structural: chapter 1: overview of structural analyses

8/14/2019 STRUCTURAL: Chapter 1: Overview of Structural Analyses

1/3

Chapter 1: Overview of Structural Analyses

Go to the Next Chapter

Go to the Table of Contents for This Manual

Go to the Guides Master Index

Chapter 1 * Chapter 2 * Chapter 3 * Chapter 4 * Chapter 5 * Chapter 6 * Chapter 7 * Chapter 8 * Chapter 9

* Chapter 10 * Chapter 11 * Chapter 12 * Chapter 13 * Chapter 14

1.1 Definition of Structural Analysis

Structural analysis is probably the most common application of the finite element method. The term

structural (or structure) implies not only civil engineering structures such as bridges and buildings, but also

naval, aeronautical, and mechanical structures such as ship hulls, aircraft bodies, and machine housings, as

well as mechanical components such as pistons, machine parts, and tools.

1.2 Types of Structural Analysis

The seven types of structural analyses available in the ANSYS family of products are explained below. The

primary unknowns (nodal degrees of freedom) calculated in a structural analysis are displacements. Other

quantities, such as strains, stresses, and reaction forces, are then derived from the nodal displacements.

Structural analyses are available in the ANSYS/Multiphysics, ANSYS/Mechanical, ANSYS/Structural, and

ANSYS/LinearPlus programs only.

You can perform the following types of structural analyses:

Static Analysis-Used to determine displacements, stresses, etc. under static loading conditions. Both linear

and nonlinear static analyses. Nonlinearities can include plasticity, stress stiffening, large deflection, large

strain, hyperelasticity, contact surfaces, and creep. Chapter 2 describes static analyses, and Chapter 8

describes nonlinearities.

Modal Analysis-Used to calculate the natural frequencies and mode shapes of a structure. Different mode

extraction methods are available. Chapter 3 describes modal analysis.

Harmonic Analysis-Used to determine the response of a structure to harmonically time-varying loads.

Chapter 4 describes harmonic analysis.

Transient Dynamic Analysis-Used to determine the response of a structure to arbitrarily time-varying loads.

All nonlinearities mentioned under Static Analysis above are allowed. Chapter 5 describes transient dynamic

analysis.

Spectrum Analysis-An extension of the modal analysis, used to calculate stresses and strains due to a

response spectrum or a PSD input (random vibrations). Chapter 6 describes spectrum analysis.

Buckling Analysis-Used to calculate the buckling loads and determine the buckling mode shape. Both linear

UCTURAL: Chapter 1: Overview of Structural Analyses (UP19980818) http://uic.edu/depts/accc/software/ansys/html/guide_55/g-str/GST

3/17/2009


2/3

(eigenvalue) buckling and nonlinear buckling analyses are possible, and are described in Chapter 7.

Explicit Dynamics Analysis-ANSYS provides an interface to the LS-DYNA explicit finite element program

and is used to calculate fast solutions for large deformation dynamics and complex contact problems. Chapter

14 describes explicit dynamics analysis.

In addition to the above analysis types, several special-purpose features are available:

Fracture mechanics (Chapter 10)Composites (Chapter 11)

Fatigue (Chapter 12)

p-Method (Chapter 13)

1.3 Elements Used in Structural Analyses

Most ANSYS element types are structural elements, ranging from simple spars and beams to more complex

layered shells and large strain solids. Most types of structural analyses can use any of these elements.

Note-Explicit dynamics analysis can use only the explicit dynamics elements (LINK160, BEAM161,SHELL163, SOLID164, COMBI165, MASS166, and LINK167).

Table 1-1 Structural element types

CategoryShape orCharacteristic

Element Name(s)

SparsGeneral

Bilinear (Cable)

LINK1, LINK8

LINK10

Beams

General

Tapered

Plastic

Shear Deformable

Elasto-Plastic

BEAM3, BEAM4

BEAM54, BEAM44BEAM23, BEAM24

BEAM188, BEAM189

Pipes

General

Immersed

Plastic

PIPE16, PIPE17, PIPE18

PIPE59

PIPE20, PIPE60

2-D Solids

Quadrilateral

Triangle

Hyperelastic

Viscoelastic

Large StrainHarmonic

p-Element

PLANE42, PLANE82, PLANE182

PLANE2

HYPER84, HYPER56, HYPER74

VISCO88

VISCO106, VISCO108PLANE83, PLANE25

PLANE145, PLANE146

3-D Solids

Brick

Tetrahedron

Layered

Anisotropic

Hyperelastic

Viscoelastic

Large Strain

SOLID45, SOLID95, SOLID73, SOLID185

SOLID92, SOLID72

SOLID46

SOLID64, SOLID65

HYPER86, HYPER58, HYPER158

VISCO89

VISCO107


3/17/2009


3/3

p-Element SOLID147, SOLID148

Shells

Quadrilateral

Axisymmetric

Layered

Shear Panel

p-Element

SHELL93, SHELL63, SHELL41, SHELL43, SHELL181

SHELL51, SHELL61

SHELL91, SHELL99

SHELL28

SHELL150

Contact

Point-to-Surface

Point-to-PointRigid Surface

CONTAC48, CONTAC49

CONTAC12, CONTAC52CONTAC26

Coupled-Field

Acoustic

Piezoelectric

Thermal-Stress

Magnetic-Structural

Fluid-Structural

FLUID29, FLUID30, FLUID129, FLUID130, INFIN110, INFIN111

PLANE13, SOLID5, SOLID98

PLANE13, SOLID5, SOLID98

PLANE13, SOLID5, SOLID62, SOLID98

FLUID38, FLUID79, FLUID80, FLUID81

Specialty

Spring

Mass

Control ElementSurface Effect

Pin Joint

Linear Actuator

Matrix

COMBIN14, COMBIN40, COMBIN39

MASS21

COMBIN37SURF19, SURF22, SURF153, SURF154

COMBIN7

LINK11

MATRIX27, MATRIX50

Explicit Dynamics

Spar

Beam

Shell

Solid

Spring-Damper

Mass

Cable

LINK160

BEAM161

SHELL163

SOLID164

COMBI165

MASS166

LINK167

1.4 Types of Solution Methods

Two solution methods are available for solving structural problems in the ANSYS family of products: the

h-method and the p-method. The h-method can be used for any type of analysis, but the p-method can be

used only for linear structural static analyses. Depending on the problem to be solved, the h-method usually

requires a finer mesh than the p-method. The p-method provides an excellent way to solve a problem to a

desired level of accuracy while using a coarse mesh. In general, the discussions in this manual focus on the

procedures required for the h-method of solution. Chapter 13 discusses procedures specific to the p-method.

Go to the beginning of this chapter


3/17/2009

structural: chapter 1: overview of structural analyses

Documents