bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aerospace Composite Structures: Applications/Design/Analysis
Authors: Chamis Christos C. 
Published: January 2022

Abstract
Fiber composites are an emerging material with tailoring potential to achieve substantially “better-cheaper-faster” and even “greener” products. The lecture provides an overview on the advantages of composites design/analysis methods and applications. The review will synoptically cover analysis methods that span all composites scales from constituents (fiber, matrix) and fabrication process to structural optimization. Several typical composites applications to aerospace structures are presented to demonstrate specific advantages of composites in these structures. Recent application to space station, advanced satellites and X-33 are included as are potential applications of smart composite structural concepts for aerospace applications. Emerging simulation methods to evaluate the reliability and risk of aerospace composite structures are summarized. The presentation provides a broad perspective of what can be done with composites and the state of the composites technology readiness to meet even greater application challenges in aerospace structures.
Building Block Approach for Composite Aircraft Structure Prototypes: Allowables and Building Block Testing for DOD/NASA Vehicles
Authors: Grimes Glenn C. 
Published: January 2022

Abstract
Composite material allowables development required for prototype aircraft is discussed along with the related building block test effort necessary for such structure development. Allowables requirements are included as part of building block structural test requirements that are related to aircraft structure part criticality classifications. Then, each part of the building block is related to the test/evaluation/analysis categories that need to be interrogated to study the risk involved. For allowables, the categories are preliminary and “design-to” values related to physical defect minimum requirements in each classification. For the building block structures development test effort categories, the procedure used is progressive scale up of the size and complexity of the test program parts: from single to multiple load paths to joints and shapes. In summary, the relationship of the quality assurance requirements to those required for design allowables for flat panels to those required for intermediate structural components to those required for full size structure are discussed. Quality assurance requirement categories are discussed for each structural classification, size, and complexity of parts to be built. The building block structures test development effort satisfies the goals of:
1. Preliminary and “design-to” material allowables development,
2. Appropriate conceptual structural development,
3. Structural proof of concept and related analytical methods development,
4. Structural verification testing for analytical methods correlation, and
5. Structural integrity testing and FEM validations.
Once these goals are achieved the user has acceptable risk and cost effective prototype composite aircraft structure that has the necessary integrity and reliability needed for the specific prototype aircraft being developed.
Design Approaches for Optical Structures in Space Communication Systems
Authors: Kedward Keith T. 
Published: January 2022

Abstract
In a wide variety of space communication systems advanced composites applications have favorably impacted the performance of optical surfaces and structures. However, there is presently a thrust to advance the state-of-the-art of primary mirrors assemblies for diffraction-limited, visible systems. Such mirror assemblies typically provide areal densities (the index used to convey weight efficiency) ranging from 25 to 30 kg/m2. But composite reflectors have also established their effectiveness by achieving areal densities as low as a few kg/m2 in recent years. As a consequence, opportunities and incentives that embrace composite technology advancements with concomitant benefits to optical performance (enabled by the proven thermal stability advantages) have drawn the attention of the space optics community.
In this paper the feasibility of isogrid concepts being used currently for lightweight, precision membrane reflectors is presented and evaluated with respect to future exploitation in the higher precision, mirror applications. We begin with a review of one form of isogrid concept in which the backup structure is comprised of interlocking continuous ribs in the isogrid configuration. Consideration with respect to fiber, matrix, and laminate configuration are presented in the body of the paper. Further, critical design detail treatment is presented with respect to intersections in the backup structure and the attachment of backup structure to the reflector face sheet.
Results of a thermal distortion analysis also serve to emphasize the importance of attention to detail in composite design due to the high degree of anisotropy in stiffness, strength and thermal expansion properties. Finally, the translation of the surface precision from that of the original mold surface to the as-fabricated reflector surface as well as to environmental influences will be addressed.
A Method for Structural Life Predictions Using Time-Domain Non-Linear Dynamic Load Computations
Authors: Lin Woei-Min , Engle Allen , Hay William , Meinhold Michael J. 
Published: January 2022

Abstract
Current surface ship structural design criteria is based on the use of a standard wave for determining primary stresses. Although this approach has worked well, such methods do not explicitly account for the effects of transient hydrodynamic impacts, fatigue or their effects on longitudinal distribution other than by empirical “rules of thumb”.
With the advent of novel ship design concepts, the naval architect has been forced to move away from a static balance approach to more rigorous methods of analysis. This paper presents a procedure for structural life predictions using the results of recent efforts to develop a practical computational method that predicts non-linear time-domain hydrodynamic loads and whipping responses of ship in waves. The time series wave loads and whipping data are used to develop the database and loads spectrum required for structural analysis. The results of this analysis used in conjunction with the spectral methods developed by Sikora, provides the naval architect with predictions for a lifetime maximum combined wave plus whipping bending moment as well as a load exceedence curve that can be used in fatigue analysis.
An Approach to Flexible Modes Identification and Control
Authors: Becraft Marc D. 
Published: January 2022

Abstract
An approach is given for flexible mode identification and robust control. It was successfully implemented and tested in a lab experiment that consists of a simply supported aluminum plate with four piezo-electric actuators and four piezo-electric sensors. The approach is based on measuring mode shapes and using a frequency weighted LQR controller that permits reduced order plant modeling. Lab tests show the first four modes were reduced significantly. The discussion includes derivation of the equations for the model identification scheme. A detailed description is given of the LQR frequency weighting and plant augmentation technique. A fourth order roll-off of control authority was used to gain-stabilize high frequency unmodeled dynamics. The observer uses only mode shape information but no modal frequency information. This provides the controller with robustness to modal frequency changes. Robustness is shown to changes in modal frequency (+/−10%), as well as modal gain and damping.
Vibration Control of Rotationally Periodic Structures Using Passive Piezoelectric Shunt Networks and Active Tuning
Authors: Tang J. , Wang K. W. 
Published: January 2022

Abstract
This paper is on the development of a novel approach for multi-mode vibration suppression of rotationally periodic structures, using identical active-passive hybrid piezoelectric networks on each of the substructures. Active charge and current feedback is used together with passive piezoelectric shunts to optimize the network performance. A new algorithm is synthesized to analytically derive the control parameters through utilizing the unique characteristics of rotationally periodic structures. It is shown that this hybrid approach can suppress all the spatial harmonics, which cannot be achieved by purely passive piezoelectric shunts. It is also observed that such a configuration requires much less control effort (voltage) when compared to a purely active approach.
Hydraulic Single Axis Vehicle Motion Simulator: Hardware and High Fidelity Control Design
Authors: Kuehn Jeffrey L. , Harris Derrick R. , Epp David S. , Patten William N. 
Published: January 2022

Abstract
This paper describes the design of a single degree-of-freedom hydraulic seat simulator. The hardware design includes various provisions to reduce static friction, backlash, etc. The paper also describes the painstaking task of plant identification and the subsequent effort to conceive a control that has near-perfect tracking characteristics. Experimental results are provided which indicate the simulator has flat amplitude and no more than 15 degrees of phase distortion over the range from 0.5 to 50 Hz.
Feedforward/Feedback Active Control With Automotive Applications
Authors: Shoureshi Rahmat A. , Vance James 
Published: January 2022

Abstract
Desire for increased ride comfort through elimination of fatigue caused by low frequency noise and vibration on one hand, and the market demand for smaller and lighter vehicles with enhanced fuel economy without sacrificing safety and comfort on the other hand have forced automotive manufacturers to search for advanced technology in the noise and vibrations areas. This paper presents results of a unique active vibro-acoustic system that handles both random and repetitive excitations. The combined pseudo-feedforward feedback control technology as well as actuator designs capable of performing at low and high frequencies have provided the key elements for our unique active control system. Experimental results demonstrating successful implementation of the active vibro-acoustic technology on different vehicles are presented.
A Study on Predictive Control Using a Short-Term Prediction Method Based on Chaos Theory: Determination of the Control Force Using Plural Predicted Disturbances
Authors: Masumoto Noriyasu , Yamakawa Hiroshi 
Published: January 2022

Abstract
The main objective of the work is to determine the applications of the short-term prediction method, based on chaos theory, to active vibration control problems for mechanical structural systems. In this paper, disturbance time series of a mechanical system’s near future were predicted by the short-term prediction method and the obtained time series were used effectively to determine the control force. A method to extend the prediction range in the time series has been proposed and two methods to determine the control force, using plural predicted disturbance values of a mechanical system’s near future, have been outlined. A method to determine the number of predicted values which should be used in prediction is also proposed. The effectiveness of the proposed control methods has also been presented from the numerical results of an active suspension model for vehicles with two degrees of freedom.
Electro-Hydrodynamic Pumped Hydraulic Actuation
Authors: Kang S. , Hallinan K. P. , Kashani R. 
Published: January 2022

Abstract
A new type of actuation device has been conceptualized that meets the needs of both large displacement, force and bandwidth within a package more compact than currently available magnetostrictive and stack-type piezo actuators of similar rating. This concept relies on micro-scale electrohydrodynamic (EHD) pumping of a dielectric liquid with a small concentration of free charges. Configured as an actuator, the EHD pump(s) would be used to move fluid between two reservoirs — each having a compliant membrane that interfaces to the world to provide the means to achieve vibration cancellation or micro actuation.
Ordinarily limited to generating flow in macroscale applications, the EHD pump is shown to exhibit an exciting scaling law as its size is reduced. As the pump volume to surface area decreases, the energy going toward increasing pressure in the pump has an increasingly larger effect. Since volume/surface area is proportional to 1/a2, where a is the characteristic width or diameter of the pump, the pressure head generated scales similarly. Analytical and numerical studies have shown the EHD-pumped actuator to be capable of delivering equal force and bandwidth to magnetostrictive and stack-type piezo actuators, but with consdierably greater displacement and roughly 1/10th of the size. Further, this type of actuator offers the possibility for deployment in active vibration control or micro actuation applications at significantly greater temperatures.
Refined Micro Moire System and its Applications to Chip Scale and Flip-Chip Packages
Authors: Zou Daqing , He Xiaoyuan , Lu Minfu , Liu Sheng , Guo Yifan 
Published: January 2022

Abstract
The chip scale package (CSP) and flip-chip (FC) technologies are currently developed by electronic industry for high performance, high density and miniaturized assembly applications. The reliability of these packages continues to be a major concern due to the increase of die size, circuit density, and operating temperature.
Moiré interferometry is a full field optical method, which can be used for the thermal mechanical deformation measurement of electronic packages and packaging materials. By using ordinary moiré interferometry, fringes represent displacement contour of 417 nm. In most cases, in a solder bump of CSP and FC packages, the thermal mechanical deformation is usually only 2 or 3 fringes (with relative displacement of about 1.2 μm), but the local strain of the bump is high because of the small size of the bump. It is difficult to resolve the local strain value for ordinary moiré interferometry, which can only resolve strain values averaged over a relative larger area.
Based on high magnification and phase shifting method, refined micro moiré interferometer is expected to have a localized sensitivity and resolution for localized strain measurements.
By using high precision close-loop controller for phase shifting in the refined moiré system, excellent results were obtained in the thermal mechanical deformation study of CSP samples and in the study of the solder bump mis-registration effect of FC samples. The results also showed that refined micro moiré method is effective in resolving deformation within a small area like a corner of a C4 bump.
Analysis of Electromigration Considering Thomson Effect
Authors: Sasagawa Kazuhiko , Yagi Manabu , Saka Masumi , Abé Hiroyuki 
Published: January 2022

Abstract
A parameter dominating electromigration damage, AFD, has been recently proposed. On the other hand, it has been shown that the Thomson effect which is a kind of thermoelectric effect is not negligible for the temperature distribution in the metal line which is subjected to high current density. The effect of the temperature distribution considering the Thomson effect on the void formation induced by electromigration has not been investigated so far. In this study, the temperature distribution in an angled metal line was analyzed considering the Thomson effect, and the void formation near the corner was predicted by obtaining the value of AFD based on the temperature analysis in order to extract the effect of the Thomson effect on the void formation. The Cu line, which was expected as a next line material in near future, was treated in comparison with the Al line.
Warpage Measurement of Microelectronics Devices by Far Infrared Fizeau Interferometry
Authors: Verma K. , Han B. 
Published: January 2022

Abstract
Far infrared Fizeau interferometry is developed and it is proposed as a tool for warpage measurement of microelectronics devices. The method provides a whole-field map of surface topography. Its basic sensitivity is 5.3 μm per fringe contour and a higher sensitivity is achieved by employing the O/DFM method. The method is implemented by a compact apparatus using a computer controlled environmental chamber for real-time measurement. The method retains the simplicity of classical interferometry while providing a wide applicability to dielectric rough surfaces. Roughness tolerance is achieved by utilizing a far infrared light (λ = 10.6 μm). The detailed optical and mechanical configuration is described and selected applications are presented to demonstrate the applicability. The unique advantages of the method are discussed.
Preliminary in Process Stress Analysis of Flip Chip Assemblies During Thermal Cycling
Authors: Palaniappan Prema , Baldwin Daniel F. 
Published: January 2022

Abstract
Thermal cycling of flip chip assemblies is commonly used to establish the reliability of the package. These tests help identify potential reliability concerns in interconnect designs and processes. The CTE mismatch between the various assembly members of a flip chip assembly produces mechanical stresses, which can lead to package failure. Hence, in this study, piezoresistive stress sensing ICs are utilized for experimental stress analysis of electronic packages. ATC4.1 test chips were assembled to low cost organic substrates. In-situ stress analysis of the test vehicle assemblies was performed to investigate the stress history during thermal cycling. The work performed here provides critical data necessary for validating reliability simulation models. Furthermore, in-situ stress measurements can have an immediate impact on reliability testing costs by potentially reducing current thermal cycle times via experimentally characterized die stress tests during temperature cycle.
Oscillatory Viscoelastic Flow in Rectangular Tubes
Authors: Letelier Mario F. , Siginer Dennis A. 
Published: January 2022

Abstract
The longitudinal flow of a Green-Rivlin fluid in rectangular ducts subject to a small pressure gradient is investigated. An exact solution of the momentum equation is developed. The velocity field is computed for several aspect ratios and for several values of the fluid parameters. The elasticity of the fluid is shown to create complex patterns of flow, as depicted by the instantaneous isovels of the flow. The flow patterns depend mainly on the viscosity index of the fluid, the aspect ratio of the tube and of the selected iinstant of time.
These results are useful for understanding both the intrinsic axial flow behavior, and related phenomena such as mass and heat transfer, and secondary flows in the case of fluids best described by constitutive models of the multiple-integral type.
Natural Convection and Thermocapillary Flow of Non-Newtonian Fluids in Layered Systems Heated From the Side in Reduced Gravity
Authors: Siginer Dennis A. 
Published: January 2022

Abstract
The dynamics of the flow in two layered systems heated from the side is investigated both when the fluids are viscoinelastic and viscoelastic. The system is two dimensional and confined to a box of low aspect ratio in reduced gravity. Interfaces are assumed to be flat. The free top surface is taken to be insulated together with the bottom wall. Results are reported for both high and low values of the interfacial Marangoni number when a low Prandtl number Newtonian fluid in the lower layer is encapsulated by a high Prandtl number viscoinelastic or viscoelastic fluid in the top layer.
Interfacial Velocity in the Core-Annular Flow in a Tube
Authors: Bakhtiyarov Sayavur I. , Siginer Dennis A. 
Published: January 2022

Abstract
The lubrication of a non-Newtonian liquid by a Newtonian fluid in the concentrically stratified laminar flow of two immiscible fluids in a horizontal tube has been investigated experimentally by an opto-mechanical method. Data for the interfacial velocity and the total volume flow rate for two zero shear rate viscosity ratio are presented. The results of this investigation are useful in solving high wax content crude oil transportation problems and in the design of lubricated pipelines.
Dynamic Wetting: Displacement of the Triple Line Induced by Air Pressure Oscillations in its Close Vicinity
Authors: Bourgin Patrick , Woehl Pierre 
Published: January 2022

Abstract
The problem of a liquid sheet issuing from an ejector and being coated on a moving solid substrate is classically considered like a free surface flow problem. The viscosity of ambient air is neglected compared with that of the liquid, which equivalently means that the surrounding air is considered to be steady. However, the free surface is affected by the presence of air flows underneath the sheet and by the increase of pressure, which deforms the interface and tends to separate the liquid sheet from the solid substrate. This is a coupled problem, the two unknown functions being the meniscus shape and the pressure generated in the air wedge.
A simple model is proposed here to investigate the possible influence of slight pressure fluctuations in the air on the displacement of the triple line. This model incorporates the liquid wetting properties as well as parameters characteristic of the process and of air pressure oscillations.
Flow Patterns of Viscoelastic Fluids in a Planar Contraction Obtained With a Finite-Volume Simulation
Authors: Oliveira Paulo J. , Pinho Fernando T. 
Published: January 2022

Abstract
A new general finite-volume method based on an efficient collocated mesh arrangement, with the added advantage of indirect addressing, has been applied to predict the flow of UCM fluids in a 4:1 sudden planar contraction. First and second order differencing schemes were used, and the Deborah number ranged from 0 to 10 for a Reynolds number of 0.01.
The predicted flow patterns showed all the flow features seen in flow visualisation and in recent numerical simulations of contraction flows, namely the corner Moffat vortex, the lip vortex, the fingering and merging of the two vortex types and single vortex growth with Deborah number. The presence of a lip vortex is detected at a Deborah number of 2 and the observations of those flow features requires very fine meshes in the vicinity of the contraction plane.
Dynamic Effects of Air Entrainment in High Velocity Coating Flows
Authors: Bourgin Patrick , Saintlos Sylvie 
Published: January 2022

Abstract
The problem of a liquid sheet issuing from an ejector and being coated on a moving solid substrate (generally flexible such as for instance paper or plastic film) is considered here. Such a situation resorts of dynamic wetting and the classical free surface boundary conditions at the air/liquid interface are applied. The ambient air viscosity is classically neglected in comparison with that of the liquid, which corresponds to consider the surrounding air as steady.
However, it is well known that one of the limiting factors in high velocity coaling flows is the onset of air entrainment into the wedge between the moving solid substrate and the liquid layer. The mechanics of air entrainment of the dynamic wetting line has been studied.