Mechanical Engineering Commons^™

Direct Quadrature Method Of Moments With Delumping For Modeling Multicomponent Droplet Vaporization, Simcha L. Singer

Mechanical Engineering Faculty Research and Publications

A multicomponent droplet vaporization model which combines the computational efficiency of continuous thermodynamic approaches with the detailed species information provided by discrete component models has been developed. The Direct Quadrature Method of Moments (DQMoM) is used to efficiently solve for the evolution of the nodes and weights of the equivalent liquid-phase mole fraction distribution without assuming any functional form. The novelty of the approach is an inexpensive delumping procedure that is used to reconstruct the time-dependent mole fractions and fluxes for all discrete species. When applied to a vaporizing kerosene droplet, agreement between the full discrete component model, which solves …

A Comparison Of Specularly Reflective Boundary Conditions And Rotationally Invariant Formulations For Discrete Ordinate Methods In Axisymmetric Geometries, Jian Cai, Somesh Roy, Michael F. Modest

Mechanical Engineering Faculty Research and Publications

In simulations of periodic or symmetric geometries, computational domains are reduced by imaginary boundaries that exploit the symmetry conditions. Two boundary conditions are proposed for Discrete Ordinate Methods to solve axisymmetric radiation problems. Firstly, a specularly reflective boundary condition similar to that is used in Photon Monte Carlo methods is developed for Discrete Ordinate Methods. Secondly, the rotational invariant formulation is revisited for axisymmetric wedge geometries. Correspondingly, a new rotationally invariant boundary condition specially designed for axisymmetric problems on wedge shape is proposed to enforce the rotational invariance properties possessed by the radiative transfer equation (RTE) but violated by three-dimensional …

Realization Of Point Planar Elastic Behaviors Using Revolute Joint Serial Mechanisms Having Specified Link Lengths, Shuguang Huang, Joseph M. Schimmels

Mechanical Engineering Faculty Research and Publications

This paper presents methods for the realization of 2 × 2 translational compliance matrices using serial mechanisms having only revolute joints, each with selectable compliance. The link lengths of the mechanism and the location of the compliant frame relative to the mechanism base are arbitrary but specified. The realizability of a given compliant behavior is investigated, and necessary and sufficient conditions for the realization of a given compliance with a given mechanism are obtained. These realization conditions are interpreted in terms of geometric relationships among the joints. We show that, for an appropriately sized 3R serial mechanism, any single 2 …

On The Importance Of Displacement History In Soft-Body Contact Models, Jonathan A. Fleischmann, Radu Serban, Dan Negrut, Paramsothy Jayakumar

Mechanical Engineering Faculty Research and Publications

Two approaches are commonly used for handling frictional contact within the framework of the discrete element method (DEM). One relies on the complementarity method (CM) to enforce a nonpenetration condition and the Coulomb dry-friction model at the interface between two bodies in mutual contact. The second approach, called the penalty method (PM), invokes an elasticity argument to produce a frictional contact force that factors in the local deformation and relative motion of the bodies in contact. We give a brief presentation of a DEM-PM contact model that includes multi-time-step tangential contact displacement history. We show that its implementation in an …

Effect Of Original Layer Thicknesses On The Interface Bonding And Mechanical Properties Of Ti-Al Laminate Composites, Minyu Fan, Joseph P. Domblesky, Kai Jin, Liang Qin, Shengqiang Cui, Xunzhong Guo, Naksoo Kim, Jie Tao

Mechanical Engineering Faculty Research and Publications

It is of great significance in high-temperature aeroengine applications for large-surface-area TiAl laminate composites to be fabricated into Ti-Al₃Ti parts by plastic forming and subsequent vacuum hot pressing. Then the original layer thicknesses have an important influence on the interface bonding and mechanical properties of TiAl laminate composites, but only few reports about it have been published so far. In the present study, vacuum hot pressing was employed to fabricate TiAl laminate composites using Ti and Al foils of different thickness. The resulting interface bond and mechanical properties of TiAl laminate composites were then studied to determine the …

Thermodynamic Properties Of Se-Te(L) Described By An Extension Of The Two Domain Model, Robert F. Brebrick

Mechanical Engineering Faculty Research and Publications

The two domain model of Se-Te liquid is developed further than heretofore. Explicit equations are obtained for the excess Gibbs energy of mixing, the chemical potentials, the enthalpy of mixing, the relative constant pressure heat capacity, and the partial and total pressures. A generally satisfactory fit is obtained for the experimental activity of Te and enthalpy of mixing at 733 K, the relative heat capacity as a function of temperature, and for the total pressure for 99, 60, and 27 at.% Se between about 780 and 1130 K. This is done while leaving unchanged the site fraction of H or …

Development Of High-Order PN Models For Radiative Heat Transfer In Special Geometries And Boundary Conditions, Wenjun Ge, Michael F. Modest, Somesh Roy

Mechanical Engineering Faculty Research and Publications

The high-order spherical harmonics () method for 2-D Cartesian domains is extracted from the 3-D formulation. The number of equations and intensity coefficients reduces to (N+1)2/4 in the 2-D Cartesian formulation compared with N(N+1)/2 for the general 3-D formulation. The Marshak boundary conditions are extended to solve problems with nonblack and mixed diffuse-specular surfaces. Additional boundary conditions for specified radiative wall flux, for symmetry/specular reflection boundaries have also been developed. The mathematical details of the formulations and their implementation in the OpenFOAM finite volume based CFD software platform are presented. The accuracy and computational cost of the 2-D Cartesian are …

Assessing Postural Stability Via The Correlation Patterns Of Vertical Ground Reaction Force Components, Chih-Yuan Hong, Lan-Yuen Guo, Rong Song, Mark L. Nagurka, Jia-Li Sung, Chen-Wen Yen

Mechanical Engineering Faculty Research and Publications

Background

Many methods have been proposed to assess the stability of human postural balance by using a force plate. While most of these approaches characterize postural stability by extracting features from the trajectory of the center of pressure (COP), this work develops stability measures derived from components of the ground reaction force (GRF).

Methods

In comparison with previous GRF-based approaches that extract stability features from the GRF resultant force, this study proposes three feature sets derived from the correlation patterns among the vertical GRF (VGRF) components. The first and second feature sets quantitatively assess the strength and changing speed of …