Israeli physicists from the Weizmann Institute have used a new approach to study how materials break. In a short news release, brilliantly titled "Breaking news", they explain their new method for analyzing the progression of a forming crack. The news release even says that it could have help engineers predict "exactly how much pressure the levees protecting New Orleans could withstand before giving way." Even if this is slightly exaggerated, this method could be used by engineers and material scientists in a vast variety of applications. Read more...
Here is the introduction of this news release.
Could engineers have known ahead of time exactly how much pressure the levees protecting New Orleans could withstand before giving way? Is it possible to predict when and under what conditions material wear and tear will become critical, causing planes to crash or bridges to collapse? A study by Weizmann Institute scientists takes a new and original approach to the study of how materials fracture and split apart.
Before going further, you have to realize that many of the materials we rely upon in our daily lives are subject to cracking. And even if lots of researchers have studied cracking in the past, the Israeli team is claiming that they are the first to come up with a method for analyzing the progression of a forming crack.
So what exactly did Professor Itamar Procaccia and his team at the Chemical Physics Department?
First, they divided the cracks' ridged surfaces up into mathematically-determined sectors. For each sector they were able to measure and evaluate different aspects of the crack's formation and to assign it simple directional properties.
After some complex data analysis of the combined information from all the sectors, the team found their method allowed them to gain a deeper understanding of the process of cracking, no matter which direction the measurements started from. The team then successfully applied the method to a variety of materials -- plastic, glass and metal.
As an example, below is an image showing the "typical geometry of a dynamically generated crack, with the side branches that result from the instability leaving their mark on the faces of the crack" (Credit: Weizmann Institute of Science).
Now, an important question remains: will this method be useful? And for what?
From the concrete in dams and buildings, to the metal alloys and composites in airplane wings, to the glass in windshields, many of the materials we depend on daily are subject to cracking. The team's method will give engineers and materials scientists new tools to understand how all of these basic materials act under different stresses, to predict how and when microscopic or internal, unseen fractures might turn life-threatening, or to improve these materials to make them more resistant to cracks' formation or spread.
For more information, here is a link to the impressive list of publications of Procaccia and his team. After reading some of them, I've selected "Non-universality in Micro-branching Instabilities in Rapid Fracture: the Role of Material Properties " (PDF format, 4 pages, 142 KB) from which the above illustration has been extracted.
Sources: Weizmann Institute of Science news release, via EurekAlert!, February 3, 2006; Nature, February 3, 2006; and various web sites
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