis frames via the plate-shaped stays; (V) a measuring step of pressing a pressure element provided in a pressure device against a predetermined position of the rear bumper attached to the chassis frame via the plate-shaped stay in the step (IV) and measuring the displacement of the rear bumper; Including, The step (II) (a) calculating the section modulus (Z1, Z2, Z3···Zn), moment of inertia (I1, I2, I3···In), and cross-sectional area (A1, A2, A3···An) of the cross section of the chassis frame from dimensional data constituting the shape of the chassis frame used for a specific model of the vehicle manufacturer, among data made public by the vehicle manufacturer; (b) From the section modulus (Z1, Z2, Z3 Zn), moment of inertia (I1, I2, I3 In), and cross-sectional area (A1, A2, A3 An) of the cross section of the chassis frame calculated in the step (a), The chassis frame is most likely to bend when subjected to bending force. Chassis frame choice and The step (III) is carried out by selecting from a plurality of types of plate-shaped stays used by the specific vehicle manufacturer. Plate-shaped stays are most likely to bend when subjected to bending force. Plate-shaped stay choice The process comprises the steps of: The present invention relates to a method for testing the strength of a rear bumper, which is equivalent to a test performed on an actual vehicle.

[0013] The invention of claim 2 is a calculation sheet that describes measurement conditions and data related to the measurement results for a rear bumper strength test equivalent to the test performed on an actual vehicle described in claim 1, The data selected in step (II) Before Individual information on the chassis frame and Individual information of the plate-shaped stay selected in the step (III);A specified value for individual information of the rear bumper to be measured; Measurement conditions for the rear bumper to be measured; Information on the measurement results obtained in the step (V); It is stated that This relates to a calculation sheet obtained by a rear bumper strength test method that is equivalent to a test conducted on an actual vehicle.

[0014] The invention according to claim 3 is a method for testing the strength of a rear bumper equivalent to the test performed on an actual vehicle according to claim 1, The step (b) The chassis frame is assumed to be a cantilever beam, and two beams are selected near the free ends of each of the chassis frames. Choice The calculation is performed assuming that a rigid body of the same length as the plate-shaped stay is attached. By calculating the displacement at the tip of the rigid body, The chassis frame is most likely to bend when subjected to bending force. Chassis frame choice do, The present invention relates to a method for testing the strength of a rear bumper equivalent to a test performed on an actual vehicle, as set forth in claim 1.

[0015] The invention according to claim 4 is a strength test system for a rear bumper equivalent to a test performed on an actual vehicle, the strength test system comprising: (I-1) Among the data published by the vehicle manufacturer, data on the dimensions that constitute the shape of the chassis frame used for a specific model of the vehicle manufacturer, and (I-2) Data on dimensions that constitute the shapes of multiple types of plate-shaped stays that have been published and used by vehicle manufacturers, and a storage device storing the (II-1) calculating the section modulus (Z1, Z2, Z3...Zn), the moment of inertia (I1, I2, I3...In), and the cross-sectional area (A1, A2, A3...An) of the cross section of the chassis frame based on the dimensional data constituting the shape of the chassis frame stored in the storage device; (II-2) From the section modulus (Z1, Z2, Z3 Zn), moment of inertia (I1, I2, I3 In), and cross-sectional area (A1, A2, A3 An) of the cross section of the chassis frame calculated in (II-1), The chassis frame is most likely to bend when subjected to bending force. Chassis frame choice death, (II-3) Based on the data of dimensions constituting the shape of the plate-like stay stored in the storage device, Plate-shaped stays are most likely to bend when subjected to bending force. Plate-shaped stay choice do, A computing device; (III) by the computing device choice The two chassis frames can be mounted parallel to each other. , applicable The calculation device calculates the distance between the two chassis frames in the vicinity of their free ends. choice The plate-shaped stay can be attached to the chassis frame, and a rear bumper to be tested can be attached to the chassis frame via the plate-shaped stay. 、 A stand and (IV) a pressure device provided with a pressure element that applies pressure to a predetermined position of the rear bumper; comprising The present invention relates to a rear bumper strength testing system that is equivalent to a test conducted on an actual vehicle. [Effects of the Invention]

[0016] According to claim 1, there is provided a strength test method for a rear bumper equivalent to a test performed on an actual vehicle, the strength test method comprising: (I) a step of preparing a rear bumper to be subjected to a strength test; (II) a step of selecting a specific chassis frame from a plurality of chassis frames that differ for each vehicle manufacturer and model, the specific chassis frame being selected from the plurality of chassis frames based on the shape, dimensions, and strength characteristics disclosed by the vehicle manufacturer; (III) a step of selecting a specific plate stay from a plurality of types of plate stays that are disclosed and used by the vehicle manufacturer; and (IV) a step of attaching the two chassis frames selected in step (II) to a frame parallel to each other, attaching the plate stays selected in step (III) to the vicinity of the free ends of each of the two chassis frames, and attaching the front and rear stays to the chassis frames via the plate stays. The test method includes the steps of: attaching a rear bumper prepared as a test subject in the step (I); and (V) pressing a pressure element provided in a pressure device against a predetermined position of the rear bumper attached to the chassis frame via the plate-shaped stay in the step (IV) to measure the amount of displacement of the rear bumper, wherein the step (II) comprises the steps of: (a) calculating the section modulus (Z1, Z2, Z3...Zn), moment of inertia (I1, I2, I3...In), and cross-sectional area (A1, A2, A3...An) of the cross section of the frame from data of dimensions constituting the shape of the frame used in a specific model of the vehicle manufacturer among data made public by the vehicle manufacturer; and (b) calculating the section modulus (Z1, Z2, Z3...Zn), moment of inertia (I1, I2, I3...In), and cross-sectional area (A1, A2, A3...An) of the cross section of the chassis frame calculated in the step (a), The chassis frame is most likely to bend when subjected to bending force. Chassis frame choice and a step (III) of selecting a plate-shaped stay from a plurality of types of plate-shaped stays used by the specific vehicle manufacturer. Plate-shaped stays are most likely to bend when subjected to bending force. Plate-shaped stay choice Since the method comprises the steps of: Most flexible From the various types of plate stays that are published and used by each vehicle manufacturer Most flexible Because the stays are selected, a bumper that meets the strength test standards will also meet the strength test standards when used with other types of chassis frames and other types of plate-shaped stays, which has the effect of eliminating technical inspection for the rear bumper and allowing it to pass vehicle inspection.

[0017] According to the calculation report obtained by the rear bumper strength test method equivalent to a test conducted on an actual vehicle as claimed in claim 2, since it is based on a rear bumper strength test method equivalent to a test conducted on an actual vehicle, the effect is achieved that the rear bumper can pass the vehicle inspection with the calculation report and the strength test on which it is based.

[0018] According to the method for testing the strength of a rear bumper equivalent to a test performed on an actual vehicle according to claim 3, it is possible to provide a method for testing the strength of a rear bumper equivalent to a test performed on an actual vehicle, and to test a plurality of chassis frames that differ for each vehicle manufacturer and model. Most likely to bend when subjected to bending force From the various types of plate stays that are published and used by each vehicle manufacturer Most likely to bend when subjected to bending force Because the stays are selected, a bumper that meets the strength test standards will also meet the strength test standards when used with other types of chassis frames and other types of plate-shaped stays, so technical inspection of the rear bumper can be omitted, resulting in the streamlining of inspections for automobile sales.

[0019] According to claim 4, the strength test system for a rear bumper equivalent to a test conducted on an actual vehicle includes: (I-1) a storage device that stores data on dimensions constituting the shape of the chassis frame used for a specific model of the vehicle manufacturer, which data is publicly available from the vehicle manufacturer; and (I-2) data on dimensions constituting the shapes of a plurality of types of plate-like stays that are publicly available and used by the vehicle manufacturer. The strength test system further includes: (II-1) a storage device that stores data on dimensions constituting the shape of the chassis frame used for a specific model of the vehicle manufacturer, which data is publicly available from the vehicle manufacturer. (II-2) calculates the section modulus (Z1, Z2, Z3...Zn), moment of inertia (I1, I2, I3...In), and cross-sectional area (A1, A2, A3...An) of the cross section of the chassis frame based on dimensional data constituting the shape of the chassis frame stored in a memory device, and from the section modulus (Z1, Z2, Z3...Zn), moment of inertia (I1, I2, I3...In), and cross-sectional area (A1, A2, A3...An) of the cross section of the chassis frame calculated in (II-1), The chassis frame is most likely to bend when subjected to bending force. Chassis frame choice (II-3) based on the data of dimensions constituting the shape of the plate-like stay stored in the storage device, Plate-shaped stays are most likely to bend when subjected to bending force. Plate-shaped stay choice and (III) a computing device that performs the above-mentioned calculation. choice The two chassis frames can be mounted parallel to each other. , applicable The calculation device calculates the distance between the two chassis frames in the vicinity of their free ends. choice The plate-shaped stay can be attached to the chassis frame, and a rear bumper to be tested can be attached to the chassis frame via the plate-shaped stay. 、 and (IV) a pressure device provided with a pressure element that applies pressure to a predetermined position of the rear bumper. Most likely to bend when subjected to bending force From the various types of plate stays that are published and used by each vehicle manufacturer Most likely to bend when subjected to bending forceBecause the stays are selected, a bumper that meets the strength test standards will also meet the strength test standards when used with other types of chassis frames and other types of plate-shaped stays, so technical inspection of the rear bumper can be omitted, resulting in the streamlining of inspections for the automobile inspection and registration system (vehicle inspection). [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a diagram showing a rear bumper to be tested according to the present invention attached to a truck. FIG. [Figure 2] FIG. 1 is a diagram showing an example of a pattern of a chassis frame and a plate-shaped stay for each manufacturer, to which a rear bumper to be tested according to the present invention is attached. [Figure 3] 1 is a diagram showing a machine for carrying out a strength test on a rear bumper that is a measurement object according to the present invention. [Figure 4] 1 is a diagram showing pressing positions for a strength test of a rear bumper to be tested according to the present invention. FIG. [Figure 5A(1)] FIG. 10 is a diagram showing a model of the amount of deflection of a chassis frame. [Figure 5A(2)] FIG. 2 is a diagram showing a model of a chassis frame. [Figure 5B] FIG. 10 is a diagram showing a model of a stay. [Figure 5C] 10A and 10B are diagrams showing the state of displacement of a rear bumper measured in a strength test of the rear bumper to be tested according to the present invention. [Figure 6A] FIG. 10 is a diagram showing an example of a calculation sheet obtained by a rear bumper strength test method according to the present invention, which is equivalent to a test performed on an actual vehicle. [Figure 6B] FIG. 10 is a diagram showing an example of a calculation sheet obtained by a rear bumper strength test method according to the present invention, which is equivalent to a test performed on an actual vehicle. [Figure 7] 1 is a diagram showing an embodiment of a system for carrying out a strength testing method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] [Embodiment 1] A method for testing the strength of a rear bumper according to an embodiment of the present invention, which is equivalent to a test performed on an actual vehicle, will be described in detail below with reference to the accompanying drawings.

[0022] <Process (I)> Step (I) is a step of preparing a rear bumper to be subjected to a strength test. As shown in Figures 1 and 2, the rear bumper (2) that is the subject of the strength test in this embodiment is a part that should be installed behind the chassis (3) of the vehicle (1), and is attached via a plate-shaped stay (4) to the free end of the chassis frame (3) shown in Figure 2, which is a substitute for the chassis (3).

[0023] <Process (II)> Step (II) is a step in which a specific chassis frame (3) is selected from a plurality of chassis frames that differ for each vehicle manufacturer and model.

[0024] The chassis frame (3) shown in Figure 2 may vary in shape and material. Furthermore, each vehicle manufacturer produces multiple models of chassis frames (3), and the shape of the chassis frame (3) varies for each model. Step (II) is a step of selecting a chassis frame (3) to which a rear bumper (2) to be subjected to a strength test is attached from among chassis frames having different shapes depending on the vehicle manufacturer and model.

[0025] When selecting a chassis frame (3) to mount the rear bumper (2) that will be the subject of a strength test, information such as shape, dimensions, strength characteristics, etc. is required for strength calculations. Each vehicle manufacturer publishes information such as the shape, dimensions, strength characteristics, etc. of the chassis frame (3). Step (II) is a step of selecting a specific chassis frame from a plurality of chassis frames based on the shape, dimensions, and strength characteristics of the chassis frame (3) published by the vehicle manufacturer.

[0026] Each vehicle manufacturer produces a variety of chassis frames (3) of different sizes for each vehicle model. Among the multiple chassis frames (3) for each model Most likely to bend when subjected to bending force The chassis frame 3 has a thin plate thickness and a small outer diameter. Here, the plate thickness refers to the thickness of the steel plate used for the chassis frame 3, and the outer diameter refers to the sum of the frame height and flange length of the chassis frame. This is the representative for each model ( Most likely to bend when subjected to bending force chassis frame).

[0027] Representative by model ( Most likely to bend when subjected to bending force Compare chassis frames manufactured by the vehicle manufacturer to find the best chassis frame. Most likely to bend when subjected to bending force Identify the chassis frame. Specifically, it is determined by calculation using a formula through the following steps.

[0028] <Process (a)> A process of calculating the section modulus (Z1, Z2, Z3...Zn), moment of inertia (I1, I2, I3...In), and cross-sectional area (A1, A2, A3...An) of the cross section of the chassis frame (3) from dimensional data that constitutes the shape of the chassis frame (3) used in vehicles of the vehicle manufacturer weighing 16 tons or more, among data made public by the vehicle manufacturer. The "specific model" of the vehicle manufacturer in claim 1 refers to "the model used in vehicles of the vehicle manufacturer weighing 16 tons or more."

[0029] <Process (b)> From the section modulus (Z1, Z2, Z3 Zn), the moment of inertia (I1, I2, I3 In), and the cross-sectional area (A1, A2, A3 An) of the section of the chassis frame (3) calculated in the step (a), The chassis is most susceptible to bending when subjected to bending forces. and identifying the frame.

[0030] For each vehicle manufacturer Most likely to bend when subjected to bending forceBy selecting the chassis frame (3), the number of tests required to test the rear bumper (2), which is the subject of the strength test, can be reduced. In other words, the rear bumper (2) that is the subject of the strength test is Most likely to bend when subjected to bending force If the rear bumper is attached to the chassis frame (3) and tested, and the results meet the strength test standards, it can be assumed that the rear bumper subject to the strength test will also meet the strength test standards when attached to another chassis frame (3) of the vehicle manufacturer.

[0031] The chassis frame set by each manufacturer Most likely to bend when subjected to bending force By combining it with a plate-shaped stay, the section modulus, second moment of area, and cross-sectional area of ​​the chassis frame were investigated, Most likely to bend when subjected to bending force Identify the chassis frame.

[0032] Referring to FIG. 5A(1), in the step (b), The calculation is performed assuming that the chassis frame (3) is a cantilever beam and that a rigid virtual stay (4) is attached. By calculating the displacement amount at the tip of the virtual stay of the rigid body, Most likely to bend when subjected to bending force Identify the chassis frame.

[0033] Here, the conditions are summarized as follows: In order to observe the displacement of only the frame, the stay part is considered to be a rigid body. The rigidity between AB is EI, and the part between BC is a rigid body. The symbols in FIG. 5A(2) are as follows: Frame height h Flange length b Steel thickness t1 Steel thickness t2 Frame inner surface height h1 <Notes> The chassis frame that is normally installed on an actual vehicle is long, but one of the requirements for the RUPD test bench is that the frontmost fixed position of the RUPD and the test structure rigidity fixing device must be at least 500 mm apart during strength testing, and this requirement was also complied with in this case. First, from the bending moment acting on frame AB, calculate the deflection angle θ and horizontal displacement δx at point B. The deflection δx at point C caused by the rotation (θ) of the frame is calculated using the following formula: δx=θ·H The calculation method for the deflection angle θ and vertical displacement δy when AB is a cantilever beam is as follows. The bending moment acts uniformly as M=PL. Assuming that an elastic load PL / EI acts on a cantilever beam with span L, each can be calculated using the following equations. θ=PLH / EI δy=(PL 2 H) / (2EI) The calculation method for the total deflection of tip C is as follows: horizontal direction δx=θ·H=(PLH) / (EI)·H=(PLH 2 ) / (EI) Vertical direction δy=(PL 2 H) / (2EI) Based on the above, Most likely to bend when subjected to bending force The calculation method for identifying the chassis frame is as follows: (i) Calculate the moment of inertia I of the chassis frame (frame height (h), flange length (b), frame plate thickness (t1), frame inner surface height (h1)). When applying the formula for the cross-sectional properties of a C-type (channel), the calculation formula is as follows. I={b·h 3 -(b-t1)·h1 3} / 12 (ii) Set the load (P) to a constant value (180 kN or 85% of the total vehicle weight, whichever is smaller). (iii) Calculate the deflection angle (θ) at the base of the virtual stay (load (P), protrusion amount of the virtual stay (H), length of the chassis frame (L), elastic modulus of the chassis frame (E), second moment of area of ​​the chassis frame (I)). The calculation formula is as follows: θ= (P H L) / (E I) (iv) Calculate the vertical displacement (σy) at the tip of the virtual stay (load (P), protrusion of the virtual stay (H), length of the chassis frame (L), elastic modulus of the chassis frame (E), second moment of area of ​​the chassis frame (I)). The calculation formula is as follows: σy=(P·H·L 2 ) / (2 E I) (v) Calculate the horizontal displacement (σx) at the tip of the virtual stay (deflection angle (θ), protrusion amount of the virtual stay (H)) The calculation formula is as follows: σx= θ·H = {(P·H·L) / (E·I)}·H

[0034] In the state where the plate-shaped stay and the rear bumper to be tested are attached, Most likely to bend when subjected to bending force The chassis frame can be selected rationally.

[0035] <Process (III)> In step (III), a specific plate stay is selected from a plurality of types of plate stays that are published and used by vehicle manufacturers. choice This is the process.

[0036] In step (III), the plate-like stay (4) that is most likely to bend when subjected to a bending force is selected, and the vertical and horizontal displacements are calculated. The specific calculation method is as follows (see Figure 5B). <Cross-sectional characteristics of stays> The formula for calculation varies depending on the shape of the cross section of the mounting part or the cross section of the load position. These are commonly used for cross-sectional calculations of the stay mounting portion and the stay load position. Calculate the second moment of area (I1) of the mounting part (see Figure 5B, which is a diagram of the stay model). For I-type, the plate thickness (b) and length (h) are used and the calculation is done using the following formula. Cross-sectional area A=b×h Moment of inertia I=b×h 3 / 12 Section modulus Z=b×h 2 / 6 In the case of an L-type, the length (H), width (B), centroid distance (e1), centroid distance (e2), plate thickness (a), inner width (b), centroid distance (e1) - thickness (t) = (h) are used to calculate using the following formula (see Figure 5B, the stay model diagram). Cross-sectional area A=B×Hb(e2+h) Centroid distance e1=(aH 2 +bt 2 ) / {2(aH+bt)} e2=H-e1 Moment of inertia I=(Be1 3 -bh 3 +ae2 3 ) / 3 Section modulus Z=I / e1:Z=I / e2 The calculation method for the stay load position cross section is the same as above for both I-type and L-type. <Stay displacement calculation> The formula for calculating the horizontal displacement of a stay provided by the Japan Automobile-Body Industries Association is as follows: δ=2PH 3 / 3E(I1+I2) The second moment of area of ​​the stay mounting section is I1, and the second moment of area of ​​the stay load position section is I2. The vertical distance between the stay mounting part and the stay load position is H, and the horizontal distance is the outer diameter of the stay is L. <Stay displacement> Horizontal displacement δx=2×P×H 3 / {3×E×(I1+I2)} The calculation method for the deflection angle θ and vertical displacement δy of the stay is as follows: The bending moment M=PL acts uniformly on the stay mounting part. Assuming that the elastic load PL / EI acts on the stay height H, it can be calculated using the following formulas. The vertical displacement of the stay is Deflection angle θ=P×H×L / (E×I1) Vertical displacement δy=θ H=P×L×H / (E×I1)H=P×H 2 ×L / (E×I1) Select the largest size stay from multiple types of stays used by a specific vehicle manufacturer. , it may be selected as the stay that is most flexible. The largest size plate-shaped stay (4) means, for example, the one with the largest distance between the center point of the mounting location of the plate-shaped stay (4) and a point on the outer surface of the rear bumper (2) attached to the free end side of the chassis frame that is 60 mm away from the lowest end, but is not limited to this 60 mm point.

[0037] <Step (IV)> Attaching to the stand When testing a rear bumper (2) to be subjected to a strength test, the chassis frame (3), plate-shaped stays (4), and the rear bumper (2) to be subjected to the strength test are mounted on a frame (5) (also referred to as a rigid bench or test bench) shown in Fig. 3. Therefore, step (IV) is a step of mounting the two chassis frames (3) selected in step (II) parallel to each other on the frame (5), mounting the plate-shaped stays (4) selected in step (III) near the free ends of each of the two chassis frames (3), and mounting the rear bumper (2) prepared as a test subject in step (I) to the chassis frame (3) via the plate-shaped stays (4).

[0038] The rear bumper (2) has a vertical orientation, and when attaching the rear bumper (2) to the plate-shaped stays (4), either the vertical or horizontal orientation can be selected. However, depending on the shape of the plate-shaped stays (4), there may be orientations that are unfavorable in terms of strength. In this case, the rear bumper (2) should be attached to the plate-shaped stays (4) in the direction that is unfavorable in terms of strength.

[0039] <Step (V)> Pressure measurement Step (V) is a measurement step in which a pressure element (6) provided on a pressure device (5) is pressed against a plurality of predetermined positions of the rear bumper (2) attached to the chassis frame (3) via the plate-shaped stays (4) in step (IV), and the amount of displacement of the rear bumper (2) is measured.

[0040] As shown in FIG. 3 , the pressure device 5 includes a base 11, a chassis frame 3 mounting base 10, a pressure element 6, and a piston 7. The base 11 is a base supported by four pillars, and a chassis frame 3 mounting base 10 for fixing the chassis frame 3 can be placed and fixed on the base 11. The chassis frame 3 mounting base 10 is a base capable of fixing two chassis frames 3 identified in step (b). The chassis frames 3 are fixed to the chassis frame 3 mounting base 10 so as to be perpendicular to the base surface of the base 5. One plate-shaped frame 4 is fixed near each free end of the two fixed chassis frames 3. The rear bumper 2 to be subjected to a strength test is attached to the two fixed plate-shaped frames 4.

[0041] The pressure element (6) is a plate-like member having a vertical width sufficient to press at least the entire vertical width of the rear bumper (2) and a horizontal width sufficient to press at least two or more locations in the horizontal direction of the rear bumper (2) in sequence.

[0042] The piston 7 has a cylinder 8 and a rod 9, and the pressure element 6 is fixed to the tip of the rod 9. The cylinder 8 is filled with oil or water, and the pressure device 5 can generate pressure on the rear bumper 2 by pushing the pressure element 6 with the piston 7 using hydraulic or water pressure. The piston (5) is mounted on a beam provided on the ceiling side of the frame (11) so as to be able to move freely on a parallel axis that is parallel to at least the longitudinal direction of the rear bumper (2).

[0043] In the pressure device 5, the chassis frame 3 is attached to a mounting base 10 for the chassis frame 3, and a plate-shaped stay 4 is attached to the chassis frame 3. The rear bumper 2 to be subjected to a strength test is attached to the plate-shaped stay 4.

[0044] As shown in FIG. 4, a pressure device (5) presses a plurality of predetermined positions (five positions are shown in FIG. 4, but this is not limited to this) of the rear bumper (2) with pressure elements (6) provided on the pressure device (5). The order in which the loads are applied is not restricted as long as (ii) and (iv) are consecutive, and (i), (iii) and (v) are consecutive, in accordance with the UN regulations.

[0045] As shown in Fig. 5C, the rear bumper (2) pressed by the pressure device (5) is deformed when the pressure exceeds a certain force, and the displacement amount in a side view is measured. In Fig. 5C, the vertical displacement amount in a side view is represented as σy, and the horizontal displacement amount is represented as σx.

[0046] It is determined whether the vertical displacement σy and the horizontal displacement σx meet the strength test criteria.

[0047] <Calculation statement> In the case of rear bumpers, the strength, shape, etc. are specified in the safety standards, so a calculation sheet such as that shown in Figure 6 must be submitted.

[0048] If you submit a statement, please include the following: <1> The displacement of the rear bumper calculated by the calculation sheet falls within the safety standard value, <2> Most likely to bend when subjected to bending force The calculation is performed using the above and the calculation result is within the standard value. <3> There is no problem even with objects that are clearly superior to the test specimen in terms of structure or material (i.e., the amount of displacement is small). thing .

[0049] The items to be entered on the calculation sheet include the specified values ​​for the plate stays and chassis frame, the rear bumper to be measured, the calculation results for strength, and the measurement results for the rear bumper.

[0050] The specified values ​​refer to individual information about the plate-like stay and chassis frame, such as cross-sectional shape and dimensions, and individual information about the rear bumper to be measured, such as the cross-sectional height of the side surface.

[0051] Referring to Figure 5B, <1> The calculation methods for the vertical displacement (σy) and horizontal displacement (σx) of the rear bumper (2) in the calculation sheet are as follows: Most likely to bend when subjected to bending force When selecting the chassis frame (3), the amount of displacement in the vertical direction and the amount of displacement in the horizontal direction are calculated. Here, the symbols in FIG. 5B are as follows: 。 high Sa H External width B Inner width b Thickness t Centroid - thickness h Centroid distance 1 e1 Centroid distance 2 e2 centroid distance 1-thickness h Width and thickness a

[0052] Most likely to bend when subjected to bending force The plate-shaped stay (4) is selected, and the vertical displacement amount and the horizontal displacement amount are calculated. The specific calculation method is as follows. <Cross-sectional characteristics of stays> The formula for calculation varies depending on the shape of the cross section of the mounting part or the cross section of the load position. These are commonly used for cross-sectional calculations of the stay mounting portion and the stay load position. Calculate the second moment of area (I1) of the mounting part (see Figure 5B, which is a diagram of the stay model). For I-type, the plate thickness (b) and length (h) are used and the calculation is done using the following formula. Cross-sectional area A=b×h Moment of inertia I=b×h 3 / 12 Section modulus Z=b×h 2 / 6 In the case of an L-type, the length (H), width (B), centroid distance (e1), centroid distance (e2), plate thickness (a), inner width (b), centroid distance (e1) - thickness (t) = (h) are used to calculate using the following formula (see Figure 5B, the stay model diagram). Cross-sectional area A=B×Hb(e2+h) Centroid distance e1=(aH 2 +bt 2 ) / {2(aH+bt)} e2=H-e1 Moment of inertia I=(Be1 3 -bh 3 +ae2 3 ) / 3 Section modulus Z=I / e1:Z=I / e2 The calculation method for the stay load position cross section is the same as above for both I-type and L-type. <Stay displacement calculation> The formula for calculating the horizontal displacement of a stay provided by the Japan Automobile-Body Industries Association is as follows: δ=2PH 3 / 3E(I1+I2) The second moment of area of ​​the stay mounting section is I1, and the second moment of area of ​​the stay load position section is I2. The vertical distance between the stay mounting part and the stay load position is H, and the horizontal distance is the outer diameter of the stay is L. <Stay displacement> Horizontal displacement δx=2×P×H 3 / {3×E×(I1+I2)} The calculation method for the deflection angle θ and vertical displacement δy of the stay is as follows: The bending moment M=PL acts uniformly on the stay mounting part. Assuming that the elastic load PL / EI acts on the stay height H, it can be calculated using the following formulas. The vertical displacement of the stay is Deflection angle θ=P×H×L / (E×I1) Vertical displacement δy=θ H=P×L×H / (E×I1)H=P×H 2 ×L / (E×I1)

[0053] Calculate the horizontal displacement of the rear bumper (2). The reason why the vertical displacement of the rear bumper (2) is not calculated is because the vertical displacement of the rear bumper (2) is caused by the vertical displacement of the chassis frame (3) and the plate-shaped stays (4).

[0054] Most likely to bend when subjected to bending force The vertical displacement amount and horizontal displacement amount of the chassis frame (3), Most likely to bend when subjected to bending force The vertical displacement amount, horizontal displacement amount of the plate-shaped stay (4) and the horizontal displacement amount of the rear bumper (2) are added together.

[0055] <System> As shown in FIG. 7, the strength test method for a rear bumper (2) equivalent to a test performed on an actual vehicle may be configured as a system.

[0056] The rear bumper strength test system, which is equivalent to a test performed on an actual vehicle, includes storage devices (14, 15, 16) such as RAM and ROM, an arithmetic device (17) such as a CPU or processor, and a pressure device (5), and the arithmetic device (17) calculates the strength of the chassis frame (3) and the plate-like stays (4) based on the data stored in the storage devices (14, 15, 16). Most likely to bend when subjected to bending force Chassis frame (3) and Most likely to bend when subjected to bending force The plate-shaped stay (4) is calculated and selected. Most flexible Chassis frame (3) and Most flexible The system may be one in which a strength test of a rear bumper (2) that is the subject of a strength test can be performed by using a pressure device (5) and a plate-shaped stay (4).

[0057] The storage devices (14, 15, 16) may be divided into a first storage device (14) that stores the model of the chassis frame (3), a second storage device (15) that stores cross-sectional data of the chassis frame (3), and a third storage device (16) that stores the model of the plate-shaped stays (4). Any two of the first storage device (14), the second storage device (15), and the third storage device (16) may be configured as a single storage device.

[0058] Although not shown, it goes without saying that the pressure device (5) in Fig. 3 may have any structure that can be used by a person skilled in the art, in addition to the structure shown in the embodiment. It also goes without saying that the system in Fig. 7 may have any structure that can be used by a person skilled in the art, in addition to the structure shown in the embodiment.

[0059] In addition to the above-described embodiments, the present invention can be modified, changed, and altered in various ways within the scope obvious to those skilled in the art. [Industrial Applicability]

[0060] The method of testing rear bumpers for strength equivalent to testing on an actual vehicle according to the present invention eliminates the need to mount the rear bumper on an actual vehicle for strength testing, which can greatly contribute to eliminating the need for manufacturers that only produce and sell rear bumpers to apply for strength testing of rear bumpers for each model of each automobile manufacturer. [Explanation of symbols]

[0061] 1 vehicle 2 Rear bumper 3 Chassis frame 4 Plate-shaped stays 5. Pressure device 6 Pressure element 7 Pistons 8 cylinders 9 Rod 10 Chassis frame mounting base 11 Mounting stand 12 Pressing position 14 First storage device 15 Secondary storage device 16 Third Storage Device 17 Arithmetic unit

Claims

1. A strength test method for a rear bumper equivalent to a test performed on an actual vehicle, the strength test method comprising: (I) preparing a rear bumper to be subjected to a strength test; (II) selecting a specific chassis frame from a plurality of chassis frames that vary by vehicle manufacturer and model, the specific chassis frame being selected from the plurality of chassis frames based on shape, size, and strength characteristics published by the vehicle manufacturer; (III) selecting a specific plate stay from a plurality of types of plate stays that are published and used by vehicle manufacturers; (IV) attaching the two chassis frames selected in step (II) to a stand in parallel with each other, attaching the plate-shaped stays selected in step (III) to the vicinity of the free ends of each of the two chassis frames, and attaching the rear bumper prepared as a test subject in step (I) to the chassis frames via the plate-shaped stays; (V) a measuring step of pressing a pressure element provided in a pressure device against a predetermined position of the rear bumper attached to the chassis frame via the plate-shaped stay in the step (IV) to measure a displacement amount of the rear bumper; Including, The step (II) (a) calculating the section modulus (Z1, Z2, Z3...Zn), second moment of area (I1, I2, I3...In), and cross-sectional area (A1, A2, A3...An) of the cross section of the chassis frame from data of dimensions constituting the shape of the chassis frame used for a specific model of the vehicle manufacturer, among data published by the vehicle manufacturer; (b) identifying the chassis frame having the weakest strength from the section modulus (Z1, Z2, Z3...Zn), moment of inertia (I1, I2, I3...In), and cross-sectional area (A1, A2, A3...An) of the cross section of the chassis frame calculated in the step (a), The step (III) comprises a step of selecting a plate stay of a largest size from a plurality of types of plate stays used by the specific vehicle manufacturer. A method for testing the strength of a rear bumper equivalent to a test conducted on an actual vehicle.

2. A calculation sheet describing measurement conditions and data related to measurement results for a rear bumper strength test equivalent to the test performed on an actual vehicle according to claim 1, The data includes individual information of the plate-shaped stay and the chassis frame selected in the step (II), and specified values ​​for individual information of the rear bumper to be measured, Measurement conditions for the rear bumper to be measured; Information on the measurement results obtained in the step (V); It is stated that A calculation sheet obtained by a rear bumper strength test method equivalent to a test conducted on an actual vehicle.

3. 2. A method for testing the strength of a rear bumper equivalent to a test performed on an actual vehicle according to claim 1, The step (b) The calculation is performed assuming that the chassis frame is a cantilever beam and that a rigid body having the same length as the selected plate-like stay is attached to the vicinity of each free end of the two chassis frames. Identifying the chassis frame with the weakest strength by calculating the displacement at the tip of the rigid body.

2. The method of testing the strength of a rear bumper equivalent to a test performed on an actual vehicle according to claim 1.

4. A strength test system for a rear bumper equivalent to a test performed on an actual vehicle, the strength test system comprising: (I-1) Among the data published by the vehicle manufacturer, data on the dimensions constituting the shape of the chassis frame used for a specific model of the vehicle manufacturer; and (I-2) Data on dimensions constituting the shapes of multiple types of plate-shaped stays published and used by vehicle manufacturers, a storage device storing the The strength testing system further comprises (II-1) Calculating the section modulus (Z1, Z2, Z3... Zn), the second moment of area (I1, I2, I3... In), and the cross-sectional area (A1, A2, A3... An) of the cross section of the chassis frame based on the dimensional data constituting the shape of the chassis frame stored in the storage device, (II-2) Identify the chassis frame with the weakest strength from the section modulus (Z1, Z2, Z3... Zn), second moment of area (I1, I2, I3... In), and cross-sectional area (A1, A2, A3... An) of the cross section of the chassis frame calculated in (II-1), (II-3) Select the plate-shaped stay with the weakest strength based on the dimensional data constituting the shape of the plate-shaped stay stored in the storage device. A computing device; (III) The two chassis frames identified by the calculation device can be mounted parallel to each other; a platform on which the plate-shaped stays identified by the computing device can be attached to the vicinity of the free ends of the two chassis frames, and a rear bumper to be tested can be attached to the chassis frames via the plate-shaped stays; (IV) a pressure device provided with a pressure element that applies pressure to a predetermined position of the rear bumper; comprising A rear bumper strength testing system that is equivalent to testing performed on an actual vehicle.

Images