Re: stress intensity factor

Zhigang Suo — Thu, 17 Feb 2011 21:07:12 -0500

Your question was answered in the next lecture of the course: toughness.

stress intensity factor

kirthanlj — Thu, 17 Feb 2011 14:13:54 -0500

hello sir,

This is kirthan from bangalore. I am getting confused with SIF. How exactly SIF comes handy in analysing crack growth. According to the westergaard equation as θ and r tends to zero stress goes to infinity. And if we substitute any value of stress and crack length with r=0 and θ=0 the value gives infinity.

Books express SIF as the one which charaterises the crack growth in a material. I am not able understand the book meaning for SIF. Can u please help me regarding this.

Stress intensity factor

Zhigang Suo — Thu, 11 Feb 2010 17:18:29 -0500

We have modeled a body by using the linear elastic theory. We have modeled a crack in the body by a flat plane, and the front of the crack by a straight line. Within this idealized model, the field around the front of the crack is singular. The singular field is clearly an artifact of the idealized model, but Irwin and others made the singular field a centerpiece of fracture mechanics.

The mathematics of this singular field had been known long before Irwin entered the field. We will focus on the mathematics in this lecture, and will describe Irwin’s way of using the singular field in the following lecture.

In previous lectures, we have described the work of Griffith (http://imechanica.org/node/7470), and the reinterpretation of Irwin and Orowan (http://imechanica.org/node/7507). The descriptions centered on two quantities: energy release rate and fracture energy. This energy-based approach leads us into applications of fracture mechanics (http://imechanica.org/node/7531). Before showing you more applications, I’d like to tell you about a basic concept, possibly also due to Irwin, concerned with the modes of fracture.

The concept of the modes appeals to our intuition, but this concept is absent in the energy-based approach. Energy release rate by itself does not differentiate the modes of fracture. To describe the modes of a crack will require us to talk about the field around the front.

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Re: stress intensity factor

stress intensity factor

Stress intensity factor