Abstract Under fatigue loading, the stiffness decrease in short-fiber reinforced polymers reflects gradual degradation of material. Thus, both measuring and modeling this is critical to investigate understand entire process. Besides evolving damage, viscoelastic effects within polymer influence measured dynamic stiffness. In paper, we study a linear material model for matrix on obtained extend ...

In this paper, stiffness of planar translational wire-actuated parallel manipulators is studied. The complete form of the stiffness matrix of the two degrees of freedom manipulators is formulated parametrically. The differential form of the static force balance equations is used to incorporate the variation of wire stiffness with wire length and the change in the Jacobian matrix under external ...

in this paper we compared multivariate garch models toestimate value-at-risk. we used a portfolio of weekly indexesincluding tedpix, klse, xu100 during ten years. to estimatevalue-at-risk, first we estimated ccc, dcc of engle, dcc of tseand tsui, dynamic equi correlation models by oxmetrics. then,optimum lags were estimated by minimizing the information criteria.to estimate var, the models accu...

In vitro models of normal mammary epithelium have correlated increased extracellular matrix (ECM) stiffness with malignant phenotypes. However, the role of increased stiffness in this transformation remains unclear because of difficulties in controlling ECM stiffness, composition and architecture independently. Here we demonstrate that interpenetrating networks of reconstituted basement membran...

A bovine cartilage explant system was used to evaluate the effects of injurious compression on chondrocyte apoptosis and matrix biochemical and biomechanical properties within intact cartilage. Disks of newborn bovine articular cartilage were compressed in vitro to various peak stress levels and chondrocyte apoptotic cell death, tissue biomechanical properties, tissue swelling, glycosaminoglyca...

Background—In ventricular dilatation or hypertrophy, an elevated end-diastolic pressure is often assumed to be secondary to increased myocardial stiffness, but stiffness is rarely measured in vivo because of difficulty. We measured in vitro passive stiffness of volume-or pressure-overloaded myocardium mainly from congenital heart disease. Methods and Results—Endocardial ventricular biopsies wer...

Composites with negative stiffness inclusions in a viscoelastic matrix are shown to have higher stiffness and mechanical damping tandelta than that of either constituent and exceeding conventional bounds. The causal mechanism is a greater deformation in and near the inclusions than the composite as a whole. Though a block of negative stiffness is unstable, negative stiffness inclusions in a com...

A coupled model based on finite element method (FEM) and scaled boundary finite element method (SBFEM) for transient dynamic response of large-scale SSI systems is presented. The wellestablished FEM is used for modeling the near-field bounded domains. A local high-order transmitting boundary, which is based on SBFEM and the improved continued fraction solution for the dynamic stiffness matrix, ...

A beam-column element based on the Euler-Bernoulli beam theory is researched for nonlinear dynamic analysis of reinforced concrete (RC) structural element. Stiffness matrix of this element is obtained by using rigidity method. A solution technique that included nonlinear dynamic substructure procedure is developed for dynamic analyses of RC frames. A predicted-corrected form of the Bossak-α met...