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Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free-Shape Optimization
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
• No user-defined shape perturbation vector is necessary
• Reduce the effort to guess what would be the optimum shape
• Free Shape optimization uses a proprietary optimization technique developed by Altair, wherein the outer boundary of a structure is altered to meet with pre-defined objectives and constraints
• Can be combined with any type of optimization e.g. w/ morphing based shape optimization
Optimum
?
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
• DSHAPE card
Format
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
DSHAPE ID
PERT DTYPE MVFACTOR NSMOOTH
GRID GID1 GID2 GID3 GID4 GID5 GID6 GID7
GID8 GID9 .… .…
Optional continuation line for grid constraints
(1) (2) (3) (4) (5) (6) (7) (8) (9)
GRIDCON GDID1 CTYPE1 CID1 X1 Y1 Z1
GDID2 CTYPE2 CID2 X2 Y2 Z2
…. …..
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
변형전
변형후
BOTH (default) GROW SHRINK
NOTE : Grow 또는 shrink와 같은 설계 범위제약조건이 요구되지 않으면, ‘Both’를 사용하는것을 추천함
• DTYPE – Free shape 영역 움직임의 방향을 제어하는 parameter
초기영역 내부로의이동이 없음
초기 영역 외부로의이동이 없음
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
• MVFACTOR – Free-Shape 설계 영역에서 정의한 grid들이 하나의 iteration에서이동할 수 있는 최대 이동 비율을 정의 (default = 0.5)
• Grid movement = MVFACTOR X 평균요소크기
• MVFACTOR를 작게 부여하면 free-shape optimization은 느리게 수행되지만 보다안정적이라는 이점이 있음
변형전 형상
MVFACTOR=1.0경우 iteration당 변화
MVFACTOR=0.5경우 iteration당 변화
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
(a) NSMOOTH = 5 (b) NSMOOTH = 1
NSMOOTH : Free-shape 최적화 요소 smooth를 위한 grid 층의 개수 (default=10)
Larger NSMOOTH : 요소 파괴를 피하는데 좋지만 느리게 최적화 속도가 느림
NSMOOTH can be larger than the number of available layers.
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
Constraint on GRID (Gridcon) – Grid의 움직임을 제어하는 parameter
1. FIXED – Free-shape 최적화 중 grid의 이동을 없게 만듬
2. VECTOR – 적용된 vector 방향으로 grid가 이동하도록 강제부여
3. PLANAR – Normal 방향으로 정의한 vector를 갖는 plane내에서만 grid가 움직임
Example
1. CTYPE=VECTOR
CTYPE 미정의
Vector 를 정의하여,
GRID의 이동을 고정함
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
2. CTYPE=PLANAR
Model Setup설계 Grid 정의
CTYPE 미정의Y방향으로 Shape 변경이 발생함
CTYPE=PLANER 정의(X-Z Plane)
Y 방향의 Shape
Change가 없음
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
1-plane Symmetry Constraint : 선택한 plane에 기준한 대칭 형상을 생성하는 parameter
Free-shape 설계 grid가정의된 2-d model
Symmetry constraint 가적용되지 않은 경우
Symmetry constraint를적용한 경우
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
Extrusion Constraint : 정의된 path를 따라 단면을 일정하게 유지하고자 할 때 사용
Extrusion Constraint가적용된 결과 예
Circular extrusion
path를 적용한 결과Extrusion Path를적용하지 않은 결과
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
Side Constraint : 선택한 두 좌표 (x1,y1,z1), (x2,y2,z2) 사이에서 최대 변위량 영역을정의하는 parameter. Range는 직교좌표, 원형좌표, 구형 좌표계에 따라서 결정됨
R1, R2 반경에 따른 Side
Constraint 적용 모델
Side Constraint를적용하여 얻은 결과
Side Constraint가적용되지 않은 결과 형상
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape Optimization
Mesh Barrier Constraint : Special shell element (BMFACE)를 이용하여 수치적으로변형의 최소를 정의하는 효과를 부여하는 parameter
Mesh Barrier가적용된 형상
Mesh Barrier가적용되지 않은 결과
Mesh Barrier가적용된 결과
Mesh Barrier와1-Plane symmetry가 함께
적용된 결과
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape optimization
P
Objective :
Minimize compliance
Subject to:
Volume < 4000.00
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape optimization
DSHAPE 1
DSHAPE 2
Select Free Shape design grids
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape optimization
Move only on X-Z plane – fix the height of the beam section
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape optimization
ITER 0 : Compliance = 4.103E+00 Volume = 6.480E+03
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Free Shape optimization
ITER 26 : Compliance = 3.368E+00 Volume=3.994E+03
Objective -17.91%, Max. constraint violation 62.00% 0.00%
Copyright © 2008 Altair Engineering, Inc. All rights reserved. Altair Proprietary and Confidential Information
Example 2: shape change history
Shape history of the solid beam example