ANSYS結(jié)構(gòu)分析的基本觀念

1、Chapter 4ANSYS結(jié)構(gòu)分析的基本觀念Basic Concepts for ANSYS Structural AnalysisContents4.1 學(xué)科領(lǐng)域與元素類別Disciplines and Element Types4.2 分析類別Analysis Types4.3 線性分析與非線性分析Linear Analysis and Nonlinear Analysis4.4 材料模式Material Models4.5 材料的破壞準(zhǔn)則Failure Criteria of Materials4.6 實(shí)例: 動(dòng)態(tài)分析Example: Dynamic Analysis4.7 實(shí)例: 非

2、線性分析Example: Nonlinear Analysis4.8 練習(xí)題: 幾何非線性Exercise: Geometric Nonlinearity2第4.1節(jié)學(xué)科領(lǐng)域與元素類別Disciplines and Element Types34.1.1 學(xué)科領(lǐng)域結(jié)構(gòu)分析Structural Analysis熱傳分析Thermal Analysis流場(chǎng)分析Fluid Dynamic Analysis電場(chǎng)分析Electric Field Analysis磁場(chǎng)分析Magnetic Field Analysis耦合場(chǎng)分析Coupled-field Analysis44.1.2 耦合場(chǎng)分析Exampl

3、e 1: Thermal Stress AnalysisExample 2: Structure-Fluid InteractionsExample 3: Thermal Actuator54.1.3 元素類別Element TypesANSYS elements are classified according toDisciplineDimensionalityGeometryOrderExampleSOLID45: 3D hexahedral linear structural elementPLANE67: 2D quadralateral linear coupled thermal

4、-electric element6第4.2節(jié)分析類別Analysis Types74.2.1 分析類別Analysis TypesStatic AnalysisDynamic AnalysisTransient AnalysisModal AnalysisHarmonic Response Analysisetc.Buckling AnalysisStructural AnalysisStatic, Transient, Modal, Harmonic, Buckling, etc.Thermal AnalysisSteady-state, TransientElectric Field A

5、nalysisStatic, Transient, Modal, Harmonicetc.84.2.2 瞬時(shí)分析Transient AnalysisInertia forcesDamping forcesElastic forcesExternal forces94.2.3 靜態(tài)分析Static AnalysisWhen dynamic effects can be neglected, a problem can be solved statically.Dynamic effects can be neglected only when the deformation velocity a

6、nd acceleration are small.Two cases:Steady-state solutionapproximation solution for a real-world problem.104.2.4 模態(tài)分析Modal AnalysisModal analysis is to analysis a structure under free vibration.The solutions typically includeVibration frequencies (or periods)Vibration modes114.2.5 諧和反應(yīng)分析Harmonic Res

7、ponse AnalysisHarmonic response analysis is to analysis a structure under periodic excitation of external forces.The solutions typically include maximum responses under various frequencies of external forces12第4.3節(jié)線性分析與非線性分析Linear Analysis and Nonlinear Analysis134.3.1 線性分析Linear AnalysisSmall defor

8、mationHookes law appiesNo status or topological changes, eg., contactsLoadsResponses144.3.2 非線性分析Nonlinear AnalysisGeometric nonlinearityMaterial nonlinearityStatus nonlineaity15第4.4節(jié)材料模式Material Models164.4.1 材料模式Material ModelsMaterial models are mathematically represented by a set of equations ca

9、lled constitutive equations.The constitutive equations describe the relations between stresses and strains (or strain rates).The parameters in the constitutive equations are called material parameters.ANSYS provides many material models to be chosen from.174.4.2 彈性與塑性 (1/2)Elastic vs. PlasticElastic

10、 materials(a) Nonlinear elastic(b) Hysteresis elastic(c) Linear ElasticStressStrain(a)StressStrain(b)(c)StressStrain184.4.2 彈性與塑性 (2/2)Elastic vs. PlasticPlastic materialsStrainStress194.4.3 黏滯性與非黏滯性(1/3)Viscous vs. NonviscousNonvisousmaterialsTimeStressTimeStrain204.4.3 黏滯性與非黏滯性(2/3)Viscous vs. Non

11、viscousVisousmaterialsStressStrainTimeTime214.4.3 黏滯性與非黏滯性(3/3)Viscous vs. NonviscousCreepingTimeStressTimeStrainTimeStrainTimeStressStress Relaxation224.4.4 均質(zhì)性與非均質(zhì)性材料Homogeneous vs. HeterogeneousA material body is said to be homogeneous if it has uniform material properties everywhere in the body.

12、Otherwise it is said to be heterogeneous.Note that, homogeneousness does not necessarily imply isotropy.234.4.5 等向性、非等向性、與正交性材料 (1/2)Isotropic, Anisotropic, and Othothropic MaterialsA material is said to be isotropic if it has the same material properties along any directions in the body.Otherwise i

13、t is said to be anisotropic.An anisotropic material is said to be orthotropic, if the planes of material symmetry are mutually orthogonal.244.4.5 等向性、非等向性、與正交性材料 (2/2)Isotropic, Anisotropic, and Othothropic MaterialsHookes Law for Isotropic MaterialHookes Law for Anisotropic MaterialHookes Law for O

14、rthotropic Material254.4.6 ANSYS材料模式ANSYS Material Models材料分類材料模式名稱非黏滯性材料彈性線性線性彈性材料非線性非線性彈性材料超彈性材料塑性塑性材料黏滯性材料彈性線性線性黏彈材料非線性非線性黏彈材料塑性黏塑性材料26第4.5節(jié)材料的破壞準(zhǔn)則Failure Criteria of Materis274.5.1 延展性與脆性材料Ductile vs. BrittleDuctile MaterialStrainStressStrainStressBrittle Material284.5.2 脆性材料的破壞準(zhǔn)則Failure Criteri

15、a for Brittle MaterialsMaximum Principal Stress Failure Criteria:Fracture will occur when tensile stress is greater than ultimate tensile strength, i.e.,294.5.3 延展性材料的破壞準(zhǔn)則 (1/2)Failure Criteria for Ductile MaterialsTresca Failure Criteria:Yielding will occur when shear stress is greater than shear y

16、ield strength, i.e.,or304.5.3 延展性材料的破壞準(zhǔn)則 (2/2)Failure Criteria for Ductile Materialsvon Mises Failure Criteria:Yielding will occur when the von Mises stress is greater than yield strength, i.e.,31第4.6節(jié)實(shí)例: 動(dòng)態(tài)分析Example: Dynamic Analysis324.6.1 問題描述yH = 10 mmP = 100 NQ = 1 MPaxL = 60 mmW = 6 mmMaterial

17、E = 200 Gpan = 0.3TimeLoad0334.4.2 ANSYS分析程序 (1/6)0102030405060708091011121314151617181920FINISH/CLEAR L = 0.060 H = 0.010 B = 0.006 E = 200E9 NU = 0.3 RO = 7850 DMP = 0.0001 SIZE = 0.003 Q = 1E6 P = 100/PREP7 K, 1, 0, -H/2, -B/2 K, 2, 0, H/2, -B/2 K, 3, 0, H/2, B/2 K, 4, 0, -H/2, B/2212223242526272

18、8293031323334353637383940 K, 5, L, -H/2, -B/2 K, 6, L, H/2, -B/2 K, 7, L, H/2, B/2 K, 8, L, -H/2, B/2 V, 1, 2, 3, 4, 5, 6, 7, 8 /VIEW, 1, 2, 3 VPLOT ET, 1, SOLID45 MP, EX, 1, E MP, NUXY, 1, NU MP, DENS, 1, RO MP, DAMP, 1, DMP TYPE, 1 MAT, 1 ESIZE, SIZE VMESH, ALL FINISH344.4.2 ANSYS分析程序 (2/6)4243444

19、5464748495051525354555657585960/SOLU NSEL, S, LOC, X, 0 D, ALL, ALL, 0 NSEL, S, LOC, Y, H/2 SF, ALL, PRES, Q NSEL, ALL N1 = NODE(L,-H/2,-B/2) N2 = NODE(L,-H/2,B/2) F, N1, FY, -P/2 F, N2, FY, -P/2 ANTYPE, TRANS KBC, 1 TIME, 0.1 DELTIM, 0.001 OUTRES, BASIC, ALL SOLVE FINISH354.4.2 ANSYS分析程序 (3/6)62636

20、465666768/POST1 SET, LIST SET, LAST /VIEW, 0, 0, 1 PLNSOL, S, X FINISH SET TIME LOAD STEP SUBSTEP CUMULATIVE 1 0.001 1 1 1 2 0.002 1 2 2 3 0.003 1 3 3 . . . . . 100 0.100 1 100 100 364.4.2 ANSYS分析程序 (4/6)62636465666768/POST1 SET, LIST SET, LAST /VIEW, 0, 0, 1 PLNSOL, S, X FINISH374.4.2 ANSYS分析程序 (5/

21、6)707172737475/POST26 NSOL, 2, N1, U, Y, UY PLVAR, 2 PRVAR, 2 FINISH384.4.2 ANSYS分析程序 (6/6)7071727374757677787980/POST26 NSOL, 2, N1, U, Y, UY PLVAR, 2 PRVAR, 2 FINISH/POST1 SET, 0.002 PLNSOL, S, X TIME UY 0.001 -0.0001405 0.002 -0.0001957 0.003 -0.0001533 0.004 -0.0001843 0.005 -0.0001630 0.006 -0.

22、0001763 0.007 -0.0001692 0.008 -0.0001717 0.009 -0.0001724 0.010 -0.0001697 . . 0.100 -0.000171439第4.7節(jié)實(shí)例: 非線性分析Example: Nonlinear Analysis404.7.1 問題描述yH = 10 mmP = 100 NQ = 1 MPaxL = 60 mmW = 6 mmMaterialE = 200 Gpan = 0.3414.7.2 ANSYS分析程序 (1/6)0102030405060708091011121314151617181920FINISH/CLEAR L

23、 = 60 H = 10 B = 6 E = 200000 NU = 0.3 SY = 100 ET = 0 SIZE = 3 Q = 1 P = 100/PREP7 K, 1, 0, -H/2, -B/2 K, 2, 0, H/2, -B/2 K, 3, 0, H/2, B/2 K, 4, 0, -H/2, B/2212223242526272829303132333435363738394041 K, 5, L, -H/2, -B/2 K, 6, L, H/2, -B/2 K, 7, L, H/2, B/2 K, 8, L, -H/2, B/2 V, 1, 2, 3, 4, 5, 6, 7

24、, 8 /VIEW, 1, 2, 3 VPLOT ET, 1, SOLID45 MP, EX, 1, E MP, NUXY, 1, NU TB, BKIN, 1 TBDATA, SY, ET TBPLOT, BKIN, 1 TYPE, 1 MAT, 1 ESIZE, SIZE VMESH, ALL FINISH424.7.2 ANSYS分析程序 (2/6)4344454647484950515253/SOLU NSEL, S, LOC, X, 0 D, ALL, ALL, 0 NSEL, S, LOC, Y, H/2 SF, ALL, PRES, Q NSEL, ALL N1 = NODE(L,-H/2,-B/2) N2 = NODE(L,-H/2,B/2) F, N1, FY, -P/2 F, N2, FY, -P/25556575859606162636465 NSUBST, 20 OUTRES, BASIC, ALL SOLVE NSEL, S, LOC, Y, H/2 SF, ALL, PRES, 0 NSEL, ALL F, N1