fracture mechanics

Abstract

With the scaling of VLSI, ultra low-k dielectrics with porosity are being introduced to reduce the capacitance coupling. But due to the weak bonding strengths, low-k dielectrics may fail by environmental-assisted subcritical cracking, fracture at stresses far below the loads required for catastrophic failure, causing reliability issues. In this term paper, several references are reviewed to investigate the mechanism of subcritical cracking at multiscale levels.

The objective of this paper is to analyze the fracture of orthotropic materials, with emphasis on wood.

<!--break-->

Abstract

A double cantilever beam (DCB)
specimen is created by affixing the two halves together using a bi-layer of
PC-3 prostate cancer cells. The specimen is pinned at a bottom corner, and the
upper corner on the same end is displaced with the force-displacement profile
being recorded. This upper corner is displaced until the crack, a portion of
the specimen where cell grown has been selectively inhibited, propagates
through the cell layer. The critical value of force at which the crack
propagates through the cell layer is used, in conjunction with the initial
crack length, to determine the toughness via the compliance-energy method (Ripling, et al. 1971). A method for performing a FE analysis of the

Assignment: Each student completes a term paper of selected topics that (a) addresses a fracture phenomenon in materials or structures, and (b) involves analyses using fracture mechanics. The project contributes 25% of the final grade, distributed as follows:

one file is attached.

one file is attached.

one file is attached.

One file is attached.

One file is attached.

one file is attached

one file is attached.

hii all..

i am working on fracture mechanics. i had modeled a 4 pt bend specimen having single notch crack(in ABAQUS). i am trying to find the range of K-dominant region at the crack tip.i had modelled radial mesh at the crack tip and using 20 noded reduced integration elements. To analyze the K-dominat region, primarily i had compared the theoritical stress plots and computational stress plots. stress plots means Sxx Syy Sxy values plotted againt the angle(angle measured from uncracked segment) at particular radius.

One file is attached.

1. Introduction

2. Elements of linear elasticity

3. Stress intensity factors

4. Energy release rate

5. Fracture toughness

6. Applications of LEFM - Practical Issues 

7. Mixed mode and interface fracture

I wanted to get some insight in the transient stress intensity factor (SIF).

In the time history, we notice there is an overshoot (~27%)  from the
steady state SIF for a fixed (not propagating crack). I found the
overshoot occurs at the time when the reflected wave from the opposite
crack-tip comes back to the first crack tip. I wanted to know why this
overshoot occurs, what is the physical explanation?

Sandip Haldar 

One file is attached.

Add Problem 5: use the method of superposition to obtain the stress field around a hole in an infinite sheet under uniaxial remote stress.

Due date extended to Monday, January 28, 2008. 

Homework Problem 1: Self introduction in iMechanica (due January 21, 2008)

Homework Problems 2-5 (due January 28, 2008) 

Homework Problems 5-8 (due February 7, 2008) 

Homework Problems 9-18 (due March 3, 2008) 

Homework Problems 19-23 (due March 24, 2008) 

Homewrok Problems 24-28 (due April 9, 2008) 

1. Post a comment to this entry to explain to your teaching staff and classmates why you are taking this class. Include the following items in your comment:

• Which department or graduate program are you currently enrolled in?

• Your prior courses in solid mechanics.

• Your undergraduate major and where you were enrolled.

• What might be your strength and weakness related to this course.

• Your research group if you already belong to one (please give a link to the web page of your group).

• Your likely research direction(s).

Time: Monday and Wednesday 3:00 - 4:30 pm

Place: WRW 312, University of Texas at Austin

Instructor: Rui Huang, WRW 117D, (512) 471-7558, ruihuang@mail.utexas.edu

Lecture notes 

Homework Sets

Term Papers (with links to abstracts, presentation slides and final reports)