A method for predicting the fatigue durability life of a car door

Abstract

This invention belongs to the field of automotive technology, specifically a method for predicting the fatigue durability life of a car door. It includes the following steps: Step 1, obtaining the theoretical fatigue life curve of a first car door; Step 2, setting a reasonable initial life correction coefficient; Step 3, generating a second car door fatigue life curve based on the initial life correction coefficient and the theoretical fatigue life curve of the first car door; Step 4, determining the correction coefficient cluster; Step 5, confirming the final fatigue life prediction curve of the car door based on the second car door fatigue life curve and the correction coefficient cluster; Step 6, obtaining the predicted life at the strain value of the point of interest, i.e., through the final fatigue life prediction curve of the car door. This invention predicts the life of a car door during testing, anticipates risks in advance, saves design change time for development and verification, shortens the development cycle and testing costs, and has high practicality.

Description

Technical Field

[0001] This invention belongs to the field of automotive technology, specifically a method for predicting the fatigue durability life of car doors. Background Technology

[0002] Bench testing, as a crucial method for verifying component reliability, offers advantages such as short cycle time, low cost, good repeatability, and high controllability. With the development of automotive technology, bench testing also demands more realistic representation of various operating conditions experienced by real-world users. Therefore, verifying the durability of door systems via bench testing has become a trend. Current door opening and closing durability tests typically require 100,000 cycles, with each test lasting 18 days. This lengthy testing cycle often necessitates waiting 18 days before a conclusion is reached regarding the suitability of the solution, hindering the rapid development and verification of theoretical solutions. Therefore, shortening the testing cycle and predicting the feasibility of a solution in advance has become a critical issue. Summary of the Invention

[0003] This invention provides a method for predicting the fatigue durability life of a car door. It predicts the life of the car door during the test, anticipates risks in advance, saves time for design changes during development and verification, shortens the development cycle and test costs, and has high practicality. It solves the above-mentioned problems of existing methods for predicting the fatigue durability life of car doors.

[0004] The technical solution of this invention is described below in conjunction with the accompanying drawings:

[0005] A method for predicting the fatigue durability life of a vehicle door includes the following steps:

[0006] Step 1: Obtain the theoretical fatigue life curve of the first door;

[0007] Step 2: Set a reasonable initial lifetime correction factor;

[0008] Step 3: Generate the fatigue life curve of the second door based on the initial life correction factor and the theoretical curve of the fatigue life of the first door;

[0009] Step 4: Determine the correction coefficient cluster;

[0010] Step 5: Confirm the final fatigue life prediction curve of the door based on the fatigue life curve of the second door and the correction coefficient cluster;

[0011] Step 6: Obtain the predicted life at the strain value of the point of interest, i.e., through the door fatigue final life prediction curve.

[0012] Furthermore, the specific method for step one is as follows:

[0013] The SN curves of the easily failed locations of the car door are obtained as the theoretical curves for the fatigue life of the first car door.

[0014] Furthermore, the specific method for step two is as follows:

[0015] The initial life correction factor is initially determined based on the geometric characteristics, presence or absence of openings, surface quality, and presence or absence of reinforcing ribs of the vulnerable locations on the door.

[0016] Furthermore, the specific method for step four is as follows:

[0017] Based on the actual durability fatigue life, the second-stage life correction coefficient is determined; the second-stage life correction coefficient is the discrete point correction coefficient; the correction coefficient for each strain acquisition point is a set of correction coefficients, called the correction coefficient cluster.

[0018] Furthermore, the specific method for step five is as follows:

[0019] The correction value of the intermediate point is calculated based on the correction coefficient of each two adjacent discrete points, and the fatigue life curve of a certain point of interest of the second door is corrected to generate the final door fatigue durability life prediction curve.

[0020] The corrected formula is as follows:

[0021]

[0022] Where a and c are two discrete points spaced n times apart; b is any point between a and c; k a k is the correction coefficient for discrete point a; c is the correction coefficient for the discrete point c.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention features simple testing, low cost, short cycle time, and accurate prediction. Based on the materials and characteristics of the focus, it has the potential to create a fatigue durability life prediction database. The fatigue durability life prediction database for car doors can be extended to other models under development, showing a very broad range of applications. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0031] See Figure 1 A method for predicting the fatigue durability life of a car door includes the following steps:

[0032] Step 1: Obtain the theoretical fatigue life curve of the first door;

[0033] The specific method is as follows:

[0034] The SN curves of the easily failed locations of the vehicle door are obtained as the theoretical curves for the fatigue life of the first door. Easily failed locations include the sheet metal around the limiter mounting point, hinge mounting point, and lock mounting point. The theoretical fatigue life curves of the first door are basically the same for different locations of concern.

[0035] Step 2: Set a reasonable initial lifetime correction factor;

[0036] The specific method is as follows:

[0037] The initial life correction factor is initially determined based on the geometric characteristics, presence or absence of openings, surface quality, presence or absence of reinforcing ribs, and initial strain value information of the vulnerable locations of the vehicle door.

[0038] Step 3: Generate the fatigue life curve of the second door based on the initial life correction factor and the theoretical curve of the fatigue life of the first door;

[0039] Step 4: Determine the correction coefficient cluster;

[0040] The specific method is as follows:

[0041] Based on the actual durability fatigue life, the second-stage life correction coefficient is determined; the second-stage life correction coefficient is the discrete point correction coefficient; the correction coefficient for each strain acquisition point is a set of correction coefficients, called the correction coefficient cluster.

[0042] Step 5: Confirm the final fatigue life prediction curve of the door based on the fatigue life curve of the second door and the correction coefficient cluster;

[0043] The specific method is as follows:

[0044] The correction value of the intermediate point is calculated based on the correction coefficient of each two adjacent discrete points, and the fatigue life curve of a certain point of interest of the second door is corrected to generate the final door fatigue durability life prediction curve.

[0045] The corrected formula is as follows:

[0046]

[0047] Where a and c are two discrete points spaced n times apart; b is any point between a and c; k a k is the correction coefficient for discrete point a; c is the correction coefficient for the discrete point c.

[0048] Strain values ​​at key points are collected and recorded. Fatigue durability testing is then initiated, with the required number of cycles set (e.g., 500 cycles). The strain value at the key point is recorded after each cycle. This strain recording is repeated until sheet metal cracking or other failure phenomena occur at the key point. The strain value after every 500 cycles at the key point is then calculated. The strain value is plotted on the ordinate of the corresponding SN curve, and the cycle number on the abscissa. The resulting discrete points are marked on the fatigue life curve of a specific key point on the second door.

[0049] Based on the second door fatigue life curve and the correction coefficient cluster, the door fatigue final life prediction curve can be determined. The predicted life at the strain value of the point of interest can then be obtained from the door fatigue final life prediction curve. This results in a door fatigue durability life prediction curve that more closely matches the actual lifespan.

[0050] Step 6: Obtain the predicted life at the strain value of the point of interest, i.e., through the door fatigue final life prediction curve.

[0051] This invention features simple testing, low cost, short cycle time, and accurate prediction. Based on the materials and characteristics of the focus, it has the potential to create a fatigue durability life prediction database. The fatigue durability life prediction database for car doors can be extended to other models under development, showing a very broad range of applications.

[0052] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the scope of protection of the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, any person skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention within the scope of the technology disclosed in the present invention. These simple modifications are all within the scope of protection of the present invention.

[0053] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0054] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for predicting the fatigue durability life of a vehicle door, characterized in that, Includes the following steps: Step 1: Obtain the theoretical fatigue life curve of the first door; Step 2: Set the initial lifetime correction factor; Step 3: Generate the fatigue life curve of the second door based on the initial life correction factor and the theoretical curve of the fatigue life of the first door; Step 4: Determine the correction coefficient cluster; Step 5: Confirm the final fatigue life prediction curve of the door based on the fatigue life curve of the second door and the correction coefficient cluster; Step 6: Obtain the predicted life of the point of interest under the strain value through the fatigue final life prediction curve of the car door. The specific method for step four is as follows: The second-stage life correction factor is determined based on the actual durability fatigue life; the second-stage life correction factor is the discrete point correction factor; the correction factor for each strain acquisition point is a set of correction factors, called the correction factor cluster; The specific method for step five is as follows: The correction value of the intermediate point is calculated based on the correction coefficient of each two adjacent discrete points, and the fatigue life curve of a certain point of interest of the second door is corrected to generate the final door fatigue durability life prediction curve. The corrected formula is as follows: ； Where a and c are two discrete points spaced n times apart; b is any point between a and c. The correction coefficient for discrete point a; is the correction coefficient for the discrete point c.

2. The method for predicting the fatigue durability life of a vehicle door according to claim 1, characterized in that, The specific method for step one is as follows: The SN curves of the easily failed locations of the car door are obtained as the theoretical curves for the fatigue life of the first car door.

3. The method for predicting the fatigue durability life of a vehicle door according to claim 1, characterized in that, The specific method for step two is as follows: The initial life correction factor is initially determined based on the geometric characteristics, presence or absence of openings, surface quality, and presence or absence of reinforcing ribs of the vulnerable locations on the door.

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