按一下以編輯母片標題樣式,按一下以編輯母片,第二層,第三層,第四層,第五層,*,*,*,Chapter 4,ANSYS結構分析的根本觀念,Basic Concepts for ANSYS Structural Analysis,1,Contents,4.1 學科領域與元素類別,Disciplines and Element Types,4.2 分析類別,Analysis Types,4.3 線性分析與非線性分析,Linear Analysis and Nonlinear Analysis,4.4 材料模式,Material Models,4.5 材料的破壞準則,Failure Criteria of Materials,4.6 實例:動態分析,Example:Dynamic Analysis,4.7 實例:非線性分析,Example:Nonlinear Analysis,4.8 練習題:幾何非線性,Exercise:Geometric Nonlinearity,2,第4.1節,學科領域與元素類別,Disciplines and Element Types,3,4.1.1 學科領域,結構分析,Structural Analysis,熱傳分析,Thermal Analysis,流場分析,Fluid Dynamic Analysis,電場分析,Electric Field Analysis,磁場分析,Magnetic Field Analysis,耦合場分析,Coupled-field Analysis,4,4.1.2 耦合場分析,Example 1:Thermal Stress Analysis,Example 2:Structure-Fluid Interactions,Example 3:Thermal Actuator,5,4.1.3 元素類別,Element Types,ANSYS elements are classified according to,Discipline,Dimensionality,Geometry,Order,Example,SOLID45:3D hexahedral linear structural element,PLANE67:2D quadralateral linear coupled thermal-electric element,6,第4.2節,分析類別,Analysis Types,7,4.2.1 分析類別,Analysis Types,Static Analysis,Dynamic Analysis,Transient Analysis,Modal Analysis,Harmonic Response Analysis,etc.,Buckling Analysis,Structural Analysis,Static,Transient,Modal,Harmonic,Buckling,etc.,Thermal Analysis,Steady-state,Transient,Electric Field Analysis,Static,Transient,Modal,Harmonic,etc.,8,4.2.2 暫態分析,Transient Analysis,Inertia forces,Damping forces,Elastic forces,External forces,9,4.2.3 靜態分析,Static Analysis,When dynamic effects can be neglected,a problem can be solved statically.,Dynamic effects can be neglected only when the deformation velocity and acceleration are small.,Two cases:,Steady-state solution,approximation solution for a real-world problem.,10,4.2.4 模態分析,Modal Analysis,Modal analysis is to analysis a structure under free vibration.,The solutions typically include,Vibration frequencies(or periods),Vibration modes,11,4.2.5 諧和反應分析,Harmonic Response Analysis,Harmonic response analysis is to analysis a structure under periodic excitation of external forces.,The solutions typically include maximum responses under various frequencies of external forces,12,第4.3節,線性分析與非線性分析,Linear Analysis and Nonlinear Analysis,13,4.3.1 線性分析,Linear Analysis,Small deformation,Hookes law appies,No status or topological changes,eg.,contacts,Loads,Responses,14,4.3.2 非線性分析,Nonlinear Analysis,Geometric nonlinearity,Material nonlinearity,Status nonlineaity,15,第4.4節,材料模式,Material Models,16,4.4.1 材料模式,Material Models,Material models are mathematically represented by a set of equations called 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.,17,4.4.2 彈性與塑性(1/2),Elastic vs.Plastic,Elastic materials,(a)Nonlinear elastic,(b)Hysteresis elastic,(c)Linear Elastic,Stress,Strain,(a),Stress,Strain,(b),(c),Stress,Strain,18,4.4.2 彈性與塑性(2/2),Elastic vs.Plastic,Plastic materials,Strain,Stress,19,4.4.3 黏滯性與非黏滯性(1/3),Viscous vs.Nonviscous,Nonvisous,materials,Time,Stress,Time,Strain,20,4.4.3 黏滯性與非黏滯性(2/3),Viscous vs.Nonviscous,Visous,materials,Stress,Strain,Time,Time,21,4.4.3 黏滯性與非黏滯性(3/3),Viscous vs.Nonviscous,Creeping,Time,Stress,Time,Strain,Time,Strain,Time,Stress,Stress Relaxation,22,4.4.4 均質性與非均質性材料,Homogeneous vs.Heterogeneous,A material body is said to be homogeneous if it has uniform material properties everywhere in the body.,Otherwise it is said to be heterogeneous.,Note that,homogeneousness does not necessarily imply isotropy.,23,4.4.5 等向性,、,非等向性,、,與正交性材料(1/2),Isotropic,Anisotropic,and Othothropic Materials,A material is said to be isotropic if it has the same material properties along any directions in the body.,Otherwise it is said to be anisotropic.,An anisotropic material is said to be orthotropic,if the planes of material symmetry are mutually orthogonal.,24,4.4.5 等向性,、,非等向性,、,與正交性材料(2/2),Isotropic,Anisotropic,and Othothropic Materials,Hookes Law for Isotropic Material,Hookes Law for Anisotropic Material,Hookes Law for Orthotropic Material,25,4.4.6 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,材料的破壞準則,Failure Criteria of Materis,27,4.5.1 延展性與脆性材料,Ductile vs.Brittle,Ductile Material,Strain,Stress,Strain,Stress,Brittle Material,28,4.5.2 脆性材料的破壞準則,Failure Criteria for Brittle Materials,Maximum Principal Stress Failure Criteria:,Fracture will occur when tensile stress is greater than ultimate tensile strength,i.e.,29,4.5.3 延展性材料的破壞準則(1/2),Failure Criteria for Ductile Materials,Tresca Failure Criteria:,Yielding will occur when shear stress is greater than shear yield strength,i.e.,or,30,4.5.3 延展性材料的破壞準則(2/2),Failure Criteria for Ductile Materials,von Mises Failure Criteria:,Yielding will occur when the von Mises stress is greater than yield strength,i.e.,31,第4.6節,實例:動態分析,Example:Dynamic Analysis,32,4.6.1