Search results for "Fiber"
showing 10 items of 2343 documents
Numerical and Experimental Analysis of the Frictional Effects on 4ENF Delamination Tests Performed on Unidirectional CFRP
2015
Abstract Progressive delamination in composite materials under static or fatigue loading condition are, in many structures, one of the predominant cause of failure. In the paper, an accurate study of quasi-static delamination growth under mode II loading condition is conducted. Several experimental tests are performed on composite laminates consisting of unidirectional carbon/epoxy layers. Four-point end-notched flexure (4ENF) test is employed in order to characterize the mode II interlaminar fracture toughness. The R-curve is obtained by means of optical and numerical determination of crack tip position. The energy release rate and the crack length are calculated through experimental deter…
A Fiber Optic Strain Gage Sensor for Measuring Preload in Thick Composite Bolted Joints
2019
Mechanical fastening is a popular choice in joining composites because of the ability to transfer high loads and the ease of assembly and disassembly. In this study, the failure behavior of composite–aluminum single lap bolted joint is investigated. In particular, the effects of varying the preload on the bolt are examined. In order to accurately measure the preload, a specialized sensor that uses a fiber Bragg grating sensor embedded in the bolt is proposed and created. This sensor is realized for the current tests but can be expanded to other applications. An experimental study of bolted single-lap joints varying the tightening torque value has been carried out and, in order to validate t…
Optimal design of flax fiber reinforced polymer composite as a lightweight component for automobiles from a life cycle assessment perspective
2019
The present study combines the generalized rule-of-mixture (ROM) model and the Ashby material selection method for the life cycle assessment (LCA) of flax fiber reinforced polymers (FRPs) and glass FRPs (GFRPs). The ROM model allows life cycle environmental impact predictions according to specific parameters of flax FRPs such as fiber format, volume fraction, manufacturing technique, and load-bearing capacity. The comparisons applied in this study are constructed on two common composite structures: mat panels and injection molded struts with equal stiffness and strength as the design criteria. On the one hand, the parametric LCA predicts that the equal strength design criterion for flax FRP…
Towards High Resolution Computational Models of the Cardiac Conduction System: A Pipeline for Characterization of Purkinje-Ventricular-Junctions
2011
The cardiac conduction system (CCS) has been in the spot light of the clinical and modeling community in recent years because of its fundament role in physiology and pathophysiology of the heart. Experimental research has focused mainly on investigating the electrical properties of the Purkinje-ventricular-junctions (PVJs). The structure of the PVJs has only been described through schematic drawings but not thoroughly studied. In this work confocal microscopy was used with the aim of three-dimensional characterization of PVJs. Adult rabbit hearts were labeled with fluorescent dyes, imaged with confocal microscopy and Purkinje fibers differentiated from other cardiac tissue by their lack of …
Homology of pseudodifferential operators on manifolds with fibered cusps
2003
The Hochschild homology of the algebra of pseudodifferential operators on a manifold with fibered cusps, introduced by Mazzeo and Melrose, is studied and computed using the approach of Brylinski and Getzler. One of the main technical tools is a new convergence criterion for tri-filtered half-plane spectral sequences. Using trace-like functionals that generate the 0 0 -dimensional Hochschild cohomology groups, the index of a fully elliptic fibered cusp operator is expressed as the sum of a local contribution of Atiyah-Singer type and a global term on the boundary. We announce a result relating this boundary term to the adiabatic limit of the eta invariant in a particular case.
Nonlinear Pulse Shaping in Optical Fibres with a Neural Network
2020
We use a supervised machine-learning model based on a neural network to solve the direct and inverse problems relating to the shaping of optical pulses that occurs upon nonlinear propagation in optical fibres.
Automatic estimation of Purkinje-Myocardial junction hot-spots from noisy endocardial samples: A simulation study
2017
The reconstruction of the ventricular cardiac conduction system (CCS) from patient-specific data is a challenging problem. High-resolution imaging techniques have allowed only the segmentation of proximal sections of the CCS from images acquired ex vivo. In this paper, we present an algorithm to estimate the location of a set of Purkinje-myocardial junctions (PMJs) from electro-anatomical maps, as those acquired during radio-frequency ablation procedures. The method requires a mesh representing the myocardium with local activation time measurements on a subset of nodes. We calculate the backwards propagation of the electrical signal from the measurement points to all the points in the mesh …
Nonnegative Tensor Train Decompositions for Multi-domain Feature Extraction and Clustering
2016
Tensor train (TT) is one of the modern tensor decomposition models for low-rank approximation of high-order tensors. For nonnegative multiway array data analysis, we propose a nonnegative TT (NTT) decomposition algorithm for the NTT model and a hybrid model called the NTT-Tucker model. By employing the hierarchical alternating least squares approach, each fiber vector of core tensors is optimized efficiently at each iteration. We compared the performances of the proposed method with a standard nonnegative Tucker decomposition (NTD) algorithm by using benchmark data sets including event-related potential data and facial image data in multi-domain feature extraction and clustering tasks. It i…
Structural performances of pultruded GFRP emergency structures – Part 2: Full-scale experimental testing
2019
Abstract This paper presents an experimental testing of a pultruded glass fiber reinforced polymer (FRP) structure used for emergency applications continuing the discussion presented in a previous paper (part 1) where the study of the characteristics of material and elements are presented. First, the design of the composite structure and components and the evaluation of the structural behavior by means of numerical and analytical approach according to current regulatory codes are described. In this frame, the global and local response was observed according to load paths deriving from the design loads at limit states. Then, the experimental test on a full-scale 2D model is presented at diff…
Structural and functional features of human muscle-tendon unit.
2006
This paper reviews the architectural details and the in vivo behavior of the human muscle-tendon unit with the focus on the triceps surae and quadriceps femoris muscles. Recent advances in experimental techniques allow in vivo measurements of muscle-tendon architecture and function. In particular, the use of ultrasonography for measurement of tendon and muscle has expanded our knowledge in the last decade. Furthermore, the nuclear magnetic resonance imaging is opening up new insights not only for three-dimensional anatomical information but also for examining musculo-skeletal motion in vivo. While these two completely non-invasive methods provide kinematic data, in vivo force measurements s…