bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prediction of Remaining Life Time Based on Measurements of Stress for Thermal Barrier Coatings
Authors: Jordan E. H. , Xie W. , Gell M. , Xie L. , Tu F. , Pattipati K. R. , Willett P. , Sohn Y. H. 
Published: November 2021

Abstract
Non-destructive determination of the remaining life of coatings of gas turbine parts is highly desirable. The present paper describes early attempts to prove the feasibility of doing this based on the optical measurement of the stress in the oxide that attaches the coating to the metal component. Both regression methods and neural network methods are compared and it was found that the neural network approach was superior for the case where multiple signal features were present. All methods provide useful predictions for the idealized case considered. Challenges presented by more complicated thermal cycles are discussed briefly.
Behavior of Composite Materials Under Impact: Strain Rate Effects, Damage, and Plasticity
Authors: Abrate Serge 
Published: November 2021

Abstract
Composite materials are often subjected to low velocity impacts, ballistic impacts, or crash impacts. In order to analyze such events, realistic model of the material behavior must be used to capture phenomena no included in linear elastic models. Nonlinear behavior occurs when a unidirectional lamina is loaded in the transverse direction or in shear when the matrix material deforms plastically. The stiffness and strength of composite materials at high strain rates is often very different from what is measured in quasi-static tests. In addition, different types of damage are introduced during impart: matrix cracks, delaminations, fiber failures, fiber-matrix debonding. The introduction of this damage will affect the subsequent behavior of the material.
Many different approaches have been taken to account for the effects of strain rate, plasticity and damage on the mechanical behavior of composite materials. The objective of this paper is to assess current knowledge in this area, review and compare models used to describe the stress-strain behavior and predict failure of such materials. Continuum mechanics approaches are used to describe the behavior of laminas with different types of damage, and to model the behavior of interfaces between plies. Phenomenological plasticity models account for the nonlinear effects under transverse and shear loads. Some of these models are shown to be similar even though they were derived by very different approaches. Many accurate analyses of composite structures under impact assume linear elastic behavior and do not considered the complicating effects discussed here. The applicability of the different models for material behavior is also discussed in terms of selecting an appropriate model for analyzing a particular impact.
The Audi Space Frame on the A2: A New Body Concept in Aluminum for Superior Crashworthiness
Authors: Christlein Jens , Maar Eric 
Published: November 2021

Abstract
Vehicle concepts of the future will have to satisfy such contradictory requirements as high body rigidity and maximum safety in all driving situations, coupled with minimum weight. With this in mind, at the 1997 Frankfurt Motor Show Audi presented the Al2 study vehicle, a car which makes ultra-low fuel consumption possible thanks to its new overall technical concept based on extremely low-weight Audi Space Frame (ASF) techniques and innovative engines, but is a multi-purpose four-door vehicle despite its compact exterior dimensions. This study model was developed into a production-ready vehicle within a very short space of time: the Audi A2, which made its début at the Frankfurt Motor Show in September 1999. Only with the aid of simulation techniques it was possible to bring such a novel body concept to production maturity within such a short space of time. The following paper describes the technical highlights of the ASF body on the Audi A2.
Validation of FMVSS201 Featureless Headform Finite Element Model for Rotational Acceleration
Authors: Barbat Saeed D. 
Published: November 2021

Abstract
This paper demonstrates an application of the nine linear accelerometer scheme, proposed by (Padgaonkar et al., 1975), to the development and validation of a finite element model of a deformable featureless headform for rotational accelerations. Steps and procedures involved in the development and calibration of the model are also described. A set of tri-axial accelerometers was mounted at the headform center of gravity, C.G., which is located at the origin of the local coordinate axes of the headform. Three bi-axial accelerometers were also mounted at the front, left, and top of the headform’s aluminum skull and on the local coordinate axes of the physical headform. Nine linear accelerations were measured at the headform in drop tests against a rigid plate at impact speeds of 2.68, 4.0, 5.36, and 6.71 m/s (6, 9, 12, and 15 mph). The rotational accelerations of the headform were then calculated from the nine linear acceleration measurements. In the finite element (FE) model of the featureless deformable headform, a visco-elastic material law, available in the non-linear dynamic explicit code PAM-CRASH, was used to simulate the vinyl skin response during impact. The constitutive parameters of the headform’s skin material were calibrated through comparison of the headform drop simulations at various impact speeds with the corresponding tests. Headform responses, such as, resultant acceleration time histories at the headform C.G. and the rotational acceleration time histories obtained from the FE predictions of the headform responses during the drop tests simulations correlated very well with those obtained from experiments. Validation of the headform model for rotational accelerations provided higher level of confidence in the prediction capability of the model when used for interior head impact simulations with vehicle upper interior as specified by the Federal Motor Vehicle Safety Standard FMVSS 201.
Application of Topological Optimization Techniques to Automotive Front Structure Design
Authors: Mayer Robert R. 
Published: November 2021

Abstract
An application of topological optimization techniques to automotive front structure design was considered, for the case of crashworthiness performance. An earlier developed topological optimization technique was used by first deriving an optimality criteria. To develop an optimality criteria, a functional relationship was developed between microstructure design variables, and both strain energy and volume, for shell element structures. Its previous application was the location of holes to lighten a rear longitudinal rail. The present application applies this theory to the actual layout of automotive front structure. The nonlinear code, LS-DYNA, was used for the simulations.
An observation of various automotive front structural topologies, sometimes called structural layouts or architectures, reveals that many different design approaches are possible. In order to numerically assess the optimum layout the design space available for front structure design is built up from layers of shell elements, and the method of constructing these models using LS-INGRID is discussed. Some of these elements are deleted at each optimization iteration, resulting in a design concept. The design concept is interpreted as a number of structural load paths, and a unique design was then identified.
Engineering Across Borders: Educational Practices for Improving the Effectiveness of Globally Distributed Engineering Design Teams
Authors: David Kenneth , Lloyd John R. 
Published: November 2021

Abstract
Globalization of engineering design teams occurs both in industry and also in the engineering classroom. Strategic needs for operating multi-site operations and inter-organizational alliances call for more effective boundary-spanning partnerships: inter-divisional, inter-organizational, and often, multi-country partnerships. This paper reports a multi-discipline research study — involving engineering, anthropology and telecommunications elements — on global engineering design teams. US engineering students from mechanical, chemical, and electrical engineering worked together with counterparts from China and the Netherlands. The students learned advanced telecommunication media and transcultural communication skills needed to carry out the tri-continental design project. They used an active learning process called transcultural incident reporting that focuses on cultural and power issues that must be managed in order to accomplish high quality design. The engineers’ reports show a gain in understanding of the cultural and power issues that affect boundary-spanning project performance.
A New Approach to Teaching a Mechanical Systems Design Course
Authors: Jouaneh Musa 
Published: November 2021

Abstract
This paper discusses a new approach to teaching a senior-level mechanical systems design course at the University of Rhode Island. The MCE401 class was split into 9 teams, each with four students. Team members were selected to complement their learning styles. To each team, additional 4 students from the URI Business school were added. In the Fall semester, each team selected one of several different, product-oriented design projects or proposed their own project topic subject to certain requirements. The students were asked to perform a patent search, to critique related products, to prepare a marketing study, to propose a design of this product, and to realize their design using a 3-D solid-modeling software. At the end of the Fall semester, groups competed for funding for activities in the following Spring term that included building prototypes of their design, formulating business plans for commercialization, and applying for patent protection. The new proposed format gave students better understanding and exposure to the entrepreneurial process of product design and innovation.
Rapid Simulation of Preloaded Bolted Assemblies for Slewing Bearings
Authors: Leray Dimitri , Daidié Alain , Combes Bertrand 
Published: November 2021

Abstract
Fatigue failure is a common problem with bolted joints. Preloading can often offer great advantage, in that it reduces the intensity of the alternative part of strains. Although it is more and more usual to carry out very precise finite element calculations, it should be highlighted that the error arising from simulations or experiments may be surprisingly great when looking at supplements of strain, i.e. alternative strain.
That is one of the reasons why designing preloaded bolted joints requires great care, and sometimes turns out to be impractical.
A partnership has been established for several years with a group of industrial manufacturers and users of slewing bearings. The objective is to model a parameterised bolt-assembled slewing bearing system and to develop a simulation tool that
• allows us to check resistance of the bolts for maximum load as well as fatigue load
• runs much faster than a three-dimensional simulation in order to enable us to compare multiple configurations, in order to be used in early design stages.
Equilibrium Elasto-Hydrodynamic Analysis in Wafer Slicing Process Using Wiresaw
Authors: Zhu Liqun , Kao Imin 
Published: November 2021

Abstract
An improved elasto-hydrodynamic (EHD) model of wiresaw slicing process is summarized in this paper which incorporates the equation of equilibrium for the motion of the wire. Parametric studies are conducted, which encompass different cases in the wiresaw slicing process. Based on the results, we examine the effects of wire bow angle on the EHD properties and the slicing mechanism of wiresaw process. The simulation results provide insights to the wiresaw slicing mechanism, and suggest ways to facilitate the experimental study for industry wiresaw slicing.
A Methodology for Evaluating the Mechanical Reliability of Alternatives to Tin-Lead Solder Electronic Interconnection Systems (Focus on Electrically Conductive Adhesives)
Authors: Rafanelli Anthony J. 
Published: November 2021

Abstract
A methodology for evaluating suitable alternative materials to traditional tin-lead solder, as an electronic component interconnection media, is presented. This methodology was developed as part of prior research that addressed the mechanical reliability of alternative materials using approaches and methods, which were traditionally unique to tin-lead, solder.
The original research included evaluation and subsequent tabulation of basic mechanical, fatigue, creep, and fracture mechanics properties. Basic mechanical data was acquired either through the literature or laboratory test. Fatigue data was limited to thermal shock/cycling. Creep data consisted of observing material behavior under temperature and thermo-mechanical loads. The fracture mechanics study features the validation and subsequent use of the J-Integral as applied to solder and electrically conductive adhesives (ECAs).
This paper suggests a framework for establishing a methodology for evaluating mechanical reliability of electronic interconnection media based on the acquired materials data.
Finite Element Modeling of Processes in Optoelectronic Alignment
Authors: Ting Ben , Manno Vincent P. 
Published: November 2021

Abstract
For semiconductor lasers, fiber and optical source alignment is crucial for maintaining high optical transfer efficiency. Traditional optoelectronic manufacturing, production of butterfly packages for example, involves laser welding of fiber mountings followed by a tedious realignment procedure to reverse thermally-induced distortions. An alternate technique, laser hammering, entails manipulation of the fiber to light alignment through deformation of the fiber housing with high precision laser beams. A detailed understanding of the material and mechanical behavior, characteristics, and dynamic response is vital to successfully apply an efficient controller that can choose an optimal weld pattern based on a light to fiber misalignment. Modeling provides an effective means to determine an optimal fiber alignment control technique. Modeling is difficult due to the dynamic thermal-mechanical coupling of these processes. This paper presents the preliminary results of a series of parametric studies regarding thermal-mechanical coupling models employed in finite element analysis in order to assess the behavior and dynamic response of representative materials and geometries under various boundary conditions. Fiber ferrule and ferrule housing dimensions affect resistance to bending and torsion, which in turn governs the magnitude of the displacement field. The models are then applied to geometries typical of alignment fixtures used in laser diode packages. The effects of laser energy deposition location and resolution as well as assumed boundary and initial conditions are also discussed. Convection and the small variations in ferule geometry do not have a strong effect on the overall response.
Constitutive-Related Instabilities in Pipe Flow of a Viscoelastic Fluid
Authors: Alves Manuel A. , Pinho Fernando T. , Oliveira Paulo J. 
Published: November 2021

Abstract
The analytical solution for the steady-state flow in a pipe of viscoelastic fluids obeying the complete Phan-Thien-Tanner constitutive equation with a linear stress coefficient is derived. The results include the radial profiles of all relevant stresses, of the axial velocity and of the viscosity. The pipe flow is found to be unstable when the pressure gradient exceeds a critical value determined by a maximum shear rate at the wall. Expressions are also given for the viscometric viscosity and the first and second normal stress difference coefficients, as a function of the shear rate, in steady plane shear flow. For this case, and in line with similar results for the Johnson-Segalman model, the shear stress was found not to be a monotonically increasing function of the shear rate as strong shear-thinning sets in. A new finding is that the critical condition for the maximum shear stress in the simple-shear case is related to the condition for existence of steady-state solution in the pipe flow case. While this may seem evident “a priori” since the pipe flow is a viscometric flow, it is formally demonstrated.
Numerical Study of Mold Filling Dynamics in “Cold-Box” Sand Coremaking Process
Authors: Bakhtiyarov Sayavur I. , Overfelt Ruel A. 
Published: November 2021

Abstract
In this paper we present the results of the numerical simulations of sand core shooting process using the CFD package FLOW-3D. The simulations are based on a two-fluid flow approach. The computation results are compared to experimental data obtained earlier.
CFD Simulations of Flow Dynamics in Porous Media of Variable Permeability Arranged in Series
Authors: Bakhtiyarov Sayavur I. , Siginer Dennis A. 
Published: November 2021

Abstract
In this paper we present the results of the CFD simulations of the viscous fluid flow in two porous media of different permeability and same porosity arranged in series. FLOW-3D software package (Flow-Simulations, Inc.) has been used to predict flow velocity distributions and pressure losses when Newtonian fluid flows through the non-homogenous porous medium. The results of simulations are compared to those obtained experimentally earlier.
Steady Secondary Flows of Phan-Thien-Tanner Fluids in Pipes of Complex Shapes
Authors: Letelier Mario F. , Olguín Mauricio A. , Siginer Dennis A. 
Published: November 2021

Abstract
Some kinematic and dynamic characteristics of secondary flows in straight tubes are explored for the case where the flow is laminar steady, the fluid is described by the modified Phan-Thien-Tanner model of viscoelastic fluids, and the tube cross-section shape varies through a wide range of configurations. This analysis is aimed at providing information about the transport capacity of secondary flows. Viscoelastic fluids have been observed to enhance heat transfer in pipe flow due to the transversal motion generated in non-circular pipes.
In order to improve the design of heat exchangers it is necessary to understand how some basic variables, such as pipe geometry determine the structure of the corresponding secondary flows. In this paper it is investigated the kinematics and dynamic of some secondary flows for pipe shapes that generate different flows structures.
Full Simulation of Natural Waves in Falling Films
Authors: de Korte Edwin , Kok Jim B. W. , van der Meer Theo H. 
Published: November 2021

Abstract
The two dimensional Navier Stokes equations have been solved for a falling film flow, i.e. a laminar flow running down a vertical wall driven by gravity. The aim of this research is to describe the onset of natural waves by using full simulation of the Navier-Stokes equations. In order to find the natural wave the flow velocity at the the inlet boundary (top horizontal plane) is perturbed.
With the boundary condition described above the fastest growing wave is triggered for a range of Reynolds numbers in the laminar wavy range. The wave numbers and velocities agree with results based on Orr-Sommerfeld theory reported by Pierson & Whitaker [7] for Re = 5.90 and Re = 11.8. For Re = 23.5 a different wavelength triggered than the one predicted by linear stability analysis. However the wavespeeds are in reasonable agreement with each other. A complete understanding for this phenomenon is not found yet.
There is shown that the behavior of the waves is strongly non-linear and transient. In this work is to illustrate that the wave profiles can be calculated by simply solving the Navier-Stokes equations without any prior assumptions.
The Central Roles of Fractals, Bifurcation, and Chaos in Optimal Fluid Mixing
Authors: Bondar Farshid , Taeibi-Rahni Mohammad 
Published: November 2021

Abstract
Mixing processes are widely used in industries and are being studied by a number of scientists; even though, a fundamental insight of the subject is still lacking. In this paper, some basic thoughts are set on the analogy between fluid mixing phenomena and fractal geometry/properties/ processes. To this end, an unstable horseshoe pattern, which leads to a continuous extending boundary with maximum stretching and folding, is created and repeated. As a result, self-similarity property along with instability is imposed throughout the region, enhancing the fluid mixing. The procedures are verified computationally using the techniques of capacity and information dimensions, which are measured as time-dependent functions. The results can be used to explore how well a fractal representation can describe fluid mixing phenomena, how fractal-like processes can optimize it, when fractal properties grow rapidly in the fluid system, and ultimately how unsteady flows are impending chaotic behavior in dynamical mixing systems when local bifurcations occur.
A Non-Intrusive Experimental Technique for Constructing Poincaré Maps in 3D Chaotically Advected Flows
Authors: Sotiropoulos Fotis , Mezić Igor , Webster Donald R. 
Published: November 2021

Abstract
We propose and develop the theoretical framework for a new experimental technique for constructing Poincaré maps in three-dimensional flows exhibiting chaotic advection. The technique is non-intrusive and, thus, simple to implement. Planar laser-induced fluorescence (LIF) is employed to collect a sufficiently long sequence of instantaneous light intensity fields on the plane of section of the Poincaré map (defined by the laser sheet). The chains of unmixed (regular) islands in the flow are visualized by time-averaging the instantaneous images and plotting iso-contours of the resulting mean light intensity field. A rigorous theoretical justification for this technique is derived using concepts from ergodic theory. We demonstrate the capabilities of the method by applying it to visualize the rich Lagrangian dynamics within steady vortex breakdown bubbles in a closed cylinder with a rotating bottom. The experimental results are shown to be in excellent agreement with numerical simulations.
Transient Whole Field Flow Diagnostics
Authors: Anderson Chris , Sforza Pasquale M. , Martel John 
Published: November 2021

Abstract
A new technique is described to perform whole field flow diagnostics in highly transient environments. A modified Hartmann sensor is used in conjunction with digital imaging to provide time-resolved imagery with inter-frame times as low as 1 μsec. Details of the approach are given and experimental data from an application to two dimensional cavity flows is provided. Applications of the instrument are then discussed including transient analysis, high altitude/low density applications, and comparison with transient CFD analysis.
Simulation of the Onset of Rotating Stall
Authors: Freitas Christopher J. , Smalley Anthony J. 
Published: November 2021

Abstract
This paper presents the results of a series of numerical simulations exploring the stability of fluid flow in vaneless diffusers of centrifugal compressors. Three-dimensional, time-dependent, Reynolds-averaged Navier-Stokes simulations were performed for a fixed diffuser width ratio. Effective flow angle was varied from simulation to simulation in order to predict the threshold angle at which the instability — rotating stall — is manifested and maintained. The predicted threshold angle or stability limit is in excellent agreement with experimental data. The simulations reveal a two-stall cell configuration at the threshold condition.