Modeling the Effect of Surface Energy on Stressed Grain Growth in Cubic Polycrystalline Bodies

A recently-developed constitutive theory of stressed grain growth is augmented to include the effect of excess surface energy via a surface effect state variable. The new constitutive theory is implemented into a coupled finite-element and phase-field computational framework. Through three-dimensional simulations, the new constitutive model is shown to be capable of predicting the experimental data of the annealing-induced texture transition in polycrystalline copper thin films of different thicknesses attached to a polyimide substrate. Our simulations show that the grain growth driving force arising from the through-film thickness grain boundary curvature plays a prominent role in such a transitional behavior

Variant Reorientation in Single-crystal Shape-memory Alloys

In this work we model the variant reorientation in a single crystal NiMnGa magnetic shapememory alloy using the crystal-mechanics-based constitutive model of Thamburaja[1]. The model has been implemented in the ABAQUS/Explicit finite-element program by writing a user-material subroutine. Its numerical simulations quantitatively predict the mechanical response in simple compression and plain strain compression experiments to good accord

Anisotropic Superelasticity of Textured Ti-Ni Sheet

A recently developed crystal-mechanics-based constitutive model for polycrystalline shape-memory alloys (Thamburaja and Anand [1]) is shown to quantitatively predict the in-plane anisotropy of superelastic sheet Ti-Ni to reasonable accord.Singapore-MIT Alliance (SMA

An Investigation Of Modal Analysis For Al6061 Between Piezoelectric Film Sensor And Accelerometer

An experiment was conducted to determine modal parameters such as natural frequencies and mode shapes of aluminum 6061 (Al6061). A free dynamic vibration analysis was conducted to obtain the parameters. Al6061 was chosen as the experiment component mainly because of its wide application in automotive industries. Theoretically, if the component vibrates and produce frequency coherence with the natural frequency, resonance frequency will occur which can lead to structural failure. Modal analysis study was conducted by using both simulation and experimental method to compare their outcome. Simulation was conducted via ANSYS software while impact hammer testing was done for experimental work to determine the vibration parameter. Piezoelectric film and accelerometer were used as the sensor. The result obtained from simulation showed that frequencies for mode shape 1, 2 and 3 for circle shape were 134.60Hz, 324.73Hz and 727.52Hz. The result obtained from accelerometer showed that frequencies for mode shape 1, 2 and 3 for circle shape were 158.67Hz, 421.33Hz and 625.00Hz. Finally, the result captured from piezoelectric film sensor appeared that frequencies for mode shape 1, 2 and 3 for circle shape were 141.00Hz, 321.00Hz and 504.33Hz. There was a good results agreement between simulation and experimental work outcome

Thermomechanical couplings in shape memory alloy materials

In this work we address several theoretical and computational issues which are related to the thermomechanical modeling of shape memory alloy materials. More specifically, in this paper we revisit a non-isothermal version of the theory of large deformation generalized plasticity which is suitable for describing the multiple and complex mechanisms occurring in these materials during phase transformations. We also discuss the computational implementation of a generalized plasticity based constitutive model and we demonstrate the ability of the theory in simulating the basic patterns of the experimentally observed behavior by a set of representative numerical examples

Nanometallic Glasses: Size Reduction Brings Ductility, Surface State Drives Its Extent

We report tensile experiments on Ni80P20 metallic glass samples fabricated via a templated electroplating process and via focused ion beam milling, which differed only in their surface energy states: Ga-ion-irradiated and as-electroplated. Molecular dynamics simulations on similar Ni80Al20 systems corroborate the experimental results, which suggest that the transition from brittle to ductile behavior is driven by sample size, while the extent of ductility is driven by surface state

Length scale effects on the shear localization process in metallic glasses: A theoretical and computational study

10.1016/j.jmps.2011.04.018Journal of the Mechanics and Physics of Solids5981552-1575JMPS

A finite-deformation-based phenomenological theory for shape-memory alloys

10.1016/j.ijplas.2009.12.004International Journal of Plasticity2681195-1219IJPL

Constitutive equations for martensitic reorientation and detwinning in shape-memory alloys

10.1016/j.jmps.2004.11.004Journal of the Mechanics and Physics of Solids534825-856JMPS

The transition from homogeneous flow to fracture in metallic glasses at high-homologous temperatures

10.1016/j.scriptamat.2011.07.003Scripta Materialia659751-754SCMA