Introduction to Engineering Mechanics II: Dynamics.pptx

1. Introduction to Engineering Mechanics II: Dynamics by Professor Dr Ilias Inam

1. Engineering Mechanics II ME 2209 Dr. Mohammad Ilias Inam Professor Department of Mechanical Engineering & Technology Khulna University of Engineering & Technology

2. 2 - 2 References: 1. Engineering Mechanics Statics and Dynamics by R. C. Hibbler 2. Vector Mechanics for Engineering (Dynamics) by Ferdinand P. Beer and E. Russel Jhston

3. 2 - 3 Mechanics: Mechanics is the study of force, deformation, motion and the relation between them. Mechanics traditionally partition into three course, such as: 1. Statics: ME 1209 – Acceleration is considered zero here. 2. Dynamics: ME 2209 - Dynamics deals with the non- negligible acceleration of mass. 3. Strength of Material: ME 2211 – Strength of material, also called Mechanics of Solid, is a subject which deal with the behavior of solid objects, subject to stress and strain.

4. Stati1209 2 - 4 1. Newton First law and Third law is enough for the study of bodies at rest or in motion. 2. Here acceleration is zero. 3. Velocity could be zero or not. If velocity is not zero than velocity should be constant. 4. Equation: For particle. For Rigid Body. Statics (ME 1209)

5. Kinetics : Kinetics study of the relations existing between the forces acting on a body, the mass of the body, and the motion of the body. Kinetics is used to predict the motion caused by given forces or to determine the forces required to produce a given motion. Kinematics : Kinematics study of the geometry of motion. Relates displacement, velocity, acceleration, and time without reference to the cause of motion. F thrust F lift F drag Dynamics

6. 2 - 6 Particle: A particle is a body of negligible dimensions. When the dimensions of a body are irrelevant to the description of its motions, the body can be treated as a particle. Examples: An airplane: Yes when analyzing the flight path from Khulna to Dhaka. No when plane rotates. A space shuttle: Yes when analyzing the orbit of the shuttle. No when the shuttle turns. Rigid Body: A rigid body is a body that does not deform and the dimension of the body are not negligible. When the deformation is much less than the dimensions of the body to be analyzed and the dimensions of a body are irrelevant to the description of its motion, the body can be treated as a rigid body. Examples: An airplane: Yes when analyzing the rotational motion of the airplane. No when analyzing the vibration of the airplane wings.

7. 2 - 7 Particle No rotation No moment equation Rigid Body Rotation Exist Moment equations are important. Kinematics Relates displacement, velocity, acceleration, and time. Forces are not included in the analysis. Kinetics Relates force, mass, velocity Forces are considered

8. 2 - 8 Kinematics of particle Kinematics of rigid body Kinetics of particle Kinetics of rigid body 1. Dimensions are negligible. 2. Forces are not consider. 3. Chapter: 11. 1. Dimensions are important. 2. Forces are not consider. 3. Chapter: 15. 1. Dimensions are negligible. 2. Forces are consider. 3. Chapter: 12 & 13 1. Dimensions are important. 2. Forces are consider. 3. Chapter: 16, 17 & 18