표제지
ABSTRACT
목차
Nomenclature 8
1. 서론 15
1.1. 연구 동기 15
1.2. 연구 동향 16
1.3. 연구 개요 18
2. 충돌 해석을 위한 유한요소모델 19
2.1. 골프 공의 설계 19
2.2. 반발계수 20
2.3. 골프 클럽의 설계 21
2.4. 접촉 조건 22
3. 충돌 해석 32
3.1. 이론적인 충돌 계산 32
3.2. 유한요소해석 36
4. 여러 가지 충돌 해석 58
4.1. 마찰이 없을 경우 충돌 해석 58
4.2. 공의 강성에 따른 충돌 해석 59
4.3. 클럽 초기 속도, 로프트 각도를 변화시켰을 때 충돌 해석 61
4.4. 클럽이 공에 비스듬히 맞았을 경우 충돌 해석 62
4.5. 클럽의 무게중심에서 일정거리 떨어졌을 때 충돌 해석 64
5. 결론 82
참고문헌 85
부록 88
A.1. 궤적 운동 방정식 88
A.2. 항력, 양력, 항모멘트계수 89
A.3. 정면 충돌에서 공의 궤적, 회전 량 변화 및 최적화 91
A.4. 여러 가지 충돌의 궤적 계산 91
감사의 글 102
Table 2.1. Material property of golf ball and club head 25
Table 2.2. Mooney-Rivlin constants 25
Table 2.3. Coefficient of friction between club head and ball at impact 25
Table 3.1. Inconsistent results on contact forces at impact between ball and club head 43
Table 4.1. Velocities and spin rates of ball with club open angle(γ) varied 66
Table 4.2. Velocities and spin rates of ball for off-center hit with eccentricity (h) 66
Table A.1. Reference parameters at impact 93
Table A.2. Ball flight and trajectory 93
Table A.3. Effect of club head speed (V) on the ball flight 94
Table A.4. Effect of loft angles (Ψ) on ball flight 94
Figure 2.1. Golf ball model 26
Figure 2.2. Bouncing of golf ball 27
Figure 2.3. Coefficient of restitution vs. ball impact speed 28
Figure 2.4. Club head model and coordinates: (a) top and (b) side views 29
Figure 2.5. Dynamics of ball and club head after impact for the ball contact line (a) above, (b) through and (c) below the club head mass center 30
Figure 2.6. Contact method by FEM 31
Figure 3.1. Vector of club and ball at impact 44
Figure 3.2. The realistic velocity of the moving frame 44
Figure 3.3. Golf club head and ball models: (a) overview and (b) cut-view 45
Figure 3.4. Ball and head velocity at impact: (a) launch angle and (b) ball and head velocity 46
Figure 3.5. Normal and tangential forces at impact 47
Figure 3.6. (a) Normal and tangential forces and (b) tangential force compared to Moriyama data 48
Figure 3.7. Normal and tangential forces during contact 49
Figure 3.8. Slip and roll of ball 54
Figure 3.9. Ball spin rate at impact: (a) method to compute spin rate and (b) ball spin rate compared to FEM result 55
Figure 3.10. Tangential force, tangential velocity and spin rate at impact 56
Figure 3.11. Effective radius of deformed ball at impact: (a) node plot at minimum radius and (b) radius vs. time 57
Figure 4.1. Normal and tangential forces: no friction 67
Figure 4.2. Tangential forces along the undeformed and deformed club faces: (a) deformed club faces and (b) tangential force vs. time 68
Figure 4.3. (a) Tangential forces and (b) spin rates for elastic club head with ball stiffness varied 69
Figure 4.4. (a) Tangential forces and (b) spin rates for rigid club head with ball stiffness varied 70
Figure 4.5. Ball velocity, launch angle, spin rate and compression factor for club initial velocity and loft angle varied 71
Figure 4.6. (a) Coordinates and (b) side spin rate for zero loft angle 72
Figure 4.7. Impact for open club face: (a) side and (b) top views 73
Figure 4.8. Normal (Fn) and tangential forces (Ft1, Ft2) for open club face with (a) 5 and (b) 15 degrees(이미지참조) 74
Figure 4.9. Tangential forces (Ft1, Ft2) with the club face open angle(γ) varied(이미지참조) 75
Figure 4.10. Ball spin rate components for the club face open angle γ=10° 76
Figure 4.11. Resultant spin axis with the club face open angle (γ) varied 77
Figure 4.12. (a) Coordinates and (b) tangential forces (Ft1, Ft2) for the off-center hit with eccentricity (h)(이미지참조) 78
Figure 4.13. Ball spin rate components for h= 10 mm 79
Figure 4.14. Gear effect 80
Figure 4.15. Spin rate axis vs. eccentricity (h) 81
Figure A.1. Coordinates for golf ball trajectory 95
Figure A.2. Dimples of golf ball 96
Figure A.3. Drag and lift coefficients of ball 96
Figure A.4. Ball trajectory 97
Figure A.5. Decrease of ball spin rate in flight 97
Figure A.6. Maximum ball distance (x) vs. upper blow angle (η) 98
Figure A.7. Ball trajectory vs. club head speed (V) 99
Figure A.8. Ball trajectory vs. loft angle (ψ) 99
Figure A.9. Ball trajectory vs. club open angle (γ) 100
Figure A.10. Ball trajectory vs. eccentricity (h) 101