Discretise the structure or continuum into finite elements.
Specify the approximation equation.
Determine the shape functions for each element.
Formulate the properties of each element.
Determine stiffness matrices and equivalent load vectors for all elements.
Assemble elements to obtain the finite element model of the structure or continuum.
Apply the known loads
Apply boundary conditions.
Solve simultaneous linear algebraic equations
DOF
nodal displacements in stress analysis
nodal temperatures in heat transfer analysis
stress analysis
Compute stress
heat transfer analysis
compute temperature
Interpret results
Advantages of FEM
Model complex shaped bodies quite easily.
Handle several load conditions without difficulty.
Handle different kinds of boundary conditions.
Include dynamic effects.
Vary the size of the elements to make it possible to use small elements where necessary.
Handle time-dependent and time-independent heat transfer problems.
Engineering Applications
Mechanical Desing
Stress concentration problems
Stress analysis of pressure vessels
Composite materials
Linkages and gears
Electrical machines and
electromagnetics
Steady state analysis
of synchronous and
induction machines
eddy current and core losses
in electric machines
magnetostics
Biomedical engineering
Stress analysis of eyeballs
bones and teeth
load-bearing capacity in plant and prosthetic systems
mechanics of heart values
Nuclear engineering
Analysis of nuclear
pressure vessels and
containment structures
Steady state
temperature distribution
in reactor components
Degrees of freedom(DOF)
Specify the state of the element. They also
function as ‘handles’ through which adjacent
elements are connected. DOF are defined as
the values (and possibly derivatives) of a
primary field variable at nodal points
What is FEM?
FEM is a powerful tool for
the numerical solution of a
wide range of engineering
problems.
The basic concept in the physical
interpretation of the FEM is the sub-division
of the mathematical model into disjoint
(non-overlapping) components of simple
geometry called finite elements
Boundary conditions
Avoid the possibility of the structure moving as a rigid
body. Two approaches are used for handling specified
displacement boundary conditions.
Elimination approach
Penalty approach
Variational Formulation
The Total Potential Energy Functional (TPE)
Relation between strain energy density and external energy
The Minimum Potential Energy Principle (MPEP)
states that the actual displacement solution u(x) is that which renders Pi stationary
ANSYS
It is one of the finite element analysis
computer programming software.
ANSYS-Mechanical product is
designed for analysing
static
structural and thermal
linear and non-linear
buckling
sub-structure
acoustics
dynamic/transient
It enables users to solve a wide variety of
analyses in mechanical engineering
applications
Finite Element Discretisation
Decompose the TPE functional into a sum of
contributions of individual elements.
The same decomposition applies to the internal and external energies, as
well as to the condition of MPEP
Using the fundamental lemma of variational calculus, it can be
shown that implies that for a generic element
(e) we may write:
This variational equation is the basis for the derivation of
element stiffness equations once the displacement field has
been discretised over a bar element.