Our paper has appeared in EML (Extreme Mechanics Letters) and can be downloaded. Using strong fibers to reinforce a hydrogel is highly desirable but difficult. Such a composite would combine the attributes of a solid that provides strength and a liquid that transports matter. Most hydrogels, however, are brittle, allowing the fibers to cut through the hydrogel when the composite is loaded. Here we circumvent this problem by using a recently developed tough hydrogel. We fabricate a composite using an alginate-polyacrylamide hydrogel reinforced with a random network of stainless steel fibers. Because the hydrogel is tough, the composite does not fail by the fibers cutting the hydrogel; instead, it fails by the fibers pulling out of the hydrogel against friction. Both stiffness and strength can be increased significantly by adding fibers to the hydrogel. Before failure the composite dissipates a significant amount of energy, at a tunable level of stress, attaining large deformation. Potential applications of tough hydrogel composites include energy-absorbing helmets, tendon repair surgery, and stretchable biometric sensors.

Hydrogels that undergo a volume phase transition in response to an
external stimulus are of great interest because of their possible use as
actuator materials. The performance of an actuator material is normally
characterized by its force–stroke curve, but little is known about the
force–stroke behavior of hydrogels. We use the theory of the ideal
elastomeric gel to predict the force–stroke curves of a
temperature-sensitive hydrogel and introduce an experimental method for
measuring the curve. The technique is applied to PNIPAm hydrogels with
low cross-link densities. The maximum force generated by the hydrogel
increases with increasing cross-link density, while the maximum stroke
decreases. The force–stroke curves predicted by the theory of the ideal
elastomeric gel are in very good agreement with the experimental curves.

This paper has appeared in Soft Matter and can be downloaded from:

http://www.seas.harvard.edu/suo/papers/311.pdf

The hyperlink for review on this book on amazon.com is http://www.amazon.com/Frcature-Mechanics-Fundamentals-Applications-Third/dp/0849316561/ref=dp_ob_image_bk

This book complements the course ES 247 (Spring 2010) because it covers most of the course's material and also it contains some of the topics that are not covered in the course, with examples. The book gives comprehensive treatment to the subject and applicable to a wide audience. The first chapter is basically devoted to the history of Fracture mechanics and raises issues related to the importance and why we should learn this subject. Throughout the book, the author provides the theoritical background and practical applications related to Fracture mechanics.

The first reason why I like this book is, it's readable because it's organized in a unique fashion. We can gain physical insight in to the subject through the fundamental concepts without higher level of math but there are some chapters and appendices for advanced readers too. I found comfortable reading this book compared to most of the other text books and I don't think there are any special weaknesses with this text book, so I would like to recommend this book to other students.