M. Guagliano^1,2, S. Bagherifard², I. Fernandez Parienete³, R. Ghelichi²

Structural Durability & Health Monitoring, Vol.6, No.1, pp. 31-42, 2010, DOI:10.3970/sdhm.2010.006.031

Abstract Surface grain refinement is a relatively new process aimed to enhance mechanical material properties. In this study Al7075-T6 bars have been shot peened with parameters (shot speed and treatment duration) much stronger from those of conventional shot peening (SP). Residual stress state and microstructure gradient have been observed by means of transmission electron microscopy (TEM), X-ray diffraction (XRD) and nano indentation tester. Formation of a fine grained layer of material on top surface of the specimens was confirmed by TEM and also XRD measurements. XRD results show significant depth affected both in terms of residual stress and full width half… More >

T. Fu, C.P. Wang, B. Hou, X.D. Zhu, Z.F. Zhou, K.Y. Li, J. Lu

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.3, pp. 91-92, 2011, DOI:10.3970/icces.2011.020.091

Abstract Structural steels are widely used in engineering fields. Generally, they have the advantage of lower prices due to less precious alloy elements contained; however, their properties, especially the surface properties are inferior to high alloy steels. Surface engineering are of importance in improving surface properties of steels, and even a 'new' surface layer with high performances can be produced by surface technologies on low cost structural steels with ordinary properties.
The researches of last decade have shown that surface nanocrystallization (SNC) can markedly improve surface mechanical properties of metallic materials and accelerate thermal diffusion of N, Cr, etc atoms. In… More >

R. Matsumoto¹, M. Nakagaki¹, A. Nakatani², H. Kitagawa³

CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.1, pp. 75-84, 2005, DOI:10.3970/cmes.2005.009.075

Abstract In this paper, the internal structure-changes around the crack-tip and the pertinent crack growth behavior in an amorphous metal were studied by a molecular dynamics (MD) simulation. In order to perform a large scale calculation, the domain decomposition method was used for parallel calculation. The Finnis-Sinclair potential for$\alpha$-iron was used to describe the interatomic potential. Computed results show that nano-scaled crystalline phase grows around the crack-tip. The distribution of deformation zones and deformation mechanism are significantly altered. While grains are relatively small, they are not deformed, and the most amorphous-crystal interfaces have a large strain for phase transition. The emission… More >

G. El hajj Sleiman¹, G. Colomines¹, R. Deterre¹, I. Petit1, E. Leroy², S. Belhabib^1,*

Journal of Renewable Materials, Vol.6, No.3, pp. 270-276, 2018, DOI:10.7569/JRM.2017.634179

Abstract Poly(3-hydroxy butyrate)-co-(3-hydroxy valerate) (PHBV) is a biobased and biodegradable polyester. This semicrystalline bioplastic could be a good candidate for the replacement of some commodity plastics derived from oil. However, the control of the conditions of its processing in order to obtain optimal properties of the finished products remains a current research subject. The objective of this work is to better understand the crystallization under injection molding conditions by inline measurements during the process. We focused on the influence of two key processing parameters, namely, mold temperature and packing pressure. The modeling of inline temperature measurements allowed an inverse estimation of… More >

Jose Luis Orellana, Michael Mauhar, Christopher L. Kitchens^*

Journal of Renewable Materials, Vol.4, No.5, pp. 340-350, 2016, DOI:10.7569/JRM.2016.634126

Abstract Polylactic acid (PLA) is one of the most widely used biodegradable polymers due to the ability to synthesize it economically at industrial scale and its favorable properties for many consumer products. However, the rigid nature of PLA is not desirable for specific applications, requiring the incorporation of effective bioderived additives in order to enhance the PLA toughness and broaden applications. In this work, PLA was modified by graft polymerization of polyacrylic acid (PLA-g-PAA) to increase the hydrophilicity to promote compatibilization of cellulose nanocrystals (CNCs) or high molecular polyethylene glycol (PEG). CNCs were found to act as a nucleating agent for… More >

S.K. Pal¹, D.A. Linkens²

CMC-Computers, Materials & Continua, Vol.2, No.2, pp. 113-118, 2005, DOI:10.3970/cmc.2005.002.113

Abstract In hot rolling, the final thickness of the strip is achieved through plastic deformation of the original stock by a series of counter-rotating rollers. In this work, static recrystallization kinetics in between two stages of steel rolling has been modelled, and simulation studies have also been performed to find out the effect of entry temperature on the recrystallization kinetics. A viable bond graph model has been developed to study the kinetics of the process. Low-carbon steel has been considered for this purpose. More >

N.I. Wakayama¹, D.C. Yin², J.W. Qi³

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.2, pp. 153-170, 2005, DOI:10.3970/fdmp.2005.001.153

Abstract The production of crystals of adequate size and high quality is the "bottleneck'' for three-dimensional structure analysis of protein crystals. In this work, in order to shed additional light on the (still controversial) beneficial effect of microgravity on crystal growth, we focus on recent advanced experimental and theoretical research about the effects of buoyancy-driven convection on protein crystallization. In the light of the numerical studies the following major outcomes can be highlighted: (1) when the crystal size exceeds several dozens of µm, buoyancy-driven convection dominates solute transport near the growing crystal and the crystal growth rate becomes larger than that… More >

Y.B. Zhang¹, A. Godfrey², D. Juul Jensen¹

CMC-Computers, Materials & Continua, Vol.14, No.3, pp. 197-208, 2009, DOI:10.3970/cmc.2009.014.197

Abstract Two methods to quantify protrusions/retrusions and to estimate local boundary curvature from sample plane sections are proposed. The methods are used to evaluate the driving force due to curvature of the protrusions/retrusions for partially recrystallized pure nickel cold rolled to 96% reduction in thickness. The results reveal that the values calculated by both these methods are reasonable when compared with the stored energy measured by differential scanning calorimetry. The relationship between protrusions and the average stored energy density in the deformed matrix is also investigated for partially recrystallized pure aluminum cold rolled to 50%. The results show that the local… More >

D.P. Field¹, L. Behrens², J.M. Root¹

CMC-Computers, Materials & Continua, Vol.14, No.3, pp. 171-184, 2009, DOI:10.3970/cmc.2009.014.171

Abstract Mechanical properties of polycrystalline metals are dependent upon the arrangement of microstructural features in the metal. Recrystallization is an important phenomenon that often occurs during thermo-mechanical processing of metals. This work focuses upon aluminum alloy 7050 and uses crystallographic texture and pair correlation functions of recrystallized grains to characterize the dominance of particle stimulated nucleation in the recrystallization process. The randomization of the recrystallization texture and similar pair correlation functions for the particle distribution and the recrystallization nuclei distribution indicate that particle stimulated nucleation controls the recrystallization behavior in this alloy. More >