**1. Introduction**

**Nanomechanics** program is a branch of the basic mechanics (elastic, thermal and dynamic process) that studies physical systems within nano scope. Nanomechanics provides scientific basis for nanotechnology. As a basic science, nanomechanics take experience principle (fundamental observation) as the foundation, including: general principles of mechanics and some special principles when the object becomes smaller.

Nanomechanics are the interdisciplinary of classical mechanics, solid state physics, statistical mechanics, materials science and quantum chemistry etc.

Nanomechanics are often taken as a branch of nanotechnology, which is concentrated on the application of engineering nano structure and nano mechanical properties.

**2. Branch Fields**

1) Nano materials

2) Nano friction (nano science category friction, wear and contact mechanics)

3) Nano mechanical and electrical system

4) Nanofluidics

**3. Principles**

As a basic science, nanomechanics are based on experience principle (basic observation), including:

1) General mechanics principle;

Principle of energy and momentum conservation

Hamilton variational principle

Symmetry principle

2) Some special principles that appear as a result of research or exploration of a small object.

Because the research object is small, nanomechanics also need to consider:

1) When the size of the object and the distance of the atom can be compared, the dispersion of the object.

2) The diversity and limitation of the degree of freedom in the body.

3) The importance of expansion falls

4) The importance of the entropy effect

5) The importance of quantum effects

The principles can provide a deep understanding for the novel properties of nano objects. The novel properties refers to that this property doesn’t exist in similar macroscopic objects or the property is not the same. In particular, when the object becomes small, a variety of surface effects can occur, which is determined by the higher surface and volume of the nanostructures. These effects influence of nano structure of mechanical and thermal properties (melting point, heat capacity, etc.) for example, due to the discrete nature, solid mechanical waves to disperse, in the small area, elastic mechanics solution of special behavior. Freedom is caused by thermal expansion falling nanoparticles produce heat tunnel and cross diffusion of liquid and solid reasons through the potential barrier. Small and thermal fluctuations provide fundamental reasons for nanoparticles in Brown motion. The nano scale increases the importance of thermal fluctuations and structural entropy, so that the nano structures have super elasticity, entropy elasticity (entropy) and other new elastic. The structure entropy also makes a great interest in the self-organization and cooperative behavior of the open nano system.

Quantum effects determine the interaction forces between individual atoms in a physical system, introduces quantum effects with some mathematical average interatomic potential model in nanomechanics.

In the classical multi body dynamics, the atomic potential energy is added to the model. Data methods for solving these models are called molecular dynamics (MD), sometimes called molecular mechanics. Non deterministic numerical approximations include Monte Carlo, dynamical Moncaro and other methods. Modern numerical tools also include cross generic approximations that allow simultaneous and continuous use of atomic size models. The development of these complex models is another research topic in applied mechanics.

Quantum effects also determine the new electrical, optical and chemical properties of nanostructures. As a result of the quantum effects in the proximity of the nano science, nanotechnology, such as nanoscale electronics, advanced energy systems and nanotechnology disciplines to get more attention.

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