bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soft Body Impact Damage Tolerance of Laminated and 3D Woven Composites
Authors: Weeks Craig A. , Bertke Robert S. , Laber Mark W. 
Published: March 2022

Abstract
The Affordable Composite for Propulsion (ACP) program is investigating material designs and manufacturing processes which produce affordable and structurally acceptable parts for turbofan engine applications. In order to evaluate material architectures for engine structures susceptible to bird impact events, soft body impact tests were performed on laminated and 3D woven composite flat panels. Material architecture variables such as graphite/glass hybridization, stitching and type of stitch fiber for laminated composites, and ply-to-ply and through thickness interlock weaves for 3D materials were investigated. The primary test results of interest were damage resistance (velocity or energy to initiate measurable damage) and damage tolerance (resistance of the panel to propagation of existing damage). The results of these experiments are presented, and the behavior of the various material architectures are compared and contrasted. Material architecture variables which increase the soft body impact damage resistance and tolerance will be noted.
Modifications to Classical Shear-Lag Models Required for Prediction of Laminate Degradation due to Fiber Failure and Associated Mechanisms
Authors: Solti James P. , Mall Shankar 
Published: March 2022

Abstract
Modeling advanced composite materials can quickly become overwhelming when one starts to consider detailed phenomenological behavior of multilayered off-axis laminates with microstructural damage development resulting from aggressive thermal and mechanical cyclic loading. As such, an attempt is underway to develop a comprehensive solution algorithm, formulated from first-principle (simplified) criteria, which provides reasonable estimates of laminate behavior. The objective is to develop a detailed model based upon a series of modules each of which is derived from simplified theories. The formulation of the model in this manner is intended to reduce the complexities associated with modifying detailed micromechanical (or other) models to account for a myriad of laminate geometries, damage mechanisms and loading conditions.
This paper is an extension of previous works presented by the authors which outline the development of a simplified micromechanics model as described above. In particular, this paper examines required modifications to classical shear-lag models for considering fiber failure and other associated mechanisms such as fiber pull-out and laminate failure. The approach adopted herein assumes the development of an “effective applied stress” to undamaged fibers neighboring fibers which have fractured and/or have slipped (pull-out). Both modifications to the equilibrium relationship, as well as the net effect on the laminate strain due to these damage mechanisms are explored under specific laminate and loading conditions.
Direct Observation of Contact Damage Produced by Vickers Indentation in Diamond-Like Films
Authors: Bulsara Vispi Homi , Chandrasekar Srinivasan , Farris Thomas N. 
Published: March 2022

Abstract
An experimental study has been made of film delamination and cracking produced by indentation of diamond-like films deposited on glass substrates. In the indentation experiments, a Vickers indenter was loaded normally against a film surface with the load being kept in the range of 2g to 300g. The contact region was observed and photographed in-situ using a high resolution, optical microscope and video imaging system, while the indentation load-history was measured with a piezo-electric force sensor attached to the indenter. The experiments have enabled detailed observations to be made of the contact damage such as the initiation of film delamination and cracks in the film; the loads at which these events occur and their evolution during loading and unloading; and the ejection of fractured film fragments from the substrate. The implications of these results to characterizing the relative failure resistance of various films and for estimating their cohesive and adhesive strengths are discussed.
Effects of PVD Coatings on Thermal Fatigue Resistance of Hot-Work Tool Steels
Authors: Wang Yucong 
Published: March 2022

Abstract
Physical vapor deposit (PVD) coatings have been used to extend die-casting die life, mainly by reducing molten metal’s corrosion and erosion to the dies. The dies are made of hot-work tool steels. Among the tested PVD coatings, CrN and TiAlN coatings provided the longest die life because of their higher oxidation resistance temperatures. Die insert life can be extended three to eight times based on the in-plant tests. However, the thermal fatigue resistance of hot-work tool steels was affected differently by the PVD coatings. The research work in this area is very limited.
This paper discusses the results from a systematic study involving three H series and two maraging hot-work tool steels with and without TiN, TiAlN or CrN PVD coating, in terms of thermal cycling induced fatigue (heat checking) resistance, hardness and fracture toughness changes, as well as molten aluminum corrosion resistance. Based on the results, a die life extension approach is proposed to reduce die-casting operation cost and improve casting quality.
The Fiber/Matrix Interface in Ceramic-Matrix Composites
Authors: Zhang Y. , Yu N. 
Published: March 2022

Abstract
The fiber/matrix interface plays a key role in the toughening mechanisms and overall thermo-mechanical behavior of fiber-reinforced ceramic-matrix composites (CMCs). A debonded fiber/matrix interface induces energy-absorption (i.e., toughening) mechanisms, such as interfacial sliding and fiber pull-out, and consequently results in the graceful, rather than catastrophic, failure of fiber-reinforced CMCs; see, for example, Evans and McMeeking (1986).
Thermal Expansion Behavior of Ceramic Composites for Thermal Management Applications
Authors: Shen Yu-Lin 
Published: March 2022

Abstract
The thermal expansion response of ceramic composites containing a metallic phase for thermal management applications is studied. The two types of composites considered include a SiC particulate/Al composite (with a large extent of particle contact due to high SiC content) and a SiC/Al interpenetrating composite. Numerical modeling using the finite element method is carried out to provide insights into the experimentally measured deformation behavior. It is found that processing induced residual porosity at the particle contact areas and the sharp concave comers of SiC can govern to a significant degree the thermal expansion response of the composites. The micromechanisms responsible for such effects are identified.
Cyclic Fatigue and Resistance-Curve Toughening in In Situ Toughened Silicon Carbide at Ambient to Elevated Temperatures
Authors: Gilbert C. J. , Ritchie R. O. 
Published: March 2022

Abstract
It is now well known that the principal source of toughening during resistance-curve (R-curve) behavior in non-transforming monolithic ceramics derives from crack-wake phenomena, in particular from a zone of bridging grains behind the crack tip which screen it from the applied loads (crack-tip shielding) (Evans, 1990). Specifically, where fracture is intergranular, the elastic and frictional tractions generated via the contact of opposing crack faces act to reduce the local driving force in the immediate vicinity of the crack tip. Indeed, various attempts have been made to quantify the magnitude and distribution of bridging tractions acting across the faces of cracks growing under monotonic loads in order to understand the mechanics of R-curve toughening and how it relates to local microstructure.
Characterizing Adhesion of Thermal Barrier Coatings
Authors: Gupta Vijay , Yu Allen 
Published: March 2022

Abstract
A previously developed technology of laser-generated stress pulses has been adapted to measure the tensile strengths of interfaces between composite thermal barrier coatings of alumina and zirconia, and steel substrates. In the basic technique developed previously (Gupta et al., 1994), a compressive stress pulse is generated on the back side of the substrate disc by exfoliating a constrained metallic film via the impingement of a Nd:YAG laser pulse. This compressive stress pulse propagates through the substrate and reflects into a tensile wave from the free surface of the coating that is deposited on its front surface. The returning tensile pulse pries off the interface if its amplitude is sufficiently high. The interface stress is determined by recording the coating’s free-surface velocity by using a laser displacement interferometer. Because of the short rise time of the stress pulse, an interfacial region of approximately 70 to 150 micrometers is uniformly stressed. This results in the failure of the weakest link in the region which is spanned by the coating, interface and the substrate material. In addition, such a short pulse is able to invoke a rather local response from the interface such that minute structural and chemical changes are directly reflected in the measured strengths.
Well-Dispersed Suspension Formation for Infiltration of Ceramic Fiber Preforms With SiC-Filled Polysiloxane Resins
Authors: Erdal Merve , Boschelli Marianne , Güçeri Selçuk 
Published: March 2022

Abstract
The development of low-viscosity preceramic polymers such as Blackglas™1, introduced new opportunities to the processing of ceramic-ceramic composites. Many polymer based liquid processing technologies that have been vastly investigated and established, can now be applied to ceramic composite processing with preceramic polymers. Resin transfer molding (RTM) is one of the most promising techniques adaptable to manufacturing of continuous fiber reinforced, ceramic composite structures with reliable, cost-effective properties. A major drawback of the process is the material loss in the preceramic polymer during processing, resulting in a porous structure that needs to be densified for satisfactory structural performance. This can be accomplished through several process cycles at the expense of cost-effectiveness. One way of reducing the number of cycles and obtaining near-net shapes during the process is the inclusion of inert and/or active filler particles in the polymer during injection.
A New Multiparameter Approach to the Characterization of Mechanical Properties of Ceramics
Authors: Soboyejo Alfred B. O. , Soboyejo Winston O. 
Published: March 2022

Abstract
This technical paper describes a new multiparameter approach, consisting of deterministic and mechanistically based characterization of the mechanical properties of structural ceramics; and the appropriate probabilistic models, from which the failure probabilities and the reliabilities of engineering components made with such structural materials can be evaluated, for structural, mechanical and aerospace engineering design applications. For example, the practical application of the methodology developed can be demonstrated by the actual characterization of the mechanical properties of some new structural ceramics which are being developed for high-temperature engineering design applications.
In Situ Observation and Modeling of Damage Modes in Cross-Ply Ceramic Matrix Composites
Authors: Kim Ran Y. , Tandon G. P. 
Published: March 2022

Abstract
Ceramic-matrix composites generally exhibit matrix and/or interface damage well before final failure because of the low strain capability of the brittle matrix and weak interfacial bonding. These damages have a significant influence on the stress-strain behavior as well as on the ultimate strength of the composite. The failure process in a multidirectional laminate is further complicated by its dependence on ply orientations and stacking sequence Reported in this paper are the results of both analytical and experimental investigations carried out in an attempt to understand the initiation and propagation of damage in a [0/90]3S cross-ply laminate. A glass-ceramic matrix composite reinforced with silicon carbide (Nicalon) fibers is investigated at room temperature under uniaxial tensile loading. The initiation and propagation of interfacial debonding, microcracking, and fiber breaks were observed in situ, under applied load using a specially built loading device. The observed damage modes were then incorporated into existing micromechanical models to predict the laminate stress-strain behavior and compared with the experimental measurements.
Axisymmetric Microfracture Analysis of Fiber-Reinforced Brittle Composites
Authors: Zhang Hanqing , Liaw Benjamin , Delale Feridun 
Published: March 2022

Abstract
In many ceramic matrix composites subjected to tensile loading the damage usually starts with matrix cracking followed by multiple matrix cracking, interfacial debonding, fiber breaking and fiber pull-out. Some of these events may occur simultaneously and the specimen may separate into two or more pieces. Indeed our tensile testing of Nicalon/CAS II composites in SEM confirms this general damage pattern, which resulted in a nonlinear stress-strain curve. The analytical challenge is to construct a damage model which can predict or at least simulate the observed behavior. The linear part of the stress-strain curve corresponds to the undamaged stage of the specimen and the slope can easily be matched using the “rule of mixtures”. The non-linear portion will depend on the assumed damage model.
Mechanisms for Size Effects in Bending of Fiber Composites
Authors: Swanson Stephen R. 
Published: March 2022

Abstract
The size of the specimen or structure has often been cited as having an effect on the apparent strength of fiber composites. Bend tests are often used to infer size effects, as the stressed volume is typically smaller than in uniform tension or compression test specimens. However bend tests also have a stress gradient through the thickness. In the present work a model is developed for compression failure of fiber composites that includes through-the-thickness effects. A primary feature of the model is that through-the-thickness shear stresses are predicted to occur because of the varying bending displacement of the wavy fibers. These shear stresses have a stabilizing effect on the fibers, and thus raise the apparent compressive strength. When applied to bend tests, the model predicts that the apparent compressive strength of fiber composites will depend on the specimen thickness, in accord with experimental evidence in the literature. The result is that through-the-thickness effects are predicted to affect the compressive strength of fiber composites, and this effect is distinct from a true size effect.
Scaling Effects in Composite Laminates Under Tensile, Flexural, and Compressive Loading
Authors: Johnson David P. , Felts Joseph H. , Ho Michael T. 
Published: March 2022

Abstract
It has been demonstrated by several researchers that composite materials exhibit scaling effects both in unidirectional and multidirectional specimens. This has an important impact on the design and manufacture of full scale structures. In the current work, the authors present a wide range of experimental data for scaled composite laminates under tensile, flexural and compressive loading. Data for both blocked ply (so-called ply-level) and distributed ply (so-called sublaminate-level) thickness scaling are presented. Laminates studied include the following stacking sequences: [45/-45/45/-45]s, [45/-45/0/90]s, [45/-45/90/0]s, [45/90/-45/0]s, [45/-45/45/-45/0]s, [45/-45/0/0]s, [90/0/90/0]s. In general, ply-level scaling leads to degraded performance with increased specimen size in all stacking sequences, under all loading conditions. Sublaminate-level scaling also leads to a lowering of strength and strain to failure, although the effect is much less pronounced than in ply-level scaling. Typically, the strength of these specimens decreases by about 5% as the size of the specimens is quadrupled.
Size Effects in Tensile, Compressive and Interlaminar Failure of Unidirectional Composites
Authors: Wisnom Michael R. 
Published: March 2022

Abstract
A summary is given of experimental results on size effects for different failure mechanisms from geometrically scaled tests on unidirectional composites. Size effects for tensile failure were observed from three sets of scaled flexural tests in a four point bending rig for both glass and high strength carbon fibre/epoxy. Tests on intermediate modulus carbon fibre/epoxy in a pin-ended buckling rig produced compressive failures, and showed a larger size effect than for tensile failure. Scaled curved beam bending tests were used to investigate size effects in interlaminar tensile strength, and short beam shear tests for interlaminar shear strength. Significant size effects on interlaminar strength were found for both glass and carbon fibre/epoxy.
Statical and Vibrational Behavior of Orthogonally Reinforced Flat Panels Exposed to Thermomechanical Loading
Authors: Souza M. A. , Librescu L. 
Published: March 2022

Abstract
A number of results related with the non-linear response of orthogonally stiffened flat panels exposed to thermomechanical loading are presented. The results concern both the statical and vibrational responses.
The effects played in this context by the various reinforcement schemes and the initial geometric imperfection are considered and pertinent conclusions are highlighted. The paper constitutes a completion of a number of results previously reported by the authors of this paper (see Librescu and Souza (1992, 1997) and Souza and Librescu (1995).
Vibration of a Flexible Solar Array Caused by the Change of Thermal Input in Orbit
Authors: Tabacchi Luca , Natori M. C. , Hirikado Hiroshi 
Published: March 2022

Abstract
Behaviour of large flexible space structures (antennas, solar arrays, frames of space stations, etc.) is strongly influenced by thermal loads in orbit. Thermally induced forces can affect flexible space structures in several ways: thermal buckling and thermally induced vibrations due to relatively rapid heating are two typical phenomena. In orbit attitude disturbances of an actual spacecraft are presented as a remarkable example of such phenomena. Analytical models are developed and numerical simulations performed in order to demonstrate that the vibration of the spacecraft flexible solar arrays is the most likely disturbance source. The results are shown to be in agreement with flight data and laboratory tests.
Thermomechanical Response of Laminated Flat Panels Featuring Interlaminar Bonding Imperfections
Authors: Icardi U. , Librescu L. , Sciuva M. Di 
Published: March 2022

Abstract
In this study the problem of the implications played by the sliding interlaminar imperfections on the static and dynamic non-linear behavior of laminated composite flat panels subjected to thermomechanical loadings is addressed. Towards the end of approaching this problem, a recently developed geometrically non-linear theory of anisotropic composite flat panels featuring interlaminar bonding imperfections is used. A number of results related with the influence of interfacial bonding imperfections on the thermomechanical postbuckling and frequency-load-temperature interaction are supplied and pertinent conclusions are outlined.
A Finite Element Modal-Coordinate Formulation for Thermal Postbuckling of Composite Plates
Authors: Shi Yucheng , Lee Raymond Y. Y. , Mei Chuh 
Published: March 2022

Abstract
A finite element formulation in modal coordinates is developed for nonlinear thermal postbuckling of thin composite plates. The linear buckling mode shapes used to model the postbuckling deflection are investigated. The participation from each mode to the postbuckling deflection is presented quantitatively. The minimum number of modes for convergent solution can be assured. Postbuckling of symmetrically laminated, antisymmetric angle-ply, and unsymmetrically laminated composite plates under mechanical and thermal loads are studied. Deflection shape changes are observed in long rectangular plate. Multiple postbuckling solutions or branches are obtained for plate under combined mechanical and thermal loadings.
Oscillation Control of Cantilevers via Smart Materials Technology and Optimal Feedback Control: Actuator Location and Power Consumption Issues
Authors: Na S. S. , Librescu L. 
Published: March 2022

Abstract
A study of the vibration control of cantilevers exposed to blast pressure signatures is presented. Whereas the structure used in this analysis is in the form of a thin-walled beam of closed cross-section contour, the control is based upon the simultaneous implementation of the adaptive materials technology and the optimal feedback control.
Issues related with the influence upon dynamic response of size and location along the beam span of piezoactuator patches are investigated and the efficiency of this combined control methodology is outlined. Other issues related with the minimization of the input power required in the control process, maximization of the sensing voltage output and implications of the limitation of control input voltage on dynamic response are also addressed and pertinent conclusions are outlined.
Design Criteria for Sandwich Panels for Building Construction
Authors: Davies J. Michael 
Published: March 2022

Abstract
Sandwich cladding panels comprising two metal skins and a lightweight insulating core are finding ever-increasing use as the wall and roof cladding for a wide range of building types. Their main attraction is their outstanding thermal performance but the designers and specifiers of such panels, and competing cladding systems, have to consider a wide range of other parameters in order to arrive at the best solution for their design requirements. This paper gives an overview the current scene, with particular reference to Europe, and makes specific comments on some of the current issues. Naturally, the structural design is discussed but particular attention is also paid to some of the other issues such as fire performance and durability which are less well documented.
Consideration on the Benefits of Intentional Blade Mistuning for the Forced Response of Turbomachinery Rotors
Authors: Castanier Matthew P. , Pierre Christophe 
Published: March 2022

Abstract
The intentional mistiming of blades in order to reduce the forced response amplitudes of turbomachinery rotors is considered. The statistics of the maximum blade response amplitudes for a simple model of a 12-bladed disk are investigated. It is shown that the maximum response amplitudes are appropriately modeled by a Type III Weibull distribution. Intentional mistuning is introduced into the model by varying the nominal blade stiffnesses in rotationally periodic patterns. Of the six non-zero harmonics, the first and second harmonics are shown to provide a significant decrease in the maximum amplitudes. A more practical, pseudo-harmonic-two configuration of mistuning is also considered. This pattern requires only two unique blade designs, and it results in an even larger decrease in the maximum response than that provided by the harmonic-two intentional mistuning.