Solutions Methods

Question 1

Two kinds of dynamic analysis

Answer 1

1. Low frequency excitation

2. High frequency excitation

Question 2

Advantage of modal superposition

Answer 2

efficient calculation for a time covering several periods of vibration

Question 3

Disadvantages of modal superposition

Answer 3

• > method limited to linear problems.

- > effort increases proportional to number of regarded mode shapes

Question 4

Application of modal superposition

Answer 4

Linear dynamic vibration problems

Question 5

Advantage of implicit integration scheme

Answer 5

• > non-linearities can be taken into account

- > stable method, time step size determined by accuracy

Question 6

Disadvantage of implicit integration scheme

Answer 6

High effort and long time if the non-linearities are severe

Question 7

Application of implicit integration scheme

Answer 7

linear and non-linear dynamic problems

Question 8

Advantage of explicit integration scheme

Answer 8

• > wave propagation can be described ocurring in impac problems
• > severe non-linearities in K can be handled

Question 9

Disadvantage of explicit integration scheme

Answer 9

• > Method is stable for very small time steps ony

- > smallest element size limits time step

Question 10

Application of explicit integration scheme

Answer 10

• > Impact - problems like vehicle crash

- > metal forming like rolling and deep drawing