1. ANSYS Basic Concepts for ANSYS Structural Analysis

2. Contents Disciplines and Element Types Analysis Types
Linear Analysis and Nonlinear Analysis
Material Models
Failure Criteria of Materials

3. Disciplines and Element Types
Structural Analysis
Thermal Analysis
Fluid Dynamic Analysis
Electric Field Analysis
Magnetic Field Analysis
Coupled-field Analysis

4. Examples Example 1: Thermal Stress Analysis
Example 2: Structure-Fluid Interactions
Example 3: Thermal Actuator

5. 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. Analysis Types Structural Analysis Static Analysis Dynamic Analysis
Static, Transient, Modal, Harmonic, Buckling, etc.
Thermal Analysis
Steady-state, Transient
Electric Field Analysis
Static, Transient, Modal, Harmonic
etc.
Static Analysis
Dynamic Analysis
Transient Analysis
Modal Analysis
Harmonic Response Analysis
etc.
Buckling Analysis

7. Transient Analysis Inertia forces Damping forces Elastic forces
External forces

8. 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.

9. Modal Analysis
Modal analysis is to analysis a structure under free vibration.
The solutions typically include
Vibration frequencies (or periods)
Vibration modes

10. 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

11. Linear Analysis and Nonlinear Analysis

12. Linear Analysis Small deformation Hooke’s law appies
No status or topological changes, eg., contacts
Loads
Responses

13. Nonlinear Analysis Geometric nonlinearity Material nonlinearity
Status nonlineaity

14. 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.

15. Elastic vs. Plastic Elastic materials (a) Nonlinear elastic
Stress
Strain
(a)
(b)
(c)
Elastic materials
(a) Nonlinear elastic
(b) Hysteresis elastic
(c) Linear Elastic

16. Elastic vs. Plastic
Plastic materials
Strain
Stress

17. Viscous vs. Nonviscous
Nonvisous
materials
Time
Stress
Strain

18. Viscous vs. Nonviscous
Visous
materials
Time
Stress
Strain

19. Viscous vs. Nonviscous Creeping Stress Relaxation Stress Strain Time

20. 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.

21. 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.

22. Isotropic, Anisotropic, and Othothropic Materials
Hooke’s Law for Isotropic Material
Hooke’s Law for Anisotropic Material
Hooke’s Law for Orthotropic Material

23. Failure Criteria of Materis

24. Ductile vs. Brittle Ductile Material Brittle Material Stress Stress
Strain
Stress
Strain
Stress

25. Failure Criteria for Brittle Materials
Maximum Principal Stress Failure Criteria:
Fracture will occur when tensile stress is greater than ultimate tensile strength, i.e.,

26. Failure Criteria for Ductile Materials
Tresca Failure Criteria:
Yielding will occur when shear stress is greater than shear yield strength, i.e., or

27. Failure Criteria for Ductile Materials
von Mises Failure Criteria:
Yielding will occur when the von Mises stress is greater than yield strength, i.e.,