KR20220142121A - Method for analyzing stiffness change of vehicle front frame before and after accident repair and method for evaluating safety of repaired vehicle using thereof - Google Patents

Abstract

The present invention relates to a method for evaluating safety about a repaired vehicle by analyzing a stiffness change of a vehicle body due to an accident repair of the vehicle and, more specifically, to a method for analyzing stiffness changes of a vehicle front frame before and after an accident repair, and a repaired vehicle safety evaluation method using the same. In accordance with the present invention, in order to solve limitations of existing technology which is unable to solve vague distrust and anxiety about a repaired vehicle due to inability to provide accurate information about the safety of the repaired vehicle, the method comprises the following steps of: conducting a crash test through the same method as that of an actual vehicle; checking a damaged part and the condition thereof in case of a crash which is the same as an actual vehicle crash through simulation; interpreting and analyzing a state change of the vehicle after repair through finite element analysis (FEA); and based on the analysis result, comparing stiffness changes of the vehicle body before and after the accident to check and evaluate the safety of the corresponding vehicle, thereby solving vague distrust and anxiety about the repaired vehicle and securing safety and reliability.

Description

Method for analyzing stiffness change of vehicle front frame before and after accident repair and method for evaluating safety of repaired vehicle using thereof

The present invention relates to a method of analyzing a change in the stiffness of a vehicle body according to an accident repair of a vehicle and evaluating the safety of a repaired vehicle based on the analysis result, and more particularly, generally, the skeleton of the vehicle body during a vehicle crash accident If damage or deformation occurs in major parts such as the frame or the frame, even if the damaged part is repaired, the strength of the car body will be lower than that at the time of initial shipment, which raises concerns about the performance and safety of the vehicle. In order to solve the problems of the prior art, in which a method for providing accurate information on the safety of a repaired vehicle was not provided in order to resolve such distrust or anxiety, although the value of the vehicle is greatly reduced due to the increase in distrust and anxiety. , A method of analyzing the stiffness change before and after accident repair of the vehicle front frame, and analyzing the change in stiffness before and after accident repair of the vehicle front frame, which is configured to evaluate the safety of the repaired vehicle through the result, and the safety evaluation method of the repaired vehicle using the same is about

In addition, the present invention, as described above, in order to solve the limitations of the prior art that could not solve the vague distrust and anxiety about the repaired vehicle because accurate information on the safety of the repaired vehicle was not provided, the current sales frequency in the domestic market One passenger car with a high value is selected and the vehicle's drawings, materials, and related data are used to conduct a crash test in the same way as the actual vehicle. , for example, through finite element analysis (FEA) using a commercial program to analyze the state changes of the vehicle accompanying the repair of a crash accident, such as tensile strength, F-D curve, relative displacement, etc. Based on this, it is configured to confirm and evaluate the safety of the vehicle by comparing the change in stiffness of the front frame before and after the accident, thereby resolving vague anxiety and distrust of the repaired vehicle and ensuring safety and reliability. It relates to a method for analyzing the stiffness change before and after accident repair of a front frame and a method for evaluating the safety of a repaired vehicle using the same.

Recently, as automobiles have been established as one of the main means of transportation, most households purchase automobiles and operate them for the purpose of business, commuting, and leisure activities. .

In addition, if a collision or contact accident occurs while driving the vehicle, repairs are made at the repair shop. On the other hand, in the case of damage to major parts in which body deformation occurs, such as the skeleton or frame of the vehicle body, distrust and anxiety about the vehicle being repaired increases due to concerns about vehicle performance and safety. There are many cases where the value goes down or a lawsuit is filed for collapse loss.

That is, in general, if the body frame, which is the main skeletal part, is deformed during a collision or contact accident of a vehicle, characteristics such as rigidity of the body frame are deteriorated compared to the time of initial shipment through the repair process. If the safety of the driver or passengers is not guaranteed due to the change in the rigidity of the vehicle body in the event of a re-accident while driving, a small accident can lead to serious personal injury.

Therefore, since the change in the rigidity of the vehicle body frame before and after the accident repair is a part directly related to the safety of the vehicle and the safety of the driver, it is desirable to accurately grasp the degree of the changed rigidity after the repair and to operate the vehicle after confirming the safety of the vehicle.

Here, as an example of the prior art related to the apparatus and method for analyzing the stiffness of a vehicle body as described above, first, for example, "a method of analyzing the stiffness of a vehicle body" as presented in Korean Patent Publication No. 10-1974892 There is this.

More specifically, in the above-mentioned Registered Patent Publication No. 10-1974892, a mass corresponding to the mass of the equipment or cover is set at a predetermined position within an area where the equipment or cover is fixed or connected to the fixed connection part of the vehicle body skeleton model. and a stiffness analysis step of performing a stiffness analysis in consideration of the inertial force acting on the mass-setting vehicle body skeleton model when the vehicle is running with respect to the mass-setting vehicle body skeleton model, comprising: Even before the equipment or cover is determined in the model, by setting the mass equivalent to these in place of the equipment or cover, the rigidity of the vehicle body is constructed so that accurate stiffness analysis can be performed in consideration of the inertial force acting when the vehicle is running. how to interpret it.

In addition, as another example of the prior art related to the apparatus and method for analyzing the rigidity of a vehicle body as described above, for example, "a method of analyzing the rigidity of a vehicle body" as presented in Korean Patent Publication No. 10-0288236 have.

More specifically, the above-mentioned Korean Patent Publication No. 10-0288236 provides a method comprising: performing a low-frequency idle vibration analysis through a vehicle body finite element model; Detailed modeling of the sensitive panel sensitive to high-frequency vibration from low-frequency idle vibration analysis and analysis data of previous vehicle models; setting a target stiffness for the panel sensitive part, and setting an excitation node, an excitation direction, and an excitation frequency region for high-frequency vibration analysis from analysis data of the previous vehicle model; Calculating the frequency response characteristics through random response analysis by point mobility of the panel sensitive unit with the excitation direction and the excitation node set in the set excitation frequency region; According to the frequency response characteristics, the rigidity level of the panel sensitive part is identified, and if the determined rigidity level is greater than the set rigidity target value, including the step of manufacturing a prototype car and performing a test evaluation, the booming area ( 200Hz to 400Hz), reduce the number of test cars manufactured by reflecting the improvement plan in the prior development stage by performing stiffness analysis on the stiffness level and sensitive parts for cowl, dash, follower, roof, package tray, spare tire room, etc. It relates to an automobile panel stiffness analysis method using point mobility, which is configured to reduce the production cost of automobiles by shortening the development period.

As described above, in the prior art, various technical contents for analyzing the rigidity of a vehicle body have been presented. However, since most of the contents of the prior art as described above are applied in the design or production stage of a vehicle, the limitations were clear.

That is, as described above, it is not possible to know how much the stiffness reduction occurs after the body frame is repaired, and as a result, the safety of the repaired vehicle is not guaranteed. In order to solve this problem, a method for analyzing the change in stiffness before and after accident repair of a body frame of a new configuration configured to confirm the safety of the repaired vehicle through analysis of the change in stiffness before and after repair of the vehicle body frame and vehicle safety using the same It is desirable to present an evaluation method, but a device or method that satisfies all such requirements has not yet been proposed.

Korean Patent Publication No. 10-1974892 (2019.04.26.) Korean Patent Publication No. 10-0288236 (2001.02.05.)

The present invention is to solve the problems of the prior art as described above, and therefore, an object of the present invention is to repair the damaged part when damage or deformation occurs in major parts such as the skeleton or frame of the vehicle body during a vehicle crash accident. Since the strength of the vehicle body is lowered compared to when it was initially shipped, concerns about the performance and safety of the vehicle arise. In order to solve the problem of the prior art in which a method that can provide accurate information on the safety of the repaired vehicle was not presented in order to solve the anxiety, the stiffness change before and after the accident repair was analyzed for the vehicle front frame, and the results were analyzed. The purpose of this study is to provide a method for analyzing the stiffness change before and after accident repair of a vehicle front frame, which is configured to evaluate the safety of a repaired vehicle, and a method for evaluating the safety of a repaired vehicle using the same.

In addition, another object of the present invention is to solve the limitations of the prior art that could not solve the vague distrust and anxiety about the repaired vehicle because accurate information on the safety of the repaired vehicle was not provided as described above. Select one passenger car with high sales frequency in and, for example, tensile strength, F-D diagram, relative displacement, etc., to analyze the state changes of the vehicle accompanying the repair of a crash accident through finite element analysis (FEA) using a commercial program, and based on the analysis results The vehicle front is configured to confirm and evaluate the safety of the vehicle by comparing the change in stiffness of the front and rear frame of the vehicle before and after the accident, thereby resolving vague anxiety and distrust of the repaired vehicle and ensuring safety and reliability. The purpose of this study is to provide a method for analyzing the stiffness change before and after accident repair of a frame and a method for evaluating the safety of a repaired vehicle using the same.

In order to achieve the above object, according to the present invention, in the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame, the specifications for various actual vehicles and data on the front collision test are collected, respectively, and the vehicle front frame A database building step in which the process of constructing a database for analyzing stiffness change before and after accident repair is performed; a modeling step in which a process of establishing an analysis model for a finite element analysis (FEA) for an analysis target vehicle to be analyzed is performed based on the contents of the database constructed in the database building step; a test step in which a process of measuring a state change before and after accident repair for the front frame of the vehicle to be analyzed is performed through a front collision test using a finite element analysis (FEA) using the analysis model modeled in the modeling step; and an analysis step in which, based on the test result of the test step, an analysis step of performing an analysis of a state change before and after accident repair is performed on the front frame of the analysis target vehicle is performed by a computer or dedicated hardware There is provided a method for analyzing stiffness change before and after accident repair of a vehicle front frame, characterized in that it is configured to be so.

Here, in the database building step, data on the specifications of various actual vehicles, data on the results of performing a front crash test for each vehicle, and data on the tensile test results before and after the repair of the front frame are collected, respectively. It is characterized in that by storing it in the form of a database, it is characterized in that the process of establishing a database for analyzing the stiffness change before and after the accident repair of the vehicle front frame is configured to be performed.

In this case, the database construction step includes crash test data according to a crash test method and a repair method based on the Research Council for Automobile Repairs (RCAR) or New Car Assessment Program (NCAP) standards for each vehicle and data on the state after repair It is characterized in that it is configured such that the process of collecting and building the database is performed.

In addition, in the test step, using the analysis model modeled in the modeling step, collisions before and after accident repair on the front frame of the vehicle to be analyzed for each speed through a front impact test using finite element analysis (FEA) and a process for measuring stiffness, stress, strain rate, energy absorption rate (Force), and displacement amount (Displacement), respectively, is configured to be performed.

In addition, in the analysis step, based on the test result of the test step, an F-D curve for energy absorption force and displacement is calculated, and before and after accident repair for the front frame of the vehicle to be analyzed The process of performing an analysis on the change in energy absorption according to the speed of and calculating a change in the amount of displacement over time for each speed and performing an analysis on the amount of displacement before and after accident repair on the front frame of the analysis target vehicle.

Furthermore, according to the present invention, there is provided a computer-readable recording medium in which a program is recorded, which is configured to cause the computer to execute the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame described above.

In addition, according to the present invention, in a safety evaluation method of a repaired vehicle, an inspection step in which a process of inspecting the state of the repaired vehicle is performed using the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame described above; and an evaluation step in which a process for evaluating the safety of the repaired vehicle is performed based on the inspection result of the inspection step, wherein the process is configured to be performed by a computer or dedicated hardware. this is provided

Here, in the evaluation step, based on the inspection result of the inspection step, when a specific inspection result value does not satisfy a predetermined reference value or a predetermined reference range, it is determined that the safety of the repaired vehicle is insufficient and operation is unsuitable It is characterized in that the processing is configured to be performed.

Alternatively, in the evaluation step, based on the inspection result of the inspection step, each inspection result value is compared with the value at the time of initial shipment of the repaired vehicle, and the difference between the specific inspection result value and the value at the time of initial shipment is a predetermined reference value However, when it does not satisfy the predetermined reference range, it is determined that the safety of the repaired vehicle is insufficient, and a process for determining that the operation is unsuitable is performed.

Alternatively, the evaluation step is configured to classify the safety of the repaired vehicle according to a predetermined criterion, and a process for determining the safety of the repaired vehicle by grade based on the inspection result of the inspection step is performed. do it with

As described above, according to the present invention, according to the present invention, one passenger car with high sales frequency in the domestic market is selected, and a crash test is performed in the same way as a real vehicle by using the drawings, materials, and related data of the vehicle, and simulation is performed. In the same collision as in the actual vehicle collision, the damaged part and condition are checked through A method of analyzing the stiffness change before and after accident repair of the vehicle front frame configured to check and evaluate the safety of the vehicle by analyzing it through analysis (FEA) and comparing the stiffness change of the vehicle body front frame before and after the accident based on the analysis result And by providing a safety evaluation method of the repaired vehicle using the same, the safety and reliability of the repaired vehicle can be secured, thereby eliminating vague anxiety and distrust of the repaired vehicle.

In addition, according to the present invention, as described above, the stiffness change analysis method of the vehicle front frame before and after accident repair is configured to analyze the change in stiffness before and after the accident repair with respect to the vehicle front frame and to evaluate the safety of the repaired vehicle through the result. And by providing a method for evaluating the safety of a repair vehicle using the same, when damage or deformation occurs in major parts such as the skeleton or frame of the vehicle body in a crash accident, the strength of the vehicle body is lower than that at the time of initial shipment even if the damaged part is repaired Therefore, there are concerns about the performance and safety of the vehicle, which increases vague distrust and anxiety about the vehicle being repaired, and the value of the vehicle decreases significantly. It is possible to solve the problems of the prior art in which a method for providing accurate information is not provided.

1 is a view showing the specifications of a test vehicle used in a crash test applied to an embodiment of the present invention in a table.
2 is a diagram schematically showing the contents of a finite element analysis modeling work applied to an embodiment of the present invention.
3 is a view showing a state of performing a test on the tensile strength of the vehicle frame.
Figure 4 is a view showing the results of comparing the tensile strength of the normal parts and the parts after welding is summarized in a table.
FIG. 5 is a view showing the results of comparing the errors for each part between the test results of the test vehicle and the test results of the analysis vehicle, arranged in a table.
6 is a graph showing the amount of deformation and force according to speed with respect to the front frame, which is a test component.
7 is a view showing an FD curve obtained for each speed through collision analysis for each speed with respect to the front frame, and is a view showing the FD curve for the front frame at 15 km/h.
8 is a view showing an FD curve obtained for each speed through collision analysis for each speed with respect to the front frame, and is a diagram showing the FD curve for the front frame at 30 km/h.
9 is a view showing an FD curve obtained for each speed through collision analysis for each speed with respect to the front frame, and is a view showing the FD curve for the front frame at 40 km/h.
10 is a view showing an FD curve obtained for each speed through collision analysis for each speed with respect to the front frame, and is a view showing the FD curve for the front frame at 50 km/h.
11 is a view showing the results of comparing the relative displacement after a collision test for each speed of a normal vehicle and a repair vehicle in which the front frame is welded in I-type and Z-type after an accident, the displacement with respect to the front frame at 15 km/h; ) is a diagram showing
12 is a view showing the results of comparing the relative displacement after a collision test for each speed of a normal vehicle and a repair vehicle in which the front frame is welded to I-type and Z-type after an accident, the displacement with respect to the front frame at 30 km/h; ) is a diagram showing
13 is a view showing the results of comparing the relative displacements after a collision test by speed of a normal vehicle and a repair vehicle in which the front frame is welded in I-type and Z-type after an accident, and the displacement with respect to the front frame at 40 km/h (Displacement) ) is a diagram showing
14 is a view showing the results of comparing the relative displacement after a collision test by speed of a normal vehicle and a repair vehicle in which the front frame is welded in I-type and Z-type after an accident, respectively, the displacement of the front frame at 50 km/h ( Displacement).
15 is a flowchart schematically showing the overall configuration of a method for analyzing a stiffness change before and after accident repair of a vehicle front frame according to an embodiment of the present invention.
16 is a flowchart schematically showing the overall configuration of a method for evaluating the safety of a repaired vehicle using a method for analyzing a change in stiffness before and after accident repair of a vehicle front frame according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, a specific embodiment of the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame according to the present invention and the safety evaluation method of the repaired vehicle using the same will be described.

Here, it should be noted that the content described below is only one embodiment for carrying out the present invention, and the present invention is not limited to the content of the embodiment described below.

In addition, in the following description of the embodiments of the present invention, for parts that are the same as or similar to those of the prior art, or that can be easily understood and implemented at the level of those skilled in the art, the detailed description is provided for the sake of brevity. It should be noted that o was omitted.

That is, in the present invention, as will be described later, when damage or deformation occurs in major parts such as the skeleton or frame of the vehicle body during a vehicle collision accident, even if the damaged portion is repaired, the strength of the vehicle body is lower than that at the time of initial shipment. Concerns about the performance and safety of the vehicle are raised, and as a result, vague distrust and anxiety about the vehicle being repaired increases, and the value of the vehicle is greatly reduced. In order to solve the problems of the prior art in which a method that can provide It relates to a method for analyzing changes in stiffness before and after accident repair of a frame and a method for evaluating the safety of a repaired vehicle using the same.

In addition, the present invention is currently sold in the domestic market in order to solve the limitations of the prior art that could not solve the vague distrust and anxiety about the repaired vehicle because accurate information on the safety of the repaired vehicle was not provided, as will be described later. One high-frequency passenger vehicle is selected and the vehicle's drawings, materials, and related data are used to conduct a crash test in the same way as the actual vehicle, and through simulation, the damaged area and condition are confirmed in the same collision as the actual vehicle. Thus, for example, through commercial programs, changes in the state of the vehicle accompanying the repair of a crash accident, such as tensile strength, F-D diagram, relative displacement, etc., are analyzed and analyzed, and based on the analysis results, the stiffness of the front frame of the vehicle body before and after the accident By comparing changes, it is possible to check and evaluate the safety of the vehicle, thereby resolving vague anxiety and distrust of the repaired vehicle, and analyzing the stiffness change before and after accident repair of the vehicle front frame, which is configured to secure safety and reliability. It relates to a method and a method for evaluating the safety of a repair vehicle using the same.

Then, with reference to the drawings, the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame according to the present invention and the specific content of the method for evaluating the safety of the repaired vehicle using the same will be described.

In general, the body of a passenger car is manufactured in a monocoque type, and is formed as an integrated body made by bending or overlapping several steel plates to maintain the rigidity of the body by welding. and mass production of vehicles.

Here, the vehicle body receives a load or adds a reinforcement to a part that requires vibration or rigidity or is specifically reinforced.

In other words, when repairing after a car accident, the deformed car body is pulled using a jig to maintain the basic frame, then the damaged part is stretched out and most of the original shape is maintained, and then the deformed car body is cut with a saw or cutter. , a welding operation is performed after cutting using a welding machine. At this time, the general damage repair operation process is to clean the surface of the welded area with a grinder or brush and then paint the area where thermal deformation has occurred.

In addition, the difference in stiffness and safety between the vehicle at the time of shipment and the vehicle after repair occurs due to a change in the stiffness of the vehicle body in the event of a re-accident while the vehicle is being operated after the completion of the accident repair. Therefore, in the present invention, as will be described later, a method for judging the safety of the repaired vehicle by comparing the change in stiffness before and after repairing the vehicle accident was proposed.

To this end, in the embodiment of the present invention to be described below, one passenger car with high sales frequency in the current domestic market is selected and a crash test is performed in the same manner as an actual vehicle by utilizing the drawings, materials, and related data of the vehicle. In the event of a collision the same as that of a real vehicle collision, the damaged area and condition are checked through simulation, for example, tensile strength, F-D curve, relative displacement, etc. The vehicle's condition change is analyzed through finite element analysis (FEA) using a commercial program, and the safety of the vehicle can be checked and evaluated by comparing the change in stiffness of the front frame before and after the accident based on the analysis result.

In more detail, first, with respect to the automobile crash test, there is a method of evaluating repair damage as a test method generally used by the World Research Council for Automobile Repairs (RCAR), which is, It is a test method that can represent the types of accidents that occur mainly in the middle and low speed sections, such as driving patterns on city roads, and evaluates the damage and repairability of new cars. When there is a car model with a lot of range and damaged parts and a car model with few parts, the car model with a lot of damage is judged to have bad damage, and when there is little damage, it is judged to have good damage.

In addition, in Korea, there is an RCAR test conducted by the Automobile Technology Research Institute under the Insurance Development Institute to calculate car insurance premiums before and after the launch of a new car for domestic sale. This is done in such a way that damage and repairability are assessed and graded.

In more detail, the repair cost is calculated by reflecting vehicle damage and repairability in a complex manner, and it is classified from the lowest grade to the highest grade of 26, and the damage and repairability evaluation grade is divided into grades 1 to 26 (26 steps). The higher the grade (closer to the 26th grade), the better the damage and repairability during a low-speed collision of the vehicle. , reflecting the paint evaluation) and the frequency index reflecting the damage rate of the vehicle.

Here, the vehicle's depth index (reflecting damage and repairability) is calculated by evaluating the impact characteristics, parts price, working hours, labor and painting labor for each model. The characteristics of damage and repairability due to the collision test on the rear side are indexed.

Next, when explaining the vehicle body repair method, the correction method when the front frame is deformed is largely divided into a sheet metal correction operation and a correction operation after a cutting operation. Measure in the diagonal and straight directions to determine the modified part and the degree of deformation, and use an oxygen welding machine to correct the frame by applying heat or correct the deformed part using a calibration sheet metal equipment such as a ceret, and then both lengths and angles Adjust the height to match.

Subsequently, the correction work process after the cutting operation is first, for the repair of the frame, using an oxygen welding machine, a saw, a plasma cutter, etc. After making the same shape as the cut part, butt welding is performed, and grinding and painting are performed.

Therefore, the characteristics of the body frame change through the repair process as described above, and among them, the change in stiffness is directly related to the safety of the vehicle and the safety of the driver, so the degree of stiffness changed (that is, decreased) after the repair It is desirable to evaluate the safety of the vehicle and determine whether to drive or not.

Accordingly, in the present invention, by applying the test method and repair method as described above, a crash test using an actual vehicle is performed, and the result of measuring the change in stiffness after repair and analysis using finite element analysis (FEA) Through this, the stiffness change analysis and safety evaluation were performed on the repaired vehicle.

More specifically, first, referring to FIG. 1 , FIG. 1 is a view showing the specifications of a test vehicle used in a crash test applied to an embodiment of the present invention in a table.

As shown in Figure 1, in the embodiment of the present invention, the test vehicle is a vehicle that is actually running in Korea, and the drawings and specifications were obtained after requesting the manufacturer's research institute, and the parts applied to the test are currently repair parts in the aftermarket. We purchased the parts to be sold, and selected an experienced mechanic who has been working for more than 20 years at the relevant vehicle service center to perform welding work.

In addition, referring to FIG. 2, FIG. 2 is a view schematically showing the contents of a finite element analysis modeling work applied to an embodiment of the present invention.

As shown in Figure 2, in the embodiment of the present invention, CAD data for finite element analysis (FEA) and modeling for analysis were applied, and then the test method, physical properties, tensile test, and variables were applied, and in the crash image and the actual vehicle. Through the process of comparative verification of the data, analysis and evaluation were carried out according to the previously recognized test method.

Here, the vehicle was determined to be in a normal state, and thermal deformation occurs in the actual vehicle when welding is performed in an actual accident repair vehicle. The analysis was performed by applying it, and the collision stiffness, stress, strain rate, and energy absorption rate were judged respectively in the normal vehicle and the analysis vehicle.

In addition, referring to FIG. 3 , FIG. 3 is a view showing a state in which a test for tensile strength of a vehicle frame is performed.

3, in the embodiment of the present invention, in order to test with the same parts as the frame of the vehicle, the material and location are checked in the same place as the body part of the actual vehicle, and the strength is changed after welding. To this end, a test site was cut using a new part in the frame of the vehicle, and a specimen was made and a tensile test was performed.

More specifically, first, since the inner plate and the outer plate are welded to the front frame part of the vehicle in two layers, check the deformation state and abnormality of the parts, and use an air saw to prevent thermal deformation of the material during cutting. The outer plate and inner plate were cut, and then, using a CO ₂ welder, an experienced mechanic performed butt welding, and a tensile strength test was performed.

That is, referring to FIG. 4 , FIG. 4 is a view showing the results of comparing the tensile strength of the normal parts and the parts after welding in a table.

Here, the test result shown in FIG. 4 is a test result by requesting a tensile test from the Korea Institute of Machinery and Electronics. The same parts as the front frame of the actual vehicle were applied to test the tensile strength after welding, and through this, the material properties It is possible to determine how much strength can be secured in the event of a collision by judging.

As shown in FIG. 4 , first, compared to the frame of a normal vehicle, when checking the frame inner and outer plates of the front frame after welding with CO ₂ compared to the frame of the normal vehicle, it can be confirmed that the rigidity of the frame after welding is weakened by about 20% compared to the normal frame. .

This can be used as indirect data to prove that the rigidity of the frame, which is the main part of the car body, is weaker than the initial state when repairing the welding after cutting due to a car accident, and there is a slight difference depending on the welding part, welding direction, and the skill of the mechanic. may occur, but it can be seen that the mechanical rigidity after repair is much weaker than when it was initially shipped.

In addition, since the front frame is double-bonded, if the inner part is not welded in the same way as the outer plate during welding after actual cutting, there is a part that cannot be welded on the inner side, so the strength may be lowered more than the first. may be

Next, the verification of test results by finite element analysis (FEA) will be described. Carrying out a crash test by causing a re-accident in a vehicle that has undergone accident repair is a very difficult situation to use in an actual vehicle due to the nature of the vehicle's collision. Although it is necessary to select many objects and vehicles to select a work area, testing is not easy due to too many limitations such as the limited number of test vehicles, test space, test cost, repeatability, and result analysis. In this embodiment, the test was conducted through finite element analysis (FEA).

To this end, modeling and verification were carried out using the Korean New Car Assessment Program (KNCAP) test method for the actual vehicle. was confirmed to occur.

That is, referring to FIG. 5 , FIG. 5 is a view showing the results of comparing errors for each part between the test results of the test vehicle and the test results of the analysis vehicle in a table.

As shown in FIG. 5 , in the embodiment of the present invention, the result value of the actual vehicle for the amount of deformation after the collision in the forward collision test and the result obtained by performing the test after modeling the analysis vehicle were respectively confirmed, and as shown in FIG. 5 , the actual vehicle An error of about 6% occurs compared to that, but it is considered that this is because the material properties of the barrier in the analysis vehicle cannot be equally applied to the analysis of the collision part.

Here, in the results shown in FIG. 5, the difference between the steering column part and the A-pillar is that the steering part is made of only iron plate by analysis in a state in which the interior material and plastic parts or rubber parts are removed. It has been confirmed that there is a slight difference from the A-pillar part, and the possibility of an error is considered to be insignificant because the 3D distance measurement data is used for the amount of deformation in the actual vehicle.

Continuingly, referring to FIG. 6, FIG. 6 is a graph showing test results using a vehicle welded after accident repair of a front frame, which is a test part, in order to check the amount of deformation and force by speed of a normal vehicle and a vehicle after repair. , represents the displacement and force according to the speed with respect to the front frame.

As shown in FIG. 6 , as a result of comparing the force and vehicle displacement during the collision test for each speed (Force vs Displacement), the front frame did not have a difference in energy absorption capacity (Force) and displacement at a speed of 40 km/h or less, but 40 km/h h and higher, a lot of difference occurred.

More specifically, referring to FIGS. 7 to 10 , FIGS. 7 to 10 show the speed of the front frame after a collision test by speed of a normal vehicle and a repair vehicle in which the front frame after an accident is welded in I-type and Z-type It is a view showing the F-D curves obtained for each speed through collision analysis, respectively. FIG. 7 is an F-D diagram for the front frame at 15 km/h, and FIG. 8 is F-D for the front frame at 30 km/h. Fig. 9 is an F-D diagram for the front frame at 40 km/h, and Fig. 10 shows an F-D diagram for the front frame at 50 km/h, respectively.

As shown in FIGS. 7 to 10 , in a comparative experiment between a normal vehicle and a welding vehicle with respect to the front frame, there was no significant difference in energy absorption capacity (Force) and displacement (Displacement) at a speed of 40 km/h or less, but 40 km/h At speeds above h, there is a clear difference, and it can be seen that the energy absorption capacity (Force) is lowered.

In addition, in the F-D diagram, it can be inferred that the welding vehicle after an accident has a severe change at 30 km/h and the vehicle body collapses due to the deformation of the frame, which means that the energy absorption rate is smaller than before, and the speed is increased. In the event of an accident, it is judged that the impact on the safety of passengers will be large.

Next, with reference to FIGS. 11 to 14 , the results of comparing the relative displacements after the collision test for each speed of the normal vehicle and the repair vehicle in which the front frame after an accident are welded in I-type and Z-type will be described.

That is, referring to FIGS. 11 to 14 , FIGS. 11 to 14 show the results of comparing the relative displacements after a collision test for each speed of a normal vehicle and a repair vehicle in which the front frame after an accident is welded in I-type and Z-type, respectively. As a drawing, FIG. 11 is a view showing displacement with respect to the front frame at 15 km/h, FIG. 12 is a view showing displacement with respect to the front frame at 30 km/h, and FIG. 13 is at 40 km/h. It is a diagram showing displacement with respect to the front frame, and FIG. 14 is a diagram showing displacement with respect to the front frame at 50 km/h, respectively.

11 to 14, as a result of analyzing the relative displacement after a crash test between a normal vehicle and a repair vehicle welded to I-type and Z-type after an accident, the front frame of the normal vehicle is stronger than the front frame of the repair vehicle welded It can be seen that the strength is, and when comparing I-type and Z-type, it can be confirmed that the Z-type is advantageous in relative displacement.

As described above, in the embodiment of the present invention, for a semi-medium monocoque body vehicle released in Korea, when the front frame is repaired after an accident, the front frame is cut and welded to I-type and Z-type, and the general maintenance method is a crash The middle part of the frame of the point was welded in I-type and Z-type, and the normal state before the accident and the collision stiffness after the accident repair were compared and judged using the F-D diagram and displacement amount of the repaired vehicle.

In addition, comparative tests and analysis were conducted through tensile tests and finite element analysis to check whether the damage of the repaired vehicle after an accident, which has recently become an issue, has impact on safety and whether it has collapsed damage. In the tensile strength test, it was confirmed that the strength of the material of the normal vehicle and the material after welding was reduced by about 20%. , it was confirmed that it was reduced by 2% at 40 km/h.

In addition, as a result of analyzing the change in the energy absorption rate after welding the front frame of the accident vehicle, the change was insignificant under the condition of 15 km/h, but the energy absorption rate of welding increased by 10 to 40% at 30 ~ 40 km/h, and the welding model at 50 km/h It became NG, and therefore, when a re-collision accident occurs after repairing the accident, there is no significant effect under the conditions of 15 to 30 km/h, but it is judged that it can cause damage to the passengers in the case of a re-accident at a speed of 30 km/h or more.

Moreover, even if the accident site is completely repaired, a difference occurs between the normal vehicle and the vehicle after repair when judged by the stiffness, internal energy, and F-D diagram. As a result of testing and testing the frame after welding in both I-type and Z-type methods, the Z-type is judged to be relatively superior. It is necessary to understand the double structure of the frame and review the working method, and it is judged that the work of a skilled person is necessary for the safety of the important part.

Therefore, it is possible to easily implement the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame according to the embodiment of the present invention and the method for evaluating the safety of the repaired vehicle using the same from the above contents. That is, referring to FIG. 15, FIG. 15 is a flowchart schematically showing the overall configuration of a method for analyzing stiffness change before and after accident repair of a vehicle front frame according to an embodiment of the present invention.

As shown in FIG. 15 , the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame according to the embodiment of the present invention is largely divided, and the data on the specifications of various actual vehicles and the results of performing the front crash test on the vehicle A database construction step (database construction step in which the process of constructing a database for analysis of stiffness change before and after an accident of the vehicle front frame is performed by collecting data on the data and data on the tensile test results before and after the repair of the front frame, respectively, and storing them in the form of a database ( S10) and based on the contents of the data about the actual vehicle stored in the database built in the database building step (S10), the processing of performing modeling for the finite element analysis of the analysis target vehicle to be analyzed is performed Using the vehicle model modeled in the modeling step (S20) and the modeling step (S20), the energy absorption force (Force) and the displacement (Displacement) for the front frame for each speed were measured through a front collision test using finite element analysis. Before and after accident repair on the front frame by calculating the F-D curve for the energy absorption force and displacement measured in the test step (S30) and the test step (S30) in which each measurement process is performed An analysis step (S40) in which an analysis of the change in energy absorption power according to the speed of It may be composed of

Here, in the database building step (S10) and modeling step (S20), as described above with reference to FIGS. 1 to 5, data is collected through a crash test and repair method according to the RCAR and KNCAP standards, and these Modeling for finite element analysis can be constructed using data.

In addition, the test step (S30) and the analysis step (S40) are, as described above with reference to FIGS. 6 to 14, collision stiffness and stress before and after accident repair on the front frame through a crash test using an analysis model. (Stress), strain rate (Strain rate) and energy absorption rate, etc. may be respectively measured, compared with the state at the time of initial shipment, and the process of grasping the current state of the repaired vehicle by analyzing it may be configured to be performed.

In addition, referring to FIG. 16, FIG. 16 is a flowchart schematically showing the overall configuration of a method for evaluating the safety of a repaired vehicle using the method for analyzing the stiffness change before and after accident repair of a vehicle front frame according to an embodiment of the present invention.

As shown in Fig. 16, the safety evaluation method of the repaired vehicle using the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame according to the embodiment of the present invention is performed as shown in the above-described steps (S10 to S40). Based on the inspection step (S50) and the inspection result in which the process of verifying the state of the vehicle after repair is performed, if the specific result value does not satisfy the predetermined reference value or range as a result of the analysis, the safety of the repaired vehicle is insufficient. Or, compare each inspection result value with the value at the time of initial shipment, and if the difference between the specific inspection result value and the value at the time of initial shipment does not satisfy a predetermined standard value or range, it is determined that the safety of the repaired vehicle is insufficient. It may be configured to include an evaluation step (S60) in which it is determined that the operation is inappropriate, or a process of determining the safety of the repaired vehicle by grade is performed by dividing the safety grade according to a predetermined standard.

Here, in the above-described embodiment of the present invention, the present invention has been described with respect to the case of analyzing the stiffness change before and after accident repair with respect to the front frame of the vehicle and evaluating the safety of the repaired vehicle based on the analysis result. is not necessarily limited to the case of the above embodiment, that is, the present invention is similarly applied to other main parts of the vehicle, such as the rear or side frames or panels, in addition to the front frame, before and after repair. It is possible to apply various changes and modifications as needed by those skilled in the art within the scope without departing from the spirit and essence of the present invention, such as analyzing characteristics or performance changes and comprehensively reflecting the results together in safety evaluation. It should be borne in mind that

Therefore, as described above, the method for analyzing the stiffness change before and after accident repair of the vehicle front frame according to the embodiment of the present invention and the method for evaluating the safety of the repaired vehicle using the same can be implemented, thereby, according to the present invention, in the current domestic market One passenger car with high sales frequency is selected and the vehicle's drawings, materials, and related data are used to conduct a crash test in the same way as the actual vehicle. After confirming, for example, tensile strength, F-D diagram, relative displacement, etc., the state change of the vehicle accompanying the repair of a crash accident is analyzed through finite element analysis (FEA) using a commercial program, and based on the analysis result, A method for analyzing the stiffness change before and after accident repair of a vehicle front frame, which is configured to confirm and evaluate the safety of the vehicle by comparing the stiffness change of the vehicle body front frame before and after an accident, and a method for evaluating the safety of a repaired vehicle using the same are provided. It is possible to secure the safety and reliability of the vehicle, thereby eliminating vague anxiety and distrust of the repaired vehicle.

In addition, according to the present invention, as described above, the stiffness change analysis method of the vehicle front frame before and after accident repair is configured to analyze the change in stiffness before and after the accident repair with respect to the vehicle front frame and to evaluate the safety of the repaired vehicle through the result. And by providing a method for evaluating the safety of a repair vehicle using the same, when damage or deformation occurs in major parts such as the skeleton or frame of the vehicle body in a crash accident, the strength of the vehicle body is lower than that at the time of initial shipment even if the damaged part is repaired Therefore, there are concerns about the performance and safety of the vehicle, which increases vague distrust and anxiety about the vehicle being repaired, and the value of the vehicle decreases significantly. It is possible to solve the problems of the prior art in which a method for providing accurate information is not provided.

As described above, the detailed contents of the method for analyzing the stiffness change before and after accident repair of the vehicle front frame according to the present invention and the safety evaluation method of the repaired vehicle using the same have been described through the embodiments of the present invention as described above, but the present invention provides the It is not limited to the contents described in the embodiments, and therefore, the present invention may be modified, changed, combined, and replaced in various ways according to design needs and other various factors by those of ordinary skill in the art to which the present invention pertains. It goes without saying that this is possible.

Claims (10)

In the method of analyzing the stiffness change before and after accident repair of the vehicle front frame,
A database construction step in which data on specifications and frontal crash tests for various actual vehicles are collected, respectively, and a database is constructed for analyzing the stiffness change before and after accident repair of the vehicle front frame;
a modeling step in which a process of establishing an analysis model for a finite element analysis (FEA) for an analysis target vehicle to be analyzed is performed based on the contents of the database constructed in the database building step;
a test step in which a process of measuring a state change before and after accident repair for the front frame of the vehicle to be analyzed is performed through a front collision test using a finite element analysis (FEA) using the analysis model modeled in the modeling step; and
Based on the test result of the test step, the processing including the analysis step in which the analysis of the state change before and after the accident repair on the front frame of the analysis target vehicle is performed is performed by a computer or dedicated hardware A method of analyzing stiffness change before and after accident repair of a vehicle front frame, characterized in that it is configured.
The method of claim 1,
The database building step is
By collecting data on the specifications of various actual vehicles, data on the results of performing a front crash test for each vehicle, and data on the tensile test results before and after repair of the front frame, respectively, and storing it in a database format, the vehicle A method for analyzing stiffness change before and after accident repair of a vehicle front frame, characterized in that the processing of constructing a database for analysis of stiffness change before and after accident repair of the front frame is configured to be performed.
3. The method of claim 2,
The database building step is
For each vehicle, the database is built by collecting crash test data according to the crash test method and repair method based on RCAR (Research Council for Automobile Repairs) or NCAP (New Car Assessment Program) standards and data on the state after repair. A method for analyzing stiffness change before and after accident repair of a vehicle front frame, characterized in that the processing is performed.
The method of claim 1,
The test step is
Using the analysis model modeled in the modeling step, collision stiffness, stress before and after accident repair for the front frame of the vehicle to be analyzed for each speed through a front collision test using finite element analysis (FEA), A method of analyzing the stiffness change before and after accident repair of a vehicle front frame, characterized in that the processing for measuring each of a strain rate, an energy absorption rate, and a displacement is performed.
The method of claim 1,
The analysis step is
Based on the test result of the test step, an FD curve for energy absorption force and displacement is calculated, and energy absorption power change according to speed before and after accident repair for the front frame of the analysis target vehicle the process of performing the analysis on; and
A vehicle front frame, characterized in that it is configured to perform a process including a process of calculating a change in the amount of displacement over time for each speed and performing an analysis of the amount of displacement before and after accident repair on the front frame of the vehicle to be analyzed Analysis method of stiffness change before and after accident repair of
A computer-readable recording medium on which a program is recorded, configured to cause a computer to execute the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame according to any one of claims 1 to 5.
In the safety evaluation method of a repair vehicle,
An inspection step of performing a process of inspecting the state of the repaired vehicle after repair using the method for analyzing the stiffness change before and after the accident repair of the vehicle front frame according to any one of claims 1 to 5; and
and a process including an evaluation step in which a process for evaluating the safety of the repaired vehicle is performed based on an inspection result of the inspection step is configured to be performed by a computer or dedicated hardware.
8. The method of claim 7,
The evaluation step is
Based on the inspection result of the inspection step, when a specific inspection result value does not satisfy a predetermined reference value or a predetermined reference range, it is determined that the safety of the repaired vehicle is insufficient and a process for determining that operation is unsuitable is performed. A method for evaluating the safety of a repair vehicle, characterized in that.
8. The method of claim 7,
The evaluation step is
Based on the inspection result of the inspection step, each inspection result value is compared with the value at the time of initial shipment of the repaired vehicle, and the difference between the specific inspection result value and the value at the time of initial shipment satisfies a predetermined reference value or a predetermined reference range If not, it is determined that the safety of the repaired vehicle is insufficient, and a process for determining that the operation is unsuitable is performed.
8. The method of claim 7,
The evaluation step is
Safety evaluation of a repaired vehicle, characterized in that it is configured to classify the safety of the repaired vehicle according to a predetermined standard, and to perform a process of judging the safety of the repaired vehicle by grade based on the inspection result of the inspection step Way.

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