Fiber metal laminates (FML) are hybrid materials consisting of metal and composite layers. They have great mechanical and fatigue properties. However, interface between metal and composite layers can ...be critical for their final properties. In this paper, process of determination of some fracture parameters of this interface in unusual FML material is described. Experimental tests following ASTM norm were conducted using Double Cantilever Beam (DCB). However, due to asymmetry, fracture energy cannot be obtained directly from the force–displacement curve. Finite element method simulations were carried out using cohesive elements and cohesive surfaces approach. The cohesive behavior of interface layers were modelled using traction separation law. Key properties of this law were obtained—maximal traction and fracture energy. In this particular case cohesive approach was better in reflecting experimental results. Determined values can be used in later research tasks (like modelling big structures containing this material) as material properties. The presented approach can be used successfully to obtain fracture energy in cases of materials for which standard approach is insufficient.
A structural concept in multi-material design is used in the automotive industry with the aim of achieving significant weight reductions of conventional car bodies. In this respect, the specific use ...of steel foils and continuous fiber-reinforced thermoplastics represents an interesting material combination for the production of hybrid parts in sandwich design. This contribution deals with the experimental and numerical analysis of a conventional sheet metal forming process using a composite material based on Polyamide 6 (PA6) with unidirectional endless glass fiber reinforcement and HC220Y+ZE steel foil. A unidirectional composite plate is positioned between two steel foils in sandwich design and formed under appropriate temperature conditions. For the numerical analysis of the forming process the software LS-DYNA is used.
As there is little known about the processing and the mechanical properties of thermoplastic based FRP/metal-laminates, the study focuses on the development of novel hybrid laminates with low ...residual stresses, made of metallic steel sheets and continuous glass or carbon fiber reinforced polyamide 6. In this context, the influence of several pre-operations like sand blasting, cleaning or primer application on the interlaminar shear strength (ILSS) was examined in addition to their resistance to cathodic dip paint treatment.
Fibre metal laminates (FML) are a group of materials consisting of layers of both metals and fibre reinforced composites. In this paper, the authors analyse the behaviour of fibre metal laminates ...with unusual thermoplastic matrices in composite layers under flexural loading. A three-point bending test is used to determine the flexural behaviour and interlaminar shear stress (ILSS). Two configurations of a specimen are taken into account – with fibre parallel to the specimen (A) and with fibre perpendicular to it (B). Numerical simulations using the finite element method are carried out. A model with cohesive elements is applied to model damage and a model with a continuum shell is used to determine ILSS. Both approaches can be successfully used for specimens group A. This proves that obtained previously material data is proper to use in the analysis of more complicated structures. In the case of group B, other causes than only interface damage need to be included. To investigate this, analysis of the acoustic signals is used to describe phenomenon occurring during bending for group A and B specimens. Conclusions based on AE support the hypothesis based on the optical remarks and results from numerical modelling.
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Fibre metal laminates (FML) are a specific type of material made of both metal and fibre-reinforced composite layers. In this paper, the authors analyse the behaviour of fibre metal ...laminates with unusual thermoplastic matrices in composite layers under mode II loading. A three-point bending setup was used along with end notched flexural specimen (ENF) to determine behaviour and of the interface between metal and composite layers under shear stress. Due to nonstandard layup configuration, mixed experimental–numerical method is proposed by authors to determine fracture energy. The finite element method is used to analyse conducted tests. A model with cohesive elements is applied to determine damage in the interface layer. For the purpose of understanding the damage process in particular layers, Acoustic Emission analysis was conducted for each specimen and parameters like amplitude, frequency, duration, root-mean-squared level of noise were obtained. As a result of conducted research critical energy in mode II was obtained GIIC=0.05Nmm as well as critical stress value in local shear direction (initiation criterion) tso=10MPa. The result obtained can be used as part of the material model in assessing the mixed-mode state of the researched material.
This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current nu(mu) interactions are ...compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27 x 10(20) 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336+/-14 events. The data are consistent with nu(mu) disappearance via oscillations with |Delta(m)2/32|=2.74 +0.44/-0.26 x10(-3)eV(2) and sin(2)(2theta(23))>0.87 (68% C.L.).
A multi-material concept in sandwich design using two steel foils and continuous fiber-reinforced thermoplastics represents a promising structural approach to the production of hybrid parts. This ...contribution deals with the experimental and numerical analysis of a conventional sheet metal forming process using a composite material based on Polyamide 6 (PA6) with unidirectional endless glass fiber reinforcement and HC220Y+ZE steel foil. A unidirectional composite plate is positioned between two steel foils in sandwich design and formed into the hybrid part under appropriate temperature conditions. Afterwards, the forming process is analysed numerically with the software LS-DYNA and for verification of the FEA the geometry of the hybrid part is measured optically with ATOS system of the company GOM.
The rise of the app revolution has brought small, simple, and affordable software tools to users for mastering mundane tasks with the help of mobile devices. With the success of the app paradigm, ...there is an increasing demand for applying the same spirit to problems which have traditionally been the domain of enterprise-scale solutions, e.g., system management. The challenge for building such communication-intensive applications, however, is to gather the health and performance data of a large number of machines in an agile and responsive fashion while being restricted by the scarce resources and severe power constraints inherent to mobile devices. In this paper, we present a system architecture that tackles this fundamental challenge by making data freshness an explicit concern and allowing the application to express its freshness requirements in a fine-grained way. The application runs atop a generic data cache and collection engine that fetches fresh data from the management endpoints based on these requirements. We evaluate the performance and power consumption characteristics on a broad range of Android-based mobile devices and show that this approach increases the responsiveness of the application while at the same time reducing the power consumption.
Ferrets of both sexes were killed 8 or 5 days before expected parturition as well as 7, 15, 30, or 51 days after birth, and the activities of aromatase (using 19-3Hhydroxyandrostenedione as ...substrate) and of 5 alpha-reductase (using 3H testosterone as substrate) were assayed in whole homogenates of preoptic area plus anterior hypothalamus (POA), mediobasal hypothalamus (MBH), temporal lobe (TL), and cerebral cortex. Aromatase and testosterone 5 alpha-reductase activities were also measured in these regions in adult gonadectomized male and female ferrets. Compared with adults of both sexes in which aromatase activity was low in all brain regions studied, fetal ferrets had high levels of aromatase activity in POA plus MBH and in TL. At these prenatal ages, aromatase activity in POA plus MBH was significantly higher in males than in females. Aromatase activity in POA, MBH, and TL remained high in both sexes on postnatal days 7, 15, and 30, before declining by postnatal day 51. Cortical aromatase activity was uniformly low across all perinatal ages. The existence of a sex difference in aromatase activity in fetal POA plus MBH cannot be explained by a concurrent sex difference in circulating testosterone. Administration of testosterone to pregnant female ferrets over days 30-41 of gestation caused 150- to 350-fold increases in maternal plasma concentrations of testosterone and 2- to 5-fold increases in fetal plasma testosterone. However, aromatase activity was not affected in the POA and MBH of fetuses or mothers, although activity was significantly increased in the TL of mothers given testosterone. Furthermore, castration of neonatal or adult breeding males decreased plasma androgen levels by factors of 8 and 480, respectively, but resulted in only modest reductions in POA, MBH, and TL aromatase activity (a significant reduction occurred only in the adult male TL). Relatively high levels of testosterone 5 alpha-reductase activity were found in all brain regions across all perinatal ages, as well as in gonadectomized adult ferrets; there was no sex differences at any postnatal age studied. Prenatally, males had higher levels of 5 alpha-reductase activity than females only on day -8 in the POA plus MBH. The results show that estrogen and 5 alpha-reduced androgens can be synthesized in the brains of ferrets of both sexes during the perinatal period of sexual differentiation. A functional role for this neural metabolism of androgen remains to be demonstrated in this carnivorous species.
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