TMM coursework

Contents

Contents

Summary

Contents

Introduction

Section 1. Structural analysis of the mechanism

Section 2. Kinematic Mechanism Analysis

2.1 Kinematic analysis by plan method

2.2 Marking of the mechanism

2.3 Calculation of speeds

2.4 Calculation of accelerations

2.5 Kinematic analysis by diagram method

Section 3. Power calculation of the mechanism

3.1 Power calculation by plan method

3.2 Determination of useful resistance force

3.3 Power calculation of Assur group of the second class of the second type

3.4 Power calculation of Assur group of the second class of the third type

3.5 Power calculation of Assur group of leading link

3.6 Power calculation by the method of "hard lever" N.E. Zhukovsky

Conclusion

List of literature

Summary

A course project on kinematic and kinetostatic calculation of the crank-pole mechanism of the working machine using graphic and graphoanalytic calculation methods is presented. The graphic part is made on A11 sheet, note of typewritten text - 38p., Figures 18.

Introduction

The theory of mechanisms solves the problems of structure, kinematics and dynamics of machines in connection with their synthesis and analysis.

In this work, an analysis is carried out, since the already existing mechanism is studied.

The Applied Mechanics course project provides for the calculation of the mechanism in three main sections:

Structural analysis.

Kinematic analysis.

Kinetostatic analysis.

Each section performs a specific set of calculations required to investigate this mechanism.

Structural analysis provides an overview of the structure of the mechanism under investigation. This section does not provide much computation, but only provides initial information about parts and the entire mechanism. This information will be necessary in the future when calculating the mechanism.

Kinematic analysis is based on the results of structural analysis and provides for the calculation of kinematic characteristics. This section builds the positions of the mechanism at various points in time, calculates the speeds, accelerations, movement of points and links of the mechanism. Calculations are carried out by various methods, in particular, the plan method (i.e., solving equations in a vector way), the kinematic diagram method, in which kinematic characteristic diagrams are built, and the mechanism is studied from them. Kinetostatic analysis that discusses how to solve dynamic problems using analytical or graphical statics methods. Kinetostatics is based on the D'Alembert principle, according to which the equations of motion of bodies can be composed in the form of statics equations if inertia forces are added to the actual forces acting on the body and reaction of bonds.

Section 2. Kinematic Mechanism Analysis

In this section, the problems of kinematic analysis of the mechanism of the long machine are solved, namely, the marking of the mechanism for twelve of its positions is built; Identify the extreme positions of the mechanism; position of mass centers of links is determined; plans for speeds and accelerations are being made; determining the speed, acceleration and movement of the output link; kinematic diagrams are constructed.

2.1 Kinematic analysis by plan method

Kinematic analysis by the plan method (graphoanalytic method) is quite simple, clear and has sufficient accuracy for engineering calculations. Its essence is that the relationship between velocities and accelerations is described by vector equations, which are solved graphically.

Section 3. Power calculation of the mechanism

The main forces determining the nature of the movement of the mechanism are the driving forces performing positive work and the forces

useful resistance, performing negative work. These are the forces to overcome which the mechanism is designed.

3.1 Power calculation by plan method

The main tasks are to determine the reactions in kinematic pairs of mechanisms and to determine the balancing forces (or moments) applied to the driving links, which balance the system of all external forces and pairs of forces and all inertia and pairs of inertia forces.

In the theory of mechanisms and machines, the kinetostatic method of force calculation of mechanisms, which consists of the following, was widely used. If the inertia forces mentally dummy for this system are applied to the points of the non-free system together with the given forces, then the combination of these forces is balanced by the reactions of the bonds. This technique allows you to reduce the solution of dynamics problems to the solution of static problems.

Note: The determination of reactions in kinematic pairs of the mechanism at a constant angular velocity of the crank will be carried out without taking into account friction forces.

Conclusion

When deciding the first section, a structural analysis of the feed mechanism was performed, namely: the mobility of the mechanism was calculated, the structure of the mechanism was considered.

In the second section "Kinematic analysis," calculations were made to determine the movements, accelerations, speeds of the output link of the mechanism using the plan method and the kinematic diagram method.

The final third section considers the construction of plans of forces acting on links, reactions in kinematic pairs; balancing force is determined by the method of force plan and the method of lever N.E. Zhukovsky. The results can be considered reliable because the relative error of the equilibrium moment value falls within 10%, namely, 5.45% (for the mechanism in the 3rd position of the working stroke)

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