bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autonomous Vibration Suppression Using On-Line Pole-Zero Identification
Authors: McEver Mark , Leo Donald J. 
Published: November 2021

Abstract
An on-line identification and control algorithm is developed based on the properties of collocated sensing and actuation. The feedback control law consists of second-order compensators that achieve equivalent damping in both the filter dynamics and resonant structural dynamics, thus maximizing the damping in the structure and controller. Optimal design of the feedback compensator is obtained using a pole placement algorithm applied to a single, undamped resonant mode. Numerical analysis indicates that multiple modes and structural damping do not appreciably change the damping achieved using the optimal parameters. The pole placement analysis demonstrates that only the pole-zero spacing and DC gain of the collocated transfer function are required to choose the optimal parameters. An on-line identification procedure is developed that sequentially determines the DC gain and pole-zero spacing and automatically designs the feedback compensator. This forms the basis for the autonomous control algorithm. Experimental results on a flexible beam demonstrate that the procedure can accurately identify the pole-zero spacing and automatically design the feedback compensator. A fivefold increase in damping is achieved in the first mode and a twofold increase in damping is achieved in the second mode. Discrepancies between predicted and measured damping are attributed to phase lags due to signal conditioning and low-pass filtering of the sensor signal.
Piezoceramic Hysteresis in the Adaptive Structural Vibration Control Problem
Authors: Lee Soon-Hong , Ozer M. Bulent , Royston Thomas J. 
Published: November 2021

Abstract
Structural vibration control via passive electrical shunting and active (hybrid) actuation of a piezoceramic wafer bonded onto the surface of a simply supported beam is investigated with emphasis on modeling and understanding the effect of piezoceramic nonlinearity on system performance. A nonlinear rate-independent hysteresis model, the Maxwell resistive-capacitor (MRC) model, is experimentally identified for the PZT wafer by itself and then integrated into the coupled dynamic equations of the overall system consisting of the beam and electrically shunted PZT wafer. Experimental studies of the system validate the theoretical model. This model is then used to investigate the impact of PZT hysteresis on its vibration control performance in passive and hybrid scenarios that have been optimized based on a linear system assumption. A multi-term describing function representation of the MRC hysteresis model is formulated to aid in computational studies.
Workpiece Quality Estimation in Turning by Quasi-Sensor Fusion
Authors: Shiraishi Masatake , Kikuchi Makoto , Sumiya Hideyasu 
Published: November 2021

Abstract
Two types of sensor fusion approaches are reported for quality assurance based on the decision making process via the sensor fusion technique: quasi-sensor fusion with several data-processed signals from a single sensor and general sensor fusion using multiple sensors. The former method may be expected to provide new information about an object to be measured from a single sensor, i.e., a strain gauge in this study. The latter method with a tool dynamometer and a strain gauge is, on the other hand, important on a practical production floor for real in-process measurement. Experimental results show the effectiveness of both techniques.
Application of the Radial Return Method to Compute Stress Increments From Mroz’s Hardening Rule
Authors: Tang Sing C. , Xia Z. Cedric , Ren Feng 
Published: November 2021

Abstract
It is well known in the literature that the isotropic hardening rule in plasticity is not realistic for handling plastic deformation in a simulation of a full sheet metal forming process including springback. An anisotropic hardening rule proposed by Mroz is more realistic. For an accurate computation of the stress increment for a given strain increment by using Mroz’s rule, the conventional sub-interval integration takes excessive computing time. This paper proposes the radial return method to compute such stress increment for saving computing time. Two numerical examples show the efficiency of the proposed method. Even for a sheet model with more than 10000 thin shell elements, the radial return method takes only 40% of the overall computing time by the sub-interval integration.
Prediction of Chip Back-Flow Angle in Machining With Restricted Contact Grooved Tools
Authors: Fang N. , Jawahir I. S. 
Published: November 2021

Abstract
This paper presents a new predictive model for chip back-flow angle in machining with restricted contact grooved tools. This model is derived from the recently established universal slip-line model for machining with restricted contact cut-away tools. A comprehensive definition of the chip back-flow angle is first developed, and based on this, a quantitative analysis of the effect of chip back-flow is presented for the given set of cutting conditions, tool geometry and variable tool-chip interfacial stress state. This model also predicts cutting forces, chip thickness ratio and chip up-curl radius. A full experimental validation of the predictive model involving the use of high speed filming techniques is then presented for chip back-flow angle and this validation provides a range of feasible/prevalent tool-chip interfacial frictional conditions for a given set of input conditions.
Generic Simulation Approach for Multi-Axis Machining: Part I—Modeling Methodology
Authors: Bailey T. , Elbestawi M. A. , El-Wardany T. I. , Fitzpatrick P. 
Published: November 2021

Abstract
This paper presents a new methodology for analytically simulating multi axis machining of complex sculptured surfaces. A generalized approach is developed for representing an arbitrary cutting edge design, and the local surface topology of a complex sculptured surface. A NURBS curve is used to represent the cutting edge profile. This approach offers the advantages of representing an arbitrary cutting edge design in a generic way, as well as providing standardized techniques for manipulating the location and orientation of the cutting edge. The local surface topology of the part is defined as those surfaces generated by previous tool paths in the vicinity of the current tool position. The local surface topology of the part is represented without using a computationally expensive CAD system. A systematic prediction technique is then developed to determine the instantaneous tool/part interaction during machining. The methodology employed here determines cutting edge in-cut segments by determining the intersection between the NURBS curve representation of the cutting edge and the defined local surface topology. These in-cut segments are then utilized for predicting instantaneous chip load, static and dynamic cutting forces, and tool deflection. Part I of this paper details the modeling methodology and demonstrates the capabilites of the simulation for machining a complex surface. Part II details both the model calibration procedure and discusses a case study of process optimization through feed rate scheduling.
Avoiding Tool Exit in Planar Milling by Adjusting Width of Cut
Authors: Rangarajan Arvind , Chu Chih-Hsing , Dornfeld David 
Published: November 2021

Abstract
Tool failure and milling exit burr formation usually occur when the tool cutting edges move out of the workpiece. One of the most effective methods for minimizing these problems is to prevent the tool from exiting the workpiece while removing material. This can be achieved by special tool path planning. In this paper we presents a set of geometric algorithms that avoid tool exits in planar milling of 2D polygonal and curved contours. Tool paths are generated by offsetting the workpiece edges with appropriate widths of cut, depending on the edge types (straight or circular). A tool path planner is successfully implemented with those algorithms. Tool exits are thus completely eliminated in an automatic manner.
Evaluation of Plastic Bead Blasted Ti-6Al-4V Fatigue Specimens
Authors: Brady Brian G. 
Published: November 2021

Abstract
As part of an evaluation of plastic bead blasting as a means of removing paint from aircraft, fatigue testing was performed on bead blasted material. Typical military aircraft finishes were removed from 0.063 inch (1.6 mm) thick clad aluminum, corrosion resistant steel, and Ti-6Al-4V. Constant amplitude fatigue specimens were then machined from these samples and tested. Results were compared to control samples which had not been bead blasted. Fatigue life of corrosion resistant steel and clad aluminum were unaffected by bead blasting. The bead blasted Ti-6Al-4V samples, however, exhibited a significant decrease in fatigue life when compared to the control samples.
Laboratory evaluation of the bead blasted Ti-6Al-4V samples included binocular and scanning electron microscopic evaluation, energy dispersive x-ray spectrometry (EDX), metallography, and mechanical evaluation of surface roughness. It was determined that the decrease in fatigue life exhibited by the bead blasted samples was caused by improper machining not bead blasting.
Phenomenological and Structural Aspects of the Mechanical Response of Arteries
Authors: Ogden Ray W. , Schulze-Bauer Christian A. J. 
Published: November 2021

Abstract
In this paper we present some new data from extension-inflation tests on a human iliac artery and then, on the basis of the nonlinear theory of elasticity, we examine a possible model to represent this data. The model considers the artery initially as a thick-walled circular cylindrical tube which may consist of two or more concentric layers. In order to take some account of the architecture (morphological structure), each layer of the material is regarded as consisting of two families of mechanically equivalent helical fibers symmetrically disposed with respect to the cylinder axis. The resulting material properties are then orthotropic in each layer. General formulas for the pressure and the axial load in the symmetric inflation of an extended tube are obtained. The starting point is the unloaded circular cylindrical configuration, but (in general unknown) residual stresses are included in the formulation. The model is illustrated by specializing firstly to the case of a single layer so that the consequences of the hypothesis of uniform circumferential stress in the physiological state can be examined theoretically. This enables the required residual stresses to be calculated explicitly. Secondly, the equations are specialized for the membrane approximation in order to show how certain important characteristics of the experimental data can be replicated using a relatively simple anisotropic membrane model.
Time-Dependent Response of Polymer Systems Under Cyclic Loading Conditions
Authors: Schumacher Shane , Vinogradov Aleksandra M. , Liu Zhiyu , Jenkins Christopher H. , Kitahara Isamu , Winter Robb M. 
Published: November 2021

Abstract
The paper concerns the time dependent response of polymer systems subjected to superimposed static and cyclic loads. An experimental study of two materials, Nylon 6/6 and a piezoelectric polyvinylidene fluoride (PVDF)-based composite, has been conducted with the objective to determine the degree of cyclic creep effects depending on the mean stress, cyclic stress amplitude and frequency. Creep acceleration due to cyclic loading effects has been observed in both materials even in the range of stresses well below their respective viscoelastic linearity limits. It is clear that these effects are essentially nonlinear, as the response of the materials to cyclic loading conditions does not represent a simple superposition of the responses to static and fully reversed cyclic loads applied separately. An increase of creep rates in both polymers has been observed consistently as frequencies and amplitudes of vibration tended to increase. However, the relation between cyclic creep effects and the mean stress appears to vary depending on the polymer type and loading conditions. Nylon 6/6 has demonstrated material hardening as a result of cycling. Considerable crack development in Nylon 6/6 has been detected only in the range of stresses approaching yield conditions.
Subsonic and Intersonic Failure of Composites: High-Speed Optical and Thermographic Measurements and Numerical Simulations
Authors: Rosakis A. J. , Coker D. , Yu C. , Ortiz M. 
Published: November 2021

Abstract
In this paper dynamic fracture behavior of unidirectional graphite-epoxy composite plates is investigated experimentally and numerically. Crack propagation experiments are conducted on thick unidirectional graphite-epoxy composite plates subjected to in-plane, symmetric and asymmetric, impact loading. The coherent gradient sensing technique (CGS) is used in conjunction with high-speed photography to visualize the crack growth events. Cracks are found to propagate at subsonic speeds in the Mode-I case, whereas in both mixed mode and Mode-II the crack tip speed clearly exceeds the shear wave speed of the laminate. In the case of symmetric loading (Mode-I), the crack tip speeds approach the Rayleigh wave speed of the composite (1500 m/s), however it never exceeds it as predicted by asymptotic analysis. The situation is found to be entirely different for growing shear (Mode-II) cracks. A shock wave emanating from the crack tip is observed in the optical patterns. This provides direct evidence that the crack propagates faster than the shear wave speed of the composite. The crack tip speed is then observed to jump to a level close to the axial longitudinal wave speed along the fibers (7500 m/s) and then to stabilize to a lower level of approximately 6500 m/s. This speed corresponds to the speed at which the energy release rate required for shear crack growth is non-zero as determined from asymptotic analysis. The CGS interferograms also reveal the existence of large-scale frictional contact of the crack faces behind the moving shear cracks. In addition high speed thermographic measurements are conducted that show concentrated hot spots behind the crack tip indicating crack face frictional contact. Finally, these experiments are modeled by a detailed dynamic finite element calculation involving cohesive elements, newly developed adaptive remeshing using subdivision and edge collapse, composites element, and penalty contact. The numerical calculations are calibrated on the basis of fundamental material properties measured in the laboratory. The numerical methodology is subsequently validated by direct comparison to optical experimental measurements (crack speed record and near tip deformation field structure). For shear crack growth the numerics also reveal the experimentally observed shock wave structure and confirm the optical observation of large-scale crack face contact.
Modeling Damage Accumulation in Laminated Composites Subjected to Impact
Authors: Allen David H. , Searcy Chad R. 
Published: November 2021

Abstract
Because of their high strength-to-weight ratio, laminated composites continue to be an attractive alternative to conventional monolithic media in the design of impact resistant structures. Unfortunately, the high cost of production has been a major limiting factor in the usage of laminated composites in design applications. Contributing to this cost is the complexity of the design process, which calls for an increased number of parameters necessary for the optimal design of impact resistant laminated composite structures. One way to address this complexity is through the use of damage models. Properly constructed damage models have the potential to reduce the cost of design and promote the increased usage of laminated composites in design applications.
This paper demonstrates the effective use of cohesive zone modeling to determine the optimal laminate configurations for impact resistant composites. A nonlinear finite element algorithm equipped with a micromechanically-based viscoelastic cohesive zone model is used to predict the cumulative damage in composite laminates subjected to impact. Several composite layups have been studied to determine an optimal design configuration. Some analytical predictions have been provided for a comparison with the numerical results.
The Micromechanics of Inelastic Processes in Superplastic Materials
Authors: Chandra N. 
Published: November 2021

Abstract
Superplasticity is an intriguing inelastic process in solid materials with deformation upto several thousand percent. Forming sheet and bulk materials using superplastic forming has become an established manufacturing method in aerospace and lately in other industries. Developing the right constitutive behavior is important not only for modeling the process for manufacturing by engineering mechanicians but for choosing the right composition and processing for material scientists. Such an ideal constitutive equation has been eluding the analysis so far. This paper examines some of the fundamental misgivings about the origin of inelastic process in superplasticity compared to other well known deformation processes. Also an attempt is made to understand the basic characteristics of superplastic inelastic deformation at macroscopic, mesoscopic and atomic levels.
The Mechanics of the Secondary Flows of Viscoelastic Fluids in Non-Circular Straight Tubes and the Mean Transversal Field in Pulsating Flows
Authors: Siginer Dennis A. , Letelier Mario F. 
Published: November 2021

Abstract
A survey of secondary flows of viscoelastic liquids in straight tubes is given including recent work pointing at striking analogies with transversal deformations associated with the simple shearing of solid materials. The importance and implications of secondary flows of viscoelastic fluids in heat transfer enhancement are explored together with the difficulties in detecting weak secondary flows (dilute, weakly viscoelastic solutions) in a laboratory setting. Recent new work by the author and colleagues which explores for the first time the structure of the secondary flow field in the pulsating flow of a constitutively nonlinear simple fluid, whose structure is defined by a series of nested integrals over semi-infinite time domains, in straight tubes of arbitrary cross-sections is summarized. The transversal field arises at the second order of the perturbation of the nonlinear constitutive structure, and is driven by first order terms which define the linearly viscoelastic longitudinal flow in the hierarchy of superposed linear flows stemming from the perturbation of the constitutive structure. Arbitrary conduit contours are obtained through a novel approach to the concept of domain perturbation. Time averaged, mean secondary flow streamline contours are presented for the first time for triangular, square and hexagonal pipes.
On the Flow of Mixtures Between Parallel Plates
Authors: Rajagopal K. R. 
Published: November 2021

Abstract
Here, we discuss the flow of a mixture of two fluids between two parallel plates, within the framework of the theory of interacting continua. In the case of a flow due to a pressure gradient along the plates, in marked contrast to the classical Poiseuille flow, we find a variety of solutions, from those that are close to parabolic to those solutions that are spatially periodic across the plates, depending on the values for the viscosities of the fluid.
Fluid Flow Around a Vibrating Beam and Associated Nonlinear Damping
Authors: Chakraborty G. , Mote C. D. 
Published: November 2021

Abstract
Steady flow of a viscous fluid around a transversely oscillating, simply-supported beam is driven by forces represented in the nonlinear terms of the Navier-Stokes’ equation. This flow occurs inside and outside the viscous boundary layer. The flow-velocity amplitude is proportional to the square of the amplitude of the beam transverse velocity and thus it is essentially only observable during high velocity beam vibration. This flow, known as ‘edge streaming’, does not occur in an ideal fluid. In the flow the fluid is ‘drawn in’ at the edges of the beam near the vibrational antinodal points and ‘expelled’ at the nodal points. When a rigid plate is placed parallel to the long axis of the vibrating beam and normal to the vibration velocity, vortices of different orientation are generated depending on the separation of the plate and beam surfaces. When the separation is an order of magnitude greater than the boundary layer thickness, the vortices have the rolling characteristic discussed by Rayleigh [1]. But for small separation of the order of the boundary layer thickness, the vortical axes are perpendicular to that of the former, parallel to the vibration velocity. They have been experimentally observed [6]. Owing to the streaming motion, damping, as measured by the ratio of the dissipation of energy and the total vibration energy over a time period, has a nonlinear hard representation with respect to the vibration amplitude.
Locus of the Axis of Vibration for a Vibrating System With Variable Location of a Mass Center
Authors: Dan Byung Ju , Choi Yong Je 
Published: November 2021

Abstract
A typical approach to a linear vibration analysis of an elastically supported single rigid body is to rearrange a dynamic model into a corresponding eigenvalue problem. From the geometrical point of view, the eigenvectors in the planar vibration analysis can be interpreted as pure rotations about the vibration center or pure translations. In a three dimensional space, they represent repetitive twisting motions about the axes of vibrations. By taking a geometrical approach to the vibration analysis, the vibration mode shapes may be better understood. In this paper, the influence of variable location of a mass center on the locations of the axes of vibrations and the natural frequencies are investigated by means of the locus of the axis of vibration expressed in analytical form, which represents the geometrical locus of the eigenvector. A numerical example is used to clearly illustrate the vibration phenomena of an optical pick-up used in an information storage device.
Sandwich Structures for Naval Ships: Design and Experience
Authors: Olsson Karl-Axel 
Published: November 2021

Abstract
In Sweden we have a long experience with different types of vehicles and ships in sandwich construction, especially Navy ships such as minesweepers, mine-counter-measure-vessels and corvettes. GRP (Glass fibre Reinforced Plastic) and FRP (Fibre Reinforced Plastics) have been the most common face materials, but metallic materials such as Al-alloys, coated carbon steel and stainless steel have also been used. Core materials have usually been cellular plastic foams of cross-linked PVC (Polyvinyl-chloride), but also extruded PS (Poly-styrene), PUR (Poly-urethane), PEI (Poly-ether-imide) and PMI (Poly-methacryl-imide). Different continuous and discontinuous manufacturing processes have been used. Vacuum assisted infusion has been introduced recently, because it is a closed process, gives high fibre content and a good quality of the laminates. Sandwich design has mainly been used in the transportation area, where lightweight design is needed to give higher performance and load bearing capacity. The use of sandwich construction will give high stiffness- and strength-to weight ratio. This is usually not enough from an economic point of view to justify the introduction of sandwich construction, but other integrated functions must be considered, i.e. insulation, energy consumption, damping, fewer components, lower manufacturing costs, low maintenance, signature effects (military) etc.