In this paper, a discontinuity in beams whose intensity is adjusted by the spring stiffness factor is modeled using a torsional spring. Adapting two analyses in strong and weak forms for discontinuous beams, the improved governing differential equations and the modified stiffness matrix are derived respectively. In the strong form, two different solution methods have been presented to make an a...

The paper presents the spectral stiffness microplane model, which is a general constitutive model for unidirectional composite laminates, able to simulate the orthotropic stiffness, prepeak nonlinearity, failure envelopes, and, in tandem with the material characteristic length, also the post-peak softening and fracture. The framework of the microplane model is adopted. The model exploits the sp...

Evaluation of elastic properties of major arteries is subject of great interest with respect to the development of vascular diseases. In this study changes in diameter and cross-sectional area, stress-strain elastic modulus and stiffness of the common carotid arteries in healthy and atherosclerotic women and men were evaluated by using indirect end pressure changes. Variations in diameter and c...

INTRODUCTION Which kind of ultrasound imaging technique is suitable for the assessment of the abdominal aortic stiffness are seldom reported. The purposes of this study were to explore a reliable method to evaluate the abdominal aortic stiffness in patients with hypertension among the following ultrasound imaging techniques: M-mode ultrasonography (M-mode), tissue tracking and strain rate imagi...

polyurethane/zeolite 13x nanocomposite films were fabricated using solution casting method. the synthesized nanocomposite films were structurally characterized using sem, tga and tensile analysis. sem images showed appropriate distribution of nanocrystalline zeolite particles within polyurethane matrix. better thermal stability of nanocomposite films in comparison to neat polyurethane was shown...

In this study, the natural frequencies and mode shapes of beams without cracks and cracked Timoshenko beams is calculated with different boundary conditions using finite element method. The energy method is used to solve the equations. Hardness and softness matrices for Timoshenko beam without crack are obtained by solving the potential and kinetic energy equations. Then for investigation of cr...

The performance of an 8-noded hexahedron C1* element in elasticity is investigated. Three translational displacements and their derivatives as strain in each direction are considered as degrees of freedom (d.o.f.’s) at each node. The geometric mapping is enforced using a C0 element with no derivative as nodal d.o.f.’s . The stiffness matrix of the element is also computed using a transformation...

J.H. van Dieën Spinal segments with altered stiffness causing spinal deformations and low-back pain might be identifiable by comparing stiffness values between adjacent levels, since positive or negative outliers might indicate a clinically relevant condition. The stiffness matrix of a structure can be obtained by parameter estimation techniques such as model updating, which requires the constr...