fem lesson 1

9
Finite element methods Chapter 1 The basis

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Page 1: FEM Lesson 1

Finite element methods

Chapter 1 The basis

Page 2: FEM Lesson 1

1.1 Numerical differentiation• For a given discrete function

• Taylor expansion gives the following • Taking interval

With h = x i+1-xi

Page 3: FEM Lesson 1

1.1 Numerical differentiation• Taking upto only second derivative term

• using above we can get

Page 4: FEM Lesson 1

1.1 Numerical differentiation• Hence the differentiation rule called

central derivative (first)

Similarly, second derivative

Page 5: FEM Lesson 1

1.1 Numerical differentiationFunction is u(x) vertical and the points are x on the horizontal

Page 6: FEM Lesson 1

1.2 Ordinary differential equations• Initial value problem

Given a first order differential equation

Whose initial value is given i.e we know at a point x0 what is the value of the function y(x0) and we call the value y0

Page 7: FEM Lesson 1

1.2 Ordinary differential equations• An example, given

,h = delta x = 0.1 , y(0) = - 0.2

The solution diagram

Page 8: FEM Lesson 1

1.3 ODE beam of first , second, third and fourth order

Page 9: FEM Lesson 1

1.4 Partial differential equation and plates