KR100262612B1 - Method for analysing stiffness and durability of three-door vehicle chassis - Google Patents

Abstract

PURPOSE: A method for analyzing stiffness and durability of three-door vehicle chassis is provided to expect and overcome problems on initial stage. CONSTITUTION: A method comprises the steps of: a step(S10,S20) modeling a four door model of a developing kind by revising a four door finite element vibration model of a developed vehicle; a step(S30) modeling a rear wheel house by removing a rear package tray from the modeled four door model without considering spot welding points and roughly testing stress and stiffness; a step(S40) revising the modeled rear wheel house model by representing spot welding of a lower end of the rear wheel house as a beam element of finite elements and examining front end load and axial load acting on the spot welding points based on calculation by executing finite element static analysis with torsion or bumping load condition of the vehicle; a step(S50) removing a rear door, revising a tail gate forming part and examining stiffness and durability by executing finite element static analysis using a model with revised shape of a roof rail to be identical with a three door model; a step(S60) examining stiffness and durability of a tail gate hinge and a strike joined to a tail, modeling and joining the hinge and the strike to the car chassis and connecting the hinge and the strike using the beam element and giving load on the car chassis to examine and comparing displacement, stress and life; and a step(S70) integrating result on general stiffness and durability performance and examining appropriateness to determine direction of concrete design.

Description

Body Strength and Durability Analysis Method of Three-door Vehicles

The present invention relates to a method for analyzing the strength and durability of a three-door vehicle, and more particularly, a three-door vehicle that effectively analyzes the strength and durability of a three-door vehicle using a four-door finite element vibration model that has been developed and is in mass production. It relates to the strength and durability analysis method of the.

In general, the three-door vehicle deletes the two rear doors from the four-door vehicle, and combines the rear trunk and the rear windglass into a door to enable opening and closing. Many parts support the torsional rigidity of the vehicle. I deleted them.

Therefore, finite element analysis is required to examine the strength and durability problems of the body. In this case, there are many four-door vibration models but not three-door models.

For the above reasons, the three-door vehicle was designed based on the previous experiences and specifications of foreign competitors, and the vehicle was developed and tested without analyzing the strength and durability of the three-door vehicle.

If a problem occurs in the above process, it is determined whether the product is abnormal through design change, component development, and retest.

The reason for this is that the three-door vehicle does not have much production, so the designer does not invest much effort.

When the strength and durability problems of the vehicle body occurs in the early stages of the development of the three-door vehicle as described above, it takes a lot of time to solve the problem, in the case of a problem due to the lack of fundamental rigidity, there was a very difficult problem itself.

The present invention has been made to solve the problems described above, the purpose of which is to use the four-door finite element vibration model already developed and mass production in order to effectively evaluate the strength and durability performance of the three-door vehicle to be developed in the future It is to solve the problems of the three-door vehicle in the early stages of development through the method using the finite element analysis method at the design stage without securing the strength and durability of the three-door vehicle.

In order to achieve the above object, the present invention comprises the steps of modeling a four-door model of the developed vehicle by modifying the four-door finite element vibration model of the previous vehicle developed;

Deleting the rear package tray from the four-door model of the developed vehicle modeled in the above step, detailing the rear wheel house by not considering spot welding, and then evaluating rough stress and rigidity of the vehicle body;

In the rear wheel house model modeled in the above step, the spot welding on the lower part of the rear wheel house is expressed as a finite element beam element, and the model is corrected and the finite element static analysis is performed under the torsion or bumping load conditions of the vehicle. Examining shear and axial loads acting on the spot welds;

After the review in the above step, the rear door is deleted, the tail gate shape is corrected, and the finite element static analysis is performed by using a model in which the shape of the roof rail is modified to be identical to that of the three doors. Wow;

After the strength and durability evaluation of the three-door body is completed in the above step, the strength and durability of the tailgate hinge and strike coupled to the rear of the body and the opening and closing are examined. Comparing and examining displacement, stress, and service life by applying a torsion or bumping load to the vehicle body in the state of connection using the element;

After the comparison and review in the above step is characterized in that it comprises the step of summing the results for the comprehensive strength and durability performance and examining the feasibility to determine the specific design direction.

1 is an operation flowchart showing an embodiment according to the method of analyzing the body strength and durability of the present invention, three-door vehicle,

FIG. 2 is a perspective view illustrating a critical element vibration model of a typical four-door vehicle. FIG.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

In general, the finite element method is to divide the structure into finite elements to model the actual structure, and to calculate the deformation and stress.The structure is divided into various elements and modeled. It is a method of evaluating the deformation and stress after applying the load where necessary. The required elements include beam elements, triangular and quadrilateral shell elements, and solid solid elements.

The present invention uses the finite element method as described above. In FIG. 1, A represents a previous vehicle, B represents a newly developed vehicle, and BIW represents a white portion, that is, a shell element, in the body of the vehicle illustrated in FIG. 2. .

In the early stage of the development of the three-door vehicle, since there is no three-door model, that is, there is no drawing, the stiffness analysis of the vehicle body is performed by using the finite element vibration model of the four-door vehicle, which was previously developed as shown in FIG. 2 (S10). Construct a finite element model for the four-door vehicle to be developed, but do not configure it using the drawings, but modify the model using the finite element model of the four-door vehicle, which is the previous model in step S10, and then develop the four-door vehicle. Modify the model as close as possible to the model of and then perform a rigid analysis (S20).

Then, the stiffness analysis result of the model modified in the step S20 is compared with the stiffness analysis result of the previous four door car model of the step S10 (S25) to complete the model of the four door car model to be developed (S20).

The reason why the strength and endurance model is not used in the above is that the strength and endurance model is often not present, and the model is large and inconvenient to handle.

Subsequently, the rear package tray is deleted using the four-door model of the developed vehicle model completed in the step S20, and the rear wheel house is modeled in detail without considering the spot weld (S31). After analyzing the bumping load conditions (S32) and using the results calculated in the step (S32) to evaluate the rough stress and stiffness of the vehicle body (S33).

And based on the results evaluated in the step (S33) to grasp the first phenomenon (S34) to complete the detailed modeling of the rear wheel house modeled in the step (S31) according to the load conditions (S31) (S30) .

When detailed modeling of the rear wheel house in the step (S30) is carried out without considering the load conditions for the spot welds.

In addition, the evaluation point at the time of evaluating rough stress and stiffness of the vehicle body in step S33 is not to determine how stiffness is, but to examine how stiffness decreases when the rear package tray is deleted.

In the above, the finite element static analysis is to examine the load conditions only in the linear region excluding the nonlinear region when examining the load conditions by the finite element method.

Subsequently, after the rear package tray is deleted in the step S30, the spot welding of the lower end of the rear wheel house is limited by using a developed model four-door finite element model in which the rear wheel house is modeled in detail without considering the load condition of the spot welding part. The model is modified by expressing the beam element of the element (S41), and the modified development vehicle four-door finite element model is analyzed by torsional or bumping load conditions through finite element static analysis (S42), and then calculated in step S42. Among the results, the shear load and the axial load acting on the spot welding portion are evaluated (S43).

In addition, the result evaluated in the step S43 is determined based on the result (S34), and in step S41, the rear wheel house model is modified in consideration of the load condition of the spot welding part and completed (S41). (S40).

In the step S42, the load condition is performed by the torsional or bumping load condition of the vehicle, but the bumping load is more effective.

In addition, the content of the shear load and the axial load examination acting on the spot welding in step S43 is whether the calculated load exceeds the reference value.

Therefore, when the calculated load exceeds the reference value, the step (S40) is repeated to complete the model of the rear wheel house in consideration of the load condition of the spot welding portion.

After the above process, the rear package tray is deleted from the initial four-door finite element model, and when the model of the rear wheelhouse is completed through the first review, the rear door is deleted or modified, the tail gate shape is modified, and the loop is repeated. The shape of the rail is modified to be the same as that of the three door vehicle (S51).

At this time, since there is no drawing, the designer's design composition is grasped and the model is modified as close as possible to actuality.

Subsequently, the torsional and bumping load conditions are analyzed by performing a finite element static analysis using the three-door finite element model modified in step S51 (S52), and using the result calculated in step S52, Evaluate the stress and stiffness, and also evaluate the load of the spot welding portion (S53).

The secondary phenomenon is identified based on the result evaluated in the step S53 (S54), and the tail gate shape and the roof rail shape modified in the step S51 are re-modified according to the load conditions, and the three-door model 3 The modification to the door model is completed (S51) (S50).

After executing the step (S50) and the evaluation of the strength and durability analysis for the three-door body through the secondary review is completed by modeling the tail gate hinge portion and tail gate strike portion coupled to the rear of the vehicle body (S61) the step (S50) Modify the three-door model modeled at).

Subsequently, the torsional and bumping load conditions are analyzed by performing finite element static analysis using models of the tail gate hinge part and the tail gate strike part modeled in the step S61 (S62), and the result calculated in the step S62. Evaluate the stress and rigidity of the vehicle body using the, and also evaluate the load of the spot welding portion (S63).

At this time, the load condition is modeled on the tail gate hinge and tail gate strike and coupled to the vehicle. Compare and review.

The third-order phenomena are identified based on the result evaluated in the step S63 (S64), and the models of the tail gate hinge part and the tail gate strike part modeled in the step S61 are modified to fit the load conditions. Complete the model (S61) (S60).

After the third examination of the step (S60) is completed, the results of the comprehensive strength and durability performance are summed and reviewed for their validity to determine the specific design direction (S70) to start the development of the actual three-door vehicle.

As described above, the present invention secures the strength and durability of the three-door vehicle by the method of trable shooting in order to effectively evaluate the strength and durability of the three-door vehicle using the four-door finite element vibration model that has been developed and produced in advance. In the design conception stage, the finite element analysis method can be used to predict and solve the problems of the three-door vehicle in the early stages of development. The problem can be eliminated in advance, and the four-door vibration model of the previous model can be used to significantly reduce the time and cost of the analysis, as well as test and analysis results for the previous model. It can be reliable in determining the result of.

Claims (6)

A method for analyzing the strength and durability of a three-door vehicle, the method comprising: modeling a four-door model of a developed vehicle by modifying a four-door finite element vibration model of a previously developed vehicle; Deleting the rear package tray from the four-door model of the developed vehicle modeled in the above step, detailing the rear wheel house by not considering spot welding, and then evaluating rough stress and rigidity of the vehicle body; In the rear wheel house model modeled in the above step, the spot welding on the lower part of the rear wheel house is expressed as a finite element beam element, and the model is corrected and the finite element static analysis is performed under the torsion or bumping load conditions of the vehicle. Examining shear and axial loads acting on the spot welds; After the review in the above step, the rear door is deleted, the tail gate shape is corrected, and the finite element static analysis is performed by using a model in which the shape of the roof rail is modified to be identical to that of the three doors. Wow; After the strength and durability evaluation of the three-door body is completed in the above step, the strength and durability of the tailgate hinge and strike coupled to the rear of the body and the opening and closing are examined. Comparing and examining displacement, stress, and service life by applying a torsion or bumping load to the vehicle body in the state of connection using the element; Comparing the results of the comprehensive strength and endurance performance in the above step, the total strength and durability performance of the three-door vehicle body strength and durability analysis method comprising the step of determining the specific design direction by examining the feasibility. 3. The method of claim 1, wherein the modeling of the four-door model of the developed vehicle model comprises modifying the four-door model of the developed vehicle by comparing the stiffness analysis of the vehicle body of the developed vehicle model and the previous vehicle model. 3. Body strength and durability analysis method of door vehicle. The method of claim 1, wherein the detailed modeling of the rear wheelhouse comprises evaluating the rough stress and stiffness of the vehicle body and then modifying the rear wheelhouse model according to the load condition. Body strength and durability analysis method. 2. The method of claim 1, wherein modifying the rear wheel house model modeled in the step includes reviewing the shear and axial loads by the spot welds and re-modifying the modified wheel house model according to the load condition. Body strength and durability analysis method for a three-door vehicle. The method of claim 1 or 3, wherein when the rear package tray is deleted using the four-door model of the developed vehicle in the above step to evaluate the rough stress and stiffness of the vehicle body, the point of evaluation is to examine the degree of stiffness. Body strength and durability analysis method of a three-door vehicle. The vehicle body strength and durability analysis of the three-door vehicle according to claim 1 or 4, wherein when the shear load and the axial load acting on the spot welding part are examined in the step, the calculated load exceeds the reference value. Way.

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