bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Solution Heat Treatment and Natural Ageing on the Yield Characteristics of a 2024-O Aluminium Alloy
Authors: Ashbridge M. T. J. , Leacock A. G. , Gilmour K. R. , O’Donnell M. F. , McDonnell D. 
Published: November 2021

Abstract
Recent advances in computational technology have allowed engineers to conduct previously impractical analyses, particularly with the development of the Finite Element Method (FEM). In turn, this has led the sheet metal forming industry into an economy drive, with an increasing necessity for ‘first time’ forming operations and reduced scrap rates. The successful prediction of large-scale plastic deformation in a sheet component relies on the accuracy of the material model used, especially when anisotropic materials are considered. Some stretch formed or deep drawn forms are geometrically complex and may require several draws with inter-stage anneals and/or solution heat treatments to achieve full form, and the varying material properties create significant difficulties in the modelling of these forming processes. Current orthotropic yield criteria do not allow for any sense of time dependency and although the atomic effects of solution heat treatment and precipitation hardening are well understood, the macroscopic effects of deformation behaviour are not.
A test program was developed to investigate the effects of an increasing age hardening time on an aerospace Alclad 2024-O material after a solution heat treatment. With access to industrial heat treatment equipment, extensive tensile tests were conducted at varying age hardening times and a test rig was manufactured to obtain balanced biaxial tension data. Through the subsequent analysis, a method of predicting the data needed to generate a materials model suitable for FEA was developed, based on a modified version of Hill’s 1990 non-quadratic yield criterion. This was used to generate yield loci for the various age hardening times and compared with the loci generated with the predicted loci. Evaluation of the accuracy of the new criterion, and hence the predictive method, was achieved through its implementation in a finite element code used to model a punch-stretch test. Modelled surface strains were then compared with those measured strains determined during an empirical validation test programme.
With the knowledge that the analysis came from data predicted from a minimum of empirical tests, the predicted results were found to be in good agreement with the experimental values.
The Effects of Tooling Imperfections on the Initiation of Wrinkling in Finite Element Modeling of a Deep Drawing Process
Authors: Hematian J. , Wild P. M. 
Published: November 2021

Abstract
A brief review of the literature on wrinkling in deep drawing processes is presented. It is noted that, while there is a large body of literature related to thin sheet, only one study related to thick sheet or plate has been identified. Finite element based models are used to investigate the effect of initial tooling imperfections on the initiation of wrinkling in deep drawing of thick sheet. Two sorts of tooling imperfections, punch displacement and blank tilting, are considered. The simulation results are compared qualitatively to the experimental forming operation. It is confirmed that tooling imperfections, in particular blank tilting, are an important type of imperfection governing the wrinkling behavior of the blank in deep drawing process.
Efficient Meshfree Formulation for Metal Forming Simulations
Authors: Chen J. S. , Wu C. T. , Wang H. P. , Yoon S. 
Published: November 2021

Abstract
A stabilized conforming (SC) nodal integration method is developed for elastoplastic contact analysis of metal forming processes. In this approach, strain smoothing stabilization is introduced to eliminate spatial instability in Galerkin meshfree methods using nodal integration. The gradient matrix associated with strain smoothing satisfies the integration constraint (IC) of linear exactness in the Galerkin approximation. Strain smoothing formulation and numerical procedures for history-dependent problems are introduced. Applications to metal forming analysis are presented, with the results demonstrating a significant improvement in computational efficiency without loss of accuracy.
The Search for Mechanism in Bone Adaptation Studies
Authors: Cowin Stephen C. 
Published: November 2021

Abstract
The mechanosensory mechanisms in bone include (i) the cell system that is stimulated by external mechanical loading applied to the bone; (ii) the system that transduces that mechanical loading to a communicable signal; and (iii) the systems that transmit that signal to the effector cells for the maintenance of bone homeostasis and for strain adaptation of the bone structure. The effector cells are the osteoblasts and the osteoclasts. These systems and the mechanisms that they employ have not yet been unambiguously identified. The candidate systems are reviewed here. The current theoretical and experimental evidence, which suggests that osteocytes are the principal mechanosensory cells of bone, is summarized. This evidence shows that they are activated by shear stress from fluid flowing through the osteocyte canaliculi. The evidence also suggests that the electrically coupled three-dimensional network of osteocytes and lining cells is a communications system for the control of bone homeostasis and structural strain adaptation.
A General Constitutive Equation of an ER Suspension Based on the Internal Variable Theory
Authors: Wang Biao , Xiao Zhongmin 
Published: November 2021

Abstract
A microstructural constitutive theory of ER suspensions was formulated in this investigation. The framework was based on the internal variable theory and the mechanism analysis. The ER suspension consists of fine particles with high dielectric constant and the supporting fluid. Under the action of the electric field, the polarized particles will aggregate together to form the chain-like structures along the direction of the electric field. As the size and orientation of the particle aggregates are volatile, and they adjust according to the applied electric field and strain rate, the energy conservation equation and the force equilibrium equation were thus established to determine the orientation and size of the aggregates. Following that, a three-dimensional, explicit form of the constitutive equation was derived based on the interaction energy and the dissipation function of the system. The response of the system under the action of a simple shearing load was considered and discussed in detail. It is found that the shear-thinning viscosity of an ER suspension is well approximated by the power-law ∝ (Mn)−0.82.
Prediction of Stress Jump and Elongational Viscosity via Network Theory
Authors: Kee Daniel De , Sun Ning 
Published: November 2021

Abstract
The network model, originally developed for rubber like materials and later extended to model liquids, is subject to modifications. In this work, we look at the adaptation for improved elongational viscosity predictions and to allow for stress jump predictions.
A new formulation involving non-affine motion is proposed and its applications are presented. The major improvement is that a finite elongational viscosity is predicted for finite elongational rate, contrary to infinite elongational viscosities existing at some elongational rates predicted by most previous network models. Comparisons with experimental data on shear viscosity, primary normal stress coefficient and elongational viscosity are given, in terms of the same set of model parameters. The model is successfully tested with data on a polyisobutylene solution (S1).
A further extension of the network model is related to the prediction of the stress jump phenomenon which is defined as the instantaneous gain or loss of stress on startup or cessation of flow. It is not predicted by most existing models. In this work, the internal viscosity idea used in the dumbbell model is incorporated into the transient network model. Via appropriate approximations, a closed form constitutive equation, which predicts a stress jump, is obtained. Successful comparisons with the available stress jump measurements are given. In addition, the model yields good quantitative predictions of the standard steady and dynamic material functions, for xanthan solutions and for Polyacrylamide solutions.
Electromagnetohydrodynamics (EMHD): Numerical Experiments in Steady Planar Flows
Authors: Dennis Brian H. , Dulikravich George S. 
Published: November 2021

Abstract
A new second order theoretical model of the combined interaction of externally applied electric and magnetic fields and viscous incompressible fluid flows has been rewritten as a system of first order partial differential equations. The system was solved using least-squares finite element model on an unstructured grid. The numerical algorithm is very stable and accurate. The accuracy was confirmed by comparing the numerical results against simple analytical results for a magnetohydrodynamic flow between two parallel isothermal infinite stationary plates. Effects of Joule heating and reverse pressure gradient are correctly predicted with this algorithm which is applicable to arbitrary planar flow configurations.
A Three-Phase Hydrodynamic Model for Slurry Reactors
Authors: Gamwo Isaac K. , Soong Yee , Halow John S. 
Published: November 2021

Abstract
A predictive three-phase hydrodynamic model for slurry-bubble column reactors has been developed from the point of view of kinetic theory of granular flow (Gidaspow, 1994a). The model is based on first principles method and can provide a complete description of the flow field. To experimentally validate the code, local gas holdups have been measured at the National Energy Technology Laboratory (NETL) by inserting a dual conductivity probe horizontally into the reactor at various locations. Predicted gas holdups are in reasonable agreement with the experimental results in the bulk region of the reactor.
Simulation of the Film Blowing Process Using a Continuum Model for Crystallization in Polymers
Authors: Rao I. J. 
Published: November 2021

Abstract
In this paper we simulate the film blowing process using a model developed to study crystallization in polymers (see Rao (1999), Rao and Rajagopal (2000b)). The framework was developed to generate mathematical models in a consistent manner that are capable of simulating the crystallization process in polymers. During crystallization the polymer transitions from a fluid like state to a solid like state. This transformation usually takes place while the polymer undergoes simultaneous cooling and deformation, as in film blowing. Specific models are generated by choosing forms for the internal energy, entropy and the rate of dissipation. The second law of thermodynamics along with the assumption of maximization of dissipation is used to determine constitutive forms for the stress tensor and the rate of crystallization. The polymer melt is modeled as a rate type viscoelastic fluid and the crystalline solid polymer is modeled as an anisotropic elastic solid. The mixture region, where in the material transitions from a melt to a semi-crystalline solid, is modeled as a mixture of a viscoelastic fluid and an elastic solid. The anisotropy of the crystalline phase and consequently that of the final solid depends on the deformation in the melt during crystallization, a fact that has been known for a long time and has been exploited in polymer processing. The film blowing process is simulated using a generalized Maxwell model for the melt and an anisotropic elastic solid for the crystalline phase. The results of the simulation agree qualitatively with experimental observations and the methodology described provides a framework in which the film blowing problem can be analyzed.
Free Vibration Energy and Period of a String With Time-Varying Length
Authors: Lee Seung-Yop 
Published: November 2021

Abstract
We introduce a new technique to analyze free vibration energy and natural frequencies of a string with time-varying length by dealing with traveling waves. One of boundaries is vertically fixed but it moves axially at a constant rate. When the string length is varied, the free vibration energy and period also change with time. String tension and non-zero instantaneous vertical velocity at the moving boundary results in the energy variation. When the string undergoes retraction, the vibration energy increases with time. The new technique using traveling waves gives the exact amount of energy transferred into the vibrating system at the moving boundary. The free vibration energy are compared with previous results using the perturbation method and Kotera’s approach.
A New Formula to Calculate the Fundamental Frequency of a Multistory Building by Approximate Numerical Method
Authors: Weiss George 
Published: November 2021

Abstract
A new formula has been developed in this study, to calculate the fundamental frequency of a multistory building. This formula is derived from Dunkerley’s estimate, complies with the requirements of Uniform Building Code (UBC) and the Building Officials Code Administrators (BOCA) Code, and accounts for multistory building frames of different type and size.
A coefficient Γ, function of moments of inertia and lengths of column/girder was introduced in the formula, in order to obtain a relative simple algebraic equation.
To verify the validity of the new formula a thorough investigation has been conducted. Fundamental frequencies and periods have been calculated for different building frames using the new formula (Formula 1).
A formula for buildings with rigid floors, Formula 2, has been derived from Formula 1. Formula 2 has been used to calculate the fundamental frequency for the same type and size of buildings used in the calculations with Formula 1, considered with rigid floors. In addition, three different empirical formulas have been used to calculate the fundamental period for the same buildings. Two of these formulas are recommended in different versions of the codes.
For the same type and size of buildings the fundamental frequencies and periods have been determined by computer. Comparing with the computer values, formulas 1 and 2 give the best results and can be used in preliminary design, in vibration problems or to determine seismic lateral loads for buildings with a maximum height of 160/65 ft. The empirical formulas show large differences and have to be used with caution, only in the limited range imposed by UBC and BOCA.
Adhesive Joints for Composite Sandwich Structures
Authors: Dvorak George J. , Zhang Jian , Canyurt Olcay 
Published: November 2021

Abstract
A new approach is explored for joining of thick, woven E-glass/vinyl ester composite laminated plates to steel or composite plates, with applications in naval ship structures. Adhesive is applied along through-the-thickness contoured interfaces, employing tongue-and-groove geometry. Both experimental and finite element modeling results are presented. They show that adhesively bonded tongue-and-groove joints between steel and composite plates loaded in monotonically increasing longitudinal tension, are stronger than conventional strap joints even in relatively thin plates. In particular, a single 0.25 in. wide and 8 or 12 in. long steel tongue, bonded by the Dexter- Hysol 9339 adhesive to a groove in a 0.5 in. thick laminated plate, can support a 20,000 lbs tension force. This force is expected to increase in proportion to plate thickness. Simple design rules indicate that high joint efficiency can be achieved for any thickness of the joined plates.
Study of Two Cylindrical Water Columns Subjected to Planar Shock Wave Loading
Authors: Igra D. , Takayama K. 
Published: November 2021

Abstract
Two water columns with identical initial diameters of 4.8 mm were placed 30 mm apart inside a shock tube test section and loaded by a shock wave of Mach number 1.47 in atmospheric air. The Weber and Reynolds numbers corresponding to these flow conditions are 6,900 and 112,000, respectively. Double exposure holographic interferometry was used to visualize the shock/water columns interaction. The process of the water columns deformation, displacement, acceleration was well visualized and hence the drag coefficient of shock loaded water columns was evaluated. The water column in the front behaved virtually the same as a single water column. However the displacement and acceleration of the rear water column was less significant than that of the front one. Hence its drag coefficient is less. These results show that the frontal water column has affected the flow field around the rear water column.
Discussion on Clustering Effects in Vertical Gas-Particle Flows
Authors: Helland Eivind , Occelli Rene , Tadrist Lounes 
Published: November 2021

Abstract
Simulations of 2D gas-particle flows in a vertical riser using a mixed Eulerian-Lagrangian approach are addressed. The model for the interstitial gas phase is based on the Navier-Stokes equations for two-phase flow with a coupling term between the gas and solid phases due to drag forces. The motion of particles is treated by a Lagrangian approach and the particles are assumed to interact through binary, instantaneous, non-frontal, inelastic collisions with friction. In this paper different particle clustering effects in the gas-particle flow is investigated.
Buoyant and Rotational Flows During ACRT Vertical Bridgman Crystal Growth
Authors: Derby Jeffrey J. , Yeckel Andrew 
Published: November 2021

Abstract
Axisymmetric, time-dependent simulations of the high-pressure vertical Bridgman growth of large-diameter cadmium zinc telluride are performed to study the effect of accelerated crucible rotation (ACRT) on crystal growth dynamics. The model includes details of heat transfer, melt convection, solid-liquid interface shape, and dilute zinc segregation. Application of ACRT greatly improves mixing in the melt, but causes an overall increased deflection of the solid-liquid interface. The flow exhibits a Taylor-Görtler instability at the crucible sidewall, which further enhances melt mixing.
Correction of Hot-Wire Measurements in the Near Non-Conducting Wall Region
Authors: Wenzhong Li , Khoo B. C. , Diao Xu 
Published: November 2021

Abstract
The present paper is to determine the correction of hot-wire measurements when it is used to measure the shear flows region very close to the non-conducting wall. By numerical simulation of the Navier-Stokes and energy equations using the control volume method, we found that reasonably deployed grid distribution could largely reduce the computational domain size (for a typical Reynolds number for hot-wire near-wall measurements 4.0×10−3∼1.2, the domain boundary placing 650 diameters from the cylinder in front, rear and top is fair enough for accurate simulation, other than the domain boundary which places the 2000 diameters from the cylinder in front and top, and 3000 diameters from the cylinder in rear), and obtain the similar accuracy results for the correction of hot-wire measurements in the near-wall region. Numerical simulation results also show that, only taking the εf,εw (the maximum difference between the respective values of stream function and vorticity on successive iterations) as the criterion for convergence without judge to convergence of the temperature field seems not enough to obtain a convergent simulation result. This may be the possible reason which caused the discrepancy between the simulation results for hot-wire correction when using hot wire to measure the shear flows very close to the non-conducting wall.
Concurrent and Complementary Experimental and Computational Investigations for Hydrodynamic Design System of a Surface Ship
Authors: Rhee S. H. , Hino T. , Hirata N. , Kodama Y. , Kume K. , Takeshi H. , Ukon Y. 
Published: November 2021

Abstract
Results are reported of concurrent and complementary experimental and computational investigations on surface ship hydrodynamics at Ship Research Institute of Japan. The main goal of the investigations is to conceive an integrated hydrodynamic design system that can be utilized in shipbuilding industry. Model scale experimental data, which include global force and local flow measurements, are obtained by towing tank experiments. The experimental data provide validation benchmark for computational fluid dynamics simulations and are complemented by the results of computational investigations in terms of high-resolution data and turbulence quantities. The computational results also provide the global force and local flow data and are complemented by experimental data in various aspects such as breaking waves and sinkage and trim of the hull. The uncertainty assessment for experiments and the verification and validation for computational results provide the level of uncertainties and errors. Through the overall procedure that includes experimental and computational investigations with careful uncertainty analysis, an extensive set of information that can be provided to aid field designers is obtained. The future work includes further application to wave breaking and maneuvering ships in ambient waves using an unstructured grid method computer code and building a simulation-based-design system that comprises the information obtained throughout these investigations.
Flow Structures of Cavity-Channel Flows
Authors: Sun Xiaohua 
Published: November 2021

Abstract
Laminar, incompressible flows in a two-dimensional, T-shaped geometry are numerically investigated using a commercial CFD package. The geometry studied here is a square cavity attached to one side of a long, narrow channel. Fluid enters from one end of the channel, discharges into the cavity, and finds its way into the second part of the channel and eventually flows out of the domain. While the flat, top plate of the geometry remains stationary, the bottom part of the channel and the cavity move at a constant speed, in the same direction as the inlet velocity. As the ratio of the inlet velocity over the velocity of the moving bottom, r = Vin/U, changes, the vortex structures inside the square cavity experience a series of interesting changes.
Modeling of Laminated Composite Shells Featuring Damaged Interfaces
Authors: Librescu Liviu , Schmidt Rüdiger 
Published: November 2021

Abstract
This paper is devoted to the presentation of a general linear theory of laminated composite anisotropic shells of arbitrary shape and curvature, in which the effect of the interfacial damage induced by the imperfect bonding between the constituent laminae is incorporated. In this context, the imperfect interface conditions are described in terms of linear relations between the interface tractions in the normal and tangential directions, and the respective displacement jumps. In addition to the effects of imperfectly bonded interfaces, the theory incorporates the effects of transverse shear and transverse normal strain, the dynamic effects, as well as the anisotropy of constituent material layers. Due to its general character, this theory can contribute to a more reliable prediction, in the linear range, of the load carrying capacitiy and failure of laminated composite shell structures featuring imperfectly bonded interfaces.