Automotive Structure & Safety Lab

In Kookmin University

Formula EV Design

-Part 1. Body Design-

실험실 차량구조안전실험실

지도교수 허승진교수님

팀명 Team ASK

1.

Automotive Structure & Safety Lab

In Kookmin University

Formula EV 설계

Body 설계 개요

Step 2. Load path analysis

Step 3. Pipe Size Optimization

차량 부품 종류 및 레이아웃에 대한 구조 변경

Load path analysis를 통한 프레임 최종 구조 형상 선정

효과 분석을 통한 파이프의 두께 선정 차체 프레임 제작 및 시험 검증

목표 강성 및 질량 선정

정/동 강성 시험을 통한 모델링 검증 (KORA EV3 frame)

Step 1. Reference model & Performance target

Step 4. Making & Verification

t

2.

Automotive Structure & Safety Lab

In Kookmin University

Step 1. Reference Model & Performance Target

Frame Body Modeling

shell element, mesh size 3mm

- Static stiffness simulation

- Dynamic stiffness simulation

Bending Torsion

1st torsion 1st lateral bending

3.

Automotive Structure & Safety Lab

In Kookmin University

Step 1. Reference Model & Performance Target

Front Constraint

Rear Constraint

Load Weight Dial gauge

Bending Stiffness Test

4.

Automotive Structure & Safety Lab

In Kookmin University

Step 1. Reference Model & Performance Target

Front Constraint

Rear Constraint

Load Weight

Dial gauge

Torsional Stiffness Test

5.

Automotive Structure & Safety Lab

In Kookmin University

Step 1. Reference Model & Performance Target

DAQ (LMS SCADAS mobile)

Impact hammer

3 axis accelerometer

excitation

voltage signal

Modal Test

6.

Automotive Structure & Safety Lab

In Kookmin University

Step 1. Reference Model & Performance Target

- Test result : 1st Torsion mode

Modal Test Simulation (Program : Abaqus)

1st Torsion 52.058Hz 1st Torsion 54.715 Hz

Modal Test Result Example

7.

Automotive Structure & Safety Lab

In Kookmin University

Body Design - Step 1

Test Result

항목 Simulation Test Error

굽힘강성 (N/mm) 1163.6 1096.1 6.16%

비틀림강성 (Nm/deg) 252.4 230.9 9.31 %

고유진동수 (Hz)

1st Torsional mode 54.72 52.06 5.10 %

1st Lateral Bending mode 129.91 129.12 0.61 %

1st Vertical Bending mode 136.09 134.89 0.89 %

8.

Automotive Structure & Safety Lab

In Kookmin University

Step 1. Reference Model & Performance Target

Performance Target

• FSAE 차량 20대의 Frame body 조사 결과

Minimum Average Maximum

1458 1898 2577

비틀림강성 (Nm/deg)

Minimum Average Maximum

29 35 41

질량 (kg)

• Target

Base model Target

비틀림강성 (Nm/deg) 230.9 > 1000

질량 (kg) 11.61 < 20

• 낮은 강성의 프레임

코너링 성능 ↓ , 예측 성능과의 오차 ↑

• 질량이 큰 프레임

가속 성능 ↓ , 에너지 소모↑

• FSAE 차량의 질량 대비 강성 비율

약 50 Nm/(deg·kg)

9.

Automotive Structure & Safety Lab

In Kookmin University

Stress 가집중되는부분이발생

Step 2. Load Path Analysis

Stress Analysis

Bending Torsion

Base Model

10.

Automotive Structure & Safety Lab

In Kookmin University

Step 2. Load Path Analysis

Load Path Analysis (Topology Optimization)

𝑀𝑎𝑠𝑠 ≤ 20𝑘𝑔

1𝑠𝑡 𝑇𝑜𝑟𝑠𝑖𝑜𝑛 𝑚𝑜𝑑𝑒 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 ≥ 𝐵𝑎𝑠𝑒 𝑀𝑜𝑑𝑒𝑙

𝑆𝑢𝑏𝑗𝑒𝑐𝑡 𝑡𝑜

𝑀𝑖𝑛𝑖𝑚𝑖𝑧𝑒 𝑉𝑜𝑙𝑢𝑚𝑒 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛

𝑂𝑏𝑗𝑒𝑐𝑡

𝑇𝑜𝑟𝑠𝑖𝑜𝑛𝑎𝑙 𝑆𝑡𝑖𝑓𝑓𝑛𝑒𝑠𝑠 ≥ 1000𝑁𝑀/𝑑𝑒𝑔• 목표함수및제약조건설정후 Topology optimization 진행

• 결과를토대로상세설계

11.

Automotive Structure & Safety Lab

In Kookmin University

Step 2. Load Path Analysis

Stress Analysis

Modified Base Model

Bending Torsion

기존모델대비응력감소

12.

Automotive Structure & Safety Lab

In Kookmin University

Step 3. Size Optimization

Design Variables

- 메인 프레임의 파이프 두께

- 서브 프레임 7개의 파이프 두께

1

2

3 4

5

서브프레임 7개의위치 (나머지는메인프레임)

67

side view top view

13.

Automotive Structure & Safety Lab

In Kookmin University

Step 3. Size Optimization

Design of Experiment (DOE)

해상도 IV 2-수준 일부 실시법

설계변수 8개, 실험점 32개

원형파이프의규격을참고하여수준을정의

14.

Automotive Structure & Safety Lab

In Kookmin University

Step 3. Size Optimization

Effect Analysis

15.

800

850

900

950

1000

1050

1100

1150

To

rsio

nal

Sti

ffn

ess [

Nm

/deg

]

Effect Analysis (Torsional Stiffness)

Lower

Upper

Main Sub1 Sub2 Sub3 Sub4 Sub5 Sub6 Sub7

Automotive Structure & Safety Lab

In Kookmin University

Step 3. Size Optimization

Effect Analysis

Lower

Upper

Main Sub1 Sub2 Sub3 Sub4 Sub5 Sub6 Sub7

16.

15

16

17

18

19

20

21

22

Mass [

kg

]

Effect Analysis (Mass)

Automotive Structure & Safety Lab

In Kookmin University

Result

항목 Reference Base Modified Optimum Target

질량 [kg] 11.6 16.24 18.44 19.78 <20

굽힘강성 [N/mm] 1163.6 1874.8 4902.3 5481.9 -

비틀림강성 [Nm/deg] 252.4 524.6 974.5 1119.7 >1000

고유진동수 (Hz)

1st Torsional mode [Hz] 54.72 66.67 85.28 88.26 -

1st Lateral Bending

mode [Hz]129.91 139.37 211.49 215.93 -

1st Vertical Bending

mode [Hz]136.09 145.99 221.55 226.21 -

17.

Automotive Structure & Safety Lab

In Kookmin University

감사합니다.