bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analytical and Experimental Results of the Coefficient of Thermal Expansion of High-Modulus Graphite-Epoxy Materials
Authors: Romeo Giuuo , Frulla Giacomo 
Published: April 2011

The coefficient of thermal expansion (CrE) of an arbitrary laminate can be determined by the Classical Laminate Theory. However, the results obtained have shown that the CFE is very sensitive to some orthotropic elastic constants and to the laminate layup. In particular, the non-Hookean behaviour of an unidirectional lamina in the fibres direction should have to be taken into account to exactly predict the CTE. In order to verify the theoretical analysis, a new test facility has been designed to carefully measure the CTE in specimens made of advanced composite materials having a quasi zero value of CTE. The facility is basically composed of two thermostats and contained in a vacuum chamber (10−2 Pa). Four specimens are enclosed in the first thermostat and the operating temperature range is limited to −20°C up to 80°C. Four displacement transducers are enclosed in the second one at a temperature of 20°C and kept rigorously constant within 0.1°C. The specimens are mounted on Ultra Low Expansion (ULE) frames having a CTE of 1 × 10−8/°C. It has been possible to miniize the measurement error in the CTE, by a careful choice of displacement sensors and the high control of their thermal stability. The following CTEs have been obtained along the fibre direction, normal to the fibre direction and for a quasi-isotropic laminate, respectively, for two High-Modulus (HM) graphite/epoxy materials. GY70/M18: α1 = −1.04 × 10−6/°C; α2 = 33.9 × 10−6/°C; α x = -0.095 × 10−6/C M55J/M18: α1 = −1.02 × 10−6/°C; α2 = 35.2 × 10−6/°C; α x = −0.162 × 10−6/°C The analytical results have shown as a variation of ±1° only in the lamina orientation can change the CTE of the quasi-isotropic laminate up to ±50.5% of the theoretical value; as well as, a variation of ±5% in the physical and mechanical properties can change the CTE up to ±48%.
Expert Cure System for the Carbon Fiber Epoxy Composite Materials
Authors: Choi Jin Ho , Lee Dai Gil 
Published: April 2011

In this paper, the expert cure system for thermosetting resin matrix composites, which controls the temperature and pressure of the autoclave according to the several rules, was developed to manufacture better composite products in shorter curing time. The rules were based on the on-line measured quantities such as the dielectric properties, temperature of the composites and the pressure of the autoclave. The curing time and the mechanical properties of the composite materials manufactured with the expert cure system were compared to those of the specimens manufactured with the conventional cure cycles
Notched Strength of Thermoplastic Woven Fabric Composites
Authors: Marissen R. , Brouwer H. R. , Linsen J. 
Published: April 2011

Woven fabric composites with a thermoplastic matrix form a class of promising materials for industrial use, due to their balance of properties. They combine excellent mechanical performance with ease of processing. Failure behavior of notched woven fabric composites shows a number of peculiarities, the most notorious being the dependence of notched tensile strength on notch radius below a certain hole size. This dependence, which is observed for all fiber reinforced composites, has been modelled by other authors with the aid of semi-empirical continuum mechanics models. If at all based on physical principles, the modelled fracture process rarely coincides with experimentally observed failure phenomena. This study investigates failure of notched woven fabric (0-90)4, E-glass laminates with a PETP matrix. A model is proposed which is, unlike other previous modelling efforts, related to experimentally observed fracture phenomena. It introduces the ineffective length of a critical element in the notch root, obtained by a simple shear lag-type analysis. The notched strength is shown to depend on the ratio of notch radius to the critical element ineffective length. The model is able to predict changes in notched strength with composite parameters like fiber volume fraction, fiber bundle diameter and interfacial or matrix shear strength, and takes into account the composite microstructure.
Notched and Pin Bearing Strengths of GFRP Composite Laminates
Authors: Khashaba Usama A. 
Published: April 2011

An experimental study was conducted to determine the notched and pin bearing strengths of randomly oriented GFRP composites having various values of fiber volume fractions ( V f). To achieve this, the effect of varying hole size ( D = 3 to 12 mm) on the tensile strength of GFRP specimens, with constant width ( W), has been investigated. A series of pin bearing tests has been carried out to examine the effect of W/D ratio on the bearing strength of the composite laminates. The failure sequence and the fractured surfaces of bearing specimens were examined using the scanning electron microscope. The results show that, fiber volume fraction has a significant effect on load-pin bearing displacement behavior. The value of W/D must be greater than 5 for the development of full bearing strength of the composite laminates. The stress intensity factor ( K lc) was accurately calculated for GFRP composites with various values of V f, in the range of hole sizes investigated.
New Ideas on the Measurement of the In-Plane Shear Strength of Unidirectional Composites
Authors: Pierron Fabrice , Vautrin Alain 
Published: April 2011

This paper addresses the issue of the measurement of the in-plane shear strength of unidirectional composites. It is shown from recently published material that for both Iosipescu and 100 off-axis tensile tests, failure under a homogeneous stress state is achieved. However, these stress states are not pure shear and it is shown that ignoring the presence of transverse tensile and compressive stresses, respectively in the 100 off-axis and the Iosipescu tests, would lead to important apparent differences in the in-plane shear strength measured from both tests. An analysis using a quadratic failure criterion underlines the role of the transverse stresses and values of 95 and 98 MPa for the shear strength of unidirectional T300/914 are derived respectively from the 100 off-axis and the Iosipescu tests.
Strain Measurement with Microsensors
Authors: Itoh Toru , Springer George S. 
Published: April 2011

A model is developed for determining the farfield strains in laminated composites from the strain values indicated by a microsensing device embedded inside the material. The microsensing device considered here consists of three elements: a sensor, a circuit chip, and an antenna. The sensor detects changes in the strains in the material surrounding the sensor. The circuit chip processes the sensor signals which are then transmitted, via the antenna, to a receiver located outside of the composite. The sensor and the circuit are powered by electromagnetic waves generated outside the material and transmitted to the antenna. The model proposed provides a means by which the signal emitted by the microsensing device, and picked up by a receiver, is converted to the engineering value of the farfield strain, i.e., to the strain which would exist in the material at the location of the sensor if the sensor were not present. On the basis of the model, two computer codes were written. The first code calculates the influence coefficient matrix, which is the parameter required to convert the sensor strain to the farfield strain; the second gives the farfield strain directly from the measured sensor strain. Tests were performed to verify the model and the computer codes. In these tests, a strain gauge, a rectangular steel plate, and a circular steel disk (simulating the components of a microsensing device) were embedded in a glass/epoxy beam. The sensor strains were measured by the embedded sensor; the farfield strains were measured by two surface mounted sensors. The measured farfield strains were compared to the farfield strains calculated by the present model, and good agreements were found between the measured and calculated farfield strains.
A Study on the Room-Temperature Curvature Shapes of Unsymmetric Laminates Including Slippage Effects
Authors: Cho Maenghyo , Kim Min-Ho , Choi Heung Soap , Chung Chung Hwa , Ahn Kyu-Jong , Eom Yong Sung 
Published: April 2011

The room-temperature shapes of cured unsymmetric composite laminates have out-of-plane warping after autoclave processing. In addition, they exhibit two stable room-temperature configurations due to snap-through phenomena when the side length of laminates exceed a critical value. The cured shape of unsymmetric laminates are influenced by many factors. Experiments show that the effect of tool-plate cannot be ignored and has significant influence on the cured shape. This study examines slippage effects resulting from the interaction between the laminates and the tool-plate which are ignored in the previous researches. By introducing a dimensionless slippage coefficient and correlating the corresponding value with experimental results, the influence of processing parameters is investigated. Modeling is extended to predict curvatures of general lamination layup configurations.
Material Damping in Composite Rotors
Authors: Wettergren Hakan L. 
Published: April 2011

The paper is concerned with material damping in composite rotors. The material damping for a high-modulus carbon fiber in epoxy resin has been investigated for different angles of filament winding. When the separate contributions on the damping from the stresses in the directions of the fibers, transverse to the fibers and in shear are taken into account, the damping coefficient has a minimum when the filament winding angle is between 10° and 45°, which fortunately for most applications is also the optimal interval for the filament winding angle to get minimum weight. To get the lowest possible dissipation energy for three different constraints, lateral eigenfrequency, maximum torque due to static stress and maximum torque due buckling, there exists an optimal filament winding angle interval. This interval is in the same region as the optimal filament winding for minimum weight.
Damage Development in Woven Fabric Composites during Tension-Tension Fatigue
Authors: Hansen Ulrich 
Published: April 2011

Impacted woven fabric composites were tested in tension-tension fatigue. In contrast to results from static testing, the effects of low energy impact damage in a fatigue environment were found to be the critical element leading to failure of the specimen. This difference emphasizes the need to identify and understand the fatigue damage mechanism. A relatively new non-destructive inspection technique using infrared thermography was found to be a very useful tool in detecting damage initiation and growth. Furthermore, this technique supplies valuable information to the characterization of the operating fatigue damage mechanism(s). Fatigue leads to a degradation of material properties. Consequently, in connection with impact induced local stress raisers, fatigue produces continuously changing non-uniform stress fields because of stress redistribution effects. Other models addressing evolution of fatigue damage in composite materials have not been able to simulate evolving non-uniform stress fields. Therefore. in the second part of this paper. an analytical/numerical approach capable of addressing these issues is also proposed.
The Strength of Bolted and Bonded Single-Lapped Composite Joints in Tension
Authors: Lin Wei-Hwang , Jen Ming-Hwa R. 
Published: April 2011

This work is primarily concerned with a failure analysis of single-lapped bolted and bonded mixed-composite joints, representing practical situations, both in terms of experimental data and theoretical appreciation. Two kinds of stacking sequences in adherends are tested: quasi-isotropic and cross-ply. The adhesives include thermal-setting and thermal-plastic types. The bolts used to clamp the bonded joints are made of 304 stainless steel, whilst the rivets are of NAS 1919 C05 according to National Aerospace Standards. The important invented techniques in making riveted and bolted joints and measuring their respective clamping pressure are disclosed, and the main contribution of systematic experimental data in contrast with numerical prediction is highlighted as follows. The bolting arrangements can be divided into one (1 x 1), three (1 x 3, 3 x 1), six (2 x 3) and nine (3 x 3) configurations. The empirical results indicate that the joint of six (2 x 3) bolts possess the highest strength, nine (3 x 3) bolts the second strongest, followed by (1 x 3), (3 x 1); while the one bolt geometry is the weakest. The mixed joints with more than three bolts will fail by adhesive delamination and tension failure in adherends transversely. However, the failure mechanism for the one bolt system is different, in that delamination occurs first, then bolt bending and shearing, and finally a tension-type failure. A typical tensile stress-strain diagram is linear before delamination. We also adopt the C-scan non-destructive testing (NDT) technique to examine damage initiation sites and to compare this information with the numerical prediction obtained using the finite element method. The comparison is satisfactory. Finally, the joint strength increases with increasing overlap length, until the strength approaches asymptotically a constant value for longer overlap lengths.
Composite Manufacturing: Simulation of 3-D Resin Transfer Molding
Authors: Tan Cheng P. , Springer George S. 
Published: April 2011

A technique was developed for simulating the resin transfer molding (RTM) process. The major feature of the technique is a computational steering system that enables the user to make changes during the simulation. Specifically, at any instance, the user can inspect the progress of the resin front. On the basis of the observed resin front position, the user can, as needed, change the port and vent locations, open and close ports and vents, adjust the inlet and exit pressures or flow rates, and reorient the mold with respect to the gravitational field. Additionally, the user can "rewind" the simulator to any previous time in the mold filling process, make any of the above changes, and then continue the simulation. The technique is augmented by a computer code which has three main components: the Simulator, the Gtaphics User Interface (GUI), and the Global Data Storage. The Simulator is a finite element code that calculates the resin flow inside the fiber preform. The GUI serves as the interface between the user and the Simulator; it provides the commands to the Simulator and displays the results. The Global Data Storage is the module that manages the exchange of data between the GUI and the Simulator. The computer code (designated as SUPERTM_3D) is suitable for simulating the resin flow inside two-dimensional as well as three-dimensional fiber preforms of arbitrary shapes. The use of this computer code is illustrated through sample problems. These problems demonstrate how (with this code) the designer can establish the port and vent locations, opening and closing sequences of ports and vents such that the fiber preform is filled completely in the shortest time with the fewest number of vents.
Inhibition of Inflammatory Mediators
Authors: Wang Weihua , Le Wei , Ahuja Rahul , Cho Do‐Yeon , Hwang Peter H. , Upadhyay Daya 
Published: April 2011

ObjectiveTo determine if statins induce anti‐inflammatory effects in upper airway inflammation. Mediators of innate and adaptive immunity regulate airway inflammation. Release of these mediators involves enzymatic conversion of polyunsaturated fatty acids into biologically active mediators, which can be blocked by statins. Although upper airway inflammation and chronic sinusitis occur in millions of patients with asthma worldwide, the anti‐inflammatory effects of statins in upper airway inflammation have not been previously studied.Study DesignLaboratory research.SettingTertiary referral center.Subjects and MethodsAnalysis of sinus tissues collected from patients with chronic rhinosinusitis revealed suppression of highly expressed inflammatory mediators in patients who were found to be on statins, suggesting that statins may induce anti‐inflammatory effects. Therefore, the authors performed an in vitro study to determine if these anti‐inflammatory effects were induced by statins. Cultured primary human airway epithelial cells were exposed to ambient air pollution particulates (PM) to trigger the inflammation, with and without statins, and the expression of inflammatory mediators was analyzed.ResultsThe authors found that expression of CCL5, CCL11, and IL13RA was suppressed in patients on statins. In vitro exposure to PM enhanced the expression of these mediators, while pretreatment with statins completely blocked these effects. Furthermore, the effects of statins were blocked by inhibition of the statin pathway using isopentenyl‐5‐pyrophosphate. Statins did not have any significant effect on the viability of normal cells.ConclusionStatins induce anti‐inflammatory effects in human airway epithelial inflammation. Statins may play a role in the treatment and prevention of chronic rhinosinusitis and pulmonary exacerbation of obstructive airway diseases.
Tinnitus Handicap Inventory for Evaluating Treatment Effects
Authors: Zeman Florian , Koller Michael , Figueiredo Ricardo , Aazevedo Andreia , Rates Marcello , Coelho Claudia , Kleinjung Tobias , de Ridder Dirk , Langguth Berthold , Landgrebe Michael 
Published: April 2011

ObjectiveTo determine the minimum change of the Tinnitus Handicap Inventory (THI) score that could be considered clinically relevant, the authors compared the absolute change of the THI with the Clinical Global Impression–Improvement (CGI‐I) score.Study DesignInternational studies register with standardized data collection.SettingTinnitus Research Initiative (TRI).Subjects and MethodsTwo hundred ten patients of the TRI database were eligible for this study. In the first analysis, the THI score change and CGI‐I ratings were compared with equipercentile linking. In a second analysis, the authors categorized the CGI‐I into the 4 groups much better or better, minimally better, no change, and worse and calculated the corresponding differences of the THI score and the effect sizes. An effect size separating the minimally better and the no‐change groups was chosen, and the referring THI mean score difference was calculated.ResultsAccording to the linking method, a CGI‐I value of 3 (minimally better) corresponded to a THI score reduction of 6 to 16, whereas the CGI‐I value of 4 (no change) corresponded to the range between improvement by 5 points and worsening by 4 points. For separating the no‐change and minimally better groups, an effect size d = 0.5 was determined, resulting in a minimal clinically relevant difference of ΔTHI = 7.ConclusionTwo different methods yielded comparable results in identifying a reduction in the THI score of 6 and 7 points, respectively, as the minimal clinically relevant change. This study provides a first orientation for sample size calculations and for planning the design of future studies.
The effect of exercise therapy on fatigue in multiple sclerosis
Authors: Andreasen AK , Stenager E , Dalgas U 
Published: April 2011

Background: Fatigue occurs in the majority of patients with multiple sclerosis (MS) and therapeutic possibilities are few. Exercise therapy is a therapeutic option but no studies have systematically reviewed the existing literature evaluating the effect of exercise therapy on MS fatigue. Objective: To determine the effect of exercise therapy on MS fatigue by systematically reviewing the literature. Methods: A comprehensive literature search (PubMed, SweMed +, Embase, Cochrane, CINAHL, PEDro, Sport Discuss and Bibliotek.dk) was conducted. Results: Studies evaluating the effect of exercise therapy on MS fatigue show heterogeneous results and only few studies have evaluated MS fatigue as the primary outcome. The heterogeneous findings seem to be related to the selected study population, which in many studies are non-fatigued. Most studies that have included fatigued patients with MS show positive effects, although it is not clear whether any exercise modalities are superior to others because there are no comparative studies regarding different exercise interventions. Conclusion: Exercise therapy has the potential to induce a positive effect on MS fatigue, but findings are heterogeneous probably because many studies have applied non-fatigued study populations. Furthermore, only few studies have evaluated MS fatigue as the primary outcome measure, emphasizing the need for future studies within this field.
Mutations in ANKRD26 are responsible for a frequent form of inherited thrombocytopenia: analysis of 78 patients from 21 families
Authors: Noris Patrizia , Perrotta Silverio , Seri Marco , Pecci Alessandro , Gnan Chiara , Loffredo Giuseppe , Pujol-Moix Nuria , Zecca Marco , Scognamiglio Francesca , De Rocco Daniela , Punzo Francesca , Melazzini Federica , Scianguetta Saverio , Casale Maddalena , Marconi Caterina , Pippucci Tommaso , Amendola Giovanni , Notarangelo Lucia D. , Klersy Catherine , Civaschi Elisa , Balduini Carlo L. , Savoia Anna 
Published: April 2011

Abstract
Until recently, thrombocytopenia 2 (THC2) was considered an exceedingly rare form of autosomal dominant thrombocytopenia and only 2 families were known. However, we recently identified mutations in the 5′-untranslated region of the ANKRD26 gene in 9 THC2 families. Here we report on 12 additional pedigrees with ANKRD26 mutations, 6 of which are new. Because THC2 affected 21 of the 210 families in our database, it has to be considered one of the less rare forms of inherited thrombocytopenia. Analysis of all 21 families with ANKRD26 mutations identified to date revealed that thrombocytopenia and bleeding tendency were usually mild. Nearly all patients had no platelet macrocytosis, and this characteristic distinguishes THC2 from most other forms of inherited thrombocytopenia. In the majority of cases, platelets were deficient in glycoprotein Ia and α-granules, whereas in vitro platelet aggregation was normal. Bone marrow examination and serum thrombopoietin levels suggested that thrombocytopenia was derived from dysmegakaryopoiesis. Unexplained high values of hemoglobin and leukocytes were observed in a few cases. An unexpected finding that warrants further investigation was a high incidence of acute leukemia. Given the scarcity of distinctive characteristics, the ANKRD26-related thrombocytopenia has to be taken into consideration in the differential diagnosis of isolated thrombocytopenias.