Chapter 1 Principle 1

Teaching objectives:

1. Have a clear understanding of the concept of inertia force.

2. Master the method for simplifying the inertia force of the point system, and correctly calculate the principal vector and moment of the inertia force of the ing, fixed axis rotation, and Plane Motion rigid body.

3. Be proficient in solving dynamic problems by using the DA rang principle.

4. The moment of inertia, inertia product (centrifugal Moment of Inertia) of the rigid body on any axis, and the additional dynamic pressure of the bearing on the rotating rigid body of the fixed axis are calculated.

5. Understand the concept of inertial spindle, central inertial spindle, static balance and dynamic balance.

Highlights of this chapter:

1. Concept of Inertia Force, simplification of Inertia Force System of ing, fixed axis rotation and Plane Motion rigid body.

2. Working Principle of dalang.

3. Solve the dynamic problem with the principle of DA longbo.

Difficulties in this chapter:

1. Simplify the inertial force system.

2. Concept of inertia product and inertial spindle.

This chapter describes a method for solving dynamic problems. By introducing the concept of Inertia Force, dalang's principle is to solve the dynamic problem by using a column equilibrium equation. This method is also known as the dynamic and static method ".

I. Inertia Force

If the mass of a particle is set to produce acceleration under the force, it is defined as the inertia force of the particle. It is a resistance to force objects due to inertia resistance when the motion of a particle changes.

For example, the quality of the car, under the impetus of people along the smooth linear track movement, 14.1.

Fig 14.1

The acceleration of a car is defined by Newton's second law:

Is the force of a person acting on a car;

Is the force of a car on people;

In this case, the force of the car on people happens to be the inertia force of the car itself.

Ii. Principles of DA longbo

1. Principle of particle da rang

Set the quality to a non-free particle. The composing line motion (Figure 14.2) is subject to the active force and binding force ),

Fig 14.2

Based on Newton's second law, the acceleration is:

Move the above parameters:

Introduced inertial force, including:

(14.1)

The above formula indicates that if the inertia force of the particle is added to the particle imaginary in any instantaneous moment of the particle motion, the main force acting on the particle, the binding force, and the inertia force of the particle form a balance force system. This is calledPrinciple of particle da rang.

The projection equation of formula (14.1) is

2. Principles of the quality system

It is a mass system composed of a particle. The first particle has the following force:

-External Force,-Internal Force

Inertia of a particle:

Based on the dashboard principle of the particle, there are:

Indicates the force system form:

Because the internal forces appear in pairs, there are, the above formula can be expressed:

(14.2)

The above formula indicates that the inertia force of each particle is added to each particle on any instantaneous moment of the point system motion, the external force acting on the point system and the inertia force of the point system form a balance system. This is referred to as the dalang principle of the quality system.

Generally, formula (14.2) has six projection equations:

For flat Force Series, there are: