Faculty Directory

Physical and mechanical behavior of titanium alloys, stainless steels, and other structural materials, modeling microstructure evolution in multiphase systems, finite element modeling (FEM) of deformation and damping behavior of composite materials, biomedical implants.

Investigation of Thermal Aging Effects on the Evolution of Microstructure and Mechanical Properties of Cast Duplex Stainless Steels
This research will provide a better understanding of the microstructural evolution and simultaneous change in mechanical response during aging. The results of the research will provide data that can be used to estimate degraded mechanical properties for an 80-year service life of light water reactors. Download the abstract (PDF)

Graduate students interested in working in these areas ahould contact Professor S. Ankem at ankem@umd.edu.

The Study of Twinning and Oxygen Interstitial Interactions in Model Titanium Alloys
We study the interactions between twins and interstitial elements, such as oxygen, in model titanium alloys through the use of atomistic computational materials science techniques.  In our current work, we are using Density Functional Theory (DFT) calculations in the Vienna Ab initio Simulation Package (VASP) combined with the Modified Embedded Atom Method (MEAM) calculations in Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to study the structural and thermodynamic characteristics of oxygen interstitials at the twins.  By combining energy barrier calculations, structural calculations, and experimental tests we are seeking to better understand how oxygen interstitials impact twin growth.  This will permit the future development of titanium alloys with improved mechanical properties.

 

Professor Ankem regularly teaches or has taught the following courses:

• ENES 100: Introduction to Engineering Design
• ENMA 362: Mechanical Properties, with lab
• ENMA 461: Thermodynamics of Materials
• ENMA 464: Environmental Effects on Engineering Materials
• ENMA 471: Kinetics, Diffusion and Phase Transformations
• ENMA 472: Technology and Design of Engineering Materials
• ENMA 489A/698C: Design of Composite Materials
• ENMA 484/684: Advanced Finite Element Modeling (formerly 489F)
• ENRE 648L: Materials Selection and Mechanical Reliability
• ENMA 661: Kinetics of Reactions in Materials

• "Finite Element Analysis and cellular Studies on Advanced , Controlled Porous Structures with   Subsurface Continuity in Bio-Implantable Titanium Alloys", P. Lambert, S. Ankem*, Z. Wyatt, K.M. Ferlin, J. Fisher, Journal of Biomedical Materials Research Part A, First Published online 17 May 2013. DOI: 10.1002/jbm.a.34684
• "Deformation Mechanisms and Kinetics of Time-dependent Twinning in an Alpha Titanium Alloy", Z.W. Wyatt, W.J. Joost, D. Zhu, S. Ankem, International Journal of Plasticity, 39,119-131 (2012). DOI: 10.1016/j.ijplas.2012.06.001.
• "Modeling interstitial diffusion controlled twinning in alpha titanium during low-temperature creep", P.G. Oberson, Z.W. Wyatt, S. Ankem, Scripta Materialia, Vol. 65, 2011, pp. 638 – 641. DOI: 10.1016/j.scriptamat.2011.06.049
• "The Effect of Yttrium on Ti-5111 Gas Tungsten Arc Welds", B.W. Neuberger, P.G. Oberson, and S. Ankem*, Accepted for Publication in Metallurgical and Materials Transactions A, 2010, p. 25.  DOI: 10.1007/s11661-010-0532-8.
• "Recent Developments in Mechanisms and the Kinetics of Deformation Twinning in Titanium Alloys", Z. Wyatt and S. Ankem*, Material Science Forum, Proceedings of PRICM 7, DOI:  10.4028/www.scientific.net/MSF.654-656.863
• "The effect of metastability on room temperature deformation behavior of β and α + β titanium alloys", Z. Wyatt and S. Ankem*, Journal of Materials Science, Proceedings of ICAM 2009, DOI: 10.1007/s10853-009-4178-0
• "The effect of time-dependent twinning on low temperature (<0.25 * Tm) creep of an alpha-titanium alloy", P.G. Oberson and S. Ankem, International Journal of Plasticity, Volume 25, Issue 5, May 2009, Pages 881-900. DOI: 10.1016/j.ijplas.2008.06.002
• "The Role of Deformation Twinning on Creep of Titanium Alloys", S. Ankem and P.G. Oberson, Materials Science Forum, Vols. 561-565, 2007, 121-126. 10.4028/www.scientific.net/MSF.561-565.121
• "Influence of the Second Phase on the Room Temperature Tensile and Creep Deformation Mechanisms of α-β Titanium Alloys-Part II: Creep Deformation", A. Jaworski, Jr., S. Ankem*,  Metallurgical and Materials Transactions A, Vol. 37A, 2006, pp. 2755-65.DOI: 10.1007/BF02586108
• "Influence of the Second Phase on the Room Temperature Tensile and Creep Deformation Mechanisms of α-β Titanium Alloys-Part I: Tensile Deformation", A. Jaworski, Jr., S. Ankem*,  Metallurgical and Materials Transactions A, Vol. 37A, 2006, pp. 2739-54.DOI: 10.1007/BF02586107
• "Mechanical Properties of Alloys Consisting of Two Ductile Phases", S. Ankem*, H. Margolin, C. Greene, B. Neuberger, P. Oberson. Progress in Materials Science, Vol. 51, 2006, pp. 632-709. DOI: 10.1016/j.pmatsci.2005.10.003
• "The Effect of Alpha Phase on the Deformation Mechanisms of Beta Titanium Alloys", A. Jaworski, Jr., S. Ankem*, Jour. of Mat. Eng. and Performance, Vol. 6, 2005, pp. 755-60. DOI: 10.1361/105994905X75565
• "Why Twins Do Not Grow at the Speed of Sound All the Time", P.G. Oberson, S. Ankem*, Physical Review Letters, Vol. 95, 2005, article no. 165501, pp.165501, 1-4. DOI: 10.1103/PhysRevLett.95.165501