Search results for "Stiffness"

Direct stiffness matrices of BEs in the Galerkin BEM formulation

2001

Abstract In the analysis of an elastic two-dimensional solid body by means of the Symmetric Galerkin Boundary Element Method (SGBEM), difficulties arise in the computation of some terms of the solving system coefficients. In fact these coefficients are expressed as double integrals with singularities of order 1/ r 2 , r being the distance between the field and source points. In order to compute these coefficients a strategy based on Schwartz's distribution theory is employed. In this paper the direct stiffness matrix related to the generic node of the free boundary are computed in closed form.

A four-node MITC finite element for magneto-electro-elastic multilayered plates

2013

An isoparametric four-node finite element for multilayered magneto-electro-elastic plates analysis is presented. It is based on an equivalent single-layer model, which assumes the first order shear deformation theory and quasi-static behavior for the electric and magnetic fields. First, the electro-magnetic state of the plate is determined in terms of the mechanical primary variables, namely the generalized displacements, by solving the strong form of the magneto-electric governing equations coupled with the electro-magnetic interface continuity conditions and the external boundary conditions. In turn, this result is used into the layers constitutive law to infer the equivalent single-layer…

A FE-Meshless Multiscale Approach for Masonry Materials

2015

Abstract A FE-Meshless multiscale computational strategy for the analysis of running bond masonry is presented. The Meshless Method (MM) is adopted to solve the boundary value problem (BVP) at the mesoscopic level. The representative unit cell is composed by the aggregate and the surrounding joints, the former assumed to behave elastically while the latter are simulated as non-associated elastic-plastic zero-thickness interfaces with a softening response. Macroscopic localization of plastic bands is obtained performing a spectral analysis of the tangent stiffness matrix. Localized plastic bands are embedded into the quadrature points area of the macroscopic finite elements.

La relazione tra microalbuminuria e stiffness aortica è indipendente dal filtrato glomerulare nell’ipertensione essenziale

2008

Microalbuminuria Is Associated With Increased Aortic Stiffness Independently of C-Reactive Protein in Essential Hypertension

2009

Statistics of reversible transitions in two-state trajectories in force-ramp spectroscopy

2014

A possible way to extract information about the reversible dissociation of a molecular adhesion bond from force fluctuations observed in force ramp experiments is discussed. For small loading rates the system undergoes a limited number of unbinding and rebinding transitions observable in the so-called force versus extension (FE) curves. The statistics of these transient fluctuations can be utilized to estimate the parameters for the rebinding rate. This is relevant in the experimentally important situation where the direct observation of the reversed FE-curves is hampered, e.g. due to the presence of soft linkers. I generalize the stochastic theory of the kinetics in two-state models to the…

Mountain-building under extension

2013

A mechanism is presented which explains how intra-continental rifting can cause large topographic uplift. The effect is sufficient to account for the uplift of rift flanks and the very high and strongly localized uplift of the Rwenzori horst in the Western Branch of the East African Rift System. We propose that the uplift is generated by crustal bending, which is caused by a misfit of the lateral tensile stress between the upper and middle crust. The misfit is a function of different yield mechanisms when the upper crust breaks whereas the middle crust flows. Two independent numerical schemes confirm the suggested uplift mechanism. Both models—a 2 and 2.5 D elastoplastic lattice-particle mo…

Associations of cardiorespiratory fitness, body composition, and blood pressure with arterial stiffness in adolescent, young adult, and middle-aged w…

2022

AbstractFew studies have investigated whether higher cardiorespiratory fitness (CRF) or favourable body composition are related to lower arterial stiffness in women. We therefore investigated the associations of CRF, body fat percentage (BF%), fat free mass index (FFMI), and mean arterial pressure (MAP) with arterial stiffness in 146 women aged 16–58 years. CRF was assessed by a maximal exercise test with respiratory gas analysis either on a cycle ergometer or a treadmill. Aortic pulse wave velocity (PWVao), augmentation index (AIx%), and MAP were assessed by a non-invasive oscillometric device and BF% and FFMI by a bioelectrical impedance or DXA device. CRF was inversely associated with PW…

Cyclic response of masonry infilled RC frames: Experimental results and simplified modeling

2014

The recent large interest in nonlinear seismic analysis methods, static and dynamic, has required proper strategies of modeling based on reliable, and at the same time easy to use, constitutive laws for the structural elements. Regarding the behavior of framed structures, special attention has to be devoted to infills because of the key role they play in modifying overall stiffness, strength and ductility under seismic excitation. Pointing out the attention on this topic the paper discusses a criteria for modeling the structural behavior of infills based on a macromodeling approach, that is to say on the substitution of infills with diagonal pin jointed struts. Is here shown how multilinear…

CH of masonry materials via meshless meso-modeling

2014

In the present study a multi-scale computational strategy for the analysis of masonry structures is presented. The structural macroscopic behaviour is obtained making use of the Computational Homogenization (CH) technique based on the solution of the boundary value problem (BVP) of a detailed Unit Cell (UC) chosen at the meso-scale and representative of the heterogeneous material. The smallest UC is composed by a brick and half of its surrounding joints, the former assumed to behave elastically while the latter considered with an elastoplastic softening response. The governing equations at the macroscopic level are formulated in the framework of finite element method while the Meshless Meth…