Large strain flexural testing of thin composite laminates

Carbon fiber composites are of significant interest for use in deployable space structures. Elastically folded thin laminates can be utilized as hinge mechanisms in structural systems such as solar arrays, reflectors, and instrument booms, allowing for compact packaging during launch to orbit. While the initiative to utilize composite laminates in deployable structures has increased it also has faced difficulties in design and analysis of these poorly understood materials. Data from standardized ASTM test methods fails to characterize nonlinear constitutive behavior over the full large strain range common to deployable structures. Flexural behavior is characterized by the moment vs. curvature response therefore requiring a bending test. A special test fixture is developed to allow flexural testing of thin plates at large strains. Reaching large strains during the test provides an opportunity to investigate the large strain linear and nonlinear elastic constitutive behavior of glass and carbon fibers respectively. A flexural test campaign was carried out for three unidirectional continuous fiber reinforced plastic materials in a large deformation four point bending fixture. Intermediate and high modulus PAN and S2 fibers were tested because they are commonly used in deployable structures. The fixture is designed to apply load, which through translation and rotation of wheeled carts, induces a pure moment in the sample. We utilize a previously developed first order nonlinear empirical constitutive model to represent fiber axial tensile and compressive behavior and rule of mixtures with a linear matrix model for laminate behavior. We use algorithms for nonlinear curve fitting of moment-curvature response measured using the test fixture and fit for a nonlinear constitutive parameter and fiber volume fraction. Using previously reported nonlinear tension parameter for IM7 fiber of 21.4 we estimated for the fibers nonlinear compression parameter to be γ_C=20.7. For test data of S2 fiberglass made by A.G.Y. and M55J carbon fiber made by Toray® the fit model did not differentiate between nonlinear constitutive parameter in tension or compression. Analysis of the experimental data returned a large nonlinear constitutive parameter of 97.6 for M55J fiber and a small nonlinear constitutive parameter of 6.7 for S2.\u2

Methods of noninvasive electrophysiological heart examination basing on solution of inverse problem of electrocardiography

The article represents the main noninvasive methods of heart electrical activity examination, theoretical bases of solution of electrocardiography inverse problem, application of different methods of heart examination in clinical practice, and generalized achievements in this sphere in global experience

Integrative Modeling of Electrical Properties of Pacemaker Cardiac Cells

This work represents modeling of electrical properties of pacemaker (sinus) cardiac cells. Special attention is paid to electrical potential arising from transmembrane current of Na{+}, K{+} and Ca{2+} ions. This potential is calculated using the NaCaX model. In this respect, molar concentration of ions in the intercellular space which is calculated on the basis of the GENTEX model is essential. Combined use of two different models allows referring this approach to integrative modeling

Impact of filtration elements on bioelectrical signal

Filtering of the wanted signal from the noise caused by power lines, magnetic pickup, interference from body movement, etc. in the field of medical data processing is a weighty problem of cardiography. To date, different types of digital filters have been used to clear the signal from unnecessary frequency bands. This paper presents the results of the filter simulation in MATLAB package

Computers im ulation of cardiac electrical activity using an electrocardiograph on nanosensors

The issues related to cardiovascular diseases are considered. The method to solve some of the existing problems has been proposed. Also a two-component Aliev-Panfilov model and the algorithm of the hardware- software complexes are discussed. The obtained results are presented

Visualization of the heart with help of cardiographic equipment

This study presents the problems associated with cardiovascular diseases (CVD) and Twocomponent FitzHugh - Nagumo model and heart condition imaging algorithm are considered. Aspects of work aimed at designing and developing of the hardware and software complex based on the information obtained with the help of an electrocardiograph

Morpholinium perchlorate

In the title salt, C4H10NO+·ClO4 −, which has three independent formula units, the cations are linked into chains along [100] by N—H⋯O hydrogen bonds. Each cation acts both as a donor and as an acceptor, and every cation makes one N—H⋯O hydrogen bond with a ClO4 − anion. The crystal studied was an inversion twin