## You are here

# Principal stress

Wed, 2013-09-18 09:55 - Zhigang Suo

Attachment | Size |
---|---|

principal stress 2013 09 18.pdf | 1.52 MB |

»

- Zhigang Suo's blog
- Log in or register to post comments
- 8318 reads

## Comments

## good lecture notes

good lecture notes

it is difficult for me to understand the third rank tensor.

The send rank tensor is stress, so what is the third rank tensor.

## Recipe to make new tensors

Most tensors are formed from other tensors.

A scalar is a tensor of order 0. Examples include mass, energy, and entropy. These tensors are difficult to make. We find them in nature.

A vector is a tensor of order 1. Examples include displacement, force, electric field.

Start with tensors you know, you can make new tensors by recipes like these:

You can invent your own recipes, so long as you start with known tensors and use linear maps.

Stress. By force balance, stress is a linear map that maps an area vector to the force acting on the area. See my notes on finite elasticity. The area vector is a tensor of order 1, and the force is a tensor of order 1. Consequently, the stress is a tensor of order 2.Piezoelectricity. When a stress is applied on a piezoelectric material, an electric field arises. This phenomenon is modeled by a linear map that maps the stress to the electric field. The stress is a tensor of order 2, and the electric field is a tensor of order 1. Thus, the map is a tensor of order 3.Please take a look at the recent thread on linear algebra and tensors.