L. Roy Xu's blog

interfacial crack initiated from a polymer notch (click here to view this YouTube video from our experiment),     read more below to submit your abstracts

Prof. Jun Xu, Dr. Scott Grutzik, and I organize one topic on “Dynamic failure of materials and structures” for 2019 ASME Congress. We invite you, your colleagues and group members to submit short abstracts before ASME’s deadline of Feb 25, 2019. More details below: 

Thu, 2016-03-03 17:25 - L. Roy Xu

interfacial crack initiated from a polymer notch (click here to view this YouTube video from our experiment),     read more below to submit your abstracts

Dr. Jun Xu and I organize  one topic on “Dynamic failure of advanced materials (fatigue failure is included also)” for 2017 ASME Congress. Our keynote speakers include a senior program manager of US Office of Naval Research and a distinguished researcher of US Army Research Laboratory. We would invite you (also your colleagues  and group members)  to submit a short abstract before ASME’s deadline March 6. More details below: 

 
interfacial crack initiated from a polymer notch (click here to view this YouTube video from our experiment),     read more below to submit your abstracts

Why should we investigate fracture and failure mechanics? From this Boeing 737 accident (below) to recent fatigue cracks of new Airbus  A380,  we must use failure mechanics knowledge to save our lives. Therefore, Dr.H. Eliot Fang (Program Manager at the DOE Sandia National Labs), Dr.  Larry
C. Russell (program manager at the Army Research Office) and I would invite you to submit abstracts to our symposium

Even Jay Leno tried to understand fatigue cracks at his Yesterday’s Tonight Show, our research on fracture and failure mechanics is received great attention from the general public. Read more after this photo--

You are invited to present your research work on the mechanical behavior of nanocomposite materials (Nov. 13-19, 2009 in Florida, close to Disney World). This topic will be focused on systematic mechanics experiments, modeling and simulations to solve new challenging mechanics problems such the effect of nanofiller agglomeration on the stiffness and strength reduction; interfacial stress transferring and interface strength evaluation at the nanoscale.  Deadline for abstract submission is March 17, 2009.

I would invite you to present your research work at the Society of Experimental Mechanics Conference (visit www.sem.org  for more details). You are welcome to submit your abstract my two sessions: 

1. Mechanical Behavior of Nanocomposite Materials

2. Recent Advance in Composite Materials.

You are invited to present your research work on the mechanical behavior of nanocomposite materials (Nov. 13-19, 2009 in Florida ). This topic will be focused on systematic mechanics experiments, modeling and simulations to solve new challenging mechanics problems such the effect of nanofiller agglomeration on the stiffness and strength reduction; interfacial stress transferring and interface strength evaluation at the nanoscale.

New students may start from January 2008 if the graduate students have previous research experience in solid mechanics (e.g., nano/micro-mechanics, computational mechanics) or material engineering (MD simulation, mechanical behaviors). Students will have the opportunities to conduct balanced experimental and computational work on the durabilty and impact failure of marine composite materials; failure and material designs of nanocomposite materials; or rehabilitation of infrastructure materials using composites and other materials.  An MS degree is required.

In July 2007, my friend of a consulting company contacted me for recruiting a computational mechanics engineer. I told him that all my graduate students found jobs, and there are not many mechanics students in our small department. So, I posted his ad at iMechanica. Only after one week, he asked me to withdraw this ad! Why?

Because many high-qualified applicants contacted him in one week and, he’d give the offer right away.  I believe this example is an index of active user groups of iMechanica.

They filled a pool with a mix of cornstarch and water made on a concrete mixer truck. It becomes a non-newtonian fluid. When stress is applied to the liquid it exhibits properties of a solid. Video was recorded at Barcelona, Spain.

Are not as high as we expected although very stiff and strong nanotubes or nanofibers (Young’s modulus E~1000GPa) are added into soft polymer matrices like epoxy (E~4GPa).  In our early investigation on the  systematic mechanical property characterizations of nanocomposites (Xu et al., Journal of Composite Materials, 2004--among top 5 in 2005;and top 10 in 2006 of the Most-Frequently-Read Articles in Journal of Composite Materials.) have shown that there was a very small increase (sometimes even decrease) of critical ultimate tensile/bending strengths, and mode-I fracture toughnesses in spite of complete chemical treatments of the interfacial bonding area, and uniform dispersions of nanofibers (click to view a TEM image). Similar experimental results were often reported in recent years. Therefore, mechanics analysis is extremely valuable before we make these “expensive” nanocomposite materials. Our goal is to provide in-depth mechanics insight, and future directions for nanocomposite development. Till now, nanocomposite materials are promising as multi-functional materials, rather than structural materials. Here we mainly focus on two critical parameters for structural materials: tensile strength and fracture toughness. We notice that other mechanical parameters such as compressive strengths and Young’s moduli of nanocomposite materials have slight increase over their matrices.

Vanderbilt University, Department of Civil and Environmental Engineering is seeking candidates to fill a tenure-track faculty position commencing Fall 2007.  Appointment at the assistant professor level is anticipated but higher ranks will be considered for truly outstanding candidates.  The successful candidate will have research and teaching expertise in structures with a research focus in one or more of the following areas:  structural health monitoring, systems-scale failure analysis, dynamic control, computational mechanics and micromechanics, advanced materials (e.g., nanocomposites,